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Jan 11, 2013, 11:12 AM
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Discussion

how do you tighten the slipper on the VMX 450?


I have a Venom VMX 450 that ive added the egyro to, btw it is a huge upgrade. Anyway, it seems like maybe my slipper clutch or something is slipping as when i give it gas the wheel barley moves and if i grab the wheel and give it gas the wheel doesnt spin, just the chain and sprockets and stuff. Any idea where i would tighten it up at? or do you thinki i have a different problem?

Thanks!
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Jan 11, 2013, 11:20 AM
RC Dirt Bike Action
JohnnyMc's Avatar
Try tightening the nut for the slipper a quarter turn at a time. Its the nut underneath that black rubber cover on right side of engine.
Jan 11, 2013, 11:45 AM
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Gaz-b's Avatar
it could be the set screw in the small chain sprocket they do work loose on the VMX
Jan 11, 2013, 12:16 PM
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JohnnyMc's Avatar
True Gaz, and by the description he said his chain and sprocket work but not the wheel. Only way that is possible is if the wheel/tire insert was not install correctly somehow.
Something not spinning, here are options to check:
1. slipper on spur gear is loose - tighten nut
2. front sprocket set screw not tight enough - set screw not tight enough on layshaft.
3. pinion gear set screw is loose.
4. There is a pin underneath the slipper, behind the spur gear, its unlikely, but possible it broke.
5. Tire/insert slipping on wheel? Never heard of this but wheel is not put together then.

Any of these are like a chain of events, so if one stops, it stops all movement for anything further down the chain. So you figure out where in the tranny you parts are not spinning that will tell you.
Jan 11, 2013, 12:41 PM
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Thread OP
when i try and tighten the bolt though, the c clip on the other side spins and it doesnt seem to tighten. Where or what can i hold so i can snug it up a bit?

Thanks again alL!
Jan 11, 2013, 02:01 PM
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JohnnyMc's Avatar
Just hold the wheel is what I do. If it worked while you had the mechanical gyro it should be setup fine for the egyro...weird.
Jan 11, 2013, 02:04 PM
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oh, it has worked with the egyro too, just after a recent crash at WOT it doesnt 'grab' like it should so im hoping to give it a try in a few. Thanks!
Jan 11, 2013, 03:01 PM
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Thread OP
so... not sure what you mean when you say 'hold the wheel' ? when i try and turn the bolt and hold the wheel, i can still feel it 'spinning' on both ends, meaning, i must need to grab something else as its not tightening.

Thanks!
Jan 11, 2013, 04:18 PM
RC Dirt Bike Action
JohnnyMc's Avatar
When your holding the wheel, the chain cant rotate either, and the front sprocket will stay too, so as you tighten the nut on slipper theres no way that would happen unless your front sprocket is loose. Watch the other side of the front layshaft and if your turning that nut clockwise and the shaft is rotating on the left side but the sprocket isnt rotating too, that has either come loose or has stripped off the flat part where set screw sits on.

If it happens this is the case you can either just upgrade the sprocket and layshaft to the mm450 which doesnt use set screws but a pin. I have the old version and I just took a drill and bored into layshaft where set screw sits so it goes futher in than the flat part and it never failed after that. If this isnt the case, back to square one. Your then going to have to start looking deeper into gearbox. Not a lot to these bikes when your in there.
Jan 11, 2013, 04:34 PM
If u aint 1st your last
Throttlejunkie's Avatar
He said in the first post that if he holds the wheel it does not spin only the chain & sprockets, if you are holding the back wheel the chain won't turn
Jan 11, 2013, 04:53 PM
MY '75 CZ "FALTA REPLICA" 2010
TopDave's Avatar
Quote:
Originally Posted by dropabomb
I have a Venom VMX 450 that ive added the egyro to, btw it is a huge upgrade. Anyway, it seems like maybe my slipper clutch or something is slipping as when i give it gas the wheel barley moves and if i grab the wheel and give it gas the wheel doesnt spin, just the chain and sprockets and stuff. Any idea where i would tighten it up at? or do you thinki i have a different problem?

Thanks!
OK, from what all has been said here, It sounds like the set screw that retains the small front sprocket has loosened allowing the lay shaft to spin inside the small front sprocket. If the shaft spins and the sprocket does not, that is the problem. There is a flat spot ground into the layshaft that the set screw in the small front sprocket needs to be tightened onto to lock the sprocket to the shaft. Venom/Atomik makes a new and improved shaft and sprocket set using a hardened pin to drive the sprocket and I would highly recommend getting one because its such a hassle to keep the set screw tight even with lock tite.
You can also do what Johnny Mc did which also will fix the problem: I have the old version and I just took a drill and bored into layshaft where set screw sits so it goes futher in than the flat part and it never failed after that. OR You can do what Chris (chktm) did and drill out the 3mm set screw hole and tap it to 4mm's and use a 4mm set screw that you can really tighten down much better. If fact Chris likes this fix better than the new pin and shaft set up. If you have the tools that is another option.
Last edited by TopDave; Jan 11, 2013 at 05:23 PM.
Jan 11, 2013, 09:32 PM
Registered User
Quote:
Originally Posted by TopDave
OK, from what all has been said here, It sounds like the set screw that retains the small front sprocket has loosened allowing the lay shaft to spin inside the small front sprocket. If the shaft spins and the sprocket does not, that is the problem. There is a flat spot ground into the layshaft that the set screw in the small front sprocket needs to be tightened onto to lock the sprocket to the shaft. Venom/Atomik makes a new and improved shaft and sprocket set using a hardened pin to drive the sprocket and I would highly recommend getting one because its such a hassle to keep the set screw tight even with lock tite.
You can also do what Johnny Mc did which also will fix the problem: I have the old version and I just took a drill and bored into layshaft where set screw sits so it goes futher in than the flat part and it never failed after that. OR You can do what Chris (chktm) did and drill out the 3mm set screw hole and tap it to 4mm's and use a 4mm set screw that you can really tighten down much better. If fact Chris likes this fix better than the new pin and shaft set up. If you have the tools that is another option.
It could also be a broken slipper pin behind the plate by the sounds of things if its not the front sprocket. When you say you tighten the through bolt and the shaft spins at the clip end it sounds like this problem. Edit, no I'm a dill it will be what Dave said a loose sprocket.
Last edited by chktm; Jan 12, 2013 at 08:17 AM. Reason: Dill
Jan 13, 2013, 02:28 PM
MY '75 CZ "FALTA REPLICA" 2010
TopDave's Avatar
Quote:
Originally Posted by dropabomb
I have a Venom VMX 450 that ive added the egyro to, btw it is a huge upgrade. Anyway, it seems like maybe my slipper clutch or something is slipping as when i give it gas the wheel barley moves and if i grab the wheel and give it gas the wheel doesnt spin, just the chain and sprockets and stuff. Any idea where i would tighten it up at? or do you thinki i have a different problem?

Thanks!
Have you found the problem with the slipper yet dropabomb??


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