1978 XS650E "Shakey" Build Log

So this past weekend for fun I thought id throw a can of seafoam in the tank and take her for a rip.
The bikes running great and the only issue was the chainguard falling off of the rear mount on the highway, and I almost lost the license plate (the first one feel off after the first 200k). I'm taking the attitude that if those parts don't want to be on the bike, they can walk!

Hi Simebone,
yeah, BTDT. A week after I bought my XS650 the local RCMP asked me,
Hey Fred, where's your plate?
Bolted to the plate mounting bar on the rear fender?
Look again.
So I did. All that was there were the mounting bolts and two little triangular plate corners.
Um, somewhere on the highway between here and Beausejour?
That's when I learned why absolutely every part of an XS650 except the engine was rubber mounted.
As your plate and chainguard should have been.
Flat rubber kitchen tap washers from Canadian Tire will be your friend here.
 
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Oil consumption was starting to get a little extreme (about 250ml/100km) so I pulled the engine out and changed the valve stem seals and head gasket, as well I cleaned up the valves and tops of the pistons with a wire wheel.
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After knocking off the carbon build up all the components looked new. No scoring on the cam, rockers or pistons.

One of the engine mounting bolts had sheared off (rear bottom) so I made up a new bolt by threading 10mm rod.

I installed the head gasket dry, and used yamabond 4 on the valve cover.

It was actually pretty easy to do considering this was my first time working in the inside of the engine. The key tool was the c clamp style valve compressor from Princess Auto ($60).

Took her for a 100k rip this morning and motor runs and sounds way better.
 
Put 200km on the bike in the last couple days. Oil went from top marker to halfway.

Could this be a matter of retorquing the head bolts? I can't seem to figure out where this oil is going! The bike doesn't have any visible oil leaks so it must be burning up.

Any suggestions?
 
Dry head gasket may be the problem. Your head gasket may be passing oil from the camchain tunnel into the cylinders. Its highly recommended to use a sealant such as Threebond 1104 or similar on the head gasket. Run a small bead around the camchain tunnel and the 4 outer studs. Put sealant on both sides of gasket.
I suspect your plugs turn black very quickly.

I had the same problem about 9 years ago. I did a top end re-build using Threebond 1104 as mentioned, and my engine has run perfect ever since.
Be sure to use 30 ft-lbs torque on the large studs, and re-torque a couple of times after 100 kms and 200 kms.
 
It could simply be a matter of putting too much oil in the motor. Yamaha recommends running the oil level half way between the high and low marks on the dip stick. If you put more in, it can blow out the breather. Keep an eye on it now that it is at the half way mark. Hopefully it won't continue to go down.
 
Good point by 5twins. Clean the spark plugs really well, and then monitor the plugs as you put on some kms/miles. If the head gasket is passing oil, the plugs will turn black very quickly.
 
Thanks guys, I retourqued again after about 200km, and I'll keep an eye on the oil consumption. Is it wishful thinking that another retourque in a couple hundred km will fix this, or am I delaying the inevitable?
 
Stuff that broke this week or What is dead may never die.
1) I'M ROLLIN' COAL!

Well it's been 2 weeks and the bike is smoking like a bastard again.
New head gasket on order. I'll replace that first, then run it. If it's still smokin' I'll re-replace the valve seals again.
I'm planning on installing with permatex copper spray this time.
Any thoughts on that vs. yamabond on the head gasket?
Are there any pictures of where to apply sealant to the gasket?

2) I've also developed an electrical problem in the gauge cluster where around 60+kph the red 'Brake' light starts flashing. Pretty sure its the connection to the brake lever that's the issue.
 
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This Sunday I pulled the motor to take a look at what's causing my oil consumption.

I started with a compression test: (Cold) Left 110, Right 90. I planned on checking warm, but the bike wouldn't start (Great!)
Then I connected a compressor to the engine to see if I could hear air escaping. TDC on both cylinders (I also loosened the tappets to ensure the valves were a closed as possible), I could hear air from the exhaust, with the right cylinder being louder. I could also hear a bit of air in the crankcase by listening through the oil filler.

I pulled the motor (57 minutes, a new personal best!), and connected the compressor to the motor on the bench and found that the right cylinder was definitely not sealing well. I'm hoping its some stuck carbon, but I think I'll try lapping the valves anyway
Check the white (right exhaust valve) and how greasy that head gasket was around the cam tunnel and front of the motor.
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I took my cylinder head into a machine shop to check for warping, the head is straight and doesn't need to be skimmed.
The intake valves had a nice shiny metal ring where they sat, however the exhaust valves were covered in a lot of carbon, as were the valve seats. This seems to help explain the air loss out of the exhaust when I pressurized the cylinder. I will be lapping the valves and installing the new head gasket this weekend assuming I don't break anything else.
 
The cylinder deck looked alright to me (I didn't take it in), but I did use a straight edge and a flashlight and there seemed to be a slight convexity around the cam chain tunnel (less then 0.10mm checked with my feeler gauge), otherwise it looked pretty darn good.

