TOPIC:

That looks like oil fouling but not too bad. They look dry. Test the floats with a clear tube. Also check the pilot jets. Run a fine wire through them like a guitar string or a strand from a wire brush. That's about how big they are. If the pilots are clogged, it won't run for sh*t.
Steve

If not already done, would assure that the main idle adjustment screw isn't holding the throttle slides above their lowest bench-sync position.
Which should help assure that the throttle slides are indeed at their lowest position as when they were bench-synced.

If the bench-synced throttle heights were subsequently adjusted during the running-sync procedure, perhaps one or more of the throttle slides is too high and thereby tantamount to not having the throttle fully closed when attempting to start the engine.

Perhaps time for a repeat bench-sync, being sure to have the idle adjustment screw positioned during the bench-sync so the throttle slides may be further lowered during the subsequent running-sync.

Good Fortune!

650ed wrote:

bountyhunter wrote:

ewolpert wrote: It didn't barely run, it ran quite well.

Hence how I don't understand how it can have compression of 80 psi and run quite well. The lower service limit for compression on a 750 twin is 115 PSI (nominal is 150) and the 650 is a higher compression engine.

I'm puzzled about the same issue. It's hard to imagine that the compression test is accurate since the bike ran quite well. The standard compression for the KZ650 is 156-185 psi with a service limit of 119 psi. If the compression really is 80 psi I'm very surprised the engine ran quite well, and since the compression is equal across all cylinders it doesn't sound like a valve issue. It sounds more like a faulty compression test. If it was mine I think I would have a second test performed using a different tool. Ed

Only possible scenario I could think of: Maybe the 80 psi reading is stone cold and engine dry, and the compression comes up enough when fully hot to allow it to run OK hot? Then when it sat and got cold, it would drop and be a royal bitch to start up again.

swest wrote: Hopping around isn't helping ether. On another thread he bought some coils. The wrong ones at that. It's possable that when he does get it running, the compression will come back up. I STILL HAVEN"T SEEN PICS OF THE PLUGS.
Steve

If those plugs are oil fouling, that could be the story. Both times I had to overhaul my engine it was because the valve guide seals failed and let oil drain down through the open valve after turning it off. Over time it built up a burned on gunk layer that kept the valves from seating well. Compression degraded over time until it ran like crap.

That's what happened to mine. Over time the carbon built up on the exhaust valve face and became the seal. It ran well that way. It just fouled the plugs more and more. I cleaned the exhaust valves and could have re used them but I bought new ones, springs and seals.
By the look of those plugs, I don't think it's gone that far. The rings may have to re seat.
Steve

So I just attempted to do another leak down test this time it was obvious air was coming out the engine breather. I could feel it on my hand. There was no air coming from the gasket, exhaust or intake area. I am now wondering what the next best course of action would be. Do I need to pull the motor and hope that I dont need new pistons as that is something I can ill afford as it would run $500 plus machine costs. Thoughts?

Air is supposed to come out of the aptly named breather........if air escapes out the carbs it means intake valves need looking at......if air escapes out the exhaust the it's the exhaust valves that need attention

Air is supposed to come out of the aptly named breather........if air escapes out the carbs it means intake valves need looking at......if air escapes out the exhaust the it's the exhaust valves that need attention

If the piston is at TDC I am not sure how injecting air would get to the breather if the rings/pistons are working as they should. I am going to crack the thing open and see what I see. What I do need to know is how I can tell if it is just the rings or if the pistons/cylinders are bad as well. I am no expert for sure.

If an engine is running poorly the rings won't seal as well. Over time they will leak oil and compression. Get it started and run it. It's possible they will reseat once up to operating temp. and load is applied. On high performance engines, there are holes leading to the top (compression ring) forcing the rings against the cylinder thus increasing compression. It happens in normal engines too. Try starting fluid.
Get it running, then decide what to do.
Steve

ewolpert wrote:

Air is supposed to come out of the aptly named breather........if air escapes out the carbs it means intake valves need looking at......if air escapes out the exhaust the it's the exhaust valves that need attention

If the piston is at TDC I am not sure how injecting air would get to the breather if the rings/pistons are working as they should. I am going to crack the thing open and see what I see. What I do need to know is how I can tell if it is just the rings

Do the compression test again. With the engine cold and dry, take the reading. Then squirt oil in the plug holes and let it drain down past the rings. Repeat compression test. When mine needed bore/rings, the compression readings would come up maybe 30 - 40 PSI after oil was added.

Update:
I took the head off and checked the rings, heads and pistons. The pistons had no play midway down, so I figured it wasent the rings. The cylinders looked good and had no major wear or lips on the top. I cleaned up what I could, fit a new head gasket and but the head back on. I installed the accel super coils I bought and checked everything out. after I fixed a couple of minor problems with the ignition (while moving the bike around with the timing cover off, I bent in the green contact breaker lead and it was grounding) the thing fired right up and I have since synched the carbs to within 1 cm Hg. They ended up around 15 cm Hg. The thing runs like a top. The only problem I have now is that my speedometer is more of a suggestion than an accurate measure of speed.

Thanks everyone for all of your help, suggestions and wisdom.

It's usually something stupid. Have fun.
Steve