Yamaha TRX850 Enthusiasts Forum

Well I parked the bike up a week ago after a 35k ride back from work on a fresh tank of petrol. Then the Queensland rain came and the bike sat unused until yesterday when I thought I would ride it to work. It started without a problem and idled perfectly while I opened the gate but when I revved it at the end of the driveway it backfired. I thought it was just clearing its throat but 3k's down the road it was popping and banging and was down on power. I turned around and drove the car instead but today it still seems to have the same problem. Any ideas on what might cause this issue? Nothing has happened to the bike in the last week apart from maybe getting a bit wet (it was parked under cover but the rain came in sideways).

Time for a pull down Rick, tank off, [drain]..change the plugs [iridium]..clean the carbys,..clean the coil contact at frame..check vacume lines for leaks, check the fuel filter...gotta get it back to being reliable..
Carb jet kits are cheap and easy to fit too.!

One thing that i have noticed on working with my rex, is tha way the high tension leads can sit on the top of the cam bolt edges..vibrating nicely..eventually they would rub through and ark out, causing hesitation to the motor..justa notion as im often under the hood.
Said to the wife the other day that we should get out more,..she said,.'' you,r always out,..IN the garage !''...
And thats when the fight started..
If you can find a trailer, you know where i am.

It sounds like water in the fuel. Put a capful of acetone in the tank with the fuel and it should help clear the carbs out, but it wouldn't hurt to drain the float bowls before you start the engine up again.

metho is good for water in the fuel too

I tried the acetone and metho but neither have worked. I have bought some new plugs but when I asked about the HT leads they said that the leads and coils came as one piece which is over $200 each. Does that sound right? I think I might have to take Alex up on the offer of some garage time to get the TRX running smooth again.

ricr378 wrote:I tried the acetone and metho but neither have worked. I have bought some new plugs but when I asked about the HT leads they said that the leads and coils came as one piece which is over $200 each. Does that sound right? I think I might have to take Alex up on the offer of some garage time to get the TRX running smooth again.

Ive known you to have this problem for a while now rick, going to hav to bite the bullet and get in there...definitly fixable
Have the carbs ever been serviced ?

I believe they have had a dynojet kit put through them by the previous owner but I have never had them off the bike. I have had the bike just over a year now and done about 20,000 k's so I guess they could do with a service.

ricr378 wrote:I tried the acetone and metho but neither have worked. I have bought some new plugs but when I asked about the HT leads they said that the leads and coils came as one piece which is over $200 each. Does that sound right? I think I might have to take Alex up on the offer of some garage time to get the TRX running smooth again.

Yea, yea but you can of course replace the HT leads, they require cutting and joining sections putting in, like these wee suckers here found with a very quick search:

http://www.ooracing.com/store/index.php ... uctId=4358

I use clear silicon on each end to be joined too, completes the waterproofing nicely.

Thats a good link Mince, not overly informed to the life expected from a set of leads though..certainly havent noticed any members having lead troubles as yet...however i would be thinking the [popping and banging] will be in the fueling..
With the leads, i have personally witnessed [ spark jump ] at NIGHT time from high tension plug leads under the bonnet of an old 4 litre six ford i once owned...they were rubbed or cracked through the rubber sheath and arcing over to the motor causing a miss fire...so just a thought.
Main direction will be a carb inspection and clean..new kit would be a positive.
Then the rubber pipeing and anything not normal...id like to see the bottom of the float bowls....
One trip to my wifes town over in the Philippines and visiting a relatives house there, discovered an old kawasaki 125 smoker road bike covered in a sheet and kept under the stairs...told it would leak fuel,.. prompted me to pull down the carb with my Leatherman multi tool to clean the crud from bad fuel out, .it went like a Bast**d.. after that..new family hero me,..and a crate of Miguel.