Interchangeability

[motovita]

I have a 199A and can buy some 92s for parts. Will the top ends interchange and are they significantly different? What about forks, clutch and gearbox parts?

I know you guys know.

Thanks

[woody]

The parts look the same but there are differences and they don't swap straight over

Early 325 up to model 151 are basically overbored 250 barrels with different fins. Later 325 M159 on has a thicker liner and the exhaust studs are further apart because the port is bigger, so exhausts aren't interchangeable. You can use an M158 or later 250 exhaust on the early 325.

92 has bolt on carb inlet. You'd have to swap it for a push on carb inlet from a later 250 if you want to retain the bing as the later 325 inlet is bigger and won't fit the early 325

Clutch basket and hub have different fittings, look the same but aren't

Clutch crank weight shaped differently to allow for the different shape clutch case. Later weight will foul the inside of early cover.

Gear shafts are different, mainshaft has different bearings clutch side and shafts are different diameter.

Clutch springs held with pins on early bikes, nuts on later - hub not interchangeable, different shape at the rear.

Forks have a tapered top yoke on early (or all) 92 so you'd have to swap the entire front end, not just the forks. All have the same bearings/steering stem fitting so not a problem.

Maybe more I've forgotten about...

Edited August 19, 2011 by Woody

[lorenzo]

motovita -

Woody's list is pretty comprehensive (and impressive too, if done from memory!).

May I add :

Both gearbox internal ratios and secondary drive ratios are different - few, if any parts are truly interchangeable .

Model 92 does not have a gearchange thru shaft (r.h. shift only)

In addition :

Entire rear wheel is different - model 92 is a much heavier lump altogether.

Carb. and airbox setups are obviously completely different.

Edited August 22, 2011 by Lorenzo

[motovita]

Thanks guys, you're the best! I passed on the 92s.

[woody]

Send them over here....

[motovita]

OK now I've found a 183. I can see that the airbox, swing arm and frame/skidplate are different than my 199A, what about the engine/gearbox, exhaust, wheels and forks?

[woody]

With the engine it's difficult to say as it's in that timeframe when things were changing. You may have the issues mentioned previously with the clutch and gearbox but it's difficult to give a definitive answer.

The top end, as in cylinder, head and piston will swap

The rest of the components will also swap without problem, wheels, forks, yokes, exhaust are all the same.

Edited December 11, 2011 by Woody