Model 8/G5 frame

ajsm18 · Post by **ajsm18** » Thu Feb 16, 2012 8:52 am

Hello,

Does anyone know if the 250 and 350 frames differ in the length of the headstock?

I'm collecting parts for a Model 8/G5 and have three 250 frames! I had thought that they were the same as for the 350 but was told the front downtube is about an inch longer for the 350. However, I think the engine will still fit.

I've recently bought a set of forks for the lightweight 350 but the steering stem is far too long for the frames I have. Is this because the 350 frame has a longer headstock or have I been sold a pair of heavyweight forks?

Many thanks for any advice.

Mark

Rob Harknett · Post by **Rob Harknett** » Thu Feb 16, 2012 11:24 am

One sure way to tell is check both part numbers, if they differ, how they differ does not really matter. www.archives.jampot.dk
will have all the books required for checking

ajsm18 · Post by **ajsm18** » Thu Feb 16, 2012 6:08 pm

Thanks,
I know they differ because the 350 apparently has a longer downtube, I just wanted to find out if the headstock was also different.
Mark

Ian5913 · Post by **Ian5913** » Thu Feb 16, 2012 6:23 pm

Mark
I can get you the 350 measurements off my frame. However they are different on the down tube as the 350 engine is taller (Stroke is longer, hence the barrel is longer!) If you fit a 350cc engine in a 250 Frame at the very least you will not be able to get the top end off he engine at all without dropping the motor out. If you want the measurements let me know where you want them taken from to compare Ian

ajsm18 · Post by **ajsm18** » Thu Feb 16, 2012 6:36 pm

Hello Ian,

Thanks for the offer of measurements, that would be very useful thank you. If you can manage it, could you measure the length of the non-removable headstock tube, please?

Thanks for confirming (!) what I suspected regarding having to drop the engine to remove the top end of the engine. I thought this might be the case but, as long as the engine will fit, I don't mind it being awkward to use.

The fact that the fork stem seems too long for the frame has put me off a bit!

Regards

Mark

John Jarrett · Post by **John Jarrett** » Thu Feb 16, 2012 8:09 pm

Just a suggestion... it might be that the frame headstock is the same, however, the headraces that fit in the headstock for the heavyweight forks are quite "chunky". You might be trying to offer them up to a 250 frame that took the lightweight forks with a smaller set of headraces in the frame. They have a different part number for the G2 and G5 in the early parts book. You could be unlucky and not have a G2CSR frame which would have had the races for the heavyweight forks.

ajsm18 · Post by **ajsm18** » Thu Feb 16, 2012 8:12 pm

Thanks John,

That's a good suggestion, I need to take a closer look at all three frames. I had assumed that the problem was just length of headstock but we'll see. Anyway, I think I've decided not to give up yet!

Regards

Mark

Ian5913 · Post by **Ian5913** » Fri Mar 16, 2012 8:32 pm

Sorry for the delay the black bit between the two ball races is 5 1/4" Thanks Ian