Sounds like mine...and I had ZERO compression on 3 cylinders. I'm pretty sure the timing chain slipped (which caused it to instantly shut down on the road)...bending valves.
I'm TRYING to get a new head or all parts for a valve job. OR an engine, reasonable price. 79 cb750f
Can you help me find parts for a total valve job OR rebuilt head for 79 750F dohc?
If you want the work and it would make sense to ship you the head (from Indianapolis) we could consider that.
UPDATE: I just finished doing a compression test and it pretty much confirms that the valves got bent when the chain slipped. I got 100 PSI on number four and zero on 1-3. I repeated the test and got zero again (with plugs out and throttle open. It has good spark now.
So would anyone want to...
UPDATE: I just finished doing a compression test and it pretty much confirms that the valves got bent when the chain slipped. I got 100 PSI on number four and zero on 1-3. I repeated the test and got zero again (with plugs out and throttle open.
So would anyone want to buy it for $600? Any...
I am beginning to wonder if it ever slipped the timing chain at all. When I looked at it it appeared to be one or two teeth off but now it seems to be perfectly timed and it won't fire. Previously when I checked for spark I could see it on three cylinders but I didn't consider that being the...
Thank you. Yes, I'm nearly 100% sure I have it at TDC (and the piston is indeed within less than an inch when plug is removed). I MAY have lost spark bc my socket may have pushed the two pulse generators too far from the big nut I used to turn the crankshaft. I will try to return them to the...
NOW it appears to have no spark at all, which could be a good thing if that is all the problem is. I have my doubts that it would be the coils, so I am wondering if perhaps when I was turning the crankshaft using a socket on the side where the timing mark is, if perhaps I bumped the electronic...
That's been what I have been assuming. The #1 (left side while seated) cam lobs both point toward the spark plug and the punch marks are perfectly aligned with the top of the head...when the TDC 1-4 is aligned with index mark on crankshaft.
Even when I pull the carbs and spray starter fluid...
My 1979 750f dohc slipped the timing chain and I believe I have it correctly timed but it won't fire even though I know I have spark and I have sprayed starting fluid directly into the cylinder while cranking it. I saw the following advice in another thread and I would like someone to help me...
I know I have spark and today I sprayed starter fluid into the holes going into the head on the back side of the carburetor. And yet it still would not fire. Even if a valve or two is bent I believe it should have fired. So I have to believe that I don't have it timed properly. I saw the...
UPDATE: I believe I have it timed correctly with the punch marks lined up with the edge of the head and it is at top dead center where the 1-4 mark is on the crankshaft. It has spark and fuel but it won't fire. I no longer have blowing out of the carburetor but I also don't have much sucking. I...
I just found this video and he has the head off without removing the engine but it is a single overhead cam cb500. It also appears that his frame might be curved to allow the clearance. Thoughts?
The timing chain on my 79 750f must have slipped. I have retimed it, but it won't start so I will do a compression test but I'm almost certain there must have been damaged to the valves. I have spark and fuel but it will not fire. So I am wanting to remove the head in order to do a valve job...
New chain certainly sounds like a good idea but without removing the engine from the frame it seems to be almost impossible to install a new one. And I am not set up to be able to do that because it is not in a garage. That would require me to separate a link and feed the new chain around by...
I have confirmed there are no loose wires on the coils. I was able to locate the T 1.4 mark, and when I had the pointer aimed at it, the punch marks on the two sprockets were not perfectly lined up with the edges of the head. When I lined those up, I could no longer see the T 1.4 mark. I am...
I understand what you are saying. I think a big reason that I am thinking the chain must have slipped is that the engine shut down instantly with no misfiring before it shut down. If indeed it slipped and the marks do not line up, is it possible to loosen the chain and slip it off the sprocket...
I am doubtful that valve clearance would have caused a sudden and complete shutdown. Also, my idea that the negative ground strap is corroded is probably refuted by the lights and starter working.
Good idea to check for loose coil wire. However #4 has spark.