complete '73 engine rebuild, a few questions

[twinrider]

Hi,

I bought a TX650 1973 a few months ago for 400$, literally a barn find. Needless to say she needed love, lots. I finally took her completely apart 3 weeks ago and I've spent many nights reading on this forum since.

Ran some testings on the engine with a friend mechanic and we realized that it needed a full rebuild. Rockers are shot, valves were leaking badly and cylinders are yet to be measured, but not looking good.

Anyway, now that I have everything apart, a few things are looking a bit suspicious...

1. In his 37 years, chain seems to have broken while riding at good speed and caused a bit of a mess on the left side. Shifter shaft is badly bent and some parts of the casing were ripped off. But theres that thing there (see pic 1) that looks like lead or solder, on a part that look like the end of the shift drum... Any idea of why would anybody use solder there?

2. I have the casing missing parts at hand and would like to have them welded. Is that 1973 casing made out of aluminium or magnesium?

3. I've seen that the cam chain stopper screws (see pic 2) were previously removed and one is stripped badly. There is also a weld slpatter on the side of that part. I was wondering if that is something that is commonly seen there or is it a bubba shop repair?

Looks great after a good beadblasting session!

fresh out of 10 years in a barn, at least...

 

[Sundie]

Yow. That's some bad happenings in the past.

 

[inxs]

1. In his 37 years, chain seems to have broken while riding at good speed and caused a bit of a mess on the left side. Shifter shaft is badly bent and some parts of the casing were ripped off. But theres that thing there (see pic 1) that looks like lead or solder, on a part that look like the end of the shift drum... Any idea of why would anybody use solder there?

- when the shift shaft got bent it may have snagged the shift drum and dropped the plug thats normally in the case out-dont think you can buy them and they may have bodged up a repair

2. I have the casing missing parts at hand and would like to have them welded. Is that 1973 casing made out of aluminium or magnesium?

- alu

3. I've seen that the cam chain stopper screws (see pic 2) were previously removed and one is stripped badly. There is also a weld slpatter on the side of that part. I was wondering if that is something that is commonly seen there or is it a bubba shop repair?

- they may have drilled the rivet to remove or replace the guide without breaking the chain

 

[twinrider]

thanks for the replies,

I will take my casing to a machinist that I know to make the repairs. Is there anyone with a pic of the shifter drum outer end (the broken part in the pics)?

I would like to see how it is in its original shape? that would help my machinist...

 

[inxs]

- thought about getting new cases?...come as a numbered pair

 

[twinrider]

New cases, hum... I doubt I could score any good condition used cases around here easily... I'm in quebec, canada and these bikes are not easy to come by.

most bike mechanics I've spoke about XS650 were all telling me parts were impossible to come by. But that was before I discovered xs650.com and 650rider, and ultimately mikexs...

A complete spare engine would be a godsend, as many many parts have to be changed and my rebuild costs are going up the roof...

Next week, I'm sending my head to have valve seat recut and install new guides...
A friend, who's building serious ATV racing engines, want to do some porting on it as well.

I've read somewhere though that porting the 650 is an art in itself and should be done with care. Maybe just polishing out the surface will be enough, I dont want to affect reliability as this bike will be ridden almost daily...

 

[inxs]

- there were roughly 500,000 bikes built...the largest market was the US...if the statistics are anything like they are here then approx 40 percent are still registered...about 6000 sold here, this year there were 2520 registered

- means that apart from those that have been totally scrapped, there are still a lot of bikes and motors lying around in gardens, sheds, dismantlers etc

 

[Sundie]

A friend, who's building serious ATV racing engines, want to do some porting on it as well.

I've read somewhere though that porting the 650 is an art in itself and should be done with care. Maybe just polishing out the surface will be enough, I dont want to affect reliability as this bike will be ridden almost daily...

IMHO, polishing to remove the rough casting leftovers is all you have to do. A simple flapper wheel on a drill or low speed setting on a dremel/die grinder will do wonders. I'd advise against trying to hog them out larger or taking anything significant out.

 

[Visegrippe]

New cases, hum... I doubt I could score any good condition used cases around here easily... I'm in quebec, canada and these bikes are not easy to come by.

they are out there, though, there's one on kijiji in the west island for a couple hundred as a parts bike, pretty much the same shape i got mine in. i haven't gotten an answer from him though...

but yeah, they're fairly rare here. i think i've only seen one on the road since i've started looking for 'em.

 

[twinrider]

Hey Visegrippe,

Cool to see guys from my neck of the woods here! I will take a little trip to a bike scrapyard close to my place. I hope to find a few jewels, I'm looking for a tank, clipon handlebars, headlight, ultimately a complete engine!

Will my 256 engine parts fit in 447 cases? I doubt I'll find 256 but 447 I think I have a better chance...

will let you know if I find something interesting...

 

[twinrider]

Know what???!!!!

Just missed a 1974 in good working order and quite clean going for 300$!!! noooooooo!

just tell me you bought it Vise! and let split the parts with a XS brother! LOL