TRX250R.ORG
Workshop => Engine and Bottom End => Topic started by: udontknowme on September 28, 2013, 02:01:51 PM
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so the esr pipes have to small stinger causing excess heat on the piston ? dude on the other site says jerry hall been fixing the problem. doesnt bdt claim theyre the best and better than the rest. certainly after all these years of being the best wouldnt you know about a problem like this. i meen with hundreds of sharpie dynos under his belt wouldnt you know the correct stinger size for a given pipe. never seen carla even mention about this stinger issue. but i guess when your just the salesman behind the cash register you dont get into the technical aspects
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The trx250r standard is 1" ID at the stinger. If you are going over 400cc it is advised to increase stinger size to 1.125 ID. Some have been referring to the 1.125 stinger diameter as big bore pipes or BB as BDT calls it. The are a couple companies that make the big bore pipes. This one on ebay http://www.ebay.com/itm/350296312069?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649 I use for reference. LRD made some and Shearer use the bigger diameter for all Puma or Saber pipes. You would have to ask BDT if their pipes are made with the 1.125" stinger. I modify all my ESR pipes to use the 1.125" ID stinger for the BB's
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The trx250r standard is 1" ID at the stinger. If you are going over 400cc it is advised to increase stinger size to 1.125 ID. Some have been referring to the 1.125 stinger diameter as big bore pipes or BB as BDT calls it. The are a couple companies that make the big bore pipes. This one on ebay http://www.ebay.com/itm/350296312069?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649 I use for reference. LRD made some and Shearer use the bigger diameter for all Puma or Saber pipes. You would have to ask BDT if their pipes are made with the 1.125" stinger. I modify all my ESR pipes to use the 1.125" ID stinger for the BB's
When you mention stinger, isn't that the small end of the pipe?
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Yup part thst connect s to your silencer
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Yup part thst connect s to your silencer
The last 6-12 inches of the pipe and 6-8 inches that goes into the silencer. Since BB mufflers are not readily available the BB pipe builder usually builds a muffler for the pipe. You will see this with our site sponsor LED. Arlan offers pipes either way and mufflers also.
Shearer puma pipe right with BB stinger. FTZ whale pipe left standard stinger.
(http://i40.tinypic.com/2rz4074.jpg)
Closer look
(http://i42.tinypic.com/15dkh1c.jpg)
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The last 6-12 inches of the pipe and 6-8 inches that goes into the silencer.
(http://i40.tinypic.com/2rz4074.jpg)
Closer look
(http://i42.tinypic.com/15dkh1c.jpg)
So Tony, under 400cc does not require the larger 1.125 I.D. stinger? I ask because of my situation.
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Two stroke pipes, are such a complicated thing, that it is pure mind boggling at how different they need to be for every single engine build. So complicated, that when you build one & it matches up to the porting & build of that engine, the power that engine will produce, you'll be amazed.
But, just because that pipe built for & matched up to your engine worked like it was suppose to, dont mean you could sell that pipe to someone & it would work the same on their engine build.
That engine that the pipe worked so well on, when you change anything about how that engine is set up, even no more than fitting the next size larger piston, it causes the engine tune to be off some amount with that pipe, because you changed the bore size. The difference in change might not even be enough for a rider to tell or feel the difference, but it is there.
Building the engine, only part of what all has to be done & everything that has anything to do with the engine must match up, from the tip of the air filter element all the way through to the tip of the silencer outlet.
Getting a cylinder ported, like when your building for top performance, if that is all you've done, is compared to like one ant from a large ant nest.
It might be surprising, but there could be times on an engine build, even using the OEM 250R cylinder, that a larger stinger would be needed. All about that build & what the engine is being used for.
