Yamaha TRX850 Enthusiasts Forum

Hi all, I'm messing with my race TDM again and looking for a little more power and have been told the standard down pipes are a little restrictive at 33mm OD would some kind sole please measure the OD of a set of TRX down pipes before I go splashing the hard earned!!

If someone happens to have an Akrapovic that they don't mind measuring including the lengths to any changes in diameter and the lenght of any transitions sections I would be very greatfull as then I can just get a custom one made to fit.

Ta
Ad.

MadAd wrote:Hi all, I'm messing with my race TDM again and looking for a little more power and have been told the standard down pipes are a little restrictive at 33mm OD would some kind sole please measure the OD of a set of TRX down pipes before I go splashing the hard earned!!

If someone happens to have an Akrapovic that they don't mind measuring including the lengths to any changes in diameter and the lenght of any transitions sections I would be very greatfull as then I can just get a custom one made to fit.

Ta
Ad.

Standard is 38 mm all the way, Akrapovic is 32mm at the head and then taper up...but that´s ID of cource.
KEDO have aftermarket headers for the TDM they claim 4bhp on IIRC.

MadAd wrote:Hi all, I'm messing with my race TDM again and looking for a little more power and have been told the standard down pipes are a little restrictive at 33mm OD would some kind sole please measure the OD of a set of TRX down pipes before I go splashing the hard earned!!

If someone happens to have an Akrapovic that they don't mind measuring including the lengths to any changes in diameter and the lenght of any transitions sections I would be very greatfull as then I can just get a custom one made to fit.

Ta
Ad.

Its not just the ID of the pipes that restricts the air flow on standard pipes, it is the pipe bends at the head.

And as KW says, the Akra pipework works very well due to the tapers - which is hard to replicate and one of the reasons they are so effing expensive (worth it though)

Yeah but you can't get them any more! I am talking to some zorst fabricators who can bend me up a set of tubes. If some one can give me some measurements, that would be helpful should be £350 to £450ish - cans. Might be able to negotiate a group deal if a few people are interested

SDN wrote:Yeah but you can't get them any more! I am talking to some zorst fabricators who can bend me up a set of tubes. If some one can give me some measurements, that would be helpful should be £350 to £450ish - cans. Might be able to negotiate a group deal if a few people are interested

Well, if org. carbs and no headjob i think 38mm should be correct size...if mikunis or FCR´s the MAB size of 42mm ID with according headjob, inlet rubbers and funnels should do the trick....with some nice bends.

Cheers KW

All the measurements are here

Kevtrx849 wrote:All the measurements are here

I measured out mine at the head to 32mm with the caliper, mine´s also 60mm at end but 52mm ID so i guess previous owner fixed it to take all 1kcc bike cans....

Remember these dimemsions will probably change with a 2-1-2 pipe setup like the Over pipes as Akra's are 2-1 pipework

Kenny wrote:Remember these dimemsions will probably change with a 2-1-2 pipe setup like the Over pipes as Akra's are 2-1 pipework

Not really, after exhausts exit the head pipes (2-1-2, 2-1) just have influence on the exit speed of gas....hence akra make them tapered and 2-1 as the ignition from two ports help gas to faster exit exhaust system....and the taper. BUT you have the linkage in a 2-1-2 setup wich enable the exhausts to exit in either pipe.

Kevtrx849 wrote:All the measurements are here

thanks for that Outside diameter sizes I am gerssing?

All

Thanks for the input it's given me some food for thought for the winter upgrades on the race bike!!

Regards
Mad Ad

SDN wrote:

Kevtrx849 wrote:All the measurements are here

thanks for that Outside diameter sizes I am guessing?

That's correct, all outside diameter measurements.