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tztwofifty

Ossa gripper engine

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Hi folks, currently stripping my 250 gripper engine.. quick question about removing the crank, there appears to be a washer needing removed in order to pull the crank from the case.. does this simply pull off as it seems quite tight, hope this makes sense? Pic attached of said washer. Cheers John.

 

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The piece you mention is part of the crank cush drive and is secured on a taper, do NOT lever it off it is very hard and will break up on the shoulder area, a puller is required to remove it safely.

Steve Sell Marlimar OSSA is the person to contact for all things OSSA he has the puller. Steve Sell Marlimar 07800 788040 leave your name and number he will call you.

Edited by trialsrfun

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Agree, you must have the puller to even consider reusing the part.

Even with the correct puller, the cush drive spline on my 73 MAR still broke during removal.  

The shaft and cush drive spline are a tapered fit with no keys or driving locks.  Simply tne tapers press fit, by tensioning the bolt secures it on the crankshaft.

As you go back together with it, proper torque is a must for not only the cush drive spline but also the flywheel, and clutch basket.  My buddies MAR with a previous owner homebuilt engine overhaul died and would not run, after a bit of troubleshooting, I sorted out the flywheel had sheared the key.  Essentially, the flywheel was not properly tightened.  I explained to my friend, after seeing the flywheel issue, and several other issues, we needed to check the torque on other stuff.  Sure enough, the cush drive was not tight, and tne chutch nut was finger tight.

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1 hour ago, fantic303 said:

Three pictures the way i did it

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Pretty much the same type tool we bought from Alex Snoop in New York

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Thanks for the replies guy's, still not sure 100% what I'm looking at.. everything so far came apart without needing a puller, although the washer  i thought was in two half's should maybe not be? Here are some pics of it coming to bits.. it's just the final wee washer that's stuck, the pullers I'm seeing appear for a different bit? Should the last washer pull off allowing the crank to be pulled to let me renew the seal? Should my crescent washers be just one with a split? Should I leave well alone and put back together lol.. cheers guy's, John

 

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Edited by tztwofifty

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1 hour ago, tztwofifty said:

Thanks for the replies guy's, still not sure 100% what I'm looking at.. everything so far came apart without needing a puller, although the washer  i thought was in two half's should maybe not be? Here are some pics of it coming to bits.. it's just the final wee washer that's stuck, the pullers I'm seeing appear for a different bit? Should the last washer pull off allowing the crank to be pulled to let me renew the seal? Should my crescent washers be just one with a split? Should I leave well alone and put back together lol.. cheers guy's, John

 

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Your photos are accurate.  Yes, it appears the split lockwasher has failed and broken into two halves.  

You should take the extra effort to replace the seal.  My MAR had the original seals in it, and they slid out with little more than finger pressure.

On these OSSA engines, what is confusing is that what appears to be a washer is not.  The entire spline comes off the crankshaft.  Most modern bikes have the spline machined as part of the crankshaft.  The puller is reasonably priced and must be used to remove the short spline adapter shaft.  From the washer as you call it to the top of the spline will come off.

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Ahh see what you mean now.. remove the split washer, slide on the puller sleeve, replace the washer to give the sleeve something to pull against and remove the whole spline...? Thanks for that ?do you know if the split washer is still obtainable?. Off to try and source a puller now. Cheers John

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It's not a split washer, the two halves locate in the groove in the spline and sit behind the big weight which sits up against them when tightened up. They also double up for use with the tool to remove the taper as PMK's photos show

They weren't used as a part in the MAR engine so I guess they must have been available along with the puller from Ossa agents.  Before you try and remove it measure the length as there are three different lengths for these. You'll need to know which one if trying to source a replacement should it break

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Thanks for the replies guy's, fashioned a puller tonight and pulled the spline off no problem. Yes I see the washer is meant to be in two parts now so all good and on with the refurb. Any more daft questions and I'll be back soon....

 

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Appreciate the help guys, gripper all back together now and seems to be running fine, ready for the next trial.. wee pic of it cos we all like photos...! ? cheers John.

 

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lovely bike mate I've just finished building my gripper 350 but having timing issues . there docent seem to be any timing marks could anyone shed any light on the matter 

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There aren't any actual timing marks,  what you do is line up the hole in the flywheel with the hole in the stator plate and that is the firing point,  so you just move the stator so that they line up at whatever point before TDC you want it set at.  The hole in the flywheel is about 5 o'clock with the engine at TDC  (or about 8 o'clock if it has an earlier ignition fitted)   To line them up there is an actual motoplat part called a timing pin but you can use something like a pushbike spoke or similar.

Did you use a genuine TR80 piston if you have fitted a new piston?

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