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View Full Version : Inner Bearing change for OS 50 Hyper engine


hallamnet
12-04-2010, 11:10 AM
Hello people. Trying to change an inner bearing on my OS 50 Hyper.

I have seen a vid on the site where you heat the engine up quite a bit and then bang the engine on a hard worktop/vice. I have tried this and the bearing will just not move.

Can any onme help me on this.

I have included a photo of the bearing below and you can see the state of it!

http://img686.imageshack.us/img686/8729/img1375n.jpg

Thanks,

Hallamnet

Primus
12-04-2010, 11:14 AM
Try to heat to a higher temp. Be careful, please, you don't want to burn yourself.

hallamnet
12-04-2010, 11:20 AM
Thanks for the speedy reply. I used a hair dryer last time and heated it up for about 5 mins.

If I was to put it in the oven, what temp and how long should I leave it or should I keep to the hair dryer?

Lol, sounds like ready steady cook!

Thanks,

Hal

Primus
12-04-2010, 11:32 AM
I've changed mines few days a go. Heat it in the oven to about 180 Celcius deg, for 5 minutes or so. Forget about the hair dryer on this.

hallamnet
12-04-2010, 11:37 AM
Wicked! Thanks for this! I will give it ago now.

I will let you know how this turns out!

Thanks,

Hal

hallamnet
12-04-2010, 11:55 AM
Sorted, one bang and it came out.

I have tried to put the new bearing in and it has gone it but not all the way.

Do i use a hammer for this or not.

Thanks,

Hal

Bob O
12-04-2010, 12:19 PM
Sorted, one bang and it came out.

I have tried to put the new bearing in and it has gone it but not all the way.

Do i use a hammer for this or not.

Thanks,

HalDo not use a hammer.

Put the motor back in the oven at 350*F for ten minutes tops and push the bearing with your finger to seat it all the way. If it doesn't go in, go ahead and tap the motor to get the bearing back out.

After things have cooled to room temp, put the bearing in the freezer for ten minutes. Then heat the motor for ten minutes again, pull it from the oven and immediately drop the frozen bearing into place. If it doesn't go in all the way, a slight push with you finger should do it.

Good luck.

GunnyGlow
12-04-2010, 12:29 PM
After things have cooled to room temp, put the bearing in the freezer for ten minutes. Then heat the motor for ten minutes again, pull it from the oven and immediately drop the frozen bearing into place. If it doesn't go in all the way, a slight push with you finger should do it.

Good luck.


+1 The 'ol bearing in the freezer trick! Gets em every time! :thumbup:

MXRACERX43
12-04-2010, 12:32 PM
An even easir way is to put the bearing on the crankshaft then use the crank to guide and pull the bearing into place.

GunnyGlow
12-04-2010, 01:09 PM
I"ve read, more than once, that using the crank to pull the bearings in will created tiny divots in the races. Might as well use a hammer/wooden block or dowel if you're going to force it in with the crank.


The freezer trick works wonders. It is WELL worth the effort!

MXRACERX43
12-04-2010, 01:24 PM
I am talking as a guide and so you dont burn your hands. The bearing should basically fall into a hot case anyway. The crank just lets you guide it into place easily.

I am also not a big fan of putting two different metals with different expansion rates in contact with each other at such extreme temp differences.
The freezer method will work well its just not neccasery

GunnyGlow
12-04-2010, 01:36 PM
gotcha! A good idea!!

hallamnet
12-04-2010, 02:56 PM
Just to let you know i got the bearing with the freezer trick!

All good.

Time to put her back together now!

hallamnet
12-04-2010, 03:32 PM
All was going well until I tipped the engine the normal way up (clutch up, sump down) when I decided to spin the engine with my hand to make sure all was ok. I found that when I spun it, the crank shaft was slightly hitting the bottom of the engine case. If you hold the engine with the bottom facing to the side, it is fine. The con rod drops about 2mm causing it to catch.

When I put the engine back together, I found the con rod would only go in one way so I thought this would be ok.

Any ideas on this, I'm stumped!

Thanks,

Hal

Bob O
12-05-2010, 12:30 AM
All was going well until I tipped the engine the normal way up (clutch up, sump down) when I decided to spin the engine with my hand to make sure all was ok. I found that when I spun it, the crank shaft was slightly hitting the bottom of the engine case. If you hold the engine with the bottom facing to the side, it is fine. The con rod drops about 2mm causing it to catch.

When I put the engine back together, I found the con rod would only go in one way so I thought this would be ok.

Any ideas on this, I'm stumped!

Thanks,

HalMake sure the bearing is fully seated, and the crankshaft is fully seated. The bushing in the bottom of the connecting rod is chamfered on one side. That side goes on to the crankpin first.

hallamnet
12-05-2010, 04:01 AM
Thanks for that. When you say the chamfered side first, is that the side that looks like it is scratched? If it is, I could not get that to go chamfered side down on the crank. I know the bearing is seated right and the crank shaft is all the way in.

Can you physically put the con rod on both ways. I found that i could only get it back on with the chamfered side facing the bottom, not facing towards the the clutch.

Thanks,

Hal

hallamnet
12-05-2010, 10:28 AM
lol, looking a the con rod, i can see the chamfered side (Inner edge rounded off). This is fascing the crank shaft and all looks fine. Still got the issue of movement when the engine is right side up.

The way i am feeling at the moment, i might just go and buy a new engine soon and sell this one off.

:arggg:I just can't work out why the con rod is moving down bout 2 mm and hitting the crank case.:arggg:

newhelliguy
12-05-2010, 10:41 AM
do you have the back plate on? the backplate holds the rod in place. without the backplate on the rod will fall off when it is in that position. the rod rubs the backplate and this is what holds it in place on the crankshaft.

hallamnet
12-05-2010, 11:04 AM
I did not no. It looked like the con rod did not move when i had the back of the engine off.

But if that is the wy it is then GET IN!

Thanks for this.

:YeaBaby:Hal:YeaBaby:

hallamnet
12-05-2010, 11:06 AM
Will update soon to let you know how this went!

hallamnet
12-05-2010, 07:09 PM
Just to let you all know the engine is now back together! At least I know what to do next time!

Thanks for all of the help!

Hal

newhelliguy
12-05-2010, 10:22 PM
One more thing for next time, Mark the piston so you can be sure to replace it the way it was.

siconic
12-05-2010, 11:30 PM
One more thing for next time, Mark the piston so you can be sure to replace it the way it was.

I think, at least with the OS 50, some common sense is in order. The piston only goes in one way. Watch the orientation of the split in the ring. It goes tword the front, and exhaust port. That easy... :D