Chains 410 vs 415 drive chain, catasrophic failure brand new engine

Well worth it, Ron, in my opinion. What other motor vehicle has no gears? The smaller the engine, the more it needs gears.
It's great to only have to work the engine to accelerate, then plop it into 6th and idle along at 30mph.
Changing from 415H to 410 chain was just another finishing touch - I've never had a chain actually come off. As we both know, it's all about alignment. I just didn't like the idea of such a large chain on such narrow sprockets.
 
The Grubee skyhawk 410 chain is #### I had same problem

Luckily mine never broke parts, but it eventually chewed up the chain.

I put a KMC Z chain on it and now it works ok.


I bought My engine kit from a site called pistonbikes.com. It is a 66cc grubee skyhawk GT-5. The kit came with a 410 bike chain. My second trip I ran into problems with the chain jumping the drive sprocket and mangling the chain and damaging inside of the clutch arm cover. I cleaned up the damage to the cover with a buffing pad, Fixed & lubed the chain, going link by link to be sure they were bending w/o seizing, and adjusted my sprocket alignment with some washers at the back wheel. Everything seemed fine for the next two trips, but on my third trip since the fix, the chain jumped the drive sprocket again, this time breaking the cover off of the engine and taking the outer bolt hole off with it.

The guy at piston bikes is refusing to send me the parts to fix this persuant to their "30 day parts" warranty based on "user error". In other words , I fuxed it up. He said that this was caused by bad sprocket alignment. He recommended that I buy a whole new engine(from him of course) and keep this one for parts. This is not an alignment issue.

It's a Brand New Engine! It engine barely has 10 Miles on it. I have built 2 kits before, and both came with 415 bike chains. I have NEVER had a problem with the chain jumping the Drive Sprocket. I bought the Grubee because I read that they were considered the best quality(as far as that goes.)

Has anyone out there had similar issues with 410 bike chains, and/or skyhawk kits? Do skyhawk kits come with a 410 chain standard, or did these guys sell me sub-standard parts? Any advice would be greatly appreciated.

Attatched are some pictures if my engine and alignment that I also sent to robert@pistonbikes.com
 
I just recently joined this site and have been reading the posts about the chain locking up. You are a really fine bunch of people. I have enjoyed so much just reading your interactions here. I bought a grubee at spookytooth and have had a problem with my chain jumping the rear sprocket, and reading all about what others have gone through has helped me immensely in dealing with the problem. I really love this site and you people. Just thought I would say hello and tell you good job everyone, well done indeed. What a lift for my spirits to find such a great place.
 
410

I have had the chain jump and lock up the rear tire when it gets bunched up under that cover. Once I adjusted the chain tension properly the problem went away permanently. Too much slack and wham, skid marks on the road and in your pants!

Yes but this is not the same as an alignment or tension issue the smaller chain allows it to fall off the front sprocket making it possible to "Rats nest" up under the cover causing the inevitable explosion of the cover opposed to the larger #415 chain it cant fall off the front sprocket. Not easily anyway eliminating the chance of the ever dreadful "Rats nest" I received one of those smaller chains on my last build just last month and tossed it waited for the real deal .They try to save themselves a dollar by sending this poor bloke & us this smaller chain & that's why this happened now they want him to buy a new motor to cover their screw up up I say we all email this guy i realize it was just under a year ago this week but I just saw this post ., these smaller 410 chains are a time bomb just waiting to fall off. &that my friends is unacceptable
 
My 410 chain was junk. I tried a Bell chain from WM and it wasn't much better. I'm running a KMN (?) 415 chain rite now and it hasn't run better. Its a big burly chain and it was surprisingly heavy. 60 miles on it so far and no hitches.
 
The KMC 415 dirt jump chain is thick! The Bell Walmart chains are for kids bikes that never see the daylight half the year. I used one for a spare, lol. Made it 10miles, then that sucker snapped and about cut my leg. haha. It says on the box though, not for motorized bicycles. It should say, not for adult bicycles.
 
i guess im another victim of the cheap chain.
chain broke 1/2 a link,it piled up inside the engine sprocket cover and blew out (in,rather)
the casting separating the mag housing.now i have a 20mm x50 mm hole in front of the small sprocket.its gonna fill with whatever the chain slings.
barely 100 kilometers on the motor and its broke.gomnna epoxy a piece of sheet metal in to fill the hole,until i can tear it down to bare bones and weld up the crevice.
 
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"Tooljunkie"
Perhaps you could cut out a piece of thin plexi glass and either super glue or screw it over the hole. In a pinch I would get some of that super adhesive postal box tape .. You know the cleaqr stuff better yet walmart sells rolls of gorilla tape looks just like the grey duct tape but this stuff is thicker than the normal#357 duct tape and it is black instead of grey.

I use that suff on anything I cant screw or nail down. Like mounting flashlights on my helmet or cameras on my helmet they charge $8 bux for the larger roll. I use about 4 rolls of that stuff a year it's great and will help keep the water and road smeg our of your engine
 
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