Trials for back pain

[Kombivan]

no its not the same as that that has the hole for the exhaust to go through formed by the extra bracing. the black bike has the y section only.

[sherpa]

Sorry I didn't mean to confuse the issue. There were two frame types for the M91/M92 models , the prototype photo is of a factory bike that was being developed from the original frame style with the addition of the extra angled members. Interestingly the 325 frames have the engine moved further rewards to assist with traction- the 325 frames have an indent in the rear downtube to allow clearance for the swingingarm.

[JC1]

Sherpa, did the 250 M91 not have the engine moved rearward (with that indent in the rear downtube for the swingarm) like the 325)?

[Kombivan]

Sorry I didn't mean to confuse the issue. There were two frame types for the M91/M92 models , the prototype photo is of a factory bike that was being developed from the original frame style with the addition of the extra angled members. Interestingly the 325 frames have the engine moved further rewards to assist with traction- the 325 frames have an indent in the rear downtube to allow clearance for the swingingarm.

This is the one same as the black one.

[sherpa]

I have always assumed moving the engine rearwards was only on the 325 bikes, but I have never actually had a close look at a 250 in person to confirm it. There doesn't seem to be anywhere near as many 250s as 325s in this model, possibly because it was the first 325 and it would have been the flagship model. Interestingly though the 325 had a smaller 25mm amal [250 had 27mm] and a one tooth smaller counter shaft sprocket and of course much heavier flywheels.
Cheers Greg