Facts or fiction on later type engine in early bike?

[marcm]

I've not done or attempted it,but can anyone on here offer any feedback on the later 3tb type engine or the tt motor that's 4g something ? With a kickstart,into early tenere?.....
I know the motor is slightly wider,is it impossible to get over any sprocket alignment issues?...will the chain wear out in 500 miles,or will the sky fall in because the engines silver?...
Any feedback would be very interesting...

[Mezo]

Paul (xpag) has done this Marc & has just finished his big trip, Dave did mention there was some wear on the casing i'm guessing from the chain rubbing?

Mezo.

[xtrider]

Depending on the amount of offset and direction, I would think a person could put spacers behind the rear sprocket to push it out maybe 6mm( a guess) Otherwise some offset motor mounts would need to be fabbed up pretty easily with a decent workshop.

Or a bit of sanding on the engine case mounts to allow the motor to move over a bit and then spacers on the other side to tighten it back up. Or a bit of both methods to get the most movement.
There may be more to it than I know of.

[Mezo]

Its all been discussed on here & the HUBB, try the search engine (top right) a guy in South Africa did it & explained how.

Or ask Paul how he did it?

Mezo.

[xpag6259]

G'day,

I put a '91 xt600 ex-army motor in my 34L. I used a '91 drive sprocket, reversed it, removed some of the boss and then welded a spacer on the flat side. My first attempt wasn't a complete success, the 'o' ring chain ate in to engine casing and popped all the o rings out of the chain. I made a slight change to the measurements and fitted a std. 520 chain. Had no rubbing issues. When we were in Barnaul, Russia, I changed both sprockets and had to fit an O-ring chain, which fortunately cleared the cases and caused no issues. I'll check in the shed for measurements as my spares are still with the bike in Vladivostok and won't be back here in Melbourne for about 8 weeks.
I have some pics which I will load later.

paul

[xpag6259]

As discussed, these are the pics of the modified sprocket. I don't have the measurements, but from memory, the boss was machined back to the base of the chamfer. The other welded on ring should be equal to the amount removed from the boss.





The area marked in red was the section was the part rubbed away when I was using the 15 tooth sprocket with the O-ring chain. I used a 16 tooth drive sprocket with a 40 rear. This gave 103kph at 4000rpm.

[tall-mike]

I like that gearing myself , motor handles it easily . Only drawback is using your motor for steep down-hill breaking. But cruising from point A to B it's the King. Mike

[Mezo]

So a 520 chain would have cleared the casing Paul? or just grind down that lump beforehand?

Mezo.

[xpag6259]

Mezo,

The o-ring that wore away at the casing was a 'budget' unit and may have been a smidge wider. I increased the welded on ring a 'little' for my next batch of sprockets. The o-ring that i had fitted in Russia was an EK and although I haven't had the time to inspect the case after the last 10,000km, I suspect that it hasn't rubbed.
I noticed a bit of polishing on the outside of the drive sprocket which may indicate that the sprocket is out of alignment with the rear sprocket, and that the rear could be moved outwards by the use of washers/spacers. However the chain then would be getting very close to the frame.

I've done at least 10,000km with the sprockets and chain with no significant wear on any of the components and that included many days on the Pamir Hwy, all dirt and gravel and riding over a big lump of Mongolia. One of my mates on his DR650 did the whole 22,000km on his original stock sprockets and chain.

The Tenere was a great bike to do the trip on. If i hadn't run out of talent and thrown it into a couple of big rocks, it would have completed the journey with very little wear and tear.

paul

[xpag6259]

Mezo,

I forget to mention

going back to the pic showing the worn off section,...... to get more clearance, I did grind away the 2 mounting lugs for the bearing retainer. I also had to make a new bearing retainer that would fit and used countersunk screws.

paul