'80 KZ750E1 - Engine sounds like V8

Hey guys,

Hope the subject is not too confusing, I'm finding it difficult to put my problem into a specific, 1 line term, thus searching for it rendered no results.

After a lot of small and minor problems, we eventually fired up the old lady after about 4 years. But the problem is that the bike is not idling, not picking up revs, and it sounds like its running on 2 cylinders.

The coils, spark plugs, CDI, Cam Timing and Ignition timing (hopefully) are all in order.

According the the exhaust, cylinders #1 and #2 heats up very nice, #3 is a little colder than #1 & #2, and #4 is about 60% of #1 and #2. The bike does not struggle to start, but the way the engine is running is WAY off.

I cant explain the problem anymore than this, thus, I attached 2 sound clips of the starting process for someone to perhaps give their opinion on. Apologies for the echo, we are working in a small garage with the phone miles away.

If anyone can identify the sound or have experienced a bike sounding like this, kindly share your thoughts. Anything will be helpful.

Thank you all in advance






EDIT: If anyone is skeptical about the zip files, please let me know and I'll post some VirusTotal reports.

Need more info , but check plug wires on right cylinders

Clogged idle jet circuits in the carbs is likely after 4 years. You could try Seafoam and strike luck, meaning you could save yourself a carb strip.

MP3's worked fine for me.

Wow. You're right, it does have that uneven rumble of a v8 with dual exhausts.

To me it sounds like it's missing on one cyclinder, but possible the other cylinders are firing at very uneven power levels.

I would start at the beginning with a compression test.

If that's all good, then I'd check for spark on all four plugs, one at a time and make sure each one, individually can get a 1/4 inch spark. Don't go over a 1/2 inch gap as that will stress the coils and ignition. At idle, you don't need a lot of spark voltage.

If that's all good, then I'd start checking the idle circuits in the carbs. EDIT: Faffi beat me to it.

Anybody want to open then re-post these zip files so they will play for everyone?

These will be temporary:


First Start.mp3

Second Start.mp3

You need to correct the title of this thread. It should say "Engine sounds like a Ford V8." :laugh:

Do you have the spark plug wires on right? Getting spark to all 4? If so next would be to check compression. If compression is good, spark good, then probably fuel.

Hey guys,

Thanks for all your help. We cleaned out the carbs and voila! Its running lekker

I dont know if I should start a new thread about it, but we are struggling with the pilot system (not running as smooth as on higher rev's) and a rich mixture with some sooty deposits on one plug.

All your help is appreciated

650ed wrote: You need to correct the title of this thread. It should say "Engine sounds like a chevy V8." :laugh: