TOPIC:

Earlier this year I got an 1981 KZ750 H2 pretty much for free. I have been trying to get some work done on this, and finally got it started and running great. It then started to spring a leak on the overflow tube on the number one carb. I had the carbs worked on, by someone that really knows what they are doing, and ended up having to swap for some mekunis from tekei's. This included buying some new intakes. To make a long story short, I can't seem to get this to fire up like it did. I have reset the valve clearances, but it still didn't help. It fired right up on my last valve adjustment, and then died on me half way around the block. It just sounded like it was flooding out. I haven't been able to get back in and remeasure the clearances, but I have been able to see that 1 and 2 are firing. I have noticed that it seems that the gas mixture from the carbs is moving the wrong way on 3 and 4. I have checked the electricle and timing and both are perfect. Is my valve adjustment off again, or am I missing something in the carbs. I am honestly about ready to give up. I have put about 300 into this KZ and I am none the closer to riding. In fact it seems I took two steps back. I already plan on going back and checking the valve clearances. Can anyone give me another reason why the air fuel mixture would blow back like that besides having that air intake valve open?

I also wanted to add that I put my hand over the intake with the carbs off, and felt some major vacume. Now I don't know how constant it was, but hopefully my gaps will tell me if the valves are in spec.

Hi Guy,
This is Steve from Australia. I too have an 81 750H2.
Do your self a favour and go back to the original carbs. If fuel was leaking from the overflow on number 1 carb then the fuel level in this carb is too high. This can be caused by a worn out float needle or the float level is out of adjustment.
remove the carbs from the bike and check adjustment on all four. If you need more info I can help, just contact me.

Well they had more problems than that. I also found out that one of the air screws was stuck inside the carbs, and there was no way to get it out. Apparently I was only hitting on three cylanders to begin with. He then gave me a choice on either waiting or changing to these. I just wanted to see if anyone had any other ideas on what could be blowing the mixture back out. I trust the guy that built the carbs, I just want to make sure that I am not missing something easy. I also thought maybe something got jarred in there when he shipped them back to me. Perhaps I am just grasping at straws, but I figured I would try one more time to get this running before I gave up.

Give Wiredgeorge a call or send him a U2U, he is a carb wizard and helped me immensely with my jetting on my KZ550.

Intake valves not seating ?

Leak down test.

Check plug wires 3 & 4 for firing order.

Post edited by: hwms, at: 2005/12/15 13:52

Post edited by: hwms, at: 2005/12/15 15:51