Need 250r Master Mechanic

[250rinLV]

Lost left side main bearing and stator.Replaced the mains.When we were putting it back together everything went fine,until we tighten up the case bolts.Crank binds up.Only talking about last 1/2 turn on the bolts.Tranny spins fine.Gotta a couple ideas from others,gotta couple of our own.How about you guys?

Please,this kid is driving me nuts

[BLACKeR]

is the crank seated all the way in on the one side?

[machwon]

The crank bearings are not pressed all the way into the cases.

[Mechanix311]

It could be that the main bearings arent in the case all the way or the crank is not seated in the bearing all the way. Take a dead blow mallet and hit the crank on each side back and forth until it frees up. If it doesnt free up it is probrably a main bearing not in all the way. Alot of people end up putting motors together that way and they run so poor because of all the drag. I had one guy whos bike was running so poorly it would hardly rev. HE thought it had great compression because it was so hard to kick.

[atvmxr]

throw it in the oven at 200 or less for thirty minutes. Should fall together after that

[Rich250RRacer]

Originally posted by Mechanix311
It could be that the main bearings arent in the case all the way or the crank is not seated in the bearing all the way. Take a dead blow mallet and hit the crank on each side back and forth until it frees up. If it doesnt free up it is probrably a main bearing not in all the way. Alot of people end up putting motors together that way and they run so poor because of all the drag. I had one guy whos bike was running so poorly it would hardly rev. HE thought it had great compression because it was so hard to kick.

Do NOT hit the crank with any kind of mallet or hammer! The crank is a press fit into the left side bearing and the PROPER way to assemble it is with the special tool from Honda. If this isn't available, heat the inner race of the bearing and freeze the crank, it should go together then.

[Mechanix311]

If you could hurt that crank with a deadblow plastic mallet i would give you 100 dollars. If you hit it with a metal hammer your asking for trouble. I have built tons of motors and have learned from alot of proffesional motor builders. All your looking for is a little crank freeplay.

[Mechanix311]

Not trying to say you are wrong Rich because you are technically right. It would be better to press it in but if you dont have the tool that will work too.

[Aceman]

He's worried about knocking it out of true, not actually damaging the crank.

[250rinLV]

Thanks kids,but don`t stop writing.What we did was a little tap,ok a couple, on the enter race of left side.It freed up,but we are still not sure it`s good.Haven`t done anything else yet.Question,looking at the crank from above can we mic the crank to see if it`s in right?

Thanx again,any thoughts will help

[matt250r21]

If I were you I would take it all apart and start over. Heating and freezing the parts are your best plan of attack. I would not hammer any parts ONLY very lightly tap the crank with rubber or plastic mallets if you have to. Put the whole engine in an oven at 350 for 20 minutes and pull everything apart. Freeze the bearings and crank over night and heat the other parts. They will fall togther if you work fast and know what you are doing. I do all my motors this way, never needed a press.

[Rich250RRacer]

Originally posted by Aceman
He's worried about knocking it out of true, not actually damaging the crank.

Thanks:D

[Aceman]

You could say I've learned a little bit from your posts Rich.;)

[Dave83]

Originally posted by 250rinLV
Thanks kids,but don`t stop writing.What we did was a little tap,ok a couple, on the enter race of left side.It freed up,but we are still not sure it`s good.Haven`t done anything else yet.Question,looking at the crank from above can we mic the crank to see if it`s in right?

Thanx again,any thoughts will help
I use feeler gauges to center the crank from the top.Tap with a rubber mallet to get the clearance even on both sides.Also,heating the cases and freezing the bearings to install the bearings works best for me.If a crank is stubborn going in,I put a few of the case bolts in and snug them,then tap the cases with the mallet and snug the bolts some more.Dont over tighten or youll pull the threads in the case.