Can’t get it running 😔

Hi there!

I have this KZ750e -81 that I’m close to giving up on.
I bought it in pretty bad shape, barely running.

I have done the following, although it was some time since I did some work on the bike.

- honed the cylinders (they were in spec)
- new pistongrings
-lapped the valves and adjusted them into spec
- new gaskets head and cylinder
- cleaned and renovated the carbs. Cv34’s
- new ignition coils 3ohm Dynatek (the bike has Dyna S)

The timing is on spot and the compression were not the best but at least pretty equal.

Since the original airbox were shot I put on pods together with 4 into 1 exhaust on and rejetted with jets from 6sigmajetkits.

Before rejetting I tried to start it and it started well but ran very poorly on higher revs, of I remember correctly.

The problems today

1.
After rejetting it starts well but climbs up in revs fast without me touching the throttle. 
After starting I have to cut the engine off within seconds.

2.
It does not fire on all cylinders anylonger for some reason.

I really want to get this bike back on the road, but now I don’t know what to test or do anymore.
I’m about to give up, but that would be to admit defeat.

Please help me out on this and I will keep you updated on the progress!
Let us get this thing running as it should!

Kind regards
Kristian Larsson from Sweden
 

Have you replaced the carb to head rubber manifolds (if they haven't been changed there is a good change they have hardened and are causing air leaks)

Hi!
Missed to mention that but yes, they have been replaced.

But maybe they haven’t seated correctly? Although I doubt it. But definitly a thing to check.

But thank you for your input!

Are the vac ports capped on the carbs (except the vac pipe to the fuel tap)

Yes, they are.

What make of pods are you using ?
Have you done a thumb test to check the diaphrams ?
Have you tried re-fitting the stock jetting ?
Climbing revs would normally indicate an air leak or mechanical issue with the throttle linkage

I don’t remember the brand of the brand of the pods but they are high quality.

Hopefylly I’ll get some time in the garage this weekend and I’ll test those things 👍

Which cylinders are firing?  

Sounds like carb problems.  I suggest  you source a stock airbox.

When cleaning the carbs, did you ungang them? Soak in carb dip after removing all hard parts?  Replace all the various O-rings.

The bleed pipes and pilot jets must be removed and held up to a light, to make sure the tiny hole is open.  And the pilot circuit must be clean.

 

Every Spring I force spray lube down the throttle cable inner sleeves as they can dry out over Winter. A little bit of lube also helps on the throttle sleeve and carb slides as well, you can do this even with the stock air box.

You need to make sure the slides "snap" back on there own, if not adjust the cable nuts at the throttle end until it happens. You need to make sure the idle does not race (throttle hang)

As for the cylinders not firing issue, have you checked compression/valve lash on the non running cylinders? Valve lash can close up if set too tight.

Other idle issue such as pilot jets has been mentioned, there are diagrams on here about spraying carb cleaner in those orifices to make sure internal circuits are functioning.

These orifices are often not blown out with compressed air after cleaning which could cause running issues at idle. Just because you stick carbs in a ultra sonic tank does not mean you cleaned them (not saying you did that)