Neil
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The trx250r standard is 1" ID at the stinger. If you are going over 400cc it is advised to increase stinger size to 1.125 ID. Some have been referring to the 1.125 stinger diameter as big bore pipes or BB as BDT calls it. The are a couple companies that make the big bore pipes. This one on ebay http://www.ebay.com/itm/350296312069?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649 I use for reference. LRD made some and Shearer use the bigger diameter for all Puma or Saber pipes. You would have to ask BDT if their pipes are made with the 1.125" stinger. I modify all my ESR pipes to use the 1.125" ID stinger for the BB's
I've always thought the stinger length and diameter were determined by the length and diameter of the header pipe? and not because of bore and stroke of the cylinder
and more of a measure of the exhaust port then bore size
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So Tony, under 400cc does not require the larger 1.125 I.D. stinger? I ask because of my situation.
If you read between the lines the bigger motors need to breath better. Yes, a 330 is being choked. A 350 and 370 are in the same group. But they do not see as much of an overheating problem as the 400+cc. What pipe and silencer are you running now? Some silencers are restrictive, other don't impede the flow at all.
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The B pipes dropped the temp 10ish deg and wont require a larger stinger on a big bb that may have wanted it in the past. Some may still though.....
Std 5's and 9's have been used just fine on 370 and under for a long long time. Maybe some of them would have liked the changes, maybe they were perfectly fine.
Watch your temps and if you need it lots of people could change it up for you.
As Tony said guys have been doing it as needed on the real big boys for a while.
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I've always thought the stinger length and diameter were determined by the length and diameter of the header pipe? and not because of bore and stroke of the cylinder
and more of a measure of the exhaust port then bore size
header x .58 to .62 is the typical stinger sizing stock 250r flange is 45mm x .58 = 26.1mm or 1.03 ID upto 45mm x .62 = 27.9m or 1.10" ID
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header x .58 to .62 is the typical stinger sizing stock 250r flange is 45mm x .58 = 26.1mm or 1.03 ID upto 45mm x .62 = 27.9m or 1.10" ID
so would it make sense to say that once you go to the larger exhaust flange you would be smart to go to the 1 1/8 stinger
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so would it make sense to say that once you go to the larger exhaust flange you would be smart to go to the 1 1/8 stinger
Yes but like I have stated along with arlan hp, engine size and type of use play a factor in the stinger needs.
If you hold the throttle wide open for longer peroids of time you should increase stinger size
If you Increase engine size you will normally increase exhaust port area and stinger size should increase with it and many times the header/flange size also.
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Pipes are vary, some pipes will run better on some motors than other. I always thought the difference in the BB and SB was the total pipe.
the BB i would think would have to breath better, vs a small bore.
We took my silencer and put a straight pipe in it, kindof sneaky at the asphalt track when you can only run mufflers.....
A note I do love shearer pipes, I have ran the esr pipes (and my rider has a esr pipe, Came with the quad).
I don't knock anyone elses product (unless you are , well nevermind on them , it s a banshee thing anyway)...
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The straight pipe has slightly less restriction because of no perferations that would create turbulance and if you were runing longer passes than in the dunes this would help keep piston heat down some
you are correct about a big bore pipe being more than just the same pipe with a bigger stinger, but there is a gray area where a simple stinger increase does the job very well.
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You guys just blow my freakin' mind! I know the pipe theory is a complicated mistress. What to do? I need to borrow some pipes. :fat:
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yes borrow some pipes and go to the dyno
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well I know this,,, I have a pro-x 350 ,, and an esr 350,, I built a moto-x trike for a race in may,, I took an old fmf pipe,, made it centermount and went with a larger AND SHORTER stinger ,, it woke up that motor in the mid and topend power like crazy,,, I pulled the holeshot pretty easy in both motos too,,, no doubt in my mine the seat of the pants dyno was HAPPY!!!
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proof is in the puddng F-Red order up a shiny new BB pipe :)
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The "issue" with the esr pipes, supposedly, was they are poorly welded and have lots of slag on the inside restricting the flow. It's simply to verify. If you have an esr pipe pull the silencer and use long screw driver etc to see for yourself
Or at least that was my interpretation of the original post on ' net
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proof is in the puddng F-Red order up a shiny new BB pipe :)
Where do I begin? Besides LED, who else offers BB pipes? Without testing each pipe, it's kind of an expensive, roll the dice purchase.
