Makita 6401 loose main bearings

[Mac&Homelite]

So I recently got an early 6401 ex HD parts saw and was intending on putting a BB kit on it for my chainsaw mill. Piston and cylinder were scored, and I expected it to have been run lean or without mix. I was moving the saw around on the bench and noticed that the flywheel had some lateral slop to it and that it turned over kinda funny. Upon closer inspection the bearing was rotaing in the race in the crankcase on both sides. This caused some rubbing on the counterweight against the case. When I popped the case half apart, the flywheel side fell off immediately, and the clutch bearing was still spinning in the race, but that side required a little pressing force to come out. Since I don't really know how these dolmar/makita's are set up with their bearing tolerances, do I spend roughly $40 and put new bearings and seals in and risk it not working for long and destroying my new cylinder, or would I be better off just buying a good complete used crankcase that I know will work.

 

[Mad Professor]

Do you mean the bearing races were spinning in the case recesses?

If so those should be a press/interference fit in case, and case is probably scrap metal.

 

[Mac&Homelite]

Yes, the outer bearing races were spinning in the case halves. But where I am confused is if that bit of play is supposed to be there, because dolmar says that one of the sides (i believe the flywheel side) is secured in with bearing retaining compound. So perhaps the bearing compound dissipated or wore away. Either way, I don't think there is supposed to be as much play as what there was. I wish had taken some video's or pictures while it was still together to show the issue. Perhaps @fordf150 has some tips since he has quite a bit of experience with these saws.

 

[Mad Professor]

Post pictures of the case halves showing where the bearings seat. If saw was ran w/o oil or lean bearings may have started to lock up and then they spun in case

The retaining compound is most likely to prevent what you have seen happen.

I'm sure some here with Dolmar experience will give you advice.

 

[fordf150]

bearings are still press fit just not the typical tight press like a stihl. if the bearings spun in the case, cases are scrap.

 

[Mac&Homelite]

bearings are still press fit just not the typical tight press like a stihl. if the bearings spun in the case, cases are scrap.

That's what I was figuring too, but I wanted someone who had more experience with dolmar's to confirm. Thanks for the help guys. Now to work on finding a set of used cases to put it back together with.

 

[fordf150]

worst case....buy new. they are $100 each and come with bearings already installed. just need to buy a $3 case gasket and a couple $8 seals. allot of money but if everything else you have is in good shape it may be worth it.

 

[Mac&Homelite]

If the rest of the saw parts were better I would, plus I don't really trust the crankshaft either at this point so I will probably get a complete used lower end for it. Crankshaft has some wear I don't trust. If anyone has one under $100 I would be ecstatic, otherwise it is destined to become a frankensaw with a used dolmar case off of ebay.

 

[blsnelling]

If the topend was toast, it sounds like the entire saw is shot. Time to call this a parts saw and start over.

 

[IthacaMan]

I have a 6421 used Home depot saw that I am looking for parts for to sell it. Dahmer taged you in my parts wanted add and I found this thread that way.Anyways, I wanted to see if you would be interested in buying my saw to make one good one from the parts on yours? Was going to PM you about it,but cant figure out how to do that now,I havent been on the site in a while.Do I have to follow you first? Thanks,Ralph

 

[Mac&Homelite]

I have a 6421 used Home depot saw that I am looking for parts for to sell it. Dahmer taged you in my parts wanted add and I found this thread that way.Anyways, I wanted to see if you would be interested in buying my saw to make one good one from the parts on yours? Was going to PM you about it,but cant figure out how to do that now,I havent been on the site in a while.Do I have to follow you first? Thanks,Ralph

Pm sent, should see a notification in the top right corner as usual.