TRX250R.ORG
Workshop => Carburetor, Intake, and Exhaust => Topic started by: havinnoj on February 09, 2016, 09:26:12 PM
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Starting this thread based on Chat Box convo regarding companies who manufacturer "big bore" 250R pipes - specifically those with a stinger inner diameter (I.D.) equal to 1-1/8" (1.125"). Standard pipes have an I.D. of 1".
With that said, please feel free to post up additional pipes until we have a comprehensive verified list. Post up what ya got and I will edit the master list. Eventually this would make a nice sticky or Tech Article.
How about FTZ, Trinity, CT, PSI, etc.?
CPI Racing
Curtis Sparks
- 330 HR (need to verify)
- 330 MX (need to verify)
- BB TT? (what was the actual name of this - it is hand coned).
LED Performance Engines
- 350G Team
- Puma Pipe (Gen 1 - circa ~????)
- Puma Pipe (Gen 2 - circa ~ 2014?)
LRD Performance
- 350B
- 350D? (?? possibly the successor to the 350B?)
- ?
Shearer
Note that stinger diameter is not the only thing to consider when looking at a BB pipe. "Big Bore" can be relative - for example, ESR's TRX11 pipe is considered a BB pipe for motors up to 370cc.
Related Info for future..
http://trx250r.org/threads/6998-Modifying-5b-cm?p=64291#post64291
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Starting this thread based on Chat Box convo regarding companies who manufacturer "big bore" 250R pipes - specifically those with a stinger inner diameter (I.D.) equal to 1-1/8" (1.125").
With that said, please feel free to post up additional pipes until we have a comprehensive verified list. How about FTZ, Trinity, CT, etc.? Post up what ya got and I will edit the master list. Eventually this would make a nice sticky or Tech Article.
CPI Racing
- Puma
- Packard Pilot cylinder
- ?
Curtis Sparks
LED Performance Engines
- 350G Team
- Puma Pipe (Gen 1 - circa ~????)
- Puma Pipe (Gen 2 - circa ~ 2014?)
LRD Performance
Shearer
- Puma drag, torque, and center mount
- Sphinx drag and torque
- ?
Related Info for future..
http://trx250r.org/threads/6998-Modifying-5b-cm?p=64291#post64291
Hope there's more
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Esr added a B to the part number of most of their pipes. Eddie told me it stood for big bore. They still have the small stinger id but the head pipe is bigger diameter.
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Esr added a B to the part number of most of their pipes. Eddie told me it stood for big bore. They still have the small stinger id but the head pipe is bigger diameter.
Thanks. Maybe it would be good to expand this list to a few different categories - ones with 1-1/8" stingers and others that are built for (the fairly ambiguous term) "Big Bore" motors.
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I know this post will get "corrected" by a certain someone soon but I am going to make it anyway. A lot of people are believing they need a larger stinger when they don't necessarily need it. Big bore or bb does not mean big stinger. As an example the esr b bb pipes lower the temps over standard pipes and there is another well known pipe builder who also uses a standard size stinger with his pipes for 370ish bb engines. There is more to it from flange to stinger tip then just the stinger size and the thought that a 330 to 370 needs a larger stinger is not always correct. There is a give and take to the stinger size as part of the total package or a cr125 would have had the cr250 size stinger and a cr250 would have had the cr500 size stinger etc. Someone attempting to make you think a pipe builder is wrong and does not know what they are doing if they use a std size stinger on their bb pipes for 330 to 370 bb 250r engines is what is wrong.
>>>>>"IMO"<<<<<
edited
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I know this post will get "corrected" by a certain someone soon but I am going to make it anyway. A lot of people are believing they need a larger stinger when they don't. Esr b pipes lower the temps over the previous standard pipes and there is another well known pipe builder who also uses a standard size stinger with his pipes for 370ish engines. There is more to it and a 330 to 370 needs a larger stinger is not always correct. There is a give and take or a cr125 would have had the cr250 size stinger and a cr250 would have had the cr500 size stinger etc. Someone attempting to make you think a pipe builder is wrong and does not know what they are doing if they use a std size stinger on pipes for 330 to 370 bb 250r engines is what is wrong.
>>>>>"IMO"<<<<<
Yes there are a couple schools of thought on this. What you're describing was referenced in the link I posted in the original post. And to be clear, this thread wasn't created to discuss which setup was/is better - it's just to document pipe options with 1-1/8th stinger tubes for reference.
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My cpi puma inframe , has the 1 1/8 stinger?? its a hand coned but I don't know if it has a certain name imposed by Mike at CPI
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My cpi puma inframe , has the 1 1/8 stinger?? its a hand coned but I don't know if it has a certain name imposed by Mike at CPI
Thanks - I just added it as "Puma Inframe" for now.
