help! 1983 gs450 left side COLD

[dickidav]

i just did the valves today and there is no compression on the left side. in fact if the plug is out the bike runs great. if i put the compression tester on it or put the plug in it dies and won't start. i'm confused. please help.

[tkent02]

What did you do to the valves and how did it run before that?

[Nessism]

Check spark on the dead side by putting a plug in the socket and laying the plug against the engine. Sounds like you have a cylinder that is not firing either due to carb or spark problems and when you put the plug back in the extra compression is causing the engine to die.

[dickidav]

i checked the plug laying on the fin and there is spark.

[Nessism]

i checked the plug laying on the fin and there is spark.

Next is to remove the carb drain plug on the bottom of the float bowl (see if there is any gas inside). Also, as Tkent asked, did the bike run properly before the recent work was done?

One other question: what makes you think there is no compression on one side?

[dickidav]

there is gas, ithe bike wouldn't run on the left before the valve check. i checked the valves with a feeler set and swapped out the ones to make it in spec. i used a compression guage and the right side was at 120 the left nothing. i checked the coil by switching them and no difference.
you can feel air comming out the plug hole but if you put anything in it it will stall

[tkent02]

If you have zero compression, you must have a burnt valve, or a hole in the piston. Even very badly worn rings or valves would still have a little bit of compression. Could also be a chunk out of the headgasket.
Look in the spark plug hole with a flashlight, can you see any damage?
Do the valves seem to be opening and closing correctly?

[dickidav]

just looked in hole don't see anything out of the ordinary.the only part of the valves i can see is the part where the shim is. they seem to be going up and down ok

[chef1366]

Unless the cam timing is off you should have compression.
Put a little oil in the cylinder and see if you get compression. If the timing is right and the oil doesn't get any compression you either have a burnt, stuck or bent valve.
If you do get compression I'd say you have a broken ring.

[dickidav]

i put oil in and still no compression. the timing is set on this bike.

[chef1366]

I'm talking about the cam chain timing from the crank to the cams.

[dickidav]

don't know how to find out if the cam timing is off.

[chef1366]

You have to take off the valve cover and the ignition cover.
There are timing marks on the cams and crank trigger.

[dickidav]

now i AM confused. total newbie for all of this.

[chef1366]

Under the ignition cover there are timing marks. Turn the motor till you find TDC 1 and line up the marks.
With the valve cover off look at the exhaust cam. The #1 mark should be pointing straight at the top of the head. #2 will be facing up and #3 on the intake cam will be 18 link pins between #2 and #3. This also includes the links directly over the arrows.