Engine Rebuild


New member
hi guys

im currently on with stripping down a 2010 gasgas ec300 six day that is in need of a new set of main bearings. i have a couple of questions that i would like answering before i have a go at it and these are;

1. What parts except from mains bearings and seals will i require? (any o rings or other parts that i am unaware of?)
2. is there any tips or things i need to be aware of such as washers or springs falling out etc when i take the bike apart?
3. does anybody know the codes for the main bearings and seals so i can see if i can source these from a local bearing shop?
4. does anybody have any instructions on the method of taking one of these apart that i can follow or is it quite a simple task?

Read Jakobi's thread 'S3 Race Custom Modified EC250 Complete Rebuild'.It's all there.Like the title, a little long windded but good info.
All bearings and seals can be had from the local bearing shop.
Conrod kit from mx parts store.
Oem gasget set.

Get into it.
If you need new main bearings, you may want to consider a crank rebuild at the same time.
thanks for the help, jakobis thread on engine rebuild seems to tell me pretty much everything i need to know. regarding crank rebuild ive checked the bearings of the crank and they seem in good condition. apparently these 2010 models have sealed bearing and the bike was stood for a year before i bought it so im thinking that the grease has dried up and that's why i need new mains

Long winded rambling skippy!

I'm with the others of the opinion that if you take the time to pull it down you might as well give it the full treatment. Its very little extra in 'work' to replace everything, and honestly the bulk of the time is spent cleaning and removing things down to the stage where you actually remove the internals.

With the trans, take lots of photos and references to how it all goes together. Turning the counter shaft gentle you should be able to put the bike through its gears even with the set only sitting in half an engine case. Again, even more easily once the cases are together but not yet torqued up.
OK I'll have to strip the motor and see what state everything is in then and go from there. in terms of parts what would be needed to give the whole engine a once over?