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valve clearance?
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Posted by: pacman

Hi guys,
New member here. Thanks in advance for any help.

So I bought my kids a 2002 TRX90 for their birthdays. Awesome little quad and I can't wait to give it to them this coming weekend.

However, It's running poorly. It will not idle. It breaks up real bad a 1/4 to 1/2 throttle. When you pull the plug it's black and sooty.

I've completly disassembeled the carb and cleaned it out. The pilot was completly clogged. I was excited when I saw this because I thought for sure that was the whole problem... I guess it wasn't. Anyway, the carb is now clean as far as I can tell.

I've swapped out the gas that was in it. I put in a new spark plug. I've checked the spark and it DOES have a good strong spark. The filter is clean.... The only things I can think of at this point are the valves or possibly a bad piston/ring. It feels like it has good compression though.... ????

I ordered the shop manual, but I don't have it yet. Does anyone know the valve clearance for a 2002 trx90?

Does anyone have any other suggestions for the fix?

Thanks guys...

pat.

Posted by: pacman

the valve settings are .05mm (.002in).

I checked the valves and there was no clearance, so I adjusted them. It's still not running right....

Any thoughts????

Posted by: double d 1

what about the rubber boot that connects the carb to the head. sometimes even a hair line crack that is very hard to see could cause it to run poorly? other than that i dont have a clue. let us know what the problem is when you get it fixed. thanks

Posted by: burkebrothers

check the coil wires, that is most likely your problem, make sure you check them with a meter because the breaks can be inside the wire cover if its not broke or breaking where they plug in

Posted by: pacman

Thanks guys. I'll check these out tonight. I'm not sure how to check the coil wires, but I'll try and get my buddy (mechanic) to come over and help.

Posted by: burkebrothers

most times when you put a little pressure on the wires they will break from the connector, if the break is inside the wires cover you need to check with an ohm meter

Posted by: pacman

thanks for the quick reply. Have you had this happen specifically to a TRX90 or is this just general advice?

Posted by: burkebrothers

this is very common on the trx 90 it will present like a fuel problem but is actually electrical seen many trx 90's dnf racing last year and most were because of coil wires

Posted by: pacman

wow.. very good to know. Thanks again.

Posted by: pacman

I just wanted to follow up. I hate when people ask questions and then never follow up to let you know what the outcome was. anyway...

I checked the coil wires, they were fine.

The problem was that after I rebuilt the carb, I put a NEW spark plug in the engine that was a BAD plug.
After my last post, I went home and did what you guys suggested. I also pulled the spark plug so I could get a read on it. When I put the plug back in the motor, it SNAPPED in half while threaded in the engine. It snapped from almost no pressure at all. It must have been cracked right out of the box and I didn't notice it.

I put a new plug in it and it runs great now.

So to sum it up:
It had a bad plug
It needed the valves adjusted slightly
it needed new gas
it needed the pilot jet cleaned.

It runs great. Kids are STOKED on it! It was a great birthday. Thanks to all who helped.

I'll post up pics ASAP.

Thanks again,
Pat.

Posted by: double d 1

thats great you got it fixed!!!!!!!! cheap to. thanks for lettings us know.

Posted by: pacman

here's me and the boy on our trail on my property. That quad is pure fun in the snow. It's a little rough on the first lap, but once you cut through the snow and get your wheel ruts established... it's good times.

thanks again guys.

Pat.
http://a731.ac-images.myspacecdn.com/images01/54/l_8166fb3e7cfee40e0f3c67570fc15232.jpg

Posted by: ROBBSRACING

Isnt riding in the snow the best ? Me and my boys will be doing the same thing this weekend. There is a HUGE snowmobile park near us that has miles of kick -ss trails for us to ride. TGIF