Yamaha TRX850 Enthusiasts Forum

Hi All,
I've a 1999 Aussie spec with a pair of staintune cans that's done 60K (as of today). My friends have told me of late that it smells really rich when they're behind me and I have noticed this from time to time when riding (even I can smell it some times).
I had the emultion tubes and needles replaced about 5K ago as it was rich prior to that due to wear and seemed to be brilliant after they were replaced (with standard yamaha items as was gonna take a while to get the US ones).
I discovered that there was a coolant leak where it feeds into the L/H carb (presumably an anti-freeze set up)but couldn't get to it without unbolting the carbs and tilting them forward. This seems to be roughly from memmory when it may have started running rich again.
I have a manual for the 'H' model (96????) which says if you disconect the TPS on the L/H side of the engine, turn on the ignition and plug the TPS back in, it should read 4000RPM. Mine reads 1000 (approx'). Is this the correct reading for a 99 Aussie model? The TPS bracket is tight & I don't have the tool needed to loosen it anyway but it doesn't appear that it's been moved at all at any stage.
Would this be the issue (ie I've accidently knocked/moved something at the other end of the TPS), or something else???
Any suggestions appreciated.
PS: I still get on average just over 22km per litre and I usually use Shell VPower (closest petrol station to home).

Please, Please, Please, Please, Please!

Oh yeah, I forgot that I had a BMC(?) hi-flo filter put in it when I had the emultion tubes done (while being serviced).

To quote Con Rod from another thread

"With the TPS you can test it by following
1. Turn on ignition.
2. Disconnect TRP
3. Reconnect TPS
4 Observe Tacho.

If your tacho swings to 4000rpm your tps is set correctly"

So the manual says at 8000 the angle is too wide and at 1000 it's too narrow, but what does that mean (I'm not a tech head & from previous experience figure if it aint broke, don't try to fix it)?

I ended up buying some tool tips and adjusting mine from 1000 to 4000 and it seems to idle better than it did and doesn't seem to have such a deep, almost wet sounding growl when I screw the throttle.
The seemingly excessive vibration it's had (since day 1 in May 2000 when I took delivery of it with 300 metres on the clock) compared to other TRXs I've ridden, mainly in R/H grip and peg, seems to have eased (at least on the few km I rode it this afternoon).
It's got me buggered as to why the thing was on 1000 (both adjustment screws were pretty tight). The only things I can think of is that someone cocked it up during pre-delivery, or it was set like that deliberately at the bike shop & was supposed to be adjusted at the first service but was missed.

It doesn't smell as rich now but will need one of my riding buddies behind me to confirm it (they also said it was puffing a cloud of black smoke when I gassed it too).

Does anyone have any thoughts?

Mine smells pretty rich too Rexxie, might be worth me checking the TPS also. Other than that, I've nothing to offer to this discussion I'm afraid.

I can here the difference between the std system on one of my bikes set up with std carbs and TPS and it has that growl but when I put the same system on the other bike with the TPS mod and timing set full advance its just not quite the same on idle /3000 rpm

have a look at the plugs, they will tell you if it is running rich or not.

Thanks for the replies guys & the tip about the plugs Paul. I actually have a new pair of plugs that I bought about 5 yr ago but as I don't have anything to clear dirt/gravel out of the hollows in the top of the engine, I've always feared removing the plugs in case any debris falls down the plug holes (as mentioned above, I've previously buggered things things by pulling them apart for investigation) but if I can figure a way around it, I'll sus it out.

rexxie01 wrote:Thanks for the replies guys & the tip about the plugs Paul. I actually have a new pair of plugs that I bought about 5 yr ago but as I don't have anything to clear dirt/gravel out of the hollows in the top of the engine, I've always feared removing the plugs in case any debris falls down the plug holes (as mentioned above, I've previously buggered things things by pulling them apart for investigation) but if I can figure a way around it, I'll sus it out.

just use a hose to blast it out, obviously leave the plugs in when you do..


worn out plugs could be part of you problem

Bl**dy Hell. I never though of that (Duh) . Always thinking I needed an air compressor & line or tiny powerful vacuum and tiny brush. What a wally . Thanks Con Rod.

Ok. Just did about 250km around the back of Sommerset & it now seems to get 23+ km to the litre. Didn't stink of fuel from where I sat & seemed like a crisper throttle response with less (cleaner) cackle when backed off the throttle. Haven't sussed the plugs yet but so far seems much improved. Vibration still there but seems finer & more balanced between the left & right sides. Still got me buggered as to why the tps was out like that tho.