Doms XS650B US import

Had to sell my old girl about a month ago! After 20 years of ownership I decided it was time for it to move on to a new home. Its new owner promised to do as the OP Dom has done, and make a complete resto of the thing, so I don't feel too bad. Plus I now have sufficient funds to start a full 'frame-up' build using all 'spare' parts I've collected over the past 25 years of XS650 involvement. This will probably be my last Hurrah in the XS650 world, but a fitting departure. Dom, Damn nice Job!!
 

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Thanks, let's hope it stops a bit quicker than it did before! I have overhauled the entire front brakes and master cylinder, I'd rather keep it original so a smaller diameter master cylinder isn't really an option- unless there is one in the same style used on another Yam?
 
Dom said:
Thanks, let's hope it stops a bit quicker than it did before! I have overhauled the entire front brakes and master cylinder, I'd rather keep it original so a smaller diameter master cylinder isn't really an option- unless there is one in the same style used on another Yam?
Click to expand...

I know a lot of guys swear by a smaller master cylinder, but I’ve never had a problem with the stock set up. The only upgrade I did was add a steel braid brake line , and I could always stop hard with just two fingers on the lever.
 
My lever has a fair amount of slop before contacting the master cylinder plunger, that's with the adjustment screw fully adjusted. It makes for a not very nice feeling action.
 
Dom said:
Thanks, let's hope it stops a bit quicker than it did before! I have overhauled the entire front brakes and master cylinder, I'd rather keep it original so a smaller diameter master cylinder isn't really an option- unless there is one in the same style used on another Yam?
Click to expand...
The smaller Ø master cylinder fitted on Miss November was listed by MCP for RD250 or RD200 so it's Yamaha style and the mirror thread matches other Yamaha fittings. Huge improvement over the original. That felt wooden and just awful, now the brake has much more feel and I can really pin the front end to the tarmac.
 
Raymond said:
The smaller Ø master cylinder fitted on Miss November was listed by MCP for RD250 or RD200 so it's Yamaha style and the mirror thread matches other Yamaha fittings. Huge improvement over the original. That felt wooden and just awful, now the brake has much more feel and I can really pin the front end to the tarmac.
Click to expand...
I've googled mcp but so many places come up. Do you have a link?
 
Raymond said:
The smaller Ø master cylinder fitted on Miss November was listed by MCP for RD250 or RD200 so it's Yamaha style and the mirror thread matches other Yamaha fittings. Huge improvement over the original. That felt wooden and just awful, now the brake has much more feel and I can really pin the front end to the tarmac.
Click to expand...
I've googled mcp but so many places come up. Do you have a link?
 
I've just been for a short test ride, all pretty good really except the brakes do need looking at they arent good at all. Ive spotted a litle weep that seems to be coming from the head gasket, probably be sorted by torquing the head bolts as I've not done them, are there any recommended revised torque specs on these or just within the range in the manual?
 
The only "revision" I do on the head bolt torques is raise the value slightly on the 8 large acorn nuts. The book calls for 26 or 27 ft/lbs and I go 28 to 30. I start with 28 but will go as high as 30 if there are still small leaks. If it still leaks after that then well, it's head gasket replacement time, lol. The one on my '78 has gone bad and no amount of retorques have fixed it. I even went up to 35 pounds and all that did was stress the studs. I could feel them stretching, lol, and it still leaked. That's why I limit my max to 30 pounds now.

Yes, drilling the disc should improve even the dry weather braking a little. I noticed this on my '83 when I swapped on a drilled disc to replace the original solid one.

NewWheelMounted6.jpg
 
5twins said:
The only "revision" I do on the head bolt torques is raise the value slightly on the 8 large acorn nuts. The book calls for 26 or 27 ft/lbs and I go 28 to 30. I start with 28 but will go as high as 30 if there are still small leaks. If it still leaks after that then well, it's head gasket replacement time, lol. The one on my '78 has gone bad and no amount of retorques have fixed it. I even went up to 35 pounds and all that did was stress the studs. I could feel them stretching, lol, and it still leaked. That's why I limit my max to 30 pounds now.

Yes, drilling the disc should improve even the dry weather braking a little. I noticed this on my '83 when I swapped on a drilled disc to replace the original solid one.

View attachment 241862
Click to expand...
Tganks @5twins ,I presume I need to get the top engine mount off to get to the inner nuts. I've done the drilled disc mod and braided lines but in a fairness the pads are probably not that new, there's plenty of meat on them but I'd say they are ancient. Other than that I think the MC is the limiting factor.
 
Yes, the top motor mount will need to come off. Something else I'll mention is that I've discovered that the factory lock nuts don't grab as well after a few removals and installs. So, I add lock washers to them, nothing special, just a regular split ring type. And when doing the retorque, don't forget the two bolts under the spark plugs. They are part of the head gasket bolt pattern. The other 4 smaller M8 bolts on top of the head are not, so you needn't do those.
 
5twins said:
The only "revision" I do on the head bolt torques is raise the value slightly on the 8 large acorn nuts. The book calls for 26 or 27 ft/lbs and I go 28 to 30. I start with 28 but will go as high as 30 if there are still small leaks. If it still leaks after that then well, it's head gasket replacement time, lol. The one on my '78 has gone bad and no amount of retorques have fixed it. I even went up to 35 pounds and all that did was stress the studs. I could feel them stretching, lol, and it still leaked. That's why I limit my max to 30 pounds now.

Yes, drilling the disc should improve even the dry weather braking a little. I noticed this on my '83 when I swapped on a drilled disc to replace the original solid one.

View attachment 241862
Click to expand...
Thanks @5twins ,I presume I need to get the top engine mount off to get to the inner nuts. I've done the drilled disc mod and braided lines but in a fairness the pads are probably not that new, there's plenty of meat on them but I'd say they are ancient. Other than that I think the MC is the limiting factor.

Would new copper washers be a good idea at this point?
 
If you've never changed the 4 outside rubber/metal washers to copper then yes, this would be a good time for that. Once I change them, I rarely replace them again. I suppose I might if I tore it down again for another rebuild but I don't for just all these routine re-torques.

ButtonHeads.jpg


Just make sure the copper washers you choose are thick enough or the acorn nuts may bottom out on the stud before the head is torqued down tight enough. You want washers at least 2mm thick.
 
5twins said:
If you've never changed the 4 outside rubber/metal washers to copper then yes, this would be a good time for that. Once I change them, I rarely replace them again. I suppose I might if I tore it down again for another rebuild but I don't for just all these routine re-torques.
Click to expand...
Final question I promise! What size copper washers?
 

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