78 KZ1000 LTD Issues

My first bike 78 KZ100 LTD B, It was running fine. I get brave and change the oil, oil filter, and air filter. I over filled (I'm an idiot) and rode. I've drained to proper level but now lose power up hills, at higher speed and the bike cuts off. The throttle just doesn't help. It cuts off at stops too. The fuel tank is full. I think the petcock is only working in the 'Reserve' position, when I put in 'On' it doesn't want to run. I left it on Reserve one time and leaked fuel.
So some questions for all of the experts
1. If I replace the petcock, what is the tank opening measurement? I'm thinking about getting a universal replacement and am not sure what adapter to buy.
2. Since I over filled the oil do I need to check somewhere to see if it is full of oil where it shouldn't be? Air intake?
3. How do I check the venting of the fuel cap?
4. Any other ideas on how to get it roaring again?
Thanks! :evil:

You changed oil. Too much oil. Now bike "loses power" and "cuts off". Ok... I need some help in order to provide a meaningful bit of feedback...

The "lose power" issue may be a slipping clutch. The "cuts off" issue... well, I am not sure what you mean by "cuts off". Do you mean the bike stalls? When does it stall? At speed and it just quits running or when idling?

I suspect you have a number of minor problems to work out. As always, I would highly recommend purchase of a Kaw Factory Shop Manual (eBay good source) or Clymers. Follow the tune up procedures in the order described. I would also consider flushing the gas tank and removing the petcock and cleaning the screen to remove any debris. When replacing, install an inline gas filter into the gas line feeding the carburetors. I know this sounds vague and like it might be work that is over your head if this is your first bike but your riding pleasure will certainly be marred if the bike isn't up to snuff.

The "cuts out", if you mean the engine dies, is very likely an electrical issue. The power that powers our coils goes through your ignition and kill switch and it could be that you are losing contact at times somewhere along the line and your coils are not being powered. This is VERY common. I will let you get back and amplify before going farther on this issue in the event I am reading your comments wrong.

Don't worry, once we get more specific, lots of help/tips will start rolling in. Right now, the issues you are having are sort of hard to diagnose due to lack of detail but we can slog through this. The one joy of an old KZ is that they are easy to work on. Also, don't start spending money and replacing stuff till we get the issues sorted out.

I had a loss-of-power problem once... felt like I was running out of gas at speed. But I had plenty of gas in the tank. Then when I stopped, the bike wouldn't idle. If I didn't blip the throttle, it would just die.
Turned out that my choke lever was on. Just a little bit, and I couldn't tell to look at. But when I pushed the lever down, it moved about a quarter-inch, and the motor immediately started idling smoothly. No more problem at speed, either. I don't know if your problem will be as simple to solve, but check your choke lever, just in case.
Good luck.

wiredgeorge, I'm not sure I have the terminology right. I'll try to give examples.

I think it is stalling at speed. I can be going 50 up a slight incline and I start to lose power. When I roll on the throttle there is no increase in power. The engine is not revving harder but does not seem to respond to the throttle. I slowly lose speed and the engine stalls as I roll to a stop. I can then get it started again after a few tries. When it stalls the lights are still on so electricity is still flowing somewhere.

When I come to a stop, not every time, the engine will stall out. Like the RPM die down until it stops.

Fuel starvation?
I pulled the tank off and the petcock fuel valve off. The mesh on the short side has a tear in it and the plastic side support is bent? Not sure if anything is inside of it. The screen seemed clear. There was a couple of paint chips from where the tank had been painted in the past but not on the screen or in the two intakes?
There are inline filters on both fuel lines coming out of the petcock valve. They are little clear ones I can see inside of.

I'll have to check the choke ltdrider to see if I'm not getting it down all the way.

Appreciate any input

"When I come to a stop, not every time, the engine will stall out. Like the RPM die down until it stops."

That's exactly how I would have decribed my idle problem when my choke was on.

Post edited by: ltdrider, at: 2005/11/08 19:23

RE: The penautimate parragraph, IE: "there are in-line filters on both fuel lines comming out of the petcock".
Do you mean the fuel line and the vacuum line?
Why would there be a filter in the vacuum line? If there are, in fact, two fuel lines please ignore this posting.
Harry

Does the 1000 LTD have a breather tube from the crankcase to the airbox? Could the excess oil have gone into the airbox, clogging the air filter? It was stated that the bike ran fine before the oil change, so maybe now it's being strangled by an oily air filter.

