Yamaha TRX850 Enthusiasts Forum

Hello chaps

Could any of you kind fellows with a 2 into 1 exhaust system on their rex, please take a photo of the Y connector piece along with some dimensions/diameters and also the outside diameter of the link pipe.....please please please.

I would be ever so grateful and it may just finally resolve the running problems ive been having for the last few months. Cheers in advance.

buy kaylas

Would FCR's still run ok with standard size headers then???

billy budge wrote:Would FCR's still run ok with standard size headers then???

they will run fine but you will lose some of the benefit as the stock headers are very restrictive

phuk72 wrote:

billy budge wrote:Would FCR's still run ok with standard size headers then???

they will run fine but you will lose some of the benefit as the stock headers are very restrictive

I find this a tad confusing as the standard headers are 38mm? And my Akra 32mm...although they taper up....
Really think it´s the TRX standard cans wich restricts....

Killerwhale wrote:

phuk72 wrote:

billy budge wrote:Would FCR's still run ok with standard size headers then???

they will run fine but you will lose some of the benefit as the stock headers are very restrictive

I find this a tad confusing as the standard headers are 38mm? And my Akra 32mm...although they taper up....
Really think it´s the TRX standard cans wich restricts....

It has very little to do with the actual diameter of the pipes - it is how this causes the gases to flow (this being achieved by Akra through complex tapers etc.)

also, the restriction in the standard pipes is caused by the 90 degree bend at the head

Cheers for the info Pete.

Trouble is ive got a full over system on mine and dont really want to get rid of it as it looks the nuts. I had a supposed professional modify the system from 2-1-2 to the 2-1 system and i told him how i wanted the Y piece done and to make a slightly larger bore on the link pipe, however all he did was cut the Y piece straight down the middle, peened the edges over and welded it up. looks total shite and i believe its being restrictive and causing me the overheating problems im seeing on idle.

Its the only thing that hes tampered with and it never did it before it went off to him, ive checked the complete cooling system and its fine. To finalise my point, once ive put the water pump together again, i want to run the bike without the Y piece straight through the headers and see if it overheats. Gonna be mental loud i know but ive had enough of this problem now. Just wanted to see what a 2-1 system from the factory measures just incase i need to get a new Y piece and link pipe made up so any measurements would be greatly appreciated.

I'd be surprised if it was sufficiently restricted to cause overheating (but I'm prepared to be proven wrong)

I'm not at home at the moment but if you haven't got what you need by the weekend, PM me and I'll take some pics / measurements of my akra

Blinder, cheers Pete...really appreciate it.

I know my theory seems far fetched but its all ive got left!!!! Theres not alot to see on the waterpump from taking the cover off so i wonder if its that but im not sure what i can check??? and how i can prove its that without stripping the motor???
So very frustrating that in all the 12 years ive had it from new its never gone wrong and i give it to some cowboy and now its not working, might just take up arson for a hobby!!!!

Billy you say it overheats on tickover, does it cool right down when your on the move? And also how long does it take to overheat and does the fan kick in? I also can't see that the exhaust should cause those problems, Have you tried running it without the silencer on!! (Yes it will annoy the neighbours).

Dave E

From a search, Hansj is the waterpump expert (ex spurt ), maybe a pm to him.

Dave E

Hi Dave, how you doing??

Its quite a bizarre thing that it does now, from memory its never really been above 75 degrees and ive only ever heard the fan come in once. However now within 5-8 mins its up to 90 plus degrees and does not cool down alot when moving. The rad and rad hoses, headers and the front of the engine (header region) gets untouchably hot but not alot else. Dont want to run it anymore until i know whats going on, scared its gonna melt something!! Dont recall hearing the fan but then i tend to shut it off before it hits that temp range. Yet to try it without the silencer, just got to put the waterpump cover back on and re-fill the coolant.

billy budge wrote:Hi Dave, how you doing??

Its quite a bizarre thing that it does now, from memory its never really been above 75 degrees and ive only ever heard the fan come in once. However now within 5-8 mins its up to 90 plus degrees and does not cool down alot when moving. The rad and rad hoses, headers and the front of the engine (header region) gets untouchably hot but not alot else. Dont want to run it anymore until i know whats going on, scared its gonna melt something!! Dont recall hearing the fan but then i tend to shut it off before it hits that temp range. Yet to try it without the silencer, just got to put the waterpump cover back on and re-fill the coolant.

Mine does the same in traffic or if I leave it idling for too long, but once on the move it drops back. Unless I get stuck in traffic again, then it goes back up...

Is yours the same of is it a lot worse?

Bill, CBA to read the other threads but the most common reasons for overheating (IME) are defective thermostat or a blown head gasket. Both are simple checks

slow codger wrote: From a search, Hansj is the waterpump expert (ex spurt ), maybe a pm to him.

Dave E

You rang?



Hard to say anything. My experience was that after tuning, including JE-pistons and bore, the engine runs cionsiderably warmer than before. I had the FCRs and full race system before the tuning, and i can't recall the temp to have been over 65-70 anytime. Now it goes up in rolling city traffic to 80-90 with ambient temp as low as 5-10 degrees. In summer it sometimes runs hot so that the fan kicks in even when rolling along ine 30 km/h. On the other hand, trashing it on track in ambient temps of 30 does not make the temp go over 70 (although temp rises as sooon as i go into the pits). I've used one of those electronically oven temp gauges for cooking meat,and put the feeler in to the oil reservoir as a routine (especially when on warm track days), and never had any alarming numbers, so i've decided that it's "normal". I changed thermostat, flushed the radiator, tried with race coolant etc, but didn't see any significant improvements.

My guess is that an engine that outputs more HPs also runs warmer. Especially so if the cylinder walls are thinner (the bigger bore). There is a possibility to change the radiator for an R6 (think it was around 2003 model), which has a lrager front area (curved). Shouldn't be toomuch hassle, but lie i wrote , I've decided it's part of my engine's "new" behaviour. As long as the oil temp doesn't reach critical levels, I am fine with it...