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Well my builder says I need a big bore and I'll have to just take his word for it. Don't matter anyway since I needed a pipe so might as well get what is recommended
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Well my builder says I need a big bore and I'll have to just take his word for it. Don't matter anyway since I needed a pipe so might as well get what is recommended
That's the best. Find a builder that u trust and do what he says. Finding the builder that u trust is the hard part.
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Dynoport???? I wonder what they offer? i'll make the call and post up what I find out.
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Rich Daly (Dynoport) offers bb pipes I know that for sure
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I have an LRD adjustable pipe for an ATC that is bb.
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I thought I say somewhere someone had a big bore trinity
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Unfortunate this thread didn’t get more results. Hard to know what to do on stinger size if you r in the 330-370 cc range. Anyone know the stinger size for the following pipes?
New Esr trx10
Ktm 380 dirt bike OEM
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Inside stinger diameter can get complicated real fast and involves a lot of variables and I can usually answer this question on stinger sizing quicker using the dyno and monitoring the piston crown temperature rather than trying to model the system using partial differential equations. Listed below are the variables that must be considered and some of the basic science on how these variables affect stinger sizing.
1. The horsepower of the individual cylinder not the displacement is the most important variable when sizing stinger diameter and length.
a. A 1 HP cylinder creates a given quantity of exhaust gas and wasted heat. A 100 HP cylinder creates 100 times more exhaust gas and wasted heat than the 1 HP cylinder
2. The time between power pulses must be long enough for the exhaust to exit the pipe on each engine revolution
3. The flow rate of the stinger and muffler has to provide the proper amount of back pressure at the exhaust port to work with the diffuser and tail cone shape profiles.
a. Anytime length is added to pipe or tubing, the flow rate is reduced.
b. Anytime a bend is added to pipe or tubing the flow rate is reduced. The total number of degrees of of bend in the stinger/muffler is cumulative. One bend of 50 degrees will offer approximately the same amount of restriction as five bends of 10 degrees each in the same length of tubing.
c. Turndowns on the end of mufflers reduce the flow rate but help fool the sound meters that the officials use when conducting sound level testing.
d. Anytime the inside diameter is reduced due to using cheap tube benders or worn out tube bending mandrels, the flow is reduced.
e. Anytime the inside diameter is reduced due to a weld booger inside the pipe flow is reduced.
f. The transition between the tail cone and stinger entrance should be straight and not bend at the junction.
g. The muffler's perforated tube reduces the flow rate. The hole pattern and hole diameters affect the flow rate and the sound attenuation of the muffler.
A combination of "a" through "g" can be used to obtain the desired flow rate (back pressure) of the stinger/muffler. On some engines the length of the stinger/muffler will show a slight benefit due to the tuning of some of the secondary wave activity in stinger/muffler tract but the proper restriction is most important.
Small displacement cylinders are usually more thermally sound and their pistons will usually allow more back pressure to be run at the exhaust port. Some of us engine builders can get a lot of power from the old two stroke engines that have been updated and are not using 25 year old pipe and cylinder port technology.
It has been my experience that the two stroke piston crown profiles (minimum thickness and thickness profiles) are poorly designed on most of the forged pistons being manufactured for our sport, especially the ones we have to use on the big bore cylinders. I believe the piston manufacturers have gone overboard in trying to make the lightest piston possible at the expense of not being able to dissipate the heat that is proportional to the power that can be found in some of the newer cylinders. Most of the time thin piston crowns will not sag or burn through even after 500 runs on the dyno, when the dyno runs are in the 2 to 7 second range, but will sag or burn through when being run for WOT 10 to 15 seconds when tuned for max power up a long steep sand mountain or across a dry lake bed in a Baja race.
Back to the stinger topic:
The stinger inside diameters (exhaust flow rate) is adequate on many of the big bore pipes until the power level is pushed to a much higher level. If this high level is reached it may be necessary to increase the inside diameter of the stinger/muffler combination or the length of the stinger/muffler combination may have to be substantially reduced or bends removed the the stinger/muffler combination to increase the flow rate so that the back pressure does not cause a piston crown failure.
A decision has to be made if the power level drops, the over-rev portion of the power curve is substantially reduced after the stinger inside diameter is increased or other measures were taken to improve the flow rated through the stinger....... Am I willing to sacrifice power for reduced piston crown operating temperature?.....or...... use a stinger/muffler combination that makes the most power&over-rev and shorten the number of seconds that the engine is run at WOT with 30 seconds or so of rest between each WOT period?