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2747 Views 55 Replies 7 Participants Last post by  Bigjohnson20
I have a trailboss 325 and in neutral and reverse it revs up like it should, but once I put it in drive it only goes like 20 mph. I put a new primary clutch on it and I put new buttons in the secondary. Don’t know the problem.
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Is it you have no power to rev past 20mph? or is it revving high but not moving like it should?
It is not revving high in drive.
What year? if i remember correctly the 4stroke trail boss had problems with original cams back in the early 2000s

It looks like part numbers changed from 3086803 to 3087247 for the cam.

Did you buy it this way?
Any popping or backfiring?
have you replaced any electronics yet like CDI box?
It is a 2001. I bought it not running and got it running. Once I got it running it would spitter and die out. I put a used( in working condition) top end in it. That fixed the sputter problem and now it is doing this.
The only thing I did not touch on it was the bottom half of the motor. Does anyone think that could be the problem?
What is compression and are valves in spec.
Compression is $90 and they are adjusted to spec
Does it rev in neutral? If it does then it’s a clutching problem.
Yes it does rev in neutral. I put a new primary on it and new buttons in the secondary one
I don’t know if this has anything to do with it, but I was in neutral revving it and turned the lights on to see if they worked. The more I revved it the brighter they got and the bulbs blew I think because they shut off.
Sounds like a charging system issue for starters off that last remark. Bad belt?are the secondary sheaves be t or cracked and have you checked that the shins and deflection are right? Mine would only do about 25 amd I bought a higher end belt for 110$ and spun the pucks on secondary because it wouldn’t open all the way… these clutches work by primary closing on the belt and the secondary(driven) clutch open and belt drops down as ths primary pinches it as it rides up…ingenious design, u might want to pop off clutch cover and remove clutches and clean them with a Scotch brite pad and service secondary if it’s in need. What color spring is on the primary and weighs?
Your cdi box. Coil, rectifier, stator or pulse trigger coil and even flywheel could possibly be nicked up…plug, wire .and cap..theres your ignition/spark ,,is your air filter setup properly.
So when in neutral the rev is nice and smooth? And You have full power in reverse when you hold down yellow overdrive button with no hesitation?

What was wrong with the old head?
I think my air filter is set up right. One thing that does not make sense is that when I take the cover off the air box the engine will backfire and Not rev even in neutral.
It don’t seem like there is any hesitation in reverse. Maybe like a little bit
Hmm, latebird may be better qualified,, the weird is that it’s behaving like the override function is functional backwards lol….im really confused, these machines will never run right tho if that box isn’t sealed and the lines going in and out are connected to their corresponding areas..ask me how I know lol
Ya I am lost on it as well.
Have you tried cleaning/checking carb? you have less load in reverse.. tires pulling not pushing and less weight on rear.
sounds crazy but your problem is a head scratcher. if you never had it running right maybe its hard for you to tell what's normal. I'm thinking not getting enough fuel or air leak. but cant pin point it. anything more you can share to help? what was wrong with old top end?
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