Chain rubbing on case at front sprocket

[jimthebarron]

I have got the rear wheel central, the engine 1/2" offset and inline with rear sprocket, everything seams ok apart from the chain at the front sprocket rubbing the engine case. The sprocket is far from central, is this normal or should I return the engine.
Cheers
Jim

 

[Venice Motor Bikes]

What I do when the chain hits the case like that is to screw in the gear puller tool into the opposite side of the engine & smack it with a hammer (to move the whole gear shaft over) until the gear has enough clearance. You will have to readjust the clutch tension after doing this.

The small sprocket isn't supposed to to be centered in the opening; it's supposed to be closer to the engine case.

 

[Wm Holden]

venice would know....I'm sure thats the solution....I just ground away the front area of the cover to silence my chain rubbing...but it's not rubbing on the right...so its a different problem.

 

[jimthebarron]

Cheers Guys

I will take the cover off and give it a little tap.

 

[Venice Motor Bikes]

You have to take off the 'star' nut & clutch pressure plate first!!
I screw in the gear puller tool & use that to hit so that you mess up the engine parts hitting them with a hammer!!

 

[biknut]

A #415 chain would help alot. It's a lot thinner than that stock one.

 

[jimthebarron]

Hi

I have tried hitting the whole gear shaft over as you say Venice, but it only moves when I take the other side cover off, then when I put everything back together it moves back and the chain rubs again. Do I need to grind a bit off the end of the stud (pic) to stop it being pushed back to the engine case.

Cheers
Jim

 

[GearNut]

That stud is the clutch release bar. Don't do anything to it.

I have no knowledge of shifting the transmission shaft over like Venice has shared, but I believe him as he is awesome with these engines.
I had a similar problem with my chain rubbing and I fixed it by getting an offset engine sprocket. I don't even know if those are sold anymore though.

Wait until Venice comes back. I am sure he can help you out further, rather than you going out and trying to find a different sprocket first.

 

[Venice Motor Bikes]

I've never had one move back after I moved it! (but I've only had to do it to three bikes in my life.)
You can also just use a heavy duty BMX chain for Grubee engines.. (KMC 410H)

Here's a link... Heavy Duty Chain for Grubee Engines, VMB store

 

[jimthebarron]

Hi Venice

I can't get the KMC 410H over here in the UK, will a Taya be ok?

Regards
Jim




TAYA SINGLE SPEED CHAIN 1/2"X1/8"X112 LINKS BNIB 410H

Taya single speed chain.

1/2"x1/8"x122 links.

Weight 369g boxed.

Presented BNIB and never been fitted.

Tensile strength over 8,000N ( 820kgf ).

Model 410H / ISO 9001

Suitable for BMX / CHILD BIKE / CITY BIKE

 

[Venice Motor Bikes]

I'm not familiar with that brand.
I do know that the KMC 410H Has thicker side plates for heavy duty use.

 

[flatblack]

I'm currently running a #41 and had a rubbing issue on the front of the case. Chain is just too big. Heavy duty but definitely clearance issues on a Cranbrook. I'll ordering a KMC 415 to replace it.

 

[jimthebarron]

Hi
I can get a kmc 415h over here in the UK, so will that be ok.

Regards Jim

 

[jimthebarron]

I have bought a KMC 410H chain and gone to fit it, but it wont go on the front sprocket for some reason, just doesn't line up like the one supplied with the engine kit, goes on the rear ok.

 

[Venice Motor Bikes]

There are some engine sprockets that have thicker teeth than most... you can grind the face of the sprocket teeth down a little until the chain fits.

 

[jimthebarron]

Cheers Norm,

I will whip it off and give it a go tomorrow.

Regards

Jim

 

[DaveC]

Ok, I may be seeing an optical illusion but the engine looks to be orentiated to the right of the center line on an angle. Confirming that is the fact you have the sprocket dished side out meaning you did that to help clear the chain. Try useing a long straight edge. The cover itself can confirm alignment, . Lay the straight edge on the cover, measure the distance from motor sprocket face to straight edge. Now, measure the back sprocket-to-straight edge. The number should be the same. The straight edge can also be used to confirm the motor's alignment with the frame.

The motor just looks like it's pointing off 10 degrees to the right, or so....

 

[DaveC]

I looked over the whole situation in photos. Your problem looks to be a motor too far over to the right. The motor mounted centerline is wrong for that frame. Start with remounting the rear sprocket, dished side in. Now you have to rethink the motor mounts to move the whole thing to the left. The reason is the larger than designed for width of your back tire. These mounts need to be moved over like the motor on a OCC Chopper, just not as much. That's a 3" tire on you bike if I'm not mistaken.

Like I said in my previous post use a straight edge when you measure to set things up. Measure off the centerline at the front and back of things to keep things square. You got a little more work to do but it will pay off in the end