Yamaha TRX850 Enthusiasts Forum

Well, as someone already pointed out the akra ups the backpulses quite a bit....it coffs and huffs and puffs.
What´s the best remedy?

Can add that the head is ported so the roof of the exhaust is welded and floor is much bigger than standard....a theory of mine is that as the akra pipe at the head has smaller diameter than the MAB exhausts are smashing into it!?
How thin would you dare to do the stubs?? They are kinda thick so should be ok taking up a bit?

A. Graham Bell advises that the exhaust header pipe should be a little larger than the exhaust port to help prevent reversion. If there's plenty of meat on the exhausts then I don't see why you couldn't grind the pipes out to suit but don't blend them into the port, make them oversize.

Didnt he invent the telephone, was that above to stop it entering his ear!!!

Dave E

I noted with the acra pipe there is a balance pipe just after the bend out of the headers from the head.??? When you look at the std header s or even the greenhill system this is much further down.. Could this be your culprit at low rpms's with a 270 degree crank maybe not so previlent with a triumph running a 180 degree crank as this being a std position not far out of the head for it????

Killerwhale wrote:Well, as someone already pointed out the akra ups the backpulses quite a bit....it coffs and huffs and puffs.
What´s the best remedy?

Can add that the head is ported so the roof of the exhaust is welded and floor is much bigger than standard....a theory of mine is that as the akra pipe at the head has smaller diameter than the MAB exhausts are smashing into it!?
How thin would you dare to do the stubs?? They are kinda thick so should be ok taking up a bit?

mine doesn't

and yeah, you should be fine