KZ750 N1 Spectre Won't Start

you are thinking too much, that is like the train leaves Chicago question or the half full or half empty glass. #1,4 tdc z7ex toward the front wheel aligned with the head and in toward the back wheel aligned with the head with a little slack in the middle.

Well yeah that's how I set it. I was just thrown off when I opened it back up and at 1-4 TDC they were not facing out they were facing in, but as you pointed out I think it's 6 and 1/2 dozen. I just checked for compression and spark on all cylinders. The numbers are:

1. 165 psi
2. 140 psi
3. 150 psi
4. 155 psi

Spark on all plugs.

Should I worry about the 140? Seems like I recently read that they should all be within 15psi.

I tried the starting fluid again and no dice. It does still try to cough once or twice when I first try it on gas only but then nothing after that.

I'm thinking of pulling the carbs next and going through them again, but that is going to take some time. Also, I still don't have exhaust header gaskets. Could leaks there be causing that much of a problem? And I didn't rejet with the new exhaust. Could it throw it that far out of tune where it won't start?

Man you dudes are gonna get sick of me quick.

Thanks for all the help so far. I'm determined to get this thing going.

Jordan.

So this morning I put a couple of drops of gas in each cylinder through the spark plug hole and it fired of for maybe a second or two (longest yet). Then when it quit there was smoke coming out of the airbox. What does this mean? I still feel cam timing could be off, but the only way I know to test that theory is to ignore the manual and set the cams at the 2-3 TDC mark and see what happens. Is this a terrible idea?

Thanks
Jordan.

jjackson7 wrote: Well yeah that's how I set it. I was just thrown off when I opened it back up and at 1-4 TDC they were not facing out they were facing in, but as you pointed out I think it's 6 and 1/2 dozen. I just checked for compression and spark on all cylinders. The numbers are:

1. 165 psi
2. 140 psi
3. 150 psi
4. 155 psi

Spark on all plugs.

Should I worry about the 140? Seems like I recently read that they should all be within 15psi.

I tried the starting fluid again and no dice. It does still try to cough once or twice when I first try it on gas only but then nothing after that.

I'm thinking of pulling the carbs next and going through them again, but that is going to take some time. Also, I still don't have exhaust header gaskets. Could leaks there be causing that much of a problem? And I didn't rejet with the new exhaust. Could it throw it that far out of tune where it won't start?

Man you dudes are gonna get sick of me quick.

Thanks for all the help so far. I'm determined to get this thing going.

Jordan.

I just installed 4-1 exhaust on my bike (I literally have the same bike lol) without the copper gaskets and it still fired up. (btw with the copper gaskets it will seal perfectly ) From everything I've read, you have compression, the spark plugs are firing, and the ignition timing is okay, I would guess that this might be with fuel. Or timing maybe. The pilot jets wouldn't need to be changed for the exhaust swap. Are you using a vacuum petcock?

also I'm a novice at this still so take my advice with a grain of salt :whistle:

Yeah it's a vacuum petcock. I can see the fuel filter is full of gas and I've checked the float drains to make sure there is gas in there. I would expect with petcock issues I would at least be able to start if for a while before it crapped out.

The smoke coming out of the airbox makes me think the intake valves are opening during the exhaust stroke and the exhaust valves are opening during the intake stroke. I'm just not confident enough to go against the manual. The only thing I haven't checked for is that maybe the the cam sprockets are not installed correctly but that is a long shot.

Insufficient clearance for intake valve may also result in backfire through the carb.

Good Fortune!

Yeah i'm gonna take the valve cover off again and recheck all valve clearances and stare at it a while to see if anything looks fishy.

Battery seems a likely culprit but .............

When you did the head gasket job I'm guessing you would have taken the coils off to give yourself some room.

Is it possible that in putting the coils back on the frame you might have connected the wrong wire to the wrong coil ? You should have a red wire going to each coil and then I think its a green and a black and I cant remember which goes to the 1-4 and which goes to the 2-3 coil but if you mix them up it puts the firing out 180 degrees and the bike will cough and maybe splutter but will never start.

I did this once after grinding in new valves and it took me ages to figure it out and then Doh ! Slap forehead !

I have red and green on the left side ignition coil going to 2 and 3. The red and black are on the right side coil going to 1 and 4. I have both of the red wires on the top green and black are below (not sure if that matters). The suggested test was to turn the crankshaft by hand and make sure the plugs spark at the appropriate TDC mark, which they did. I will double check of course.

This is going to be something stupid. I'm looking forward to being able to look back and laugh.

jjackson7 wrote: I have red and green on the left side ignition coil going to 2 and 3. The red and black are on the right side coil going to 1 and 4. I have both of the red wires on the top green and black are below (not sure if that matters). The suggested test was to turn the crankshaft by hand and make sure the plugs spark at the appropriate TDC mark, which they did. I will double check of course.

This is going to be something stupid. I'm looking forward to being able to look back and laugh.

Wiring to and from the ignition coils looks just fine.

Good Fortune!

jjackson7 wrote: So this morning I put a couple of drops of gas in each cylinder through the spark plug hole and it fired of for maybe a second or two (longest yet). Then when it quit there was smoke coming out of the airbox. What does this mean? I still feel cam timing could be off, but the only way I know to test that theory is to ignore the manual and set the cams at the 2-3 TDC mark and see what happens. Is this a terrible idea?

Thanks
Jordan.

It sounds like nothing more than a circuit plugged in the carbs! You say it fired and ran with a little gas in the plug holes, that says 2 things, your ignition is right and your have enough compression which was evident with the cylinder pressure numbers. beyond that, fuel. Smoke out of the air box, betting you had it wide open when it died? Not uncommon to see that.

Les

Cleaning carbs again tonight. We'll see what happens. To be honest looking at them again I probably did a shit job the first time. Chock it up to experience I guess.