kz750 twin starting trouble / clutch trouble

Hi!

I recently replaced all of the top end gaskets and re-built the carbs on my '79 kz750b4. now I can't start her up! she'll backfire when i'm tryin' to kickstart or switch start.

I was going to try and push start her but found that the clutch isn't working quite right. with the lever pulled and being in gear, i get some resistance (less than when it's in gear without the lever pulled, though).

So, my questions are: could it be that the carbs aren't adjusted correctly? ( i followed what the service manual said), could it be that the timing is off (again followed service manual), or could the clutch irregularity be causing the trouble (manual followed!).

Any responses are greatly appreciated (i wanna get her goin!!!!!!!!)


thanks,

john.

If you removed the timer advance mechanism, it may be in 180 out of time.

If not that, check the static timing using an Ohm meter to get in the ballpark.

Check the puel levels in the carbs (use a clear tube).

The clutch won't make the engine backfire. A little drag on a wet clutch is normal, not sure how much yours is dragging. Your clutch may be OK.

I will look at the timing again.

the bike really jumps when i try to start while in gear and with the clutch lever pulled, something that didn't happen at all before I took it off!

well, no luck today (so far)! i'm just plain stumped! everything seems to be adjusted correctly. that's what really worries me, because it obviously is not!

i really don't wanna take it in to the shop

Post exactly what the symptoms are, and exactly what you have done so far, and I'll be back on here later tonight to help.

the symptoms are: engine is not starting, will backfire about every 2 to 3 kick attempts, the clutch won't disengage the gear fully

i took off the carbs(carbs then rebuilt), cylinder head cover, cylinder head, cams, clutch, clutch cover, put in new oil filter

So you didn't remove the timing advancer?

In that case, the ignition timing won't be 180 degrees out (the normal cause of backfiring when trying to start).

When you installed the cams, did you follow the manual, 32 pins between cam marks, advancer on the "T", etc?

Was the bike running fine prior to your work?

Let's get the motor running then we'll work on the clutch.

I don't mean to be pushy, but did you check if the auto-advancer is 180 degrees around? It is a very common mistake that people make during re-assembly, because you can't tell the difference, and it creates the exact sympton you describe.

Also, I've had the clutch stick like that, too, on one of my 750s during clutch work. The good news is, as soon as you get the engine to fire, that problem goes away. I had even soaked my new clutch plates in oil for 24 hours before installation. To this day, if the bike has been sitting for a week, I'd better be revving up a bit when I shift into 1st for the first time or it will stall... goooooood clutch springs....

EDIT: Drat, looks like Steell posted basically the same thing between my "refresh" and post...

The timing advancer was not removed , and I remember checking between 4 and 5 times that the timing chain was put on the correct pins, and that I made sure the advancer was on the correct mark.

I had a buddy helping me out and I read him the steps in the manual while watching and making sure he did his part right!

So it sounds like the timing is off, should I go back and re-install the cams/cam chain to make sure that all is put on right?

Thanks for your help everyone ;]

I would check cylinder compression first. If your valve timing is off, I'd wager the compression won't be good.

Pull the spark plugs: on the 750T, you can see the edges of the valves through the plug holes with a small light as the valves open. Take off the timing cover and rotate the crankshaft with a 17mm wrench and you can check and see if the valves are opening and closing as you go by TDC. If the compression is good, and the eyeball check on the valves opening looks right, your camshafts are probably in time.

If you do end up taking the valve cover off to check things, be sure to check valve clearance.

BTW: I would still recheck the position of the timer advance mechanism and make sure the points are opening when the pistons are going up to TDC just to be sure it isn't 180 out.

did you completely loosen your cam chain tensioner before reinstalling your cams?

Bountyhuner: I'll check that when I get home from work!
Ronjones: yes! that was the first thing we did!

Right where the exhaust meets the muffler, one of the pipes is rusted out and almost coming off, would that have anything to do with the problem? I can't afford a new system until next paycheck!

Also: the bike was running prior to takin it apart.

It would start to sputter when I got it up to 65 for more than a minute