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Where do I begin? Besides LED, who else offers BB pipes? Without testing each pipe, it's kind of an expensive, roll the dice purchase.
LED now and LRD made a few a while back. What pipe do you usually run?
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The "issue" with the esr pipes, supposedly, was they are poorly welded and have lots of slag on the inside restricting the flow. It's simply to verify. If you have an esr pipe pull the silencer and use long screw driver etc to see for yourself
Or at least that was my interpretation of the original post on ' net
If I remember correctly Jerry Hall gas welds all his pipes because of less slag, which on the ESR pipes he could just cut the stinger off and gas weld them after cleaning up, but instead he also increases the stinger size so while weld slag could be a problem the real issue for some larger motors is the fact that they need less back pressure and a increase in stinger size is the solution.
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LED now and LRD made a few a while back. What pipe do you usually run?
I'm running a ESR TRX5 with Eddie's silencer.
If I remember correctly Jerry Hall gas welds all his pipes because of less slag, which on the ESR pipes he could just cut the stinger off and gas weld them after cleaning up, but instead he also increases the stinger size so while weld slag could be a problem the real issue for some larger motors is the fact that they need less back pressure and a increase in stinger size is the solution.
So Dave, to keep cost at a minimum, could I send the pipe to Tony, have him weld a larger stinger on the TRX5? :glee:
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Where do I begin? Besides LED, who else offers BB pipes? Without testing each pipe, it's kind of an expensive, roll the dice purchase.
The stinger is sole piece that controls back pressure in the pipe, so you have the choice of modding your existing pipe if you can weld or know someone that can weld (not mig, preferably tig or gas) or go with a ESR or LED/old LRD BB pipe with a 1-1/4" O.D. stinger
Pick the style pipe that fits your riding MX,TT or Dune and go with it, it really no differant than picking one with a 1-1/8 O.D.
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i'm running a esr trx5 with eddie's silencer.
So dave, to keep cost at a minimum, could i send the pipe to tony, have him weld a larger stinger on the trx5? :glee:
yes!
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If Tony can not send it to Jerry Hall
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If Tony can not send it to Jerry Hall
Forgive my ignorants, This the Jerry Hall in Glendale, Az.? Halls Percision Racing Products
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yes! halls precision racing products
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might not hurt to even ask arlan, he may even put a little love in your esr pipe
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My welding guru's won't work on used pipes. I always have to get new ones and modify. Some guys can weld anything and do not care about the carbon build up. I suggest going with someone that has experience with used pipes.
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Thanks for the info. Dave. I've got some phone calls to make.
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My welding guru's won't work on used pipes. I always have to get new ones and modify. Some guys can weld anything and do not care about the carbon build up. I suggest going with someone that has experience with used pipes.
Thanks Tony.
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Maybe I missed it but what size is your engine again f-red?
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That was in the ESR330 failure thread. Carlos claims a bigger stinger is a band aid to the real problem. But problems are real and Carlos's claims are unreal. The people that spent money on a poor cast are just looking for a way to make it work. You can only learn from mistakes whether you made them or someone else did.
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Wasn't sure of engine size and true larger stinger less heat help but I remember now and less ex side heat help from the large stinger would't hurt that's for sure. With his ex side water jacket mod and a stinger mod f-red sure addressed any possible help in that ex side area. Neither would be a step back and could only help, not hurt.
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I have been watching this thread but wan't able to join until now. I have a ESR 330+4 mil, not sure if it has the cooling passage mod or not (will verify that tonight) and I'm going to run a trx-5 pipe and ESR silencer but I am unsure if this stinger/silencer size mod is needed or warranted for a 344. I don't really plan to hold it wide open for long periods of time, but I'm sure it will have to endure a few 2nd through 5th gear drag races. Would you all recommend going from 1-1/8 od to 1-1/4 od for my situation?
