Crank Rebuild Questions

[risk74]

I will be building two 2011 Gas Gas EC300 engines for the 2019 hare scrambles racing season and have a few crank questions:

1. Who are we using for crank rebuilds in the US now? RB won't do it, Cooksey hasn't been taking in cranks for months now. What are some good options?

2. I've read up on balancing the crankshafts, but opinions seem to vary from "it's a great idea" to "the factory got it pretty good the first time, don't waste your money". Anyone have any real world experience with balancing the GG crankshaft?

3. After stripping these engines, they have the sealed crank bearings that most seem not to like. What bearings are recommended for longevity and what is a good source?

Thanks in advance.

Kris

 

[Jakobi]

Hey mate.

Use open rollers for the bearings, or purchase OEM and remove the seals. The sealed ones work fine, but why keep oil out of where it's needed.

Crank work in the US.. I'm not the man to answer the question.

Re balance, my research led me to believe that you'll never get a single crank balanced. You just move around the area that they vibe. Stock is fine. A well trued crank though will be friendlier across the board. Find someone who'll get it as true as possible and then be kind transporting and installing it.

 

[450exc115]

I been using Ken Oconnor Racing here locally in CT for all my bike cranks and he has done a few. Crazy anal about details and good pricing. He's done a bunch of vintage bike cranks for me that are a PITA to get true and he is never happy unless they are less than .001" inline.

http://www.kenoconnorracing.com/

I was always told that you could only balance the crank if you sent the piston, pin, bearing with it as you need the whole assembly to get it right.

 

[risk74]

I been using Ken Oconnor Racing here locally in CT for all my bike cranks and he has done a few. Crazy anal about details and good pricing. He's done a bunch of vintage bike cranks for me that are a PITA to get true and he is never happy unless they are less than .001" inline.

http://www.kenoconnorracing.com/

I was always told that you could only balance the crank if you sent the piston, pin, bearing with it as you need the whole assembly to get it right.

Thanks for the info, Ken sounds like the man, will be emailing him shortly!

 

[Davehuge]

I've read up on balancing the crankshafts, but opinions seem to vary from "it's a great idea" to "the factory got it pretty good the first time, don't waste your money". Anyone have any real world experience with balancing the GG crankshaft?

Personally I haven't rebuilt any crankshafts, but I used to watch my best mate rebuild them, sadly he's not around anymore.

When I was younger and slimmer, I used to race his bikes, Van Veen Kreidler 50cc GP bikes, we used to rev them to 18,000rpm, they ran like turbines.

He never balanced the crankshafts, after installing new conrod,big end and pressing them back together, he aligned the two flywheels using dial gauges, giving them a firm tap with a copper hammer to adjust them.

I raced his bikes for around 10 years and we never had a crank failure.

I realise it's quite a bit smaller than a 300cc crank but the principal is the same and at 18,000rpm they had to be right!

 

[Harry]

DaveHuge,

Do you have any photos etc. of your Kreidler? I love small bore GP bikes

Regards,
Harry

 

[(F5)]

He's posted in the pics section. Way cool bikes.

 

[Davehuge]

Do you have any photos etc. of your Kreidler? I love small bore GP bikes

Regards,
Harry

Hi Harry, just in the middle of posting a few photos, hope they interest you.

Didn't want to take this thread off subject!

See them here...http://www.gasgasrider.org/forum/showthread.php?t=24021

All the best, Dave

 

[Neels]

Ken O'Connor

I do believe this Ken guy will be receiving my cranks in the future. Very well priced indeed.