I bought my wife an '05 trailboss 330 a few months ago. After cleaning the carb and putting the spark plug that is supposed to be in it it's been running great. We were out playing in the mud yesterday and she was doing fine until she got in some sticky mud and there were a few loud pops and then it jumped out of forward. She tried forward again and had the same result, even with trying to hold it in gear. This doesn't happen in reverse, only in forward. Once we got her out of that hole it didn't do it anymore but I know that something needs to be fixed. It sounds to me like the "silent" chain in the tranny but hopefully someone can point me in the right direction if it isn't the silent chain.

 

Check the sprockets,especially the front for any worn down/broken teeth and also too much chain slack first. Then check that the shift linkage and transmission lever (belcrank) is tight. If these check out ok, she might have jumped teeth on the silent chain sprockets while under a load or the forward gear slider dogs may be worn,kicking out of gear... OPT
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The sprockets and chain were the first things I checked after we got her pulled out, and they seem to be fine(i.e. no missing or badly worn teeth or bound up links). I will have to wait till tomorrow to check the bolt that holds the bellcrank onto the transmission. If the bolt is tight, how would I go about checking the internals? Are there any special tools after I get the trans out of the quad? Are there any spring-loaded missiles to watch out for inside?

 

Not very many surprises,BUT has that funky combo drain plug/transmission brace that's best to take out first out of the way. The hardest part is just getting it out of the frame. Take pictures as you take it apart or just get a manual.Always replace the silent chain and the forward gear sprocket if the engagement dogs are worn,plus check the slider gear dogs and shift fork along with ordering new circlips and seals. Don't reuse the old ones! Also just look up "gearcase" as a reference as to what's involved. Browse OPT

 

I've got a manual for my trailblazer 400 and from just looking at them they look identical. If they are the same tranny then I should be in good shape, but I will definately take a picture with every step I take with this being my first atv tranny. Should the wear be noticeable if it's bad enough to make it act like it was? I've just never taken one of these apart, and want to know what to look for if/when I tear into it.

 

Other than probably silent chain stretch,look close at the gear dogs and teeth for sharp,shiny edges,plus shift fork for grooving where it rides on the slider gear. Have had a couple trannys that just kicked a circlip out of the groove on the input shaft and caused problems. Could be something simple as that,but check all the gears closely. Use either Three Bond or Yama bond to reseal the case halves. OPT

 

how much free play would be considered acceptable? thanks for the info on some of the small things to look out for if I hafta go inside.

 

New chain is not overly tight,BUT always replace it,not that expensive. No sense in having to go back in twice,plus the chain is what wears out the quickest in most cases. OPT

 

I took a better look at the drive chain and sprockets today and the rear sprocket looks fairly worn but shouldn't be bad enough to make it jump like it was doing. Unless mud was getting between the chain and the teeth maybe. I'm going to try replacing that first, but while I was looking at the sprockets I noticed there is no chain guard on the bike. I looked it up and there's supposed to be one, so I guess I'll be ordering one of those as well. I sure hope that if I have to go inside the trans that the chain is the only thing wrong with it because that internal stuff adds up REALLY FAST!

 

ok... well it appears that I have made a hasty assumption about the transmission..... I finally got time to go for a ride and did the "push a tree test". The wheeler just spun down until the sprocket was in the dirt and THEN it started popping and jumping. I am thinking the tranny is just fine, it's the rear sprocket that is in need of maintenance. I will be ordering one tomorrow along with a chain guard, but THANK YOU VERY MUCH OPT! We're all really happy to have you around here with your endless knowledge about these headaches... I mean toys