Compression release rubbing cylinder head cover and gasket

[Ghost25]

I have a 2004 KLR650 that I bought about a year ago. I haven't ridden it much and I haven't done too much work on it besides some fluid changes and basic maintenance.

I finally got around to replacing the cylinder head gasket because it was leaking oil. I was adding quite a bit of oil and figured since I knew it was leaking there that would be the first thing to address.

When I pulled off the cover I saw the inside portion above the compression release was badly scored, the gasket groove was broken, and the gasket was chewed up. What do I do? Do I need to replace the compression release spring? Someone I talked to thought there might be a problem with the chain tensioner. My Clymer manual doesn't really go into servicing the compression release except to identify it.

Apparently some people call it the KACR (Kawasaki Automatic Compression Release) and some people remove it, but doing so may cause some issues with kickback when starting.

I obviously need a new cover.

https://i.imgur.com/QHFp9xo.jpg?1
https://i.imgur.com/zaBAiyj.jpg
https://i.imgur.com/hF8dXDI.jpg
https://i.imgur.com/0rOV81K.jpg
https://i.imgur.com/WARaM1s.jpg

[stinkwheel]

I have no idea how it works but it looks a little like a mechanical ignition advancer like you'd get on a points bike so presumably the exhaust valve timing is slightly advanced when it's spinning slowly and when it spins faster, a little weight flys out against that small spring which causes something in the assembly to rotate and sets the timing to normal.

If that's the case, it suggests there is a stop somewhere that is damaged or defective, allowing the weight to fly out further than it should (and possibly over-retarding the valve timing in the process). On mechanical ignition advancers, there is usually an oval hole that runs on a pin. One end of the oval is the fully in position, the other end is fully out. If there is such a hole, I wonder if it's worn or if the pin is bent.

A simpler thought might be that someone has used a sub-standard or incorrect rocker cover gasket that's too thin...

Another simple thought would be a loose cam cap, but that should make a godawful racket..
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[stinkwheel]

My guess was close. Found this video. it doesn't alter the cam timing, just the position of a little steel rod that pops the valve open at low rev speeds. The bob weights flying out in a grooved hole was on the money though, very like a mechanical ignition advancer.
https://youtu.be/K-i8PvkjCT4

Interestingly, on that video, the bit that's striking seems to be sticking up higher when the weights are being pulled in by the spring (ie at low revs), it should drop down when the engine is running more quickly and the weights fly out (really anything faster than the starter motor can turn it).

I wonder if the mechanism is sticking.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[MaybeGuy]

They're a governer style decompression system.

I'd be removing it. Seems to me like the part which limits how far the inertial forces can throw the weight is worn out, allowing it to flail around in there.
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Blue_SV650S wrote: it was a sh1te wheelie, but it proves that he can get it up in 3rd and can do angles. In summery, mattsprattuk is a gobby little sh1tebag, dopehead tw4t, but sadly for all of us, he probably isn't THAT full of sh1te!!
Kickstart wrote: Hi I tend to agree with Matt. All the best Keith

[jeffyjeff]

[jaffa90]

https://www.klrforum.com/threads/acr-failed-and-broke-the-valve-cover.46369/

https://www.youtube.com/watch?v=K-i8PvkjCT4

I had a KLR 650, my problem was short legs.

[Easy-X]

With regards to the cam cover this might be one of those times where "dab it with some JB Weld" will do, once you sort out / delete the compression weight issue obviously. Specifically I'd go with the "metal putty" type of epoxy. It shouldn't be a pressured area so the putty won't need to really do much.

Cleaning up & filling the top gouge should be straightforward but that gasket valley Push in or file the edges of the hole so they don't impinge the gasket rubber and drop in a little flat piece of tin foil to cover the hole and as wall reinforcement. If you can find something like a drill bit the same diameter as the width of the valley to hold it in place so much the better, then slap on the putty. Bit of patience in the clean-up / reshaping but you might never know there was any damage
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Royal Enfield Continental GT 535, Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[Robby]

So when the decompressor is working, it puts a bit less strain on the starter motor. When it isn't working, it chews up your rocker cover and throws slivers of metal at the camshaft.

Starter motor brushes are cheaper, and easier to change, than camshafts.

[jaffa90]

[jeffyjeff]

Judging from the exploded view, it appears the compression release only comes as a complete assembly. That should simplify the repair, if not the diagnosis. One would expect that the flyweight's arc of travel would be limited mechanically. Something is either worn beyond tolerance or broken, allowing the rotating weights to contact the valve cover.

That mechanism also appears to be among the last components to receive lubrication on cold start. Upon completion of repair, might be worthwhile to investigate oil flow to the top end. The knackered compression release could be the symptom of an underlying problem. Run the engine briefly sans valve covers. You'll probably get oil slinging off the cam chain, but you should see oil flow out from between the cam journals and cam caps. You'll make a mess, but if you start with a cold engine, you'll gain an appreciation for how long it takes the oil to migrate to the far reaches of the lube system.
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History shows again and again how nature points out the folly of men - BOC

[stinkwheel]

This is why kickstarts were a good idea. On a cold start, you could turn it over compression with the kickstart before engaging the starter motor.

Enfield came up with a novel solution to this problem when their bikes kept killing sprag clutches. They fitted a "black box" that dumps the first spark so it won't fire until the second revolution, thereby almost totally eliminating the chances of a kickback.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[Tankie]

I think i would be looking for the cause, like maybe the cam bearings have failed on that end of the camshafts!
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Always learning, everyday is a school day

[Easy-X]

Isn't kickback more a 2-stroke thing? Does it / can it happen much on a 4-stroke?
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Royal Enfield Continental GT 535, Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[wr6133]

[Nobby the Bastard]

[redeem ouzzer]

[Robby]

[jeffyjeff]

[Nobby the Bastard]

[jaffa90]

I`ve had a few kick backs starting with a 750 Norton Commando and a Enfield 550.

[stinkwheel]

My 612 enfield can and will hurt you if you prod half hartedly at the kickstart and don't hold it at the bottom of the swing with each kick untl it had decided to start or not to start.

Two bikes legendary for kicking back violently and frequently were the slope-engine Panther 650 and the Yamaha XT500. Panthers are reputed to have broken peoples legs if they forgot to retard the ignition for a cold start.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[Easy-X]

[Nobby the Bastard]

I've only heard of engines running backwards as something that could happen and its usually people who fucked Jordan that reckoned it happened to them.

A 500 or 650 single 2t will kick back to a extent but not compared to a Vincent.....
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Triumph Sprint ST 1050

[jeffyjeff]

It is quite easy for a two stroke engine to run backwards. Since it is the vertical movement of the piston that causes aspiration and exhaust, direction of crank rotation is irrelevant.

A 4T engine, not possible since engine breathing and exhaust are a function of camshaft-valve action. The camshaft must be turning in the correct rotation for intake to be drawn in through the throttle body or carburetor. Turning backwards would draw air in through the muffler and exhaust it through the throttle body and out the air filter. Where's the fun in that?.
____________________
History shows again and again how nature points out the folly of men - BOC

[Nobby the Bastard]