Quick make over.......or so I thought.....The ubiquitous XS650 - UK

lchris21

Active Member
DTT BOTM WINNER
After I got it idling, I used my "socially distanced" neighbour to get some video footage of my "unnecessary" journey up and down the street to see what it rode like.............it rode nice but I noticed on the video that it was smoking a bit too much for my liking, still running a bit rich but something a bit more......oily............decided an oil stem valve seal change in-situ was a good shot so made a widget up to do that? The engine had checked out ok for compression and leak-down but it was worth a go anyway. In hindsight I should have learned my lesson from my last builds, and completely teared down the engine for a full once over, but as it was running fine all those years back I decided to gamble.....which has bitten me in the arse
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lchris21

Active Member
DTT BOTM WINNER
Thought Id carry on the thread as even though the bike is finished, there might be some useful information that future builders might be able to use....
..............mid lockdown still nowhere to give it a good run, I took it up a local quiet road and gave it some beans..........it runs surprisingly well, that work mat seat might need some extra padding though ......

After that "spirited run" I as greeted by a bit of an ooze .....................so only one thing for it.........
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lchris21

Active Member
DTT BOTM WINNER
First investigation indicates a common fault with them apparently?,the head gasket loosens over time and leaks oil on the return gallery .....tried re-torquing it but no joy. So whilst Im in there I'll change the rings, as the oil scrapers are on the limit, the bores are good so just a hone for them, the front cam chain guide (another Achilles heel of the design) had made a break for it so that needs attention, plus the two inlet valves are a bit too worn on the tappet end so I ordered a couple of those.............this oil leak has got a bit more serious...................but what else can you do in lock-down. Pain in the rear, but at least it should run better.........
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lchris21

Active Member
DTT BOTM WINNER
Clean up first, the pistons were treated to an ultrasonic clean. Tip I read was to put them in a bag then use the cleaning chemicals in the bag at a higher concentration to enhance the process, worked a treat.

Checked the head out for warpage. Came in at 0.003" which was well within the manual specs of 0.010" so set at trying to get it better with some 650-grit on a flat surface. this was turning into a right ball ache so as I was leaning on the milling machine at the time I decided to put it too good use. Only had a small fly cutter so made one of my boring bars fit and used a CBN tip to get the head as flat as a flat thing.

Also had to order some new inlet valves as the stem heads were looking a bit too worn. Lapped them in with the old cleaned up exhaust valves.

Polished up the cam rockers and got rid of all the grime and paint.

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lchris21

Active Member
DTT BOTM WINNER
Got some new paint on the head and barrels and set about baking them as per the paint manufacturers instructions.............90degC for the head, 200degC for the barrels.......

Whilst I was baking the barrels I heard a noise coming from the oven.........both sleeves had decided to make a break for it ................quite comical really.

Left them all cool down, cleaned up the bits and bobs, reheated then refitted them.....3 times......had to make a clamping jig up in the end to hold them in place while they cooled to prevent the liners creeping. All good and flat again.

Cracked on with the new rings, and checked them against the old ones, and the bores. The old ones were on the limit and the new ones confirmed this.
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lchris21

Active Member
DTT BOTM WINNER
Whilst the head was off, i took the opportunity to get rid of the original rocker shaft covers. They'd seen some screwdriver action over the years and were looking pretty shabby, so I turned up some new ones and broached a hex in the end using an off cut allen key.

Turned my attention to the front cam chain guide which I found lying in the crankcase when I took the head off. Common fault with these apparently? The bonding deteriorates over the years and the wear strip just falls off and sits there, sometimes it falls to pieces and ends up in the oil pump screen, other times its just sits there leaning against the chain. Luckily mine just sat there, and I manged to find all the parts in the crankcase. Ordering a replacement was an option but most suppliers have online virtual queues so as Ive had enough of queuing for groceries lately I ordered a piece of appropriate material (Nylon66+Moly) and made my own. Bonded it in place with some JB weld and belt and braces it with some recessed aluminium rivets...............if it lasts 44 years like the last one, I'll be in my 90's and not that bothered about it next time it fails
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lchris21

Active Member
DTT BOTM WINNER
as they say in the Haynes manual......................assembly is just the reverse of disassembly..........now to get it back in with all them sharp sticky-out bits and no scratches...
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lchris21

Active Member
DTT BOTM WINNER
Managed to get in a more serious shakedown test few weeks ago. Engine is now running well, no more oil leaks and sounds good. Absolute blast to ride, and will sit all day at 50-60mph, ideal for a relaxing country blast.. :) ....project 2 officially finished......Thanks for the input and great comments.....on to the next:cool:

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pidjones

Well-Known Member
Well, I just woke to this, and after going through it I am exhausted already. Good woork and great result. A big old Navy Bravo Zulu to you!
 

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