KZ750 1976 Engine won't start

thune wrote:

Hi! 

If the carb holders are tight against the carburettor, would it be sufficient to have an oring/gasket between the carb holder and cylinder block? Have anyone tried that before? Just to see if the holders are the issue before I order. 

Not something I have ever tried to do ? remember tight doesn't always = sealed !

When installing new carburetor boots I put a little 3Bond on them to help seal them.  Be careful to check the inside once the boots are installed to ensure no gasket seal squeezes into the manifold intake.

Have you done a compression check?  Is the air intake and air filter correctly installed when you try to run the bike?

Looking at one of your pictures it seems you have the manifold vacuum ports connected with a tube between pairs.  Would this affect the vacuum in each cylinder's carburetor?  Those connections are for connecting to sync gauges and normally sealed with rubber caps.

I see! It was like that when I took the bike from my dad so I kept it like that. I also saw a drawing of the assembly here:  www.megazip.net/zapchasti-dlya-motocyklo...head-cover-10414227#  

Thinking that it should be connected. But I have no idea whether it should or should not be connected with the tube. 

Thanks for the suggestion. Should there be gaskets between the boots and the engine? I haven't seen any that I can buy going from the assembly drawing. Can you point me towards where I could buy these? 

Have seen a parts list for the 76 750 twin that shows the tube between the test ports on the carb holders and calls it a balancer tube #25 in the attached

As others have said I would get new carb holders as the current ones are close to 50 years old.

New carb holders will also make taking the carbs off and on easier. 
Don't remove the pressed in brass fittings in the carbs, just make sure they are clear. One item often overlooked is the well in the carb bowl for the choke tube. If these are clogged the engine will not be able to draw fuel through the enrichment circuit to start. I always fill the bowl with gas and make sure the well fills up as well. 
Consider doing a valve clearance check as it this service item is often delayed. 

Thanks for the information. New carb holders are ordered. Had to go with eBay though. They were not that easy to find. 

Looking forward to new carb holder. It has, as you stated, been difficult to put the carb on and off. 
I will double check and clean the well and also get to the valve clearance check. Thank you!