1986 FZ600 Problems turning over

[scspiegel]

It all started with the bike not starting and when I would press the ignition, there would just be a click and nothing would happen. I've gone through and checked everything in the ignition system and everything is working properly (even rebuilt the starter motor) and nothing helped.

Eventually I took the clutch cover off trying to gain access to the starter clutch assembly in case that was the issue. In that process I (not sure why) decided to try to turn over the motor manually by using the bolt securing the primary gear in place (I realize I probably shouldn't have been doing this).

From this, I was able to find that the motor wasn't starting because at a certain point in the crankshaft rotation, the motor freezes(?). I can manually crank the motor backwards to a point where I think cylinder 2 is almost at TDC and then manually crank the motor forwards until cylinder 3 is almost at TDC (it's definitely cylinders 2 and 3 but I'm not quite sure which is backwards and which is forwards). However, it won't crank past either point.

So the reason the ignition system would just click when trying to start the bike is because the motor was at the forward position where it won't crank any further.

Today I took the valve cover off to try to see if possibly the timing chain slipped or something but after looking at that the only thing I can think of is maybe a valve got bent or something and is preventing either cylinder 2 or 3 from reaching the top its stroke.

I guess what I'm looking for is any possible explanation besides a bent valve that I could look for without having to remove the engine and start to dig into the cylinder head.

Thanks for any help.

 

[opnwhlmnd]

Quite possibly a broken valve. The head breaks off the stem and turns sideways preventing the piston from going up.

Was it running ok last time you had it started?

If had a broken/bent valve would have been missing badly

 

[scspiegel]

That's one of my issues. It's actually my girlfriend's bike and I don't really ride it. She was riding it (later she said there weren't any issues at the time) and then went out of town. I was doing something in the garage and decided to ride it around the apartment complex and it wouldn't start for me. I did try to roll start it initially but that failed.

We've had problems in the past with it not starting and it was always a bad battery but that is definitely not the case now.

When I was first trying to get it to start it all of a sudden started to leak gas slowly but I was able to determine that the problem there was a bad o-ring on the cylinder that the float valve resides in.

I guess the point of my reply is I have no idea how it was running before that.

 

[Morrisey]

The timing could possibly have slipped if you have been messing with something you shouldn't.

I'm not familiar with that engine, but i would check that the timing marks (if any) on the cams match up.

 

[TownsendsFJR1300]

As stated above, find the cam marks and crankshaft marks and get it to TDC and check valve timing. Confirm the cam chain has NOT jumped a tooth. If it has, re-set the cam(s) and see what happens.

If you can get it to TDC, where you would check valve clearances, (on the compression stroke, checking the spec's should show something not right (much wider valve spec if the valve is bent and open).

Should the cams be timed correctly, with the valves closed in the suspected bad cylinder(s), pull the spark plug and get some some compresed air in thru the spark plug hole.

If the valves are closed fully you shouldn't hear any air coming out. If the exhaust valve/intake valve is bent open you should be able to hear it.

If you look down the spark plug hole with a good flashlight, you may be able to see and marks/damage to the top of the piston.

I would think you could pull the head while the motor is in the frame if need be...

I just looked up your engine on Babbits. Your cam is centered in the engine between cylinders 2 and 3. It is very possible that with the age of the bike, the cam chain tensioner lost some of its tension (allowing the chain to jump) or the cam chain itself stretched and jumped (or both). I'd also measure (per what ever manual your using) the cam chain lenth tolerance to check for stretch as well..

I found this as well:

http://www.fixya.com/motorcycles/t2793349-need_set_timing_chain

Good luck.

 

[scspiegel]

Since I haven't messed with the timing at all besides just observing it with the valve cover off, there aren't any marks on the cam, cam gears, or timing chain (that I've seen) so I'm not sure how to tell if the timing chain has jumped. From what I can tell though, the gear teeth themselves look good (almost new?). The timing chain jumping was the original reason for me opening the valve cover but I have no idea how to determine if that happened without any marks.

The other problem I have is that with the way its sticking, the only cylinder that I can get to TDC is 4. I can get 1 to the top of the exhaust stroke but 2 and 3 get stuck just before they reach the top.

I tried to check if the tensioner loosened a bit by trying to tighten it (using the manual) and by barely applying any pressure to tighten (trust me I didn't apply much to it in fear of breaking the bolt) the bolt broke. I might have moved it like a sixteenth of a revolution (if that) so the tensioner was tight and still is, and I'm definitely going to replace that.

I'm not sure how to check if the chain itself stretched being that the chain goes down to the crankshaft and I would think I have to do a major overhaul to remove that and put it back. Also both manuals I have don't mention a specification for the length of the chain.

Thanks again for helping me. Even though it's (extremely) frustrating at times, I really enjoy the process. It just kind of sucks because it's not actually my bike and my girlfriend and her friends are giving me a hard time because her bike was working fine and now in their words 'it's in pieces'.

 

[scspiegel]

Quick question. When I manually crank the engine, should it also be turning the gear that connects to the starter motor? I guess to rephrase that, is it possible that the starter clutch is permanently engaged or something and won't 'release' the gear to the starter motor?

 

[TownsendsFJR1300]

Quick question. When I manually crank the engine, should it also be turning the gear that connects to the starter motor? I guess to rephrase that, is it possible that the starter clutch is permanently engaged or something and won't 'release' the gear to the starter motor?

Some bikes the starter dis-engages, some stay engaged with with gears in the engine...

If you look your bike up on babbits, for parts, you should be able to find the starter and the gear it engages with or stays engaged with...

 

[TownsendsFJR1300]

Quick question. When I manually crank the engine, should it also be turning the gear that connects to the starter motor? I guess to rephrase that, is it possible that the starter clutch is permanently engaged or something and won't 'release' the gear to the starter motor?

Looking up your bike on Babbits shows the starter has an idler gear and of course the gears that go along with it. With that set up, the engine should turn over forward(CC as you sit on the bike). The starter should engage when activated but the starter itself SHOULD NOT be turning over with the engine when the engine is rotated forward (as if the engine was running).

Below is the site with picture and parts descriptions:

http://www.babbittsonline.com/yamaha-motorcycle-parts#/Yamaha/FZ600S_-_1986/STARTER