Sherpa Gears.

[bulltaco]

Hi,

I have a 199a with a Dave Renham electronic ignition on it. I also have a spare 199b engine unit.

I'd like a 6 - speed 325 motor with electronic ignition!.

I wonder if anyone could give any pointers as to which way round would be the easiest course of action. Can the 199a cases be machined to take the six speed gear cluster?. Or could the 199a crank, barrel, ignition, etc be swapped to the 199b?.

[woody]

You're going to an awful lot of bother for little gain, if any, to be honest

If you compared a 325 and 340 motor back to back, without being told which was which, chances are you'd not tell which was the 325, which was the 340 (power that is, gears excepted of course) You may as well just fit the ignition to the 340 engine and use that.

If you want a 6 speed with 325cc, easiest thing to do is fit the ignition and 325 top end on the 199b engine, but the 199a crank will fit as well if you want to go that far.

The crankcases are very different inside the gearbox for the 5 and 6 speed. I'm no engineer but I don't see how the 5 speed could be altered to take the 6 speed cluster..

[bulltaco]

Thanks for that.

It's quite a long time since the 340 was running but as I recall it never seemed to have the poke and pickup that the 325 has. Maybe redoing seals, rings, etc would improve things.The electronic ignition makes a big difference but I'm sure I remember there was something different about the one for the 340, if so that would be another £200 . I'll check it out.

Thanks again.

[nigel dabster]

I would check the timing on the 340 as electronic wont make it run any better than properly set up points.

It may be that your electronic is set at 2.9 btdc?

[woody]

The ignition is the same on all the Sherpas from the first 5 speed models, so you can swap over no problem (never had a 4-speed so didn't want to commit to including that...)

I remember the M159 '76 Sherpa as being very quick in its power delivery after the earlier models. The later bikes seemed to be a bit softer, more like the early models. I have a M92 325 which is soft but pulls like a train and would probably pick up a lot better with a new carb (still on the original well used Amal and everything else...)

I agree with ND on the electronic. It won't make the bike develop more power, or run or pull any better than good points. There is a lot of hype over electronic. What it can do is get the engine to rev a bit more due to the advance curve they can build in. I have a Motoplat on my 340 and it revs like hell (also has a tiny bit of porting and exhaust baffles removed, but I suspect it is more down to the ignition and spot on carburation) You also get a bit more peace of mind with electronic when submarining through water... And no maintenance issues. But more power - I don't believe you do, but just personal opinion.