Chain breaking at master link?

[Not2worried]

I cant seem to get a chain to last on my Thunderbird with the Predator engine. It appears like it breaks at the master link ( or falls off or?? ).
Chain, clutch and sprocket are new ( old sprocket has same issue). Eye ball the alignment looks ok, though I'm not 100%.
The master link is the correct direction. I feel like the chain is not overly tight or overly loose ( see pics below).
Mainly happens at higher speeds/rpm.
What am I missing here?

 

[I74]

Spring loaded chain tensioner would help ''a bunch'', to dampen things ect.
Under accel, chain is tight on top & loose on bottom.
When letting off especially after high revs,, the top will get pretty slack, then when hitting throttle again,, it's like cracking a belt, & ''very'' hard on chains ect.

I

 

[I74]

Added,,
In the Baja section their is a recent thread called ''chain tensioner''.

suprfly made the last post on it with a pic. of a ''real slick'' tensioner set up that he made.

Something like that would more than likely solve your problem, especially with you having rear suspension.

 

[DaddyJohn]

I clean the link area off really will with thinner, brake cleaner, etc. and add a dab of silicone or Automotive Goop to the master link clip to keep it from flinging off. Old dirtbike trick that seems to work if nothing else is out of whack...

 

[pomfish]

Your engine plate is flexing, had 4 of these bikes and the whole design of the frame is made for a 150lb max rider with 3.5 hp engine.
The single downtube and thin/flexable metal of the frame allows the plate to twist at the front when power and weight is increased.
When upgraded to Predator and larger adult rider on a bike that has your butt positioned right over the centerline of the rear axle the wheel does not spin, the frame takes the torque load and things twist thereby changing the angle of the engine/clutch to the chain and it grabs at the sides. The master link by design it the weakest and is usually a bit wider than the other links so it grabs easier and at bad angles bad things can happen.

Solution;
Beef up the engine plate, either remove the plate or weld thicker plate right over existing plate and weld in triangle supports at front of plate, file the edges of the master link pins to make them more smooth and reduce chain tension, your chain looks too tight to me in pictures.
When I was about 14 I had a Cat Slingshot and I always thought the chain had to be as tight as possible and it used to chew up master links and throw chains till I wised up and gave it a little slack and smoothed those pins.
HTH

Later,
Keith

 

[Not2worried]

Your engine plate is flexing, had 4 of these bikes and the whole design of the frame is made for a 150lb max rider with 3.5 hp engine.
The single downtube and thin/flexable metal of the frame allows the plate to twist at the front when power and weight is increased.
When upgraded to Predator and larger adult rider on a bike that has your butt positioned right over the centerline of the rear axle the wheel does not spin, the frame takes the torque load and things twist thereby changing the angle of the engine/clutch to the chain and it grabs at the sides. The master link by design it the weakest and is usually a bit wider than the other links so it grabs easier and at bad angles bad things can happen.

Solution;
Beef up the engine plate, either remove the plate or weld thicker plate right over existing plate and weld in triangle supports at front of plate, file the edges of the master link pins to make them more smooth and reduce chain tension, your chain looks too tight to me in pictures.
When I was about 14 I had a Cat Slingshot and I always thought the chain had to be as tight as possible and it used to chew up master links and throw chains till I wised up and gave it a little slack and smoothed those pins.
HTH

Later,
Keith

Sigh, me and another member were talking about if the motor plate needed to be beefed up. Looks like I'll be welding this weekend.

 

[electrathon]

What pomfish said sounds likely. I would also add to remove the master link and just use a chain. I rarely use a master link unless I am being lazy, it is just a weak link to cause trouble.

 

[pomfish]

Another thing I found helpful is to drill extra holes on the seat frame into the wood of the seat, the stress on the seat with only 3 contact points causes the screws to get hogged out/loose.
Fun bike to ride, wheelies galore with the Predator!

 

[Hemi Charger]

Your engine plate is flexing, had 4 of these bikes and the whole design of the frame is made for a 150lb max rider with 3.5 hp engine.
The single downtube and thin/flexable metal of the frame allows the plate to twist at the front when power and weight is increased.
When upgraded to Predator and larger adult rider on a bike that has your butt positioned right over the centerline of the rear axle the wheel does not spin, the frame takes the torque load and things twist thereby changing the angle of the engine/clutch to the chain and it grabs at the sides. The master link by design it the weakest and is usually a bit wider than the other links so it grabs easier and at bad angles bad things can happen.

Solution;
Beef up the engine plate, either remove the plate or weld thicker plate right over existing plate and weld in triangle supports at front of plate, file the edges of the master link pins to make them more smooth and reduce chain tension, your chain looks too tight to me in pictures.
When I was about 14 I had a Cat Slingshot and I always thought the chain had to be as tight as possible and it used to chew up master links and throw chains till I wised up and gave it a little slack and smoothed those pins.
HTH

Later,
Keith

He is Absolutely Correct !!! I would add a Good Racing go kart chain quality...Yes Looks to tight to me also/ twisting