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Hello All in the UK,

Could someone please enlighten me about using a 500's transmission in a 350 case..

Is it a simple drop-in swapover or are the bearing & shaft diameter differences ??????

Robert in California

Robert, I was wondering the same thing. No one has been able to tell me for sure but I think it will go. The bearings listed in the parts list are different (some roller, some ball) but they are the same diameters. I was pondering fitting a six speed cluster from a 350 to a 500W engine I'm using. Until it has a good reason to come out and be taken apart though I'm putting off finding out.

5 or 6 speed? And why, for strength?

Good question SuperMotoDave,,,,

In My Land speed racer,,, 6-speeds are the way to go over the 5-speeds in the 500 transmission normally,,,

However, I can't fit a countershaft sprocket larger than a 14 tooth nor a rear wheel sprocket smaller than a 29 tooth,,,It seems I'm at an impasse as to

High speed gearing options ........

So, I could fit a larger and heavier rear tire. or change to the 500's gears that are wider stronger and 5th gear is much more overdrive than 6th gear in a 350 gearset.

I hope to get North of 130 mph one day with enough gearing ,supercharger boost, and good aero....

Robert in California

What about using the 350 or 500 primary gears (they are different) or a combination
. Would this help give you the gearing you need?

Thanks, Simonnorthroad,,,

I'll look into it

robert

If the crankcases are the same, why would the different gearbox internals not fit?

Are the primary drives the same?

Questions by the way, I do not know the answer...

I'm pretty sure that the gearsets are interchangeable, but I believe that the 350 and 500 clutch centres are different. Paul (EvGuru) will know for sure.

If the only thing preventing a larger drive sprocket is the cast 'loop' around it, can you not just machine it away? should clear the clutch arm ok.?
George

George 350 wrote:I'm pretty sure that the gearsets are interchangeable, but I believe that the 350 and 500 clutch centres are different. Paul (EvGuru) will know for sure.

If the only thing preventing a larger drive sprocket is the cast 'loop' around it, can you not just machine it away? should clear the clutch arm ok.?
George

George if the clutch centres were different surely that would mean different crankases? With bearing bosses cast and machined at differnt points? As mentioned above and was pointed out to me by another member, the primary transmission gears are different 350 to 500, same centres but different sized pinions. A 500 primary on a 350 would be an quicker way to raise the overall ratio than a crankcase split to change the gear cluster.

I've looked at the 500 primary ratio gears set , and it is the way to go for me....

Using the 2.03:1 gears I could keep the 6- speed and gear up to 143 mph if I wish...Wow this is what I need...

Many thanks for this suggestion !

If anyone has the parts or knows where I might acquire them, please let me know..

Robert in California

Try here...

https://www.ebay.co.uk/str/explodedbike ... 0595875012

I would be careful of Excalibur as it may be lower geared... Best to count teeth and ask!

Hi, the 500 5 & 6 speed engines use the same primary gears with 31/63 teeth;

When I had a 501 engine apart I didn't notice any difference from the 500s yet I didn't count the teeth, but looking at the 501 Camel owners manual they quote the same primary drive ratios as the 500 so they must be the same?

In ATG 288Pete Crawford compared 350 & 500 primary gears with straight cut gears:
When looking at the 500/350 drives he found that the 350 clutch gear was much heavier (1322 grams) and carried its mass towards the outer edge giving a greater flywheel effect than the lighter 500 gear (1166 grams).

Have fun in your quest, Ian

What about a 19” rear wheel, and a new rear hub allowing a smaller sprocket, the bigger diameter wheels are supposed to give better traction on the salt.

500 shafts are beefed up compared with the 350 trans and they have needle roller thrust bearings (The otherwise similar 250 single 5-speed makes do with plain thrust faces like the 350 trans). The output shaft is splined, rather that a double flat.

The 500 primary gear has a larger plain bearing and the clutch gear/basket bush is stepped, rather than parallel, so it has to be installed before the side case. To do this it really helps to havr a tapered guide bush. Some of this detai will be in my 500 clutch rebuild video.

One thing to consider is whether a 428 chain would do the job, there are heavy duty versions available. The 250 twin runs a 428 chain and a 16 tooth gearbox sprocket.

EVguru wrote: One thing to consider is whether a 428 chain would do the job, there are heavy duty versions available. The 250 twin runs a 428 chain and a 16 tooth gearbox sprocket.

Indeed. The 250 uses the early 350 style 6 bolt rear sprocket (45T) mounting with scope for a smaller diameter, and the gearbox sprockets are interchangeable. I've run a 350 rear sprocket on mine for the road and 520 alloy versions on the hill climber. Not sure how many teeth you could get down to on the back in 428 but certainly worth doing the calcs. I reckon under speed trial rather than on/off throttle conditions it would cope.

I managed to run a 520 13T sprocket (two flat fixing) to earth in Italy recently which is going to go on the Forgotten Error as an experiment - it will then be geared for 85 at 9200 in 5th which should liven it up a bit