5500 rpm Pinging??

[thovda]

Hi guys, this is on the 74 KZ400 that I've gotten a ton of help on from everybody, and wouldn't have had such a blast riding this weekend if it wasn't for the help I've gotten here. Can't say thanks enough for the patience and help! Hopefully I'll be able to pass on some of the knowledge I've learned to other guys here, albeit very limited. ;D

I think that's the best description, a really really high pitched metal sound, pretty faint but it is noticeable. It happens at any gear, and always starts right at 5500 rpm. It's definitely a noise in my right ear so I'm sure it's coming from the right side of the bike. I think it goes away at around 6500-7000, but the bike is loud enough then I don't if it's gone or I just can't hear it. The searching I've done, it can be gas/ocatane combustion, I'm running 91 octane in the bike, with a bit of sea foam. Any ideas, I mainly want to keep from harming the bike. I haven't had a second set of ears handy to see if I can pinpoint it. Any ideas...what to check?

 

[Sonreir]

If it is pinging, ignition timing would be the most likely culprit. Running a bit lean could also be a potential cause.

 

[thovda]

Sounds good, thanks! I'll double check the timing to make sure all is good, it checked out a month ago, but need to rule it out again. If it's lean at that throttle position, I'm thinking it might be because I think it goes away with higher throttle, would that damage anything? Would it be best to do a plug chop at the pinging rpm, how long do you need to run it the throttle position to get a correct read on the plug?

 

[kopcicle]

Do check timing but ...
If stock air box secure one thickness of oil damp shop rag or cotton sock over the inlet and test .
If the ping goes away it was lean . If individual filters then socks over both and test . 5,500 is about where the stock CV slide begins to open and it's needle begins metering main circuit . If non adjustable needles then shim up in .015" increments as needed .

Rich knock test is the opposite . remove the filter from the stock air box or use velocity stacks on individual carbs . If it clears up it was rich .

If stock Kawasaki electronic make sure the polarity of the pickup (wire color) is not reversed at the plug to the harness .

Check valve adjust and cam chain tension again .

Note : I have never been able to get the stock CV's to work with individual filters . Never . Not in 30 years . So I just must be an idiot .

~kop

 

[fresh_c]

He's running Mikuni VMs.

In my supercharged truck I get rid of pinging my retarding the timing in said rpm/boost range. I also get early detonation if I run less than 93 octane, but then again I'm also running 9 psi of boost. Regular pump gas should be fine in a stock compression bike.

 

[thovda]

Thanks kop, so i have Mikuni VM 30s with K&N air filters, should've said that I guess.

What you described makes me wonder if my main jet at 145 is too small, I've been working on the pilot and midrange so much it's the one throttle position I haven't worked with at all yet, and it isn't bogging at WOT, so i thought it was ok. I've drove without the filters on and it still was pinging, so I'll try the sock test, or I could just go to 150 or 155 on the main and see what I get.

I'll also check the other things, but I think I'll try the lean mixture test first. Thanks for ideas to check guys.

 

[thovda]

He's running Mikuni VMs.

In my supercharged truck I get rid of pinging my retarding the timing in said rpm/boost range. I also get early detonation if I run less than 93 octane, but then again I'm also running 9 psi of boost. Regular pump gas should be fine in a stock compression bike.

Well that'd be a bit over my head I'm thinking, probably not something I have in the manaul. ;D I'll try the others first but still another thing to check, I'll update if/when I get it fixed.

 

[thovda]

I guess I'll be sockless on the way home from work tonight, they'll look better on the KZ anyways... ;D

 

[fresh_c]

Well that'd be a bit over my head I'm thinking, probably not something I have in the manaul. ;D I'll try the others first but still another thing to check, I'll update if/when I get it fixed.

It's a lot easier when you can tune with a laptop and AFR device.