Sorry yes with the two and's in one sentence I misunderstood. It is impossible to move both pivots further forward than the picture above, the only way I can see it would be possible is with only one pivot gearbox sprocket side. Look at vestys bike and the spindle is almost touching the cases, rhs. The only solution would be a very narrow pivot rhs is that how its done? Wouldn't this compromise stability?

It is not impossible because it has been done and a friend of mine has also done the same convertion to his 340 this year.

The righthand swing arm pivot point is very narrow and fits betwwen the frame and clutch case.

The same is done on the left side but there is more room to do the job a bit better.

Will hopefully be able to post some pics next week.

Thanks

It is not impossible because it has been done and a friend of mine has also done the same convertion to his 340 this year.

The righthand swing arm pivot point is very narrow and fits betwwen the frame and clutch case.

The same is done on the left side but there is more room to do the job a bit better.

Will hopefully be able to post some pics next week.

Thanks

Yep suppose you could get an extra 12mm or so with a new frame plate. So what happens at the back engine mount? a new tube with a bracket?

I rode JRs bike in 2 trials in December 1984. One trial in the York area and the other I think was @ Fell Beck. JR had just got his jcm and I used the Bultaco just before he returned it to Comerfords. I have a picture with us and bikes> I will try and post it. You can not see much detail on the bike other than the up and over exhaust and a non standard air box. . All I can remember about riding the bike is that it had a funky gear leaver and it was hard to shift gear.

I got to know JR when he rode the JCM.

I do remember him saying you had to remove the engine to change the gear lever !

I think he broke it in one trial and had to retire.

I would love to have that Bultaco now. It was great to be involved in trials back in the day. I just love the forward motion rule back then. It was just so smooth and flowing. I worked with JR as his minder from the late 70s through 93, As a minder back then all you did was drive the van, fill them with petrol and feed them. It was a lot of fun, traveling to all the nationals and British Championship rounds. Good times.

The J R 340 Bultaco is alive and well, currently residing in Surrey.

Dave Renham borrowed it a few years ago to display at a Malvern dirt bike show.

Pictures to follow. If I can work out how to.