OKC_Kent wrote:

Does the 1000 LTD have a breather tube from the crankcase to the airbox? Could the excess oil have gone into the airbox, clogging the air filter? It was stated that the bike ran fine before the oil change, so maybe now it's being strangled by an oily air filter.

Ditto, check that.

All the talk about oil, first made me think the clutch was slipping... OK... look at the fuel delivery system. MANY older tanks have so much crud in them that gas can't flow. You checked that. You have fuel filter on the two fuel inlet lines. Good stuff but since the bike to you is new, be aware these little filters clog very easily. Replace them asap. Next step... when the bike is bogging down, pop open the fuel cap. Any key will open the gas cap. See if that allows the bike to run normally. The whole fuel system relies on venting so that gas can flow. The cap is vented and there are vents on the carburetors themselves. These are the two brass spigots on the sides of the #2 & #4 carburetors (from memory)... in any case, these vents MUST not be obrstructed. You can put hoses on them for safety but the hoses must not be obstructed.

If gas isn't flowing and your petcock isn't obstructed in the tank, then you either have plugged gas filters or venting is obstructed.

I just got done riding for about 45 minutes
Beforehand I took apart the gas cap, there were little 'holes' for venting that may have had some stuff in them. I pulled of a cardboard type disc between the pieces. Then for good measure I pulled off the gas tank, made sure the vents on the carb are not blocked and took the crankcase breather off to make sure it wasn't full of oil.

So it starts up good, I don't have to keep the choke on to get moving. It surged a little bit as I got going in little spurts. On the road seemed fine, stopped and it didn't cut off. Rode around a little more and up a little hill it struggled a little. Cut off on a turn, but not sure I had the gear low enough for the slow down. Started up fine again. Then I stopped and opened the gas tank cap. I didn't notice any 'hiss'. Started right up. The bike did seem to run much better with that cap not closed. It seemed to have better acceleration, though not perfect. When I pulled in and stopped (cap still open) it kept running in neutral and sounded pretty good.

I don't think it is 100% but I was so happy to ride without stalling out - I hope it is warm tomorrow. Maybe I will ride to work.

Think the cap needs to be replaced? I know I can't ride around with it open all the time...

Rode to work this morning (with the gas cap closed). It didn't stall, but it did lack power up any incline. Once I reached the top and started down or flattened out the power would build back up.

Carburetor rebuild kits consist of a main jet, pilot jet, perhaps a pilot mixture screw or air screw, a bowl gasket and a float needle/seat along with a few other small parts. Essentially, you really don't need to be an expert to take the carburetor assembly off and remove the bowl and remove the old parts and replace them with the new. Many times jets get partially clogged with dried gas or gas that had moisture in it. This stuff requires a bit of work to remove properly and a jet kit just replaces the jets. Perhaps, at this time, it might be a good idea to install rebuild kits which would eliminate clogged jets or even a clogged seat as a potential source of gas deprivation. I also still suggest changing inline gas filter(s). From your symptoms, it also sounds like there is a bit of a venting issue in the the tank. The gas cap pivots on a hinge and is retained by a single pin. You can put a small punch on the pin and tap it out and remove the cap. Contact www.z1enterprises.com and see if they have a new gas cap assembly or at the least, a new gas cap gasket. Remove the old gasket and clean things as well as you can if you use the old cap and install the new gasket. You lack of power can also be from your igntion. As you increase engine speed, there is a mechanical ignition advance located under the right hand points cover (small cover about 4 inches diameter in front / right). This advance unit has two arms connected by a pivot and springs. As engine speed increase, the arms sling out from centrifical force and timing advance occurs. This allows spark to happen a tad earlier in the combustion cycle and your plugs fire when they should. If this advance has not been well maintained, keep in mind it is made of steel. Moisture gets into the cover area and will cause oxidation / rust and the advance may not be slinging out as it should. A part of periodic maintenance is to remove the mechanical advance and clean it using some steel wool and then lubricate it with light grease to ensure its timing advance function. A loss of power like you describe is OFTEN attributable to the advance not working as it should. This is a fairly easy thing to check. The only "gotcha" is to NOT stretch the springs that return the arms to closed position as these springs only stretch one way and you will ruin them if you try pulling on them. Good luck.