TRX250R.ORG
Workshop => Engine and Bottom End => Topic started by: Bowtie316 on October 21, 2013, 04:52:42 PM
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Like the title says, this project was to enlarge the stinger diameter to big bore size. There has been much debate about the need to increase stinger diameter as you increase the size of your motor. Some say 310 or above, some say not until you are over 370. I wasn't able to get much response about how it would change the characteristics of the motor, like would I loose low end torque, would it be louder etc., so I decided to give it a shot and post my findings. if it doesn't work out, I will just have to buy a new pipe and post this one for sale.
My combination is a 330 ESR cylinder setup and ported by K&T, on a +4mm stroker crank. ESR trx5 pipe, 38 A/S carb, boyesen reed cage, stock ignition, stock airbox with K&N.
So first things first, here is what my trx5 stinger measured. 1" ID except where the bending process reduced the width.
The ESR stinger material was .060" thickness, so I came up with 1.120 od.
(http://[URL=http://s851.photobucket.com/user/bowtie316/media/20131019_172423_zpsa5dec547.jpg.html][IMG]http://i851.photobucket.com/albums/ab73/bowtie316/20131019_172423_zpsa5dec547.jpg)[/URL][/IMG]
At the bend, it was quite a bit less.
(http://[URL=http://s851.photobucket.com/user/bowtie316/media/20131019_172435_zpsea35418b.jpg.html][IMG]http://i851.photobucket.com/albums/ab73/bowtie316/20131019_172435_zpsea35418b.jpg)[/URL][/IMG]
Here is what the cone to stinger interface looked like. This is exactly like they came apart, there was no slag in this pipe whatsoever.
(http://[URL=http://s851.photobucket.com/user/bowtie316/media/20131019_173011_zps838bf35a.jpg.html][IMG]http://i851.photobucket.com/albums/ab73/bowtie316/20131019_173011_zps838bf35a.jpg)[/URL][/IMG]
And another showing in the ends.
(http://[URL=http://s851.photobucket.com/user/bowtie316/media/20131019_173031_zps26255931.jpg.html][IMG]http://i851.photobucket.com/albums/ab73/bowtie316/20131019_173031_zps26255931.jpg)[/URL][/IMG]
Old 1" id next to new 1-1/8" id.
(http://[URL=http://s851.photobucket.com/user/bowtie316/media/20131019_172543_zps0d836bf1.jpg.html][IMG]http://i851.photobucket.com/albums/ab73/bowtie316/20131019_172543_zps0d836bf1.jpg)[/URL][/IMG]
Now, after that I got busy and didn't take any more pictures until I was done but it's pretty straightforward. I trimmed off and opened up the end of the cone to match the new stinger id. Then I started with the bend coming off the stinger, cutting it to the right length. It sucked trying to get it flared to go over the cone, I don't have the right tools for that. Then once I had that I cut a piece of 1-1/4 ID pipe to be used as a slip-fit sleeve, slid it over the new stinger and just kept working my way back. I didn't really start welding anything until I got the pieces all to fit together like I wanted them.
For the silencer, I cut the mount tab off the bottom of the stinger and cut the pipe off the end of the silencer. I opened up the silencer to accept the 1-1/4 od slip-fit piece, this will be used to slip the perforated core in one end and the stinger welded in the other. At both of my slip fit connections, I made my tube lengths such that there is no gap between the 1-1/8 od pipes.
This is how it turned out, I'm certainly no Pumashine but it'll have to do.
(http://[URL=http://s851.photobucket.com/user/bowtie316/media/20131021_150751_zps177ed8a1.jpg.html][IMG]http://i851.photobucket.com/albums/ab73/bowtie316/20131021_150751_zps177ed8a1.jpg)[/URL][/IMG]
I don't have a lathe so I opened up the silencer end cap with a die grinder. It could be better but should work for now. I might have one made later on.
(http://[URL=http://s851.photobucket.com/user/bowtie316/media/20131021_150735_zps1d4e1790.jpg.html][IMG]http://i851.photobucket.com/albums/ab73/bowtie316/20131021_150735_zps1d4e1790.jpg)[/URL][/IMG]
And, here is an idle video.
