Newly rebuilt KZ1000P engine will not rev...

Hey all, here's a conundrum for the masses, because I'm stumped. I just tore down a 1990 KZ1000P engine, inspected everything, and a had a machine shop do the big stuff (valves, cylinders, head, ect). Its been reassembled and started, but will stumble if revved up at all. The idle sounds like crap too. All the common things have been checked, double and triple checked: ignition, cam timing, advancer, compression, carbs. I wanted to run pods but am willing to use the airbox to make the carbs happy (they are CV). Also did a leakdown test and all the seals are near perfect. I'm fairly mechanically savvy, but I'm at a loss here so if any of you guys rebuild motors for a living your wisdom would be appreciated. I have videos if anybody would like them. Thanks in advance!

roman_dog wrote: Hey all, here's a conundrum for the masses, because I'm stumped. I just tore down a 1990 KZ1000P engine, inspected everything, and a had a machine shop do the big stuff (valves, cylinders, head, ect). Its been reassembled and started, but will stumble if revved up at all. The idle sounds like crap too. All the common things have been checked, double and triple checked: ignition, cam timing, advancer, compression, carbs. I wanted to run pods but am willing to use the airbox to make the carbs happy (they are CV). Also did a leakdown test and all the seals are near perfect. I'm fairly mechanically savvy, but I'm at a loss here so if any of you guys rebuild motors for a living your wisdom would be appreciated. I have videos if anybody would like them. Thanks in advance!

We love pictures. I dont know how to post a video, I think you need to post a link to youtube or something like that.

Down to bizniz. Did you put the air box and cleaner on? The CV carbs need the vacuum signal to work. You didn't mention valve clearances, are those right?

Im thinking carbs too. Did they work before the rebuild or did you do anything to them?

etbike - The bike ran when I got it, not great mind you, but I think a tune would have helped it. I did completely disassemble and clean the carbs, several times, but all the stock bits and pieces are there. Haven't messed with the jets yet.

TomW - I did put the airbox and filter back on, didn't make any difference. I was hoping that would be the fix too. Even physically lifting the slides yielded no change to the stumble. Valve clearances are within spec. They're on the low side of the tolerance, but still within it.

Here are two videos I've posted on youtube:





Let me know if you need anything specific.

Can you get it to rev up with the choke on?

Carb boots?

do you have the sparkplug wires right?

Good Fortune!

Baldy - Nope. Same stumble even with the enrichener on.

Nebr - Brand new carb boot sealed to the head with that liquid gasket stuff. No leaks there.

P21 - Plug wires are oriented right. They're all new, as are the plugs. Voltages and resistances all check out too.

Patton - Thanks for the diagram. I've noticed you posted that on many carb related threads and I actually cleaned mine per those instructions. No dice though.

roman_dog wrote: ...did completely disassemble and clean the carbs, several times, but all the stock bits and pieces are there....

Just confirming that the pilot jet "plugs" are fitted.



Good Fortune!

roman_dog wrote: ...1990 KZ1000P...will stumble if revved up at all....

Are carb fuel levels within specs as shown by the clear tube test?

Good Fortune!

Spray some starter fluid in the airbox/carbs while its running and see if it revs up