Recommendations

[99orton]

I have a 1980 Special I picked up cheap enough but it has no compression in 1 cylinder. It is a really clean bike so I can't decide on fixing it or parting it out. I'm not very experienced with engine internals so I am leary of trying to repair it. How tough is it to tear into one of these motors?

 

[5twins]

I don't think they're hard to work on at all. Most need to come apart anyway for cam chain and front guide. That one's in nice enough shape that I would fix it. Is the one in the background yours as well?

 

[Belle]

Whenever I look at a motorcycle I see a really cool, great big 3D puzzle. I love puzzles. If you don't it can be a PITA & you're likely to quit it losing good hard earned $. There are those that will do a complete rebuild for ya & ya can go & enjoy the sounds of the atmosphere at your leisure.
No BS.
Think clearly about..YOU...
You'll need tools.
Not very hard but, also, not very easy. If it were everyone would be able to do it--not everyone can draw a straight line even with a straight edge.

 

[99orton]

I don't think they're hard to work on at all. Most need to come apart anyway for cam chain and front guide. That one's in nice enough shape that I would fix it. Is the one in the background yours as well?

I do have mechanical ability, just never got into motors really. the black one is nice. I picked them both up at the same time. The green one is on the local C/L now.

 

[Royboy]

You stated "no compression". Really? If so, look for a hung valve, even shitty rings have some compression.

 

[99orton]

You stated "no compression". Really? If so, look for a hung valve, even shitty rings have some compression.

Yep, Nada. The right side is at 130.

 

[XSLeo]

A vale stuck open would be the first thimng to check. Pull the valve adjuster covers, watch the valves work as you turn the engine over. Do they all seem to work ok, as in move all the way down and back up?
If they all lokk godlook in through the sparkplug hole on the no compression side with the piston near to a TDC. You may find a holed piston.
Nothing to hard to fix.
Leo

 

[99orton]

A vale stuck open would be the first thimng to check. Pull the valve adjuster covers, watch the valves work as you turn the engine over. Do they all seem to work ok, as in move all the way down and back up?
If they all lokk godlook in through the sparkplug hole on the no compression side with the piston near to a TDC. You may find a holed piston.
Nothing to hard to fix.
Leo

Ok, the green one is gone and I have decided to try and repair the motor on the black one. Nothing ventured nothing gained eh? Are there any special tools I need to tear down, repair and reassemble besides a torque wrench?

 

[pregrid]

Gotta ask ya, are you mechanically inclined? Is your tool box too big to carry in one hand? If yes to both, first get a manual and rear it cover to cover. There is a ton of information on this site if you look. Take your time, pay attention to what you're doing and it can be done.

 

[Firerunner]

If I were you, I would pull the spark plug on the offending hole and take a look inside with the piston at the top, or nearly the top of the stroke. You might tap around a bit with a clean screwdriver as well. If you see or feel a big hole, then it is rebuild time.

 

[99orton]

Gotta ask ya, are you mechanically inclined? Is your tool box too big to carry in one hand? If yes to both, first get a manual and rear it cover to cover. There is a ton of information on this site if you look. Take your time, pay attention to what you're doing and it can be done.

Which tool box? The one full of Snap on tools or the one with all the other tools? With 40 years experience as a RV Technician/ Service manager I would say I am mechanically inclined. I just never have messed much with the internals of a motor. I do have a manual and have been reading the tech section.

 

[99orton]

If I were you, I would pull the spark plug on the offending hole and take a look inside with the piston at the top, or nearly the top of the stroke. You might tap around a bit with a clean screwdriver as well. If you see or feel a big hole, then it is rebuild time.

I have checked the valves thru the plug hole and with the tappet covers removed and they are moving. I also probed around thru the plug hole with a screwdriver and couldn't feel anything like a hole. Gonna have to pull the head I guess and go from there.

 

[5twins]

I guess a torque wrench would be the main "special" tool required. A lapping stick and valve lapping compound would be required for lapping in the valves. That stuff's cheap though, about $10. Parts will run a few hundred dollars (gaskets, rings, cam chain, front cam chain guide), more if you need a piston. That may seem like a lot but is probably half what it would cost to pay someone for the work.

 

[5twins]

Have you checked valve clearances? There's a chance one has tightened up and is open slightly.

 

[XSLeo]

A hand impact wrench is a handy tool. Better than a power impact for working with Phillips head screws.
Leo

 

[TwoJugs]

I would think that 0 compression will give a big clue fast. As mentioned, if the valve rockers are moving are they too tight leaving a valve or so loose that a bent valve is sticking? Is the piston moving, broken rod? Take off the exhaust and carbs since you will need to anyway with a rebuild. Look inside at the valves. Look in the sparkplug hole for piston movement.

 

[99orton]

Have you checked valve clearances? There's a chance one has tightened up and is open slightly.

I pulled the motor and removed the head. After removing the valves I found a bent intake valve on the left side. It must not have been closing completely causing zero compression. You can also see where it was just barely nicking the piston.

 

[5twins]

Well, there you go. One new (or good used) replacement valve and you should be all set. I helped a kid replace a bent valve in his Virago last summer. We stuck a good used SR500 valve (same part #) I had laying around in there and he's good to go. The shop wanted $1000 to $1100 for the job, we did it for about $100.

 

[99orton]

Well, there you go. One new (or good used) replacement valve and you should be all set. I helped a kid replace a bent valve in his Virago last summer. We stuck a good used SR500 valve (same part #) I had laying around in there and he's good to go. The shop wanted $1000 to $1100 for the job, we did it for about $100.

Shouldn't be too bad. I need to replace the cam chain guide but Mike's is O/S and so is 650 Central. So it might be awhile before I can put it back together. Any ideas where else to get one?

 

[5twins]

No, just about everybody's out of them. This happened before a couple years ago. I told myself to order a couple when they became available again, even though I didn't need them at the moment, but I never did.