How hot to heat engine

[SS109]

If that bearing wasn't smooth from the get go then something is wrong. There is no situation where any sticking/binding in a crank bearing works out ok. Sorry.

On your bearing installation problems... how long are you heating the cases for and how long are you freezing the bearings and crank for?

[Noobi06]

Oh well, I guess i need to buy another. Bearing spins so good now tho with the crank.
When I installed it, I used a torch to heat the cases very hot, then I used cooling spray on the bearings

[SS109]

I've done more a few engines and never had one that the standard heat and freeze method didn't work like a charm. Something is causing interference in your cases if that method, regular oven heating and the freezing of the bearing in a standard household freezer, doesn't let the bearing just drop in. Check the case recesses for burrs, gouges, or anything else other than just raw aluminum.

[Noobi06]

Is it bad to mix a Koyo Bearing with an SKF bearing on the crank? Can I use koyo on one side and skf on one side?
2. Can you use C3 bearing on one side and c4 on one side?

[SS109]

Mixing of brands isn't an issue. However, only use the style of bearing that is called for. If it calls for a C3 then use a C3, not a C4 or any other. GasGas, and every other manufacturer, has a reason for why they spec a certain type of bearing for any given location. Don't mess with that.

[Zman]

I am 95% sure the GG 125 bearings cross over to YZ125 and CR125 bearings of similar years. Do some research and you can find good deals for a pair of bearings on Ebay or at industrial supply houses.

[swazi_matt]

Originally Posted by SS109

Mixing of brands isn't an issue. However, only use the style of bearing that is called for. If it calls for a C3 then use a C3, not a C4 or any other. GasGas, and every other manufacturer, has a reason for why they spec a certain type of bearing for any given location. Don't mess with that.

that being said, nobody managed to work out why the 2010's had sealed crank bearings

[Noobi06]

Btw, how do I know if the crank needs balancing? I know if you dont do it when it needs to, your engine is going to have a massive fail

[SS109]

Originally Posted by swazi_matt

that being said, nobody managed to work out why the 2010's had sealed crank bearings

LOL, so true!

Originally Posted by Noobi06

Btw, how do I know if the crank needs balancing? I know if you dont do it when it needs to, your engine is going to have a massive fail

Most two stroke dirt bike cranks don't need to balanced beyond what the factory did. Most aftermarket rods and pistons are designed to be within the parameters of the stock balance the factory designed in to it. So, not absolutely necessary. However, getting a custom balance when having your crank rebuilt should make the engine run smoother which of course will make all bearings live longer (how much is debatable) and you will get less vibration through the handlebars.

Personally, I wouldn't worry about it. I've had numerous cranks done with aftermarket rods and pistons and never have had one balanced nor have I regretted not doing it. Truing the crank is the critical thing. Maybe one day when I have the extra cash and I'm doing one I'll try it just to see if it's actually worth it (ie; how much of a difference it makes)

[Noobi06]

That makes me calmer. Thanks for the answer
Ill be ordering new bearings, hopefully this shitpile will be running within a couple of weeks