I've got a 98 300ex with a 380 big bore kit with all the goodies up top - oversize valves, port & polish etc... I have no problems with the engine - has a ton of torque, it loses a little bit on the top compared to the 330 kit I had before but it is a low end monster for a small quad. My problem is with the clutch. I've burnt up three sets of fibers (2 EBC and 1 stock)and two sets of steels, tried a zillion spring combinations and now have a DP heavy duty kit (expensive -$110 tried cheap so I thought I would try high dollar)in it and it slips worse than the burnt one I removed. I did use the springs that came with the DP kit and they were softer than what I had in there, but I thought I would use the kit as a whole. The best spring setup I tried was heavy duty 350X springs shimmed with a couple of washers behind.-----Here are my questions, there are quads making twice as much horsepower as me, why am I having trouble with slipping? The basket and pressure plate are stock and in great shape, do they need to be replaced? I know the Hinson basket has holes in the fins for better cooling, but my slips just as bad cold as it does hot. It hooks great on the holeshot, through second and sometimes even third. It slips mostly around forth and a bogged down third, on the TT track, coming out of a medium sweeper nailing it for the straightaway, it slips for a hundred feet or better.
Any help would be appreciated, I'm about ready to pull my hair out. I would buy a whole new aftermarket basket and plate if I thought that would help, but I don't understand how it could be anything other than the fiber, steel and spring components.

Thanks for any help you can give.

 

my guess would be maybe your oil type, as far as i have ever heard, synthetic oil is a big no no in quad engines, you did'nt say your're running it but if you are....
some guys run some atv specific stuff but its expensive, ALOT of guys run the quaker state standard 20-50 or other similar oil, so change your oil n see how it goes, and yer clutch again if its toast, lates, josh...

 

I'm running Castrol 20W50 - I forgot to mention that, I'd been asked about the synthetic stuff already. Profab ATV built the engine and he couldn't believe that the clutch was slipping with HD springs. He asked if I used synthetic as well - I had him stumped, maybe thats why he's not in business anymore?

 

I have a 440 stroker. With 20-50 the clutch slips, with 10-40 it hooks. Try that and see. I switched back and forth car oil or bike shop oil, neither made a difference until changing weights.

Don't hurt that basket they are big bucks, and I couldn't kind an aftermarket one for our little big-bore 300.

 

I don't know much about oil, it seems to me that a heavier weight would help the clutch to hook? I was going to ask opinions about using 30 weight but it seems I'm going the wrong direction. Thanks- I'll try the 10W40 and see if that solves my problem.

 

Got what I hope to be the answer for you, unless you are already running it. See what people don't realize is that that only reason people say synthedic oil and quads don't mix, is because of the wet clutch right. Thats the case unless you get oil with friction inhibitors in it like, amsoil 10w 40 syntedic thats what I run in my 98 300ex never had a problem with the clutch to this day, I run it in the old TLR too. Its great stuff although it does burn your wallet a bit at like 11 bucks a liter. Giver a try!!

Sounds like one crazy 300ex love to hear people making them crazy

No Wing No Prayer!!

 

no, a thinner weight oil would make it hook better, you have it backwards