BRIDGESTONE 200 REPLACING THE CRANKSHAFT.

[reed]

Bridgestone 200 replacing the crankshaft.
A good friend of mine sent me a Bridgestone 200 engine with no cylinders and a set of seals plus a new crankshaft.
And i went about pulling the engine apart and i found that the o-rings on the rotary covers on both sides had gone.
When i got to the crankshaft you could see the centre seal gone,so right now the crankcases are clean and the
New crankshaft is in, on a side note the new crankshaft was in a box and when i opened it i notice that the conrods
Did not move so i applied engine assembly lubricant on the big end bearings and within seconds all nice and free.
I will post more pictures of the engine this week,this is a picture of old crankshaft with the centre seal gone and
Some time i will press the crankshaft apart and replace the seal etc.
Thanks.
Steve.

[Redrust]

Any tips on getting the pinion gear off the one side of the crank shaft. That's what's holding up my disassembly of my engine. Don't want to pop the case halves till I have both disk valve covers off.

[disc_valve]

Hi, Redrust,

The pinion gear should just slide off the crankshaft splines. Sometimes they are a bit tight, so it may need some gentle leverage. Start with a couple of small screwdriver blades, one each side of the shaft, and once the pinion begins to move, you can progress to larger blades and then to a pair of tyre levers ro complete the job. It is also worth making sure that the start washer has been removed as well as the retaining nut (the washer can jam in the threads as you try to lever the pinion off).

Graham

[Redrust]

I picked up a three ear puller and was able to nudge it off but now I need to pull the case appart and look for seals I need to replace. There was a little damage to the drive axle seal and I believe there is a seal on the crank shaft that I need to look at. The seals on the disk valve covers look clean and new but people say I should look at replacing all the seals at once. Any suggestions?

[reed]

Redrust,
I allways replace the seals around the rotary valve cover and the oil seals and on the subject of the pinion gear of which any method
You use to remove, have a good look i have seen hairline cracks in the pinion gear.
Thanks.
Steve.
   

[Redrust]

You said you pressed apart the crank to get new seals on. Was there a certain side or way of going about this and who might have all the seals for the engine. I was also wondering if there are supposed something in the holes on one of the crank barring case race.

[OldSwartout]

There is a dowel pin in the crankcase that aligns with a blind hole in the outer race of the center crankshaft bearing to keep the bearing outer race from rotating or walking axially in the crankcase. The dowel goes in the upper half of the crankcase. I can't seem to find the part number or a picture of the dowel in the parts catalog. There is also a smaller hole through the center bearing outer race that aligns with a drilled hole from one of the transfer ports into the center bearing journal in the upper crankcase half.  This provides gas/oil mix directly to the bearing.

There is a half ring that goes into a groove on the upper crankcase half that aligns with a groove in the right end ball bearing. That ring maintains the crankshaft axial location.

Start at the left end to disassemble the crankshaft to get to the seal.

I believe Richard has all the seals, including the center seal.

[Redrust]

Now I have been getting some guff about using NOS seals. All my coworkers keep saying that I should get updated seals to match if I can find some on the web. Any opinions on NOS verses modern seal tech.

[slawsonb]

Seal technology and materials are little changed since these bikes were new (except for exotic applications). The critical thing is that the NOS seals have been stored at a low temperature (<85 or 90 degrees F) and out of sunlight as both of these will cause premature hardening. I expect the seals Richard has will perform well. They will also tend to become more flexible when exposed to engine temperatures and the oil they were designed to contain (seal) in the friendly confines of the engine cases.
...bert

[OldSwartout]

All the NOS seals I've gotten over the years from Richard (and other sources) have been soft and pliable and worked fine.  Many old engines still had pliable seals that worked fine, too.

Finding new seals may be a problem. All three crankshaft seals need to be double-lipped to seal both directions. I looked for a replacement seal for the center crank seal a few years and didn't have any luck. That doesn't necessarily mean they don't exist, just that I didn't find one.

[reed]

This is what i use to remove the pinion gear etc.
Thanks.
Steve.

[reed]

Plus you can remove the main bearings with out any damage etc.
Thanks.
Steve.

[reed]

This is the crankshaft without the main bearing and the shim washers .
Thanks.
Steve.

[reed]

5-ton puller bearing separator set from Matco tools work great for motorcycles crankshaft bearing and gearbox bearings etc.
Its been a good investment for me.
Thanks.
Steve.