Doms XS650B US import

Dom

XS650 Junkie
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I've decided to go back in time to document the restoration of my 1975 XS650B US import so that I can keep everything in one place as a reference for myself and others with this model. It might take a while to work back from where I started and I will likely get things on the wrong order to which they occurred.
 
This is how it arrived with me when I got it, the previous owner bought it to ride in all weathers to preserve his other bikes from the salty British roads in winter. It was pretty grim although the photos don't really do justice to the levels of road grime and grease build up around the engine, the gauges are a real mess with mismatched items from a 650b and and RD350. Most bolts and fixings are a bit corroded and wiring is all there but in a mess so long term a new loom is needed I think, the forks are leaking badly and the front brake might as well not be there. On the plus side it came with a huge box of parts including brand new fork stantions and seals.
 

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I spent the next few weekends cleaning up sand and dried mud from between the fins which had fully blocked some of the gaps between the two cylinders, some kind of Mason bee had built mud nests in some of the pockets.

I repaired and corrected the wiring to the broken run switch using a spare used one that came with the bike, the headlight wiring is horrendous as is most of the loom but everything is present and working as far as I can tell.
 

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Although I've been told it had recently had an oil change I didn't want to rely in that so did a full service and filter clean, both filters were new but did have a few bits of fine swarf. I made a stainless filter guard from a damaged length of twin wall flue liner I had lying around, being quite a thin gauge I was able to trim it with snips easily and shape.

After I'd finished I took it out for a bit of a ride, my first real ride on it for and distance but still only 30 miles or so. It showed up a stalling issue when coming to a stop at junctions which became annoying and a but dangerous so I headed home to as the advice of you knowledgeable folk.
 

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Next up was sorting the stalling, having researched on here and being directed to the Tech section I decided to start right at the beginning, I have the Yamaha maintenance manual and a Haynes that I bought prior to purchasing this bike. Cross referencing the two and the Tech section on here means making a mistake highly unlikely. I adjusted the cam chain, a pretty straightforward task, then set the valve clearances which is a little more fiddly as tightening the lock nut altered the gap ever so slightly even when held with the Yamaha valve spanner.
Once I was happy with the clearances on both inlet and outlet valves I tried to adjust the points gap, I struggled with this more because I wasn't consistently counter clockwise rotating the crank. Cutting a long story short it turned out my points had pitted badly so I replaced with yet more items from my free parts box! Once I'd set the timing correctly and checked it with a timing light my bike went from an ankle snapper to dead easy to start. Result!
 
Forking awful!

Both fork seals were leaking, the left side very badly and both dust boots were split and taped up with self amalgamating tape, they were a sight for sore eyes!

Obviously these are the skinny 34mm forks and again I had all the necessary spares thanks to the PO except for the fork oil weight I planned on using. I stripped down each leg and removed the damper rod with a modified(butchered) socket on various extension bars. While it was out I took the plunge, I read up on the Minton mod which it appears has not been done to 34mm forks...well it has now! Time will tell if its an improvement but in all honesty they couldn't be much worse than they started out.

When I drained each leg the left had roughly half the amount that I should have due to the severity of the leak. Some heavy handed idiot has taken the lip off the right lower leg but thankfully it seems to have enough left to seal.
 

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Overhauling the brakes was very much needed, I decided to keep the stock master cylinder, caliper and disc but replace the leaking and worn rubber hoses with braided lines which I had custom made by BRT motorsport in Scotland. Great service and significantly cheaper than most of the big names.

I stripped the master cylinder to find it in very good condition, the same couldn't be said of the caliper which had seized pistons. I removed them eventually but surprisingly the seals were in good enough condition that I declined to reuse them for now at least.

I wanted to drill the discs to try and add a bit of bite, to clean up the pad face and, well it looks nice! It's definitely an advantage to have nice sharp cobalt bits and a piller drill for this.
 

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The gauges on this bike had bugged me from the very first time I went to view it, after seeking opinions on here it was decided I have an RD350 rev counter in an RD350 gauge bracket but the correct xs650b speedo so at least the mileage may be correct. Eventually I found a replacement xs650b rev counter for £25 which I thought was a bargain considering I'd been looking for weeks and some of the breakers on Ebay wanted silly money.
New gauge faces and dash fascia were ordered from Classic Gauges to fit the slightly different RD350 bracket. Once fitted the faces looked amazing but the fascia didn't live up to expectation, it's made of far thinner material than the gauge faces, poor finish and the cutouts didn't align. Classic Gauges response was that I should get my scalpel out?! Not what I expected as a response so I've decided to make my own at some point.
 

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One of my carbs was leaking from the drain screw, I whipped it off to find a fair amount of sediment sloshing around so I removed both carbs for a bit of attention. They are pretty grimey so I think it's very much overdue.

The jets and needle are all the same spec as they would have left the factory except for some rough screwdriver treatment, needles have a bit of wear but until I find some new ones I'll refit them.

Once the carbs were removed I instantly saw why I think I'd been having popping from the left cylinder, the carb boots are perished and have been letting air in.

Is there a reason the diaphragms sit at a slight angle in the carb?
 

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Is there a reason the diaphragms sit at a slight angle in the carb?
The bottom back of the slide on '77 and earlier carbs has an angled cutaway
BS38 SLIDE EARLY.jpg
 
The pic looks ok. The position of that cutaway is dictated by the tab on the diaphragm. It's possible that is off a bit, especially if someone replaced diaphragms:shrug:
 
Yesterday I polished the tops to my carbs and fitted stainless socket head bolts and spring washers, such a small thing has made quite an improvement to the look of them.

I had ordered new carb boots from Yambits to replace my perished ones, although not mentioned on their website I was pleased to see they are Tour Max. I've decided to leave a complete strip down to get the frame powdercoated until I have more room to do it so I cracked on and refitted the newly painted battery box, it's an easy job once you've done it once before. With everything back together and carbs at factory settings I turned the petcocks on and kicked it over, started on the second kick! Very happy with that, and the popping on the left cylinder would appear to be gone, it must have been the air leak from the carb boot.

Today I will try and sync the carbs and fettle with the idle, it's a bit wet to get out on it to fully tune them but already it is a vast improvement.
 
Very little progress lately...the World Cup has started so everything goes out of the window!

I'm still debating stripping it to the bare frame but can't decide A. If it's really necessary B. If I do whether I go powdercoat or rattle can or even get it sprayed professionally.
 
Looks good, I’ve been through same process with a ‘75 like yours. If you go down to the frame, I would watch out for powder coating, unless the company / guy you chose know what he does. I have done it on older bikes than these, with various results. One problem I have run into in general is hard to get a good ground unless you leave some areas with bare metal and also “clogged” bolt holes making it hard to get the intended bolts through. I’ve officially reverted to good old fashion paint to avoid the agony. :)
 
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