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trx350 exhaust and tuning

5794 Views 21 Replies 3 Participants Last post by  200xranger
anyone know where i can get a decent factory muffler for my 87 trx350 4x4? or want to trade factory for the cobra i have? ebay has one but its got holes in it and they want 90 bucks. having trouble tuning my bike and i want it quieter for hunting. cleaned carb many times, changed jets still dies when wot is applied from idle. whats got me baffled is i had some dirt in the float needle so it was overflowing. when leaking fuel the problem went away? reved up fine but cleaned it and the problem came back. cant adjust float level but would that be it? i also sometimes get a backfire and a flame out of the carb when the boot is off.
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Since it has an aftermarket exhaust, you may need to rejet. That would explain why you didn't have the problem when the float was sticking and gas was overflowing.
If you're sure it's in time and you're sure the carb is clean, try raising the jet needle up, by moving the clip down a notch.
would it run if it was a tooth off on the cam. i did just rebuild the top end so all that was disassembled.
Yes, I've seen them run a tooth off.
would it run if it was a tooth off on the cam. i did just rebuild the top end so all that was disassembled.
Yes, I've seen them run a tooth off. will run..but it won't run right with being a tooth off..this throws everything out of spec...i've owned to many of these bikes..they are really picky !!!
Yeah, that's what I meant. I know it won't run right, but it will run one tooth off.
ok so my repair manual tells me how to check timing with a light which i dont have.
That's just a check for the ignition timing, you need to check the cam timing.

which mark do i use in the index hole?
The "T" mark.

i know the timing marks should be in a straight line up thru the center of the cylinder to the valve cover right?
No, they should be parallel to the top of the head, like in the picture below.

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there is also an "O" on the other side of the cam gear above one of the bolts that points straight up. i remember those marks now and i forgot to check those. could my valves be causing this or have somehting to do with it? checking them....use the other marks or the same one? is it ok to keep my stock jetting until i get this cured or is it gonna cause problems?
The "O" points straight up. As long as both lobes on the cam are facing down when the "T" mark is lined up, it don't matter about the marks on the cam gear, anyway.

When checking the valve clearance, use the "T" mark on the flywheel, but make sure it's in time first or the valves won't be closed. The cam lobes have to be down and the valves closed to check the valve clearance.
I'm also thinking the problem is in the carb. You mentioned that you have an aftermarket exhaust. The aftermarket exhaust might be making it run lean. Backfiring is an indication that you are running lean. You might need to bump your main jet up to compensate. Either that or your carb still has some debris or something in it. Did it run right, before, with the exhaust? Did it just start doing this?
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