Yamaha TRX850 Enthusiasts Forum

Have been doing my own setup by trial and error.
The official booklet that came with them suggests more external adjusments than actually exist. The only external adjustments i have, go through enderneath the float chamber and adjust idle air i think. Are there different models?. One thing i am unsure of is correct float height, i have set it to 9mm.
The mains i have in now are 165 and it seems a lot better at the top end, it had 158 befor and was lean. but does seem to be guzzling fuel now. Runs pretty well though so might just try dropping the needles one notch befor i go so Snetterton on 1st May.
Float height anyone?

Which way do you screw the slow air jet to richen the mixture for idle / low throttle openings?

The adjustment via the fuel bowl is your fuel screw, (1 turn std)
There is a slow air screw you access via the air intake ( 1 is your main air jet 200 as std and the other your air screw std 1.5 turns)
Screw either fuel or air jets increases your flow on fuel or air.

Instead of going up on your main fuel jet, you can try a smaller main air jet (try a 190)

Here is a good link on FCR tuning
http://www.factorypro.com/tech/tech_tun ... s,Pat.html

I just checked my float height the other day and 9mm is correct.

SDN wrote:Which way do you screw the slow air jet to richen the mixture for idle / low throttle openings?

Screw the slow air in to richen / less air
Screw the fuel jet out to richen.
The link above give a thorough explanation on your boundaries on adjustments.

Brian, i had both pod filters off and there are no jets or screws visible in the intakes. However i am not too woried it goes like stink but drinks a bit of fuel, will carry on riding the wheels off it next week at Snetterton. Be interesting to see how it goes down the back straight.

Silver wrote:Brian, i had both pod filters off and there are no jets or screws visible in the intakes. However i am not too woried it goes like stink but drinks a bit of fuel, will carry on riding the wheels off it next week at Snetterton. Be interesting to see how it goes down the back straight.

I suspect that that you may have the air box adaptors fitted to the top of your FCRs. The attached photo shows what they look like, this one is upside-down.
The side piece on the adaptor covers the air jets, you have to remove the adaptor to get at them.

I've stolen the photos from the interweb, apologies if they belong to anyone on the forum.

Thanks for that, i'll have a look next time the tank comes off.