Last night I lapped the valves and put 3 good coats of permatex copper spray on the head gasket, and put everything back together. After torquing everything down and setting the valve gaps, I checked for air leaks in each cylinder by pressurizing through the spark plug hole with my compressor. Before tearing it down you could feel air leaking from both exhaust ports, now you couldn't hear it with a stethescope let alone feel it . . I'm going to retourque again after work, and put the motor in the bike tomorrow. I'm cautiously optimistic that I may have a working bike this weekend.

As a sweet bonus I found a set of rear turn signals WITH mounting brackets that I bought locally for $40!!!
 
Everything's together, and the bike started on the first couple cranks!

Except now oil is leaking out of the exhaust the engine is misfiring and I can't get advance.

I've actually made it worse. FML.
It may be time to cut my losses here.
 
Compression test:
Cold engine, sitting for 2 days.
Carbs off. Exhaust headers off. Both plugs out.
10 kicks with the kick starter
Left: 60 90 110..140
Right:60 85, 100..138
Left max ( kicked until stopped rising):140
Right max (kicked until stopped rising):142
 
Should be done on a warm engine that's been recently run.

There's two kinds of compression readings, ones that take several cycles to come up to max reading, and ones that come up to max reading quickly. Then, of course, there's the final reading itself. Yours appears to be the 'comes up slowly' type. Do the 'squirt oil around rings' thing, then repeat your compression test. Note any difference.

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Should be done on a warm engine that's been recently run.

There's two kinds of compression readings, ones that take several cycles to come up to max reading, and ones that come up to max reading quickly. Then, of course, there's the final reading itself. Yours appears to be the 'comes up slowly' type. Do the 'squirt oil around rings' thing, then repeat your compression test. Note any difference.

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Thanks. The bike isn't running well, so I'm reluctant to warm the motor and risk further damaging it. Oil leaks out of the right exhaust header, and sprays oil and a plume of white smoke out of the exhaust pipes when running. I have to assume cold compression is worse than warm, so these results seem ok for a baseline. I'm pulling the motor and checking the top end again to try to determine what I broke now.

3rd time for sure this time.
 
Simebone : boy that bike has been giving you Hell ! Most are not that onery ! rest asured that if and when you get it figured out it'll be like a new bike ! simply because you've fixed everything ON IT !!!!!!!
.... I wish I could offer some cure to Oil out the exhaust other than RINGS... but I can't .... you could be lucky and it be head gasket leaking really bad this time.... as the last one looked like it seated fairly well almost all the way around except the cam chain airea...
... if you take the engine apart Please put new rings in it ! ....
and you might try a Head gasket from Yamaha as they are reported to be thicker than the ones from Mikes.
....
good luck !
.....
Bob.........
 
Took apart the engine again to take some measurements and see if there is any apparent cause.
Cam chain guide looking rough:
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Head gasket looked great. The copper spray made a great seal that was easy to clean off with brake cleaner. No oil here.
The pistons looks good. No scratches, nice and smooth.
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Measurments with digital caliper and bore gauge:
L mm R mm
Top F/B 74.96 74.93
Top L/R 74.72 74.90
Mid F/B 74.96 74.98
Mid L/R 74.94 74.95
Bottom F/B 74.96 74.95
Bottom L/R 74.92 74.93

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Checked and measured the rings. The Left Rings were almost overlapped, coinciding with the cyclinder with the oil problem. The end gaps were checked an all were midrange at on average 0.50mm. The ring landing gaps were all<0.06mm

Wierdness: The top ring was smaller than the middle ring on both cylinders. Also, only the middle ring was stamped with 'R'.

Thickness Width
Top Ring 1.12mm 2.86mm
Mid Ring 1.44mm 3.64
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Any thoughts or reason for the variance in size?
I managed to snap both sets trying to reinstall (HAHAHHAHA) I was getting new rings anyways.

Here's my list:
Top End Gasket kit
Airbox band clamps
Cam Chain Guide
Rings (standard size) 2 sets
 
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Interesting ! the rings on the right cylinder are almost lined up if they came out of the cylinder that way that's probably SOME of the problem!
it looks to me as if those rings are passing compression, or at least some you can tell by the dark streaks down the piston toward the skirt.( this is a Matter of interpretation others will have different ideas on the coloration ,like too hot on one side)
I think I would measure the bore in a bunch of different places from top to bottom and write it down... see if there is tapered or oval to the cylinders.... it may need re-bored if so.
...I have also had excellent luck with copper-coat on head gaskets... even on warped heads I knew were bad and needed shaved !
....
do the rings stick to the piston in any places ? with all the carbon you had in the top end it's almost a given that the ring grooves will need cleaned too ( piston ring groove cleaner) that in it self could cure the low compression on the one side.
.....Also...stuff some clean rags under the piston to keep out things from falling in the bottom end !!!!! that's a MUST !!!!!!!.... piston pin clips can fall in there and you'll play hell getting them out again !
.....
Bob.......
 
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