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2 stroke pipes trials

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Hey all I've noticed that alot of the 2t trials bikes don't have a big expansion chamber I'm interested in the design and would like some pics of your pipes.

why??

because I am tring to fit a blaster 200 engine in an old rm125 frame and have got most of it in sight but the pipe ....due to the big cylinder and head fins the conventional big bellow would be dificult to make fit so I have been trying to look up pics of trials pipes and get an idea how they are fit.. I just want to be able to run the 125 in some really technical stuff..top speed really does'nt matter.

so pictures please

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give me a bit, my whole system will be coming off by the end of the month and i can show you. HOWEVER a trials bike does have an expansion chamber on it, just a very very long one that you don't really notice until u take the system apart.

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thanks looking forward to seeing it.

I really just need to make the front narrow section longer and noticed the trial seem really long.

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on the trials bike it is the strait tube followed by an area of expansion then rapid shrink. I'd have to guess (not measuring) the beta system before the muffler is about 2-3 feet long and the majority of the expansion is in the last 8" or so.

Basically my experience is there is a header, midpipe and muffler. Everything until the muffler is the expansion chamber. But i'll take everything off the beta tomorrow and put it on the ground and take a picture for you. Though the beta seems to be the longest and my guess from looking at it is the gasgas is the shortest. On the beta it litterally goes from the exhaust port to the right sides, then back around to the left side then along the left side through the only hole in the bike to the right side and turns to the end of the midpipe where it connects to the muffler.

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your out of your league kid,the blaster motor wont work worth a shit with a trials type exhaust and a massive carb.flywheel,stroke,etc.........maybe an fmf fatty for more bottom,but this guy is working on a frankenstein bike that needs to be in differnt forum?i mean look at his avatar???????????????

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Why rag on the guy? He asked a question in the trials section because of the way the exhaust is designed on trials bikes. Will it work to it's full potential? Probably not. Will it work for what he's trying to do? Maybe. At least the guy is willing to give it a shot and try something that he will probably learn a lot from, like what to do and what not to do. You'll be surprised how much you learn from projects like this. Instead of ragging on his project and his avatar, give him some worthwhile advice instead of bashing it.

Edited by geomoney
incorrect wording

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geomoney, the rest of us have learned to ignore fester and realize he's just comic relief, i recommend u do the same because this is one of his better and nicer posts.

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well I ususlly give friendy advise and ask good questions, I don't ask about mixing gas or jetting ...

I only ask for pics of pipes because TRIALS STUFF is very hard to search on the net and I have found no pictures of the exhuast and how they are set up.

I have been reading Gram Bell's performance two stroke latley and was just interested in the design applied to trials bikes.

Fester...you have to realize that some of us that are into bikes get just as much enjoyment out of wrenching and creating, if not more, than actually riding..

also some of us are creative and have small wallets, we can't all be bolt on junkies.

the blaster engine was adopted from the yamaha IT200 enduro, I dont think a 28mm carb is big at all, heavy flywheel (good thing).

your attitude sucks so go fester another zit on YOUR sack and stay away from my thread

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I have a 76 KT250 that is a slight frankenstien with a FL250 piston as oem piston seems unobtanium

very basic 2stroke pipe tuning - short, fat chamber with steep angle tapers are tuned for high rpm (80cc motobikes are good example)

longer, fat chambers with milder angle tapers are for midrange (ex stock Blaster pipe)

long, skinny pipes with very shallow tapers are for low rpm torque( trials bikes)

on my KT, the pipe routes up, over the head and straight back, but the frame, head and spark plug location are designed to allow this routing

your project is going to be a bit more interesting for clearance issues

fester does have a point in that the porting and ignition on a Blaster motor are tuned for midrange more than low end, but everything is theoretical until you try it

good luck

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ccp243

My piont is I have run this 1985 rm 125 after I rebuilt it and there is no low end and very little midrange and explosive top end that kicks in without notice.

I have run the blaster as well and its power is alot more woods friendly.

I am rebuilding the blaster engine now and the rm was due for mains and piston so I happened to have the engine out of it too ...so I set the blaster engine into the rm frame and found that I can do this very easily except for the pipe will have to be made and or adapted from another aplication.

I would realy like to see how the trials bikes are made but I'm also checking into the IT200 pipes

my goal would be to have the 200cc power plant and swap it between the blaster and the rm when ever I feel like it.

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very interesting redrider thanks!!

have you ever had the end off the pipe or does it even come off??

seems to come to shallow cone at the end there, and was wondering if there is an internal cone?

about how high does your engine rev?

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once you determine the profile of the pipe, here is an article showing how to make it with some pretty simple methods, its also pretty efficient on metal usage.

http://www.eurospares.com/frame8.htm

he shows how to make a pretty simple pipe with an elbow. i've seen old 2 stroke custom pipes where they make the profile this way, then saw at an angle, rotate the pieces 180* and weld back together to make sweeping bends.

here is another site showing the general idea:

http://www.froggy.se/skalmanmc/rd350/tuning/expan1.htm

good luck with it. should be a fun project. another option is to look for something like a kdx 200 pipe, they were tuned for woods riding and could be less work to adapt than making your own.

Mike

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the engine will rev to around 8k, but it doesn't seem happy there. peak torque is around 2 or 3k, with peak hp not much past there. If i remember right peak torque is around 35 ft*lbs, which in line with a 450 MX bike, however peak hp is around 25. Also, that last picture does split apart, i just figured i'd show u the whole system together.

As far as i can tell what u see is what you get with the pipe. It's a real slow increase in diameter, and probably more accurately cross sectional area since it doesn't stay round after the header until it reaches the end and very quickly cuts down to a 3/4" round opening... give or take i haven't measured anything.

I'll get a picture of it once my e-mail gets it off my phone.

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well I ususlly give friendy advise and ask good questions, I don't ask about mixing gas or jetting ...

I only ask for pics of pipes because TRIALS STUFF is very hard to search on the net and I have found no pictures of the exhuast and how they are set up.

I have been reading Gram Bell's performance two stroke latley and was just interested in the design applied to trials bikes.

Fester...you have to realize that some of us that are into bikes get just as much enjoyment out of wrenching and creating, if not more, than actually riding..

also some of us are creative and have small wallets, we can't all be bolt on junkies.

the blaster engine was adopted from the yamaha IT200 enduro, I dont think a 28mm carb is big at all, heavy flywheel (good thing).

your attitude sucks so go fester another zit on YOUR sack and stay away from my thread

This is the only common misstake with the yamaha 200s. The blaster only shares the piston and conectiong rod with the IT 200. The blaster is based off of the water cooled dt200 that never came to america. The IT also has a 34 mm carb. The IT doesn't really have a lot of bottom end. It's sortof like riding a big bore 2stroke. You don't need to rev it to get power. You can skip a gear and do just fine. The only problem I have is that it is not tracable power and The throttle response is a little slugish(probably just my jetting). The DG pipes for the IT can be found for around $200. The IT pipe isn't a lot smaller then the pipe on the blaster. The IT is also a bit quicker.

Good luck with your project.

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Yamaha WR200 (two stroke) available here in 91-93 is the bottom end for the YFS200 Blaster motor. Top end came from the IT I believe. I'd locate a 95-06 KDX200 pipe and make brackets to mount to the frame somehow (assuming it matches the cylinder perfectly). It's a double walled metal pipe and is shockingly quiet. Cool project.

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Why slowly...speed it up and beat it.

With out fester this would be a boring forum. I'm willing to let a few stupid threads die to have him stay. We need him to break up the long, but very nice, learning sessions from 2ply.

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