(http://[URL=http://i851.photobucket.com/albums/ab73/bowtie316/20131021_150621_zpscaec0710.mp4][IMG]http://i851.photobucket.com/albums/ab73/bowtie316/th_20131021_150621_zpscaec0710.jpg)[/URL][/IMG]
First impressions are, well, it's loud. Is it any louder I don't really know, this big bore is just loud. I took a quick spin around the yard and didn't really notice any loss of low end at all. I'm going to have to go back through the jetting and more time on it before I can comment on everything.
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Looking good! :eagerness:
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Well done. You know it was not as easy as the pics show.
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the only issue I see is you put the joint on backwards,,, its going to force the pipe goo out of the joint
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the only issue I see is you put the joint on backwards,,, its going to force the pipe goo out of the joint
Yeah I actually did that on purpose. I was tired of cleaning junk off the shock and spring. Figured this way it would atleast be out easier to get to. I'll probably seal it up a bit when I confirm that it is going to work okay for me.
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Nice job! somebody actually listened :)
You will probably notice a little more lowend power, that is because the pipe will have slightly less "effect" and thats a good thing when its "effect" is timed incorrectly like at low rpms. A pipe works perfectly in a narrow band outside that its "effect" may be worse than if you just had a straight pipe.
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Nice job! somebody actually listened :)
You will probably notice a little more lowend power, that is because the pipe will have slightly less "effect" and thats a good thing when its "effect" is timed incorrectly like at low rpms. A pipe works perfectly in a narrow band outside that its "effect" may be worse than if you just had a straight pipe.
You know, I'm glad you say that. I didn't want to jinx it and say anything but it did feel a bit more torquey on the bottom. I figured it might be due to it being a little leaner because I haven't had a chance to work on jetting any. Either way it certainly didn't loose anything down low. I can't wait to get it back out and rip on it.
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...............................Some say 310 or above, some say not until you are over 370. I wasn't able to get much response about how it would change the characteristics of the motor, ..............
It seems the majority of the internet pipe formulas and out of date books on two-stroke pipe design tie the stinger ID to some non relevant metrics like engine displacement, exhaust port area, head pipe diameter or maybe what date there will be a full moon . The optimized stinger ID depends upon the amount of power the engine is capable of making with the exhaust system dimensions that are between the inlet of the stinger and the exhaust port.
The optimum amount of back pressure created by the stinger ID may need to vary from one pipe/port design combination to the next. I am an engineer and I have not found or been able to derive a formula that will accurately calculate the optimum stinger size. I have to resort to using the dyno to optimize the stinger size by conducting a series of instrumented tests on the dyno. The number of bends, how many degrees are in each bend, the radius of the bends and the volume of exhaust that needs to flow though the stinger, determines the overall flow capability of the stinger/muffler combination.
A few rules of thumb for those that are playing with pipe restriction:
An under-restricted pipe will usually increase the low end slightly with a large loss in peak power and power after the power peak. An under-restricted pipe will usually require a much larger main jet to provide the optimum air/fuel mixture for best power.
A slightly over restricted pipe will come on the pipe a little late, make good peak power, have good over-rev, and generate an excessive amount of unnecessary heat on the piston crown and on the exhaust port side of the piston. A slightly over restricted pipe will usually require a leaner main jet so that it does not have a rich misfire in the over-rev portion of the power curve than a pipe that has the optimum back pressure.
A pipe that has the optimum restriction for the power output of the engine design will typically have good power over a wide range if the port/pipe dimensions are complimenting each other. A pipe that has the optimum restriction for the power output of the engine design will typically be easier to tune and keep tuned. A pipe that has the optimum restriction for the power output of the engine design will typically not be plagued with piston seizures, sagging piston crowns and or holed pistons.
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It seems the majority of the internet pipe formulas and out of date books on two-stroke pipe design tie the stinger ID to some non relevant metrics like engine displacement, exhaust port area, head pipe diameter or maybe what date there will be a full moon . The optimized stinger ID depends upon the amount of power the engine is capable of making with the exhaust system dimensions that are between the inlet of the stinger and the exhaust port.
The optimum amount of back pressure created by the stinger ID may need to vary from one pipe/port design combination to the next. I am an engineer and I have not found or been able to derive a formula that will accurately calculate the optimum stinger size. I have to resort to using the dyno to optimize the stinger size by conducting a series of instrumented tests on the dyno. The number of bends, how many degrees are in each bend, the radius of the bends and the volume of exhaust that needs to flow though the stinger, determines the overall flow capability of the stinger/muffler combination.
