TOPIC:

This is actually what I believe are a few related problems, so I guess the best place to start is at the beginning - please bare with me on the (long winded) details.

Ever since I got my ZN700 driveable and legal, I've been trying to locate the reason for it over-heating as badly as it does (even at 3 inches away, the radiant heat from the engine is actually starting to leave burns on my ankles! )
I've already installed new intake manifolds (the old ones weren't quite sealing properly), the carbs have been synched(sp), the valves adjusted to specs, the spark plugs/wires/boots changed out as well to eliminate and questions.

But it's actually more than just the over-heating problem, the oil level also seems to fluctuate quite a bit as well.
After riding the 25 miles from work to home it is at the ADD mark (it showed FULL when I left to go to work, and FULL when I left work heading home), I can then turn right around and drive back to work and it shows at the FULL mark once again (time warp?)
I checked the oil pump screen when I swapped the oil pan a few weeks ago and it was spotless, and I know the pump itself works fine since when I start the bike up the oil level drops right away and I can see a small amount of oil "swirling" in the bottom of the oil window.

When I first got the bike running, I changed the oil and filter and added motor flush to hopefully clean any crud and carbon that might be in there from the 8+ years it sat in the desert heat/wind/etc.
After running it for roughly 15-20 minutes I drained the oil, changed the filter, then added new oil and a can of Sea Foam. I then ran it for roughly about 100 miles and changed the oil and filter AGAIN.
Overkill? Perhaps, but oil and filters are waaaay cheaper than a complete engine rebuild.

I've now also traced an oil leak that popped up right after I switched the oil pan - the oil pressure switch itself (which is located directly behind the ignition cover) is leaking around its base...and yes, it is tightened down snugly.

Now here's the $64 question;
Does the oil pressure switch just activate the "idiot light" in the dash, or does it function as a bypass if the oil pressure becomes to great or to low?
If the latter, and if the oil pressure switch is dying/dead, can it be the cause of both the fluctuating oil level AND the over-heating problem?

BUMP!

Anybody have a clue on this one???

I always assumed it was just an idiot light. pressure causes a pin to complete the circuit. But that is on the bikes I've had (550, 750twin) I think the bypass is activated when the filter clogs and has something to do with the ball and spring inside the filter bolt. that's about all I know about it.

Post edited by: lifeliberty, at: 2006/07/24 13:39

Oil pressure switch just works idiot light. Filter bypass is indeed handled by ball and spring in filter assembly. If the bypass is not functioning it should just bypass filter. I can't see it having any great effect on level. Could be wrong though.

if the top end has been off there are these little metal oil jets on either side of the cylinder block. they are oval with a tiny hole in them and in the oil feed to the top end. the purpose is to squirt up the distance to the head. and then gravity gets the oil back down. these bikes have a low oil pressure system if they are not there you will get some oil up there but not much, not enough to cool the top end. living in phoenix I learned this the hard way when I did my top end on a 84 700 forgetfulness will really hurt your bank account.

ignition timing is another factor that raises the running temperature of the engine

Is the motorcycle running OK, no pinging, surging ect? If yes, I doubt you are overheating at all. I always thought my KZ1000 ran too hot too because whithin a mile the cylinder block is too hot to touch. It's been like this for the entire 80,000 miles, so normal apparently. Conversely, I have a 900 LTD that does overheat. Pretty evident, as after about 5 miles it starts detonating, surging, won't idle ect.
About your fluctuating oil level, simple things like using the centerstand on a surface that's not level can make a difference. Check oil just by standing the bike upright as you look at the window.

Thanks for the replies folks!

trippivot,
To the best of my knowledgae the engine nor any part of it has been apart, save for the valve cover when the valve adjustment was recently done.
I know the top end is getting oil because the idiot who did the carb synch and valve job didn't seal the gasket and cam plugs properly and now it leaks at the left front.
I would have done the valve job myself, but was pressed for time in trying to get Rose's carb situation sorted out before we went on the Boys and Girls club charity ride last month.

The timing is about as dead on as it's going to get (tested with a known good timing light), which was one of the first things I checked.

Ron,
Whether the engine is cold or hot, at idle it's a little erractic. But the throttle is very responsive, and at anything above idle it pulls like a freight train! After about 20 of the 25 mile trip home from work is when I notice just how hot the engine is, and at that point is when it starts pinging. My 650 has never run this hot, and I ride that bike a helluva lot harder than I do this bike.
Back to the ZN though. After I exit the freeway from that 25 mile ride the idle is extremely low and erratic, and I have to keep my hand in the throttle or it will die. If it dies and I try restarting it, It will rotate the crank about one time, and give somptoms similar to a battery with little to no power (the headlight and turn signals work perfectly at this point).
If it let the bike sit for about 10 minutes, it will fire right up and I can continue on my way.
I did notice something on the ride I took last weekend however. When I slowed at the bottom of the freeway offramp near my destination it wanted to die, but after driving about one city block to my destination it was fine again.
For the record, I always check the oil level with the bike on it's centerstand, and make sure that I am on a level surface.

I replaced the oil pressure sensor today, and now at least the oil leak I had is taken care of. Oddly enough, the bike seems to idle much smoother. Even after leaving it at idle in my garage for ten minutes, the idle was still consistant and the radiant heat from the engine seemed less severe.
I don't know if I'm just imaging this or not, or it might have something to do with dumping a full can of Sea Foam (after draining some of the oil out of course) in the crankcase.
I figure I'll give it about two days of back and forth to work before changing the oil and filter, and see how it does then.

I'll post an update then to see if anything I did actually made a difference or not.

RetroRiceRocketRider wrote:

Thanks for the replies folks!
Ron,
.
Back to the ZN though. After I exit the freeway from that 25 mile ride the idle is extremely low and erratic, and I have to keep my hand in the throttle or it will die. If it dies and I try restarting it, It will rotate the crank about one time, and give somptoms similar to a battery with little to no power (the headlight and turn signals work perfectly at this point).
If it let the bike sit for about 10 minutes, it will fire right up and I can continue on my way.
I did notice something on the ride I took last weekend however. When I slowed at the bottom of the freeway offramp near my destination it wanted to die, but after driving about one city block to my destination it was fine again.
For the record, I always check the oil level with the bike on it's centerstand, and make sure that I am on a level surface.

my bike was doing the same thing. everyone said it was the floats, but they are fine. problem went away after I got rid of the kawasaki petcock and installed a drag specialties petcock (higher flow). maybe check your filters on the petcock and fuel filter. I think I was stalling after highway riding because the bowls couldn't fill fast enough for the idle circuit after i closed the main jet. Giving it a rev or 2 coming down the off ramp would keep it from stalling out. and maybe if you aren't getting enough gas at higher rpm you are causing a lean condition = heat/pinging??

maybe I'm way off the mark, but a higher flowing petcock seemed to solve a lot of my problems.

Post edited by: lifeliberty, at: 2006/07/26 10:44