Risk Of Running With Zero Clearance Intake Valves

Have a KZ750B1 open on top, and just measured all the clearances. The two intake valves have zero clearance (feeler gauge 0.038mm will not fit). There are 275 shims beneath them. Probably need to swap in some 260.

What is the danger of reassembling and starting up the bike like this for a while, until we find new shims?

We are in lockdown in Arlington, MA right now, with time to work on the bike as a productive distraction from the TV.

Thanks.

mind2find wrote: Have a KZ750B1 open on top, and just measured all the clearances. The two intake valves have zero clearance (feeler gauge 0.038mm will not fit). There are 275 shims beneath them. Probably need to swap in some 260.

What is the danger of reassembling and starting up the bike like this for a while, until we find new shims?

We are in lockdown in Arlington, MA right now, with time to work on the bike as a productive distraction from the TV.

Thanks.

I have a pile of 260's...most common size to remove. Where are you at? How many do you need?

Larry, you have a pile of 750 twin 32mm shims? And never told me?

To answer the original question, if you can rotate the bucket/shim with your fingers, then there is at least a little clearance and you probably won't burn a valve. When the motor will no longer idle when hot, then you know the valves are to tight.

LarryC, absolutely! Just outside of Boston (and breathing a huge sigh of relief at the moment). We'd need 2 of them. It's a 1976 KZ750B1, just to be totally specific. I assume they're pretty commonly sized for a lot of the KZ's. Email me at sandsfish [at] gmail [dot] [com] and let me know how much you want for them. Cheers!

mind2find wrote: Have a KZ750B1 open on top, and just measured all the clearances. The two intake valves have zero clearance (feeler gauge 0.038mm will not fit). There are 275 shims beneath them. Probably need to swap in some 260.

What is the danger of reassembling and starting up the bike like this for a while, until we find new shims?

We are in lockdown in Arlington, MA right now, with time to work on the bike as a productive distraction from the TV.

Thanks.

Specified clearance for the 750 twin is 0.5 - 1.0 mm, but many allow up to 1.5 mm maximum. You are liklely between 0 - 0.5 mm now, probably not actually zero. If you have a 275, then you likley need 270 - 265 range.

0.038mm will not fit

my gauge set goes down to .001" which I think is .025 mm. Might help get the clearance measurement.

mind2find wrote: LarryC, absolutely! Just outside of Boston (and breathing a huge sigh of relief at the moment). We'd need 2 of them. It's a 1976 KZ750B1, just to be totally specific. I assume they're pretty commonly sized for a lot of the KZ's. Email me at sandsfish [at] gmail [dot] [com] and let me know how much you want for them. Cheers!

Bad news, the 750 twin is the only Kawasaki that uses that size shims, all the rest are smaller.

I recall reading a post on the Kawasaki Twins forum that one of the imported cars uses the same size shim. Could take a look over there and search for the post.

I'm thinking Larry has a bunch of under bucket 650/750 four shims

bountyhunter, I think maybe you misplaced a decimal.

Specified clearance for the 750 twin is 0.5 - 1.0 mm, but many allow up to 1.5 mm maximum. You are liklely between 0 - 0.5 mm now, probably not actually zero. If you have a 275, then you likley need 270 - 265 range.

1mm is .040", I'm sure you meant to type .1mm to .05mm

steell wrote: bountyhunter, I think maybe you misplaced a decimal.

Specified clearance for the 750 twin is 0.5 - 1.0 mm, but many allow up to 1.5 mm maximum. You are liklely between 0 - 0.5 mm now, probably not actually zero. If you have a 275, then you likley need 270 - 265 range.

1mm is .040", I'm sure you meant to type .1mm to .05mm

Yep, should never do math when I have a headache.

steell wrote: Larry, you have a pile of 750 twin 32mm shims? And never told me?

To answer the original question, if you can rotate the bucket/shim with your fingers, then there is at least a little clearance and you probably won't burn a valve. When the motor will no longer idle when hot, then you know the valves are to tight.

Oh Shit :ohmy: ..didn't notice it was the twin...... cancel that offer

I have some 32mm shims. Let me know what sizes you want for sure, and I will see if I have them.

Russ

Hi Russ - mind2find and I are working on this bike together. After realizing that we were using the wrong valve adjustment chart for these clearances (thanks bountyhunter & steell for tipping me off with those clearance specs!), it looks like we need 3 2.70s (32mm). It turns out that not only were the two intake valves tight at 2.75 each, we've got adjustments to make on the exhaust valves as well. Any chance that you've got three of these laying around?

Thanks!

I will look tonight.