Yamaha TRX850 Enthusiasts Forum

Gday all! I havent read anything along these lines on the forum yet so we may be onto a new subject here:

I have been offered some Keihin FCR39's from a Ducati 900SS, the throats are only two mm wider than the TRX coming in at 98mm, (will be easy to remedy), the main jets are 150 and the pilots 52. Im running this setup in my mikunis at present to compensate for the big bore exhaust. So my question for all the tech heads is: Is there any reason why theses carbs wont do the job? What are some issues I might have to look out for? cheers fellas.

There are many of these set-ups around and i have seen some for well under the AU $1000 mark so it might be a nice loophole for those of us who cant afford the $1500 price tag for purpose built TRX units.......

Hi mate.
These carbs should work fine. You may need shorter spiggots (tubes connecting carbs to engine) but these are available from Allens in uk.
Also wont have TPS.connection but this is easy to bypass.
may need some jetting.
All info is on this 'ere forum.
39s arent as good as 41s but are still good.
Dave

Cheers Dave, Im guessing Allens would come up in a google search?

With the Aussie dollar worth $1.05 U.S you'll find a new set from the states for under a grand. They come with cables, TPS mount and bell mouths and an air box adaptor. There's a few links on the subject showing where to get them from the states.

Keep the price under $1000 and there's no excess tax

Bewdy, thanks Cobba, I looked at the TPS mod and balked at the thought of the ingition being full advanced all the time, esp when i ride her on the street and at low revs often. Ill have a poke around and look for the links!

I've done the TPS mod on the ECU and its no real drama running full advanced. Most of the time even round the street your still over 2500/3000 rpm anyhow.

Took your advice Cobba, contacted PJmotorsports in the states, decided to spend a few extra $$ and get the correct kit, $840US plus $79 delivery. $1100 locally so the good ol USA saves the day.......

Just checked that to the UK and to get them into the country is £590 But we'd still face the uncertainty that the customs would pounce on it and whack a few quid on, just because they can Still doable though

BR RACING £813..........

Eye, I know. I used to get all sorts for my Suburban from the states and never got pinched once. I get whacked everytime with bike bits though, even off private purchases

Interested to know the benefits of the Keihin upgrade?

More precise fuel metering
Flatslides work better from low to mid revs whereas CVs (like whats on the TRX) work better from mid to high revs (Please correct me if I'm wrong)
The wonderous induction noise and the famous FCR "rattle" at idle
Easy to work on
Easy horsepower
Pose value
etc etc etc

Bob

Mid to hi revs are an improvement also with FCR's more so especially if your running the bell mouths and ditch the air box.