I have already ordered the bends, straight pipe and perforated tube to replace stinger and modify the silencer. Will this affect the power delivery of the motor? It has a "mid-top dune port", will a larger stinger give up some power somewhere?
If it's warranted for a 344, I will do it and post pictures and results.
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Regardless of the engine size, theres no use in holding back heat in a pipe for a normal everyday rider, not unless that is part of the tuning your doing on the engine. Some builders will use the pipe heat, in order to speed up the wave travel inside, but it only changes it very little.
Best thing to do, have a stinger the proper size for the bore & stroke & then if you need some pipe heat, start wrapping the pipe with exhaust wrap till its the tune your after.
The stingers more or less a bleed off for pressure in the pipe, so why hold it back, let the pipe work.
Hey Tony, them welding gurus, probably just saying that instead of saying they dont want to mess with it in the first place. One of those dollar things you know.
Always remember, if made or done in the USA, it somehow will have a dollar connected to it, unless you have respect for others & then you'll just about give it away.
Japan, China or those cross the big pond countrys, those people will do it for free, time & time again just to honor their country.
Barter, now thats a way to go.
Neil
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If you want a half way point on your increased stinger size, then cut off the 1-1/8 tail pipe 1" from the end of the pipe, take a die grinder and clean any weld disturbing flow on the inside of the 1" long stinger still on the pipe.
Slip your new 1-1/4" stinger over the 1-1/8", 1" long piece and weld your new 1-1/4 stinger and silencer on the bike.
This will put you half way between a stock 1-1/8" stinger and a larger 1-1/4" stinger
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Regardless of the engine size, theres no use in holding back heat in a pipe for a normal everyday rider, not unless that is part of the tuning your doing on the engine. Some builders will use the pipe heat, in order to speed up the wave travel inside, but it only changes it very little.
Best thing to do, have a stinger the proper size for the bore & stroke & then if you need some pipe heat, start wrapping the pipe with exhaust wrap till its the tune your after.
The stingers more or less a bleed off for pressure in the pipe, so why hold it back, let the pipe work.
Hey Tony, them welding gurus, probably just saying that instead of saying they dont want to mess with it in the first place. One of those dollar things you know.
Always remember, if made or done in the USA, it somehow will have a dollar connected to it, unless you have respect for others & then you'll just about give it away.
Japan, China or those cross the big pond countrys, those people will do it for free, time & time again just to honor their country.
Barter, now thats a way to go.
Neil
10-4 Neil, thanks for your input. The way I was looking at it, I increased the engine displacement from ~250cc to ~344cc, thats a 37.6% increase. A stinger size increase from 1" id to 1=1/8 id is only a 27% increase in cross sectionctional area. To me, logically thinking, it would work. I just don't want to get into a situation where it causes it to be a dog down low or something.
I'm going clean the inside and outside of my pipe real well, possibly bake it, then back purge with argon. I hope it works out okay.
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That was in the ESR330 failure thread. Carlos claims a bigger stinger is a band aid to the real problem. But problems are real and Carlos's claims are unreal. The people that spent money on a poor cast are just looking for a way to make it work. You can only learn from mistakes whether you made them or someone else did.
you think carlos knows anything. check every alky thread over there. he dont reply 1 time. but if someone asks how to clean a airfilter he chimes in immediatly. that tells me alot right there
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10-4 Neil, thanks for your input. The way I was looking at it, I increased the engine displacement from ~250cc to ~344cc, thats a 37.6% increase. A stinger size increase from 1" id to 1=1/8 id is only a 27% increase in cross sectionctional area. To me, logically thinking, it would work. I just don't want to get into a situation where it causes it to be a dog down low or something.
I'm going clean the inside and outside of my pipe real well, possibly bake it, then back purge with argon. I hope it works out okay.
Purging the pipe would be a good thing to do. It would help keep the backside of the weld smooth and droop free.
