Yamaha TRX850 Enthusiasts Forum

Hello all,

This might be a bit of a repeat, my recently bought TRX seems a bit jumpy on a slight throttle, for example when making slow turns at junctions. I am new to the big twin thing, having had mostly four cylinder bikes before.

I have read quite a few threads regarding carb wear and so I thought I'd pose the question. The bike has 21000 miles on it which seems genuine according to the old MOTs and the general condition.

At what sort of mileage would I be expecting to overhaul the carbs? I have adjusted the slack in the throttle cables to factory settings, which has improved matters slightly.

For around £100 for a pair of kits it doesn't sound unreasonable, but maybe I just need to get used to it?

Your thoughts would be appreciated.

Deano.

The emulsion tubes in mine were well worn by 21K..

What's in the kit?

Hello SnodBlatter,

The Keyster kits come with just about everything I think, Tubes, needles, jets, float valve. They dont have the air shut off diaphragms, these are available seperately.

I'm guessing it wouldn't hurt to do the carbs at the mileage I have. At least that way I know I'm working from a baseline.

I just bought (yet to receive) a Factory Pro kit from the states, its not a cheap kit but they are the only people (i could find) that sell a nickel plated emulsion tube, which supposedly eliminates wear. Emulsion tubes, jet kit and manually adjustable fuel screws (longer and knurled for finger adjustment, rather than squiffy screwdriver) cost me £200 including delivery, I also bought seal kit A & B from Litetek in Thailand, another £30 including delivery. £230 for everything bar the diaprghams, fingers crossed the current ones are still good!

Allens Performance quoted me £230 for everything (including Diaphragms)

The version I got was that the OEM brass emulsion tubes can wear out [oblong] after as little as 5k miles, mine is now coming up to 45k miles, as the emulsion tubes oblong you get a two fold problem; more fuel and bigger dropplets so efficieny is out the window. I couldn't justify the £1000 pounds+ for a set of upgrade carbs, so I showed the standard CV's some love.

Overlord,

Cheers for the information.

I take it that you have already had the OEM parts from Allens and they wore out again, that is why you have gone for the Factory Pro Kit?

Perhaps I should dig a bit deeper and do the job once.

Deano.

I echo Neil's advice. Factory Pro tubes but with stock Yamaha needles. The FP needles are a much steeper taper and I found it very difficult to get the low speed running right.

Litetek Viton seal kits are excellent and plenty oinfo on their website http://litetek.co/

Thanks, getting some good info on here.

Cheers,
Deano

Deano,

No, I think a previous owner used a Dynojet kit, performance is ok but I don't have a yardstick to compare against. I've put 10,000 miles on my TRX already and I'm going to put a lot more on yet so even if i get a marginal improvement [economy] it will be worth the outlay. I went with the FP kit as it made a big deal out its low RPM performance, which is where I do all my riding, so its interesting dandywarhol saying about the trouble getting a good slow running set-up. Good to know if I'm struggling that it might be the kit and not my hamfistedness!

If you can hold off a couple of weeks I should have had a chance to fit my kit, put a few miles on and can report back.

I also recommend the Factory Pro tubes but keep the stock needles.
The FP needles have a very different taper along almost the entire length, very steep at the pointy end which is the low/mid throttle opening.
I fitted them and it ran like a dog. Put the originals back in and it purrs like a kitten.

Yep - Factory Pro emulsion tubes & genuine needles sorted mine out too