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Discussion Starter · #1 ·
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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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.
first..check your timming..see if it's in time ?..as for the muffler..you may have a hard time fiding that..the parts for these bikes are getting harder and harder to find..as most are no longer being made...for your carb over flowing..either clean the carb really good !..or over haul it with a new carb rebuild kit.
 

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Discussion Starter · #3 ·
i got it to stop leaking but when it was leaking i didnt have the bogging problem. stop leaking....bogging started again. the bike will fire right up. i ease into the throttle it revs....push throttle wide open quickly and it bogs. will it run if its a tooth off on timing?
 

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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.
 

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Discussion Starter · #5 · (Edited)
i went from a 35(stock) pilot to a 40,42,50,52,58. still bogs. the main seems ok. i have the same air filter and pipe on my trx250 and didnt have to go up that much. one other thing is the type of jets. my local dealer says there are different "series" jets. mine has threads on the outside but the distance between the threads and the top are different. would that make a difference?
 

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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.
 

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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.
 

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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.
sure..it 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 !!!..lol.
 

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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.
sure..it 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 !!!..lol.
Yeah, that's what I meant. I know it won't run right, but it will run one tooth off.
 

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Discussion Starter · #11 ·
ok so my repair manual tells me how to check timing with a light which i dont have. which mark do i use in the index hole? i took the valve cover of, put at tdc, and the mark on the cam gear looked to be off. so i rotated back, looked to be about 2 teeth. put it all back together returned my jets back to stock and.........its worse now!!!!! WTF. i bought the bike not running so i dont know if it ran right before. i just rebuilt the top end. any other ideas? i know the timing marks should be in a straight line up thru the center of the cylinder to the valve cover right?
 

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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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Discussion Starter · #13 ·
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?
 

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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.
 

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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?
with the lines on the outside of the cam sprocket vertical to the top of the cylinder head like helmut posted in his post..and cam lobes facing straight down..now..with the T mark lined up on the index in the cover..you should have your piston on top dead center ?..if not..then your cam sprocket..which sets the angle of your cam lobes is off..better yet..your timming chain isn't set right on your cam sprocket..set it like me and helmut said..if your cam lobes are not facing down..then re-adjust your timming chain on the cam sprocket..MAKE SURE YOU GET YOUR PISTON ON TOP DEAD CENTER ON THE COMPRESSION STROKE !..one way to make sure you have this right..turn the crank backwards about 1/4 turn from the T mark..watch the intake rocker arm's..if they start to move..then you have your piston on the top dead center on the compression stroke.
 

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rechecked the timing with the two marks parallel to the head....in time. so still backfiring and not reving. can the valves be that much out? didnt have a chance to recheck them tonight. what next
dumb question..but..even though the marks are lined up on the cylinder ( on the cam sprocket )..how are your cam lobes ?..are they facing straight down ?
 

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yep straight down
if you know for a fact that all your timming is right..timming..cam..flywheel..rockers are set right..then your problem is in your carb..something isn't right..or clean ?..with your carb...did you pull your flywheel off your crank ?..if you did..did you make sure the woodruff key lined up with the flywheel when you put it back on ?..not saying you did this..but it can happen...if all your timming marks are lined up..your cam lobes are facing straight down..your piston is on TDC ( top dead center ) on the combustion stroke..then it should run..and run right without any back fireing..anytime you get back fireing..it's either because your timming is off..or a fuel problem..which means your carb isn't right..before you remove your carb again..lol ( been there sooooooo many times )..re-check all your work..flywheel with the T lined up right..rockers arms..if you are certain this is ok..then remove your carb..and go back through it again...i'm putting my money on your timming settings. keep us posted.
 
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