Ossa gripper engine

[rms]

On 5/28/2019 at 2:44 PM, malcolm watt said:

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 

It should be set 1,3mm to 1,8mm maximum BTDC. This is 14,5° to 17° BTDC. On my gripper, i have to turn the stator full clockwise (checked with timing lamp). Do you have to original cylinder head gasket ?

Edited May 29, 2019 by rms

[woody]

You say it should be between 1.3 and 1,8mm BTDC with the stator fully clockwise. That's fully retarded. If that is how you like it then that is ok but fully retarded isn't the Ossa recommendation for trials model which is usually 2.5 - 3mm before TDC

Ultimately it's the owner's personal choice how they set it

[rms]

The top engine of the TR80 is different from the MAR and TR77 (gaskets for the bottom engine can be used, but not for the top engine), they have a thin head gasket (copper, something like 0,6mm thickness). TR80 is not set up like other Ossa trials, and 1,3 - 1,8mm is the way it should be. Full clockwise is full retarded, this is what I meant ?

[Triad]

Hello guys, sorry to resurrect an ancient thread... I have an Ossa engine requiring new crank seals as it's drinking gearbox oil. I'm kinda skeptical about doing the job myself as I never worked on such an old bike and I don't have the pullers.

Is it hard? What kind of pullers do I need? The engine should be from a late 70s Pioneer, has the coarse teeth levers and runs, so the Motoplat rotor is good and has good compression.

I'm in Italy, can't find a shop willing to tackle the job for me.

[feetupfun]

Triad, if the primary drive crankshaft sprocket has a cush drive, then it is an easy job to change the crankshaft seal, but you need to buy a special puller for the cush drive. These pullers are available from vintage OSSA parts suppliers in the UK and USA. Buy a primary drive cover gasket and crank seal holder gasket while you are at it.