A few rules of thumb for those that are playing with pipe restriction:
An under-restricted pipe will usually increase the low end slightly with a large loss in peak power and power after the power peak. An under-restricted pipe will usually require a much larger main jet to provide the optimum air/fuel mixture for best power.
A slightly over restricted pipe will come on the pipe a little late, make good peak power, have good over-rev, and generate an excessive amount of unnecessary heat on the piston crown and on the exhaust port side of the piston. A slightly over restricted pipe will usually require a leaner main jet so that it does not have a rich misfire in the over-rev portion of the power curve than a pipe that has the optimum back pressure.
A pipe that has the optimum restriction for the power output of the engine design will typically have good power over a wide range if the port/pipe dimensions are complimenting each other. A pipe that has the optimum restriction for the power output of the engine design will typically be easier to tune and keep tuned. A pipe that has the optimum restriction for the power output of the engine design will typically not be plagued with piston seizures, sagging piston crowns and or holed pistons.
Jerry, thanks for the input. I am curious now though, what happens when a combination comes in somewhere between 1"id and 1-1/8 id? Do you jump up to the 1-1/8 size and add restriction somehow?
I figured if this combination exhibits the underestricted side effects I would slide a short piece of 1"id pipe inside where they slip together and see if that helps. Could possibly play with the length of the insert to add or remove restriction while still being less restriction than a complete 1" stinger.
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since you have bends,a connection point and a silencer it is more restricted than if it was a straight stinger. The center mount ESR pipes kind of fall in between since there is less bends.
It would probably take a dyno to see the power difference but you will see a difference in the field when it comes to detonation, you will be much safer now.
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Jerry, thanks for the input. I am curious now though, what happens when a combination comes in somewhere between 1"id and 1-1/8 id? Do you jump up to the 1-1/8 size and add restriction somehow?
I figured if this combination exhibits the underestricted side effects I would slide a short piece of 1"id pipe inside where they slip together and see if that helps. Could possibly play with the length of the insert to add or remove restriction while still being less restriction than a complete 1" stinger.
Our modified pipes actually have a much larger stinger/silencer and we use machined inserts to adjust the restriction.
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since you have bends,a connection point and a silencer it is more restricted than if it was a straight stinger. The center mount ESR pipes kind of fall in between since there is less bends.
It would probably take a dyno to see the power difference but you will see a difference in the field when it comes to detonation, you will be much safer now.
Yeah, I was really just doing it for reliability, but the kick in performance will be nice if I can get it dialed in. Just going to a mandrel bent 1"id stinger would have been an improvement on what I had.
Our modified pipes actually have a much larger stinger/silencer and we use machined inserts to adjust the restriction.
Good deal, sounds like there is hope for this project yet.
Thanks to both of you for the feedback.
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.............Just going to a mandrel bent 1"id stinger would have been an improvement on what I had.
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The bends on the ESR stingers look like they were using a pipe bender for electrical conduit.
Looking at the picture of the junction of the stinger and your tail cone is different from the ESR pipes I have had in our shop. The end of your old stinger is cone shaped and fits over the outside of the tail cone. This is the way we do it as well as the majority of the other pipe builders. Using this type of junction at the stinger and tail cone moves the weld zone to much larger diameter and allows the entrance of the stinger to flow well if there is a sloppy weld.
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I believe ESR just started doing the stinger that way recently,, I have 2 of their pipes and the newest one is that way and the older one is not,,,,
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found this info on another site. it seems to match what jerry said. " The required flow restriction depends solely on the amount of generated exhaust gas, and that is directly proportional to the generated horsepower"
somewhere i thought i saw a adjustable venturi located at the stinger inlet. not sure if that would be a simpler way than inserts but either way im sure you would get the same results in the end
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I have been saying that all along, if your 370 runs good with a 1-1/8 o.d. then your setup is not making big power, but there is no guarantee going to a bigger stinger will mean you will make more power if it is a mild setup or the wrong setup to begin with.
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May I add a few words to your statement?
I have been saying that all along, if your 370 runs good with a 1-1/8 o.d and is not showing signs of piston crown overheating then your setup is not making big power, but there is no guarantee going to a bigger stinger will mean you will make more power if it is a mild setup or the wrong setup to begin with.