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If you want a half way point on your increased stinger size, then cut off the 1-1/8 tail pipe 1" from the end of the pipe, take a die grinder and clean any weld disturbing flow on the inside of the 1" long stinger still on the pipe.
You would be surprised to see how much weld is blocking the stinger at the weld 1" back. Another place of concern is where the pipe is bent around the frame. Many of these bends allow the round shape to become oval there fore decreasing the area of the round shape. I have seen pipe only 3/4" apart at the bend.
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The entry to the stinger is actually a very important part of the pipe, much more than allot of people believe.
Some people place such high regards to its importance that they machine a piece of round stock to transition the end of the pipe to the stinger and move the weld away from the entry, some also create nozzles that taper down the back out within a larger stinger.
The nozzle is sized for proper back pressure, actually FMF has done similar but less fancy restrictions on some of their pipes to create this nozzle effect.
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The entry to the stinger is actually a very important part of the pipe, much more than allot of people believe.
Some people place such high regards to its importance that they machine a piece of round stock to transition the end of the pipe to the stinger and move the weld away from the entry, some also create nozzles that taper down the back out within a larger stinger.
The nozzle is sized for proper back pressure, actually FMF has done similar but less fancy restrictions on some of their pipes to create this nozzle effect.
I wondered about how to go about the transition. It looks like ESR used the cone to form the entry into the stinger and swelled the stinger to fit over the top for a lap-joint weld. I planned to cut the weld out and see what was underneath. I guess I will wait to see what it looks like when I cut it apart before I decide how to go about it. I can mimic what ESR did, but I'm not sure what the minimum diameter should be.
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If you going to put a bigger stinger on you cut right at the end of the cone. You will only have to sand off less than 1/4" to get it opened to 1 1/8" ID. I have done 3 of these. One trx5 and two trx9r.
I actually cut just before the weld in the cone area. Did not want to hit the weld with the band saw blade. If you put the stinger in the band saw clamps you just have to hold the pipe at a strange angle to make a straight cut. Helps to put a tube the same size at the other end of the clamp to get it to hold the stinger securely.
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well its a little easier for me on my pipes because all I build is drag pipes, if the drag pipe has a silencer the pipe is only 1-1/2" long with a flare on the end. I have a solid metal cone and a hyd press and I form a small flare on the end about 1/4-1/2" long.
I then over expand the rear of the pipe opening so the flare will fit in, then I work the end of the pipe with a body hammer closing it back down in size. Now when you go to weld, it is not a butt joint but a overlap so no weld buggers and has a smooth venturi shape to aid flow. I have butt welded them then took a grinder and cleaned everything up.
On new pipes from scratch I have also butt welded or slightly slide the tailpipe inside the cone and welded it up but before I welded the rear cone onto the belly section of the pipe I reached down the cone and blended this transition at the rear of the cone.
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If you going to put a bigger stinger on you cut right at the end of the cone. You will only have to sand off less than 1/4" to get it opened to 1 1/8" ID. I have done 3 of these. One trx5 and two trx9r.
I actually cut just before the weld in the cone area. Did not want to hit the weld with the band saw blade. If you put the stinger in the band saw clamps you just have to hold the pipe at a strange angle to make a straight cut. Helps to put a tube the same size at the other end of the clamp to get it to hold the stinger securely.
So you just cut off the end of the cone to match the same ID as the new stinger. Thats what I planned to do, then try to flare the stinger slightly to fit over the cone outlet to get away from a butt weld.
well its a little easier for me on my pipes because all I build is drag pipes, if the drag pipe has a silencer the pipe is only 1-1/2" long with a flare on the end. I have a solid metal cone and a hyd press and I form a small flare on the end about 1/4-1/2" long.
I then over expand the rear of the pipe opening so the flare will fit in, then I work the end of the pipe with a body hammer closing it back down in size. Now when you go to weld, it is not a butt joint but a overlap so no weld buggers and has a smooth venturi shape to aid flow. I have butt welded them then took a grinder and cleaned everything up.
