A forum for owners of Yamaha TTR250 trail and enduro bikes!

Hi Kaos and others,

Well that pretty well stuffs my theory that the Shorty Front Pipe gave me the impression that there was more power at lower revs and confirms the mid-range theory.

Just a tip Steve, for the next batch of these that you get made, on mine it is very close to the frame, back near to where the joint is. Maybe your manufacturer could put in a little more bend or put a small dent it there. It doesn't hit the frame but it is very close.

I am also following Lyndon Poskitt on his Dakar journey, thanks to the link posted on this Forum a few days ago. I went back to the beginning and watched all the 10 minute "episodes."

I was wondering why his two mates weren't helping him with the bike at the end of a tough day of riding but now know that he is in the Class where he has to do everything himself. A great young guy with a top attitude.

I am abit "shaken and not stirred" at the moment as yesterday I got caught in a 5 car "Nose to Tail" on Auckland's Southern Motorway. I was in our Jeep Patriot and was in the middle of the mayhem and ended up sliding down the road on the left hand side. Once stopped I was out of there in a hurry because of a possible combination of fuel leak and sparks. Our poor Patriot will be a "Write Off" as several Air Bags deployed and that is a "car killer." We are fully Insured thankfully.

Cheers and lotsa beers

Jeff

Excellent news Steve and thanks for going to the effort!

A nice easy way to get some extra ponies for your TTR plus I think the shorty pipes look great 

Brian

PS Sorry to hear of your incident Jeff. Good news that you are OK.

Good news on the Dyno

Yours is in the post today Ben 

lol its worth the wait. you guys have been such a big help. that extra 1.5 -2  hp that's a good increase  I am really having fun a the races . with the looks my son is getting on his 03 TTR250 when is getting his plaque .no 1st yet but we are getting closer.

Kaos wrote:

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Ben.
Let us know your thoughts with the new shorty pipe.

I will share my thoughts next week. I will be out this Monday on the TTR I've been mainly riding the WR so I will give it my first full day test with the shorty out in the Victorian bush. My son has been riding it and reckons its goes well. Will be riding with fast blokes on KTM300's so should be interesting.
Sappershouse
The pipe is definitely an upgrade if u r serious about the TTR.
I love surprising the new bike riders too

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 Will do. All going well my ever so humble OE won't be quite as humble. 

GraemeSydney wrote:

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The 2hp probably comes from the combination of shorty and GYT pipe.

I wonder what the shorty would do with an OEM pipe.

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No, the gain pictured on the dyno run pictured is just from the header pipe, the short header pipe compared to the standard header pipe.    Both runs used the same  the same muffler, in this case the GYTR muffler.

I would imagine a decent muffler would add another couple of HP over the standard muffler, independent of the header.    

GraemeSydney wrote:

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Not meaning to be argumentative but that is an assumption unless confirmed by the numbers of a dyno. 'Performance' pipes can, and often do, change the feel of power and move it in the power curve without adding HP.

From what you are imagining you could get 2hp from the shorty and 2hp from a performance muffler for a total of 4hp. I think that is an unsafe assumption. Mind you, I think the right combination might work together to give 4hp but coming from two different developers that would be a fluke rather than good engineering, and not every combination of performance pipe and shorty would not give the same result.

So it still leaves me wondering what the shorty would do with an OEM pipe.

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Graeme,

I have to disagree with you.   A decent after market muffler shouldn't just move power around it should give a power gain, and in my experience more gain than the shorter header pipe.

I have never bought a performance pipe without getting an increase in power. (and I have bought a few)  I'd want my money back if I didn't get more power.

On my last bike, a 2007 wr250F which I only sold last year, I ran five different mufflers at different times: stock, YZ250F, DEP and Pro Circuit and Arrow.  All gave increases in power over the stock pipe to varying degrees, YZF the least Pro Circuit the most.  That bike was dynoed with the pro Circuit exhaust, I think it picked up 3 or 4HP.   I never got a print out on that one.   But that pipe was annoyingly loud I gave it to my son and ended up running an Arrow muffler which was quieter.   My other son scored the DEP.   The YZF is still in the shed with the stocker.   All the gains were noticeable whilst riding.   Just like on the TTR, the power increase with a decent muffler is noticeable.   I have had similar experiences with DRZ400s built for racing.

My 2015 WR runs an Akropovic muffler and the power difference from stock is amazing.   My sons 2016 WR250F, exact same engine, has the stock muffler is an absoluter slug in comparison.   I just big bored the 2015, that's even stronger now ;)  

Yes I have ridden the TTR derestricted with the stock muffler and it was ok.   The GYTR muffler it actually goes better.  My butt dyno said it had more HP.   Certainly wheelied and accelerated better.   And its better again with a short header.  

I don't know how the short header would work with the standard pipe I haven't tried it. Someone may have, hopefully they will chime in.

http://ttr250.activeboard.com/t64192586/october-1999-motocross-action-magazine-on-ebay/

This is a good read, Motocross Action built a TTR250 for racing in 1999 , extra 3 HP on a muffler alone, then an extra 2HP with the shorter header, total increase from 17HP stock to 22HP.   That's 5 HP with the exhaust mods.

That's pretty consistent with my experience building mine.  23.5 HP, 263cc, ported head increased compression.

Last month Leigh put a TK muffler on his bike and describes the power difference in this thread.

http://ttr250.activeboard.com/t64598571/new-exhaust-for-my-bike-need-some-recommendationshelp/

Cheers

Steve

Glad you got it so quick and are very happy with it.

Many thanks for the feedback 

Steve

Funny you mention the clutch. I fitted a new clutch cable at the same time I installed the shorty pipe. I didn't realise just how bad the old one was until the new one was in. The clutch is now quite a bit lighter and it snicks into gear a lot better. I don't think the clutch could fully extend/release properly with the old cable. I kinda feel bad for using it as it was for so long.

Like this one. Out of my old WR250F.  With the LHRB 

6071...yes thats it..... fit straight in....

Is that the left hand rear brake ?

set it up with the motor/oil hot...


..

-- Edited by petenz on Wednesday 20th of June 2018 11:26:28 AM

Back on topic, here is how the shorty pipe looks on an OE TTR 250.

Thanks for posting the results Kaos ... been toying with the header pipe idea. 
Can anyone comment on whether re-jetting is needed for the shorty header pipe?

First I might just install an aftermarket end can, which off course will mean a re-jet, but assuming the shorty header pipe conversion would not need any further re-jetting? 

And for re-jetting, is the common consensus still as follows ...

Pilot Jet:
The stock pilot jet size is a 50; replace it with a 52.5 pilot jet.
NOTE: Use a Mikuni pilot jet with part number VM28/486. 

Main Jet:
The stock main jet is 137, replace it with a 140 small round main jet.
NOTE: You must run a small round main jet as the hex main jets hit the bottom of the bowl. The part number is Mikuni No. N102/221. 

Should really start a thread on my bike, to keep track of changes and tyres used (mileage etc.).