A pipe that is slightly over-restricted will usually make good peak power and have good over-rev. Many of the drag engines that I have dynoed have pipes that are over-restricted. I not sure if over-restricting is the result of a lack of understanding on the part of the pipe builder/designer, using improper testing procedures/equipment on the dyno or just laziness and failing to spend the necessary time getting ALL of the pipe dimensions to work with the correct back pressure.
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I am not sure if its my setups but every time I try to run a restricted stinger I made less power on the dyno, I had that problem on my oem cr500(553cc) cylinder and my Liger cylinder(613cc) both made more HP with a 1-3/8 O.D. over a 1-1/4 o.d.
The Liger detonated like crazy no matter how much fuel or compression I took out of it.
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Had a chance to further test mine out yesterday, and honestly if it lost anything anywhere with the stinger mod, I couldn't tell. I didn't even change jetting and it still felt perfect. I got to race a stock cylinder 250r and a piped yfz and I pulled both of them pretty handily. Bottom end is definitely improved, this was a surprise. Top end pulls like mad. I want to try out a little higher gearing now.
Can't wait to get it in the sand.
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Nice to hear. Glad you sound happy with the motor!
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Nice to hear. Glad you sound happy with the motor!
Yeah Wes, Thanks. Everything worked out, I was pretty nervous about it for a while but it's all good. It certainly does run strong. I was kind of reluctant to race the yfz considering all the money I spent and I didn't really set it up like it should have been with the pipe and carb size, but it ran really good. Even if I lifted the front on takeoff, I could regroup and pull him in pretty easily. Now this 450 was just bought by my buddy and might not be 100%, but nonetheless it pulls much better than before. It's going to be perfect in the sand.
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I am not sure if its my setups but every time I try to run a restricted stinger I made less power on the dyno, I had that problem on my oem cr500(553cc) cylinder and my Liger cylinder(613cc) both made more HP with a 1-3/8 O.D. over a 1-1/4 o.d.
The Liger detonated like crazy no matter how much fuel or compression I took out of it.
It depends on how well your stinger/silencer combination flows. I start seeing "the too much restriction syndrome" on some engines making 60 hp on 1 1/4 OD 18 ga. stingers. I seldom use 1 1/4 OD 18 ga. stingers on any big bore single cylinders that make over 80 HP to the rear wheels on my chassis dyno.
I encountering "the too much restriction syndrome" on some big bore single cylinder engines that are only making around 75 RWHP when using 1 3/8 OD 18 ga. stingers.
If I remember correctly your Liger was making around 100HP. You may be on the threshold on needing to go larger than 1.277" ID stinger. Give the engine what it wants, not what some pipe formula for a small bore roadracing said was optimum. Remember there is more mass in the exhaust that has to flow past a given plain in the exhaust system when using alcohol than when using gasoline making the same HP.
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Thanks Jerry, I have thought of trying some 1.5" stingers with restrictors added to it in the future. I last dyno'd at 110hp so it's maybe time to move up to the next size.
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just noticed this the other day. not sure if its owrth a crap or not http://cpiracing.com/shop/index.php?route=product/product&path=63&product_id=503
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just noticed this the other day. not sure if its owrth a crap or not http://cpiracing.com/shop/index.php?route=product/product&path=63&product_id=503
Wow, that mid section is huge. Wonder why it has 2 nineties at the stinger? I know one guy using this one and he had to have it modified to fit at a local shop. Price is good but you will probably have to fit.
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"just noticed this the other day. not sure if its owrth a crap or not http://cpiracing.com/shop/index.php?...product_id=503"
That stinger flow is insane. I am shocked at what I am looking at. Different.....
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Flow? Did a plumber do the pipe fitting? Cause it sure looks like he installed a p-trap
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That stinger flow is insane. I am shocked at what I am looking at. Different.....
Yeah. maybe goes above the seat or something. Looks like the turn down on the muffler is on the wrong side
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What Jerry said in one of his replys sounds good to me, with a larger stinger you can use larger jets.
So in turn, more fuel mix will be flowing through the engine, which will make it last longer. I'm all about having big HP, but want the engine to last longer than normal, blow those ol nay sayers out of the water saying a 2 stroke wont last any time.
Neil
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I just thought I would update this thread to say that by buddy [MENTION=904]RED RIDER[/MENTION] put this pipe on his trx9 port ESR 310, it seemed to lower coolant temperatures and it seems to run the same or a little bit better. No drawbacks whatsoever, he ended up converting his own trx5 pipe to big bore as well.
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Good to hear!