On new pipes from scratch I have also butt welded or slightly slide the tailpipe inside the cone and welded it up but before I welded the rear cone onto the belly section of the pipe I reached down the cone and blended this transition at the rear of the cone.
The way I interpret your description, it seems like it would create some turbulence where the lip of the stinger is inside the cone.
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When I flare the end of the stinger I see it as being simular to the "bell mouth"on a carburator and a tapered intake boot.
That may not be the best comparision but any turbulance right at the narrowest point where velocity is highest will be worse than any point farther away.
The end of my flare on its back side, has its edge dressed so when touching the metal of the pipe's rear cone it does not have much of a edge to disturb flow. There is a angle change at that point but that is what I refered to as my "bell mouth"
I have also slid the pipe into the end of a flared stinger like you are planning and it works very well, I actually like to that when I still have the rear cone still not welded on the belly that way I insure that the transition is smooth. and if not I can take a gringer and dress it up.
Lots of ways to skin a cat every way has its good and bad points.
One thing to remember you are going from being on the high end of the scale with the 1-1/8 stinger to now on the lowend of the scale with the 1-1/4. If you were trying to make it on a bigger Puma or saber then your transition would become more important. Not that you can bugger it up but a little disruption of flow at the end of the pipe is not going to be a big deal.
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I have already ordered the bends, straight pipe and perforated tube to replace stinger and modify the silencer. Will this affect the power delivery of the motor? It has a "mid-top dune port", will a larger stinger give up some power somewhere?
If you don't me asking, where did you get the materials, for this mod?
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When I flare the end of the stinger I see it as being simular to the "bell mouth"on a carburator and a tapered intake boot.
That may not be the best comparision but any turbulance right at the narrowest point where velocity is highest will be worse than any point farther away.
The end of my flare on its back side, has its edge dressed so when touching the metal of the pipe's rear cone it does not have much of a edge to disturb flow. There is a angle change at that point but that is what I refered to as my "bell mouth"
I have also slid the pipe into the end of a flared stinger like you are planning and it works very well, I actually like to that when I still have the rear cone still not welded on the belly that way I insure that the transition is smooth. and if not I can take a gringer and dress it up.
Lots of ways to skin a cat every way has its good and bad points.
One thing to remember you are going from being on the high end of the scale with the 1-1/8 stinger to now on the lowend of the scale with the 1-1/4. If you were trying to make it on a bigger Puma or saber then your transition would become more important. Not that you can bugger it up but a little disruption of flow at the end of the pipe is not going to be a big deal.
I see what you mean, either way there is going to be some turbulence, oh well it's got to be a step in the right direction.
If you don't me asking, where did you get the materials, for this mod?
I plan to do a full write-up on here with sources, in-process pictures and feedback on sound, temp, and power delivery when I do the mod. It looks like it will be a couple weeks before I will have the perforated tube so I will get some ride time on it with the standard stinger for comparison.
I ordered the 1-1/4 od mandrel bend, the 1-1/4 straight pipe and 1-3/8 straight pipe (for slip connection) from mandrel-bends.com. The perforated tube (the hard part to find) is coming from LAChoppers.
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That will be great...we need some good info to share
Trx5 BB conversion 1" ID to 1 1/8" ID Pipe cut at stinger and new pieces fit. I used http://www.mandrel-bends.com/catalog/mandrel-bends-34/ This is chrome to polished stainless
(http://i43.tinypic.com/17dzsn.jpg)
(http://i44.tinypic.com/5xoqpi.jpg)
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AAEN performance in WI has pipe parts
and SLP pipes out west has pipe parts
May even want to ask arlan at LED, he may sell you parts
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I plan to do a full write-up on here with sources, in-process pictures and feedback on sound, temp, and power delivery when I do the mod. It looks like it will be a couple weeks before I will have the perforated tube so I will get some ride time on it with the standard stinger for comparison.
