Scooterotica

Looking for some insight into stroking an RB20 kit with a BGM 60x110 crank. Any considerations to be made beforehand? I've never built a stroked a engine and interested in giving it a try. My next call will be to AF Rayspeed (since I bought the kit from them).


Thanks.

ulyssescale wrote:Looking for some insight into stroking an RB20 kit with a BGM 60x110 crank. Any considerations to be made beforehand? I've never built a stroked a engine and interested in giving it a try. My next call will be to AF Rayspeed (since I bought the kit from them).


Thanks.

Well you wont be able to use that crank, unless your changing the piston ? the RB 20 uses a 116mm rod.
You could use a 60/115 crank, and you wouldnt need a packer, be sure to check the rings dont catch on the "fingers" of the boost ports at btc as they are pretty close normally .
Ive used a 58/115 crank and machined 1mm off the bottom of the barrel, after a three big end faliures with the 116mm rods
Russ

You'll need a 116 rod, not a 110.

Im wanting to try a 62/116 stroke on an RB20 if any customers out there want one doing?

Main things to be aware of are deck height at TDC, over extended port timings, , piston skirt toughing casings at BDC, and if bottom ring drops below boost port legs at BDC.....you'll have to measure port timings and play with gaskets and packer plates until you get what you want. It can be tricky, but crack on and get stuck in!! ;o))

I'll just use the BGM crank for my Jet and use the AF 58x116 crank that came with the RB20 kit.

Thanks.

ulyssescale wrote:I'll just use the BGM crank for my Jet and use the AF 58x116 crank that came with the RB20 kit.

Thanks.

Does the AF crank have a welded pin now?

Toddy wrote:

ulyssescale wrote:I'll just use the BGM crank for my Jet and use the AF 58x116 crank that came with the RB20 kit.

Thanks.

Does the AF crank have a welded pin now?

Doesn't look like it.

ulyssescale wrote:

Toddy wrote:

ulyssescale wrote:I'll just use the BGM crank for my Jet and use the AF 58x116 crank that came with the RB20 kit.

Thanks.

Does the AF crank have a welded pin now?

Doesn't look like it.

another Chubby Checker ill wager

carlos fandango wrote:

ulyssescale wrote:

Toddy wrote:
Does the AF crank have a welded pin now?

Doesn't look like it.

another Chubby Checker ill wager

It's already been checked for true. I don't expect it to twist.

ulyssescale wrote: It's already been checked for true. I don't expect it to twist.

I'd get an adult to check the pin isn't a thou' too small then.

Muttley McLadd wrote:

ulyssescale wrote: It's already been checked for true. I don't expect it to twist.

I'd get an adult to check the pin isn't a thou' too small then.

Can someone point me to a history/reports of this problem? This is the first I've heard of it.