Yamaha TRX850 Enthusiasts Forum

No it's not a TRX but the engine is.



The engine is using TDM900 barrels, rods and Wiseco pistons it's running a CR of 11.2:1. The carbs have a Factory Pro Ti needle kit and a pair of K&N's.

I have not yet had the bike on the rollers but will do once it's been run in a little!! So will let you know once I have a dyno chart!!

She ain`t pretty but she`s going to be functional! Should be around 94 brake, that`s my guess.

Interesting Tdm. I'd like to know the power and torque figures when you get it dynoed. Whats the origin of the swinging arm?
Did someone use a 'gas axe' on the rear of the frame


Mark.

Gas axe.
Yes indeed it looks that way, I think that swingarm has been shortened, shorter wheelbase, turns quicker of course.
The spindle fitment could be Kawasaki in origin, ZX6R perhaps?

FZR400 swingarm i'm guessing.
std tdm850 forks.
cheers
fung

probably gonna need a whole load of lead weight on the bars!
Gas axe!! = Hot Spanner!!

Edit; "Interesting!" fuel tank securing method!

I know i'm totally OCD but.... yeah, it's different

Fung get's the prize!! FZR400RR swing arm!!

Gas axe is close it was an angle grinder!!
The fuel tank is a chopped C90 item and it was one of the things that ran out of time!!
I'm going to try and come up with something that is a little better than the 'wings' for attaching!!

The aim was not prity but functional and with the weight down to 162kg I must have done something right!!

It will get tidied up as the year goes on but I ran short on time and mechanical functional was far more important!!

Dyno plot will be posted up when I get it done, hope to be some time in the next few weeks!!

That's... different. Functional.

Is there some really big tarmac hill somewhere or will you be running knobbies on it?

Maybe this camera angle will explain the gas axe better....................................helps keep the rain water out and rusting through the frame

Yep I can see what you've done. It's sound

I the first photo it really did look as is the frame had been "cut" through using oxy-acetylene

I didn't think the possy would pick up on as much as they did.... and it was a chance to use a wonderfully evocative piece of slang

I like the bike. Hope it tears up those hills. Are the headers big bore? they look neat with the weld discolouration showing the joins

Mark

The hill climbing I do is tarmac only hence the semi-slick tyres.
Yes the second pick shows better what happened to the back of the frame!!
Although this may explain even better!!



The headers are home made the top part being stock TRX and then they taper out to 45mm od and are based on the TRX Akrapovic dimensions but made to fit the TDM frame. I like the discolouration on the exhaust it gives it a rustic functional look, not that the bike needs any help with the rustic look!!

Had the hill climber on the dyno now and it has highlighted a few problems with the fuelling. The air fuel ratio plot will show you what I mean!!

I have worked out a plan for sorting the fuelling starting with raising the float level a bit to try and combat the seriously lean part at the top end, failing that then the supply to the fuel pump will get upgraded to 8mm from 6mm. And I have decided that the cam timing needs sorting out after having skimmed the barrels!!

Oh the graph is against MPH rather than RPM, just in case you thought the numbers looked a little odd!!

Float level is critical throughout the range but once on main jet it is less crucial. I found that float level has more effect in mid range.

Hmm, the Stoichiometric (air to fuel ratio should be 14.7) mixture is all over the place! No wonder she`s not making good power.