I ordered the 1-1/4 od mandrel bend, the 1-1/4 straight pipe and 1-3/8 straight pipe (for slip connection) from mandrel-bends.com. The perforated tube (the hard part to find) is coming from LAChoppers.
Thanks. Definitely keep us posted. :smile-new:
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This was my PT type6 BB conversion for puma
Old stinger cut from pipe.
(http://i39.tinypic.com/21acryu.jpg)
Pipe sanded until stingers goes through
(http://i43.tinypic.com/34fhe6r.jpg)
Butt weld splice
(http://i44.tinypic.com/2irq2l2.jpg)
(http://i44.tinypic.com/157ljew.jpg)
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Thanks for posting the pictures Pumashine, I hope mine turns out as nice.
Only thing I haven't sourced is machining a new end cap for the ESR silencer, I don't think there is enough meat on the stock one to bore it out like it needs to be.
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I have to build the stingers for the silencer from the same 1 1/8" ID tube. Hole in casacde muffler is 1 1/8"
(http://i43.tinypic.com/2akl4l5.jpg)
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Well you really set the bar too high for me cosmetically. I hope mine comes out looking half as good.
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Depending on what riding you are doing I believe there may be a connection between stinger size and torque. By all means make sure you are temp safe first but if your riding is not wfo you may not want to go to a bigger stinger for the heck of it.
Just a thought for the woods etc guys that are not over 370cc watching this discusion about the stingers if they are already temp safe.
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Depending on what riding you are doing I believe there may be a connection between stinger size and torque. By all means make sure you are temp safe first but if your riding is not wfo you may not want to go to a bigger stinger for the heck of it.
Just a thought for the woods etc guys that are not over 370cc watching this discusion about the stingers if they are already temp safe.
Yeah that was the only thing I was questioning. I don't want to loose all bottom end torque. It's too late now, it's already in my head and pipe has showed up. I will be a guinea pig for the 344 guys. Speaking of which, mandrel-bends.com ships fast and this pipe looks huge. (http://[URL=http://s851.photobucket.com/user/bowtie316/media/20131004_163808_zpsb58f0d9a.jpg.html][IMG]http://i851.photobucket.com/albums/ab73/bowtie316/20131004_163808_zpsb58f0d9a.jpg)[/URL][/IMG]
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I have had a few of customers in the shop the last week or so that said there was some discussion about some of the modifications that we perform on two-stroke exhaust systems. I read through the threads on two of TRX250r sites about stinger size and pipes. It is obvious there are questions that many of you have about two-stroke pipes. I have read a lot of threads over the years on public forums about discussions on two-stroke pipe theory and porting formulas. Some theory and formulas are valid or close enough to give us a good starting place on a new project, while the general public still associates a lot of myth and black magic with two-stroke engines.
I do not visit and share my experience with very many public forums because of the limitations of my time. We have a well-equipped shop where we do research and development and consulting for engine manufactures as well as individuals that can afford serious engine projects. Competitors criticize our efforts on new ideas and products saying that we test too much. I feel this is what gives us the understanding we have and the ability to constantly improve our products.
Many questions are very difficult for me to answer in laymen’s terms for those that do not have a solid foundation in the physics that govern our universe but I will try. I answer questions based upon being and engineer with over 40 years of experience building high performance two-strokes. Fortunately my answers do not usually agree with many shops or competitors in a similar business to mine. I would be a dull world if everyone drove Chevys, or everyone was on the same team, or every one had equal abilities. Without opposition there could not be competition. Every race would end in a tie! Competition is what has always driven me to try to be one of the best in my field.
I am open to questions and will try to respond when time permits.
Jerry Hall
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i remember few months ago i was really scratchin my head to figure a correct stinger length. aparently the diamater is of much more importance than length. thats how i understand it anyways. looking back i guess i wasted bunch of time worrying about somethin that wasnt real critical
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welcome aboard Jerry, it a honor to have you on this site.
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Welcome Jerry...heard alot of good stuff from your shop.
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X2...welcome Jerry...look forward to reading more of your posts...