kz750 twin performance upgrades

gumby prichard wrote: but .0019inches converts to .05mm so basically .002 is hardly in spec, which would mean i need to replace the shims anyway with smaller ones....correct?

Actually, the original spec for the 750 twin is .002" - .004" but was later "opened" to .002" to .006".

Technically, .002" is in spec but I shoot for .003 - .005" on mine

gumby prichard wrote: can i find these shims at advanced auto? and pleaces liek that? or should i go straight to kaw?

These are 32 mm shims and they are not available new from anybody. Z1 Enterprises has some sizes available in used shims. Other than that, ebay has a few sometimes and some dealers will swap one with $ on the side.

oh great that makes me feel great about this. so do you think they couldnt find the correct size they needed so they threw in some larger ones?

lets say i wanted to go with bucket over shim, what bike could i steal from that would fit?

gumby prichard wrote: oh great that makes me feel great about this. so do you think they couldnt find the correct size they needed so they threw in some larger ones?

No, clearances gradually get tighter over time. The previous owner probably never checked them. The service interval for checking clearance is 3000 miles.

gumby prichard wrote: lets say i wanted to go with bucket over shim, what bike could i steal from that would fit?

Aftermarket buckets from APE, bore the 8 holes to fit the buckets, send an original retainer to APE and ask them to make you some titanium retainers for 9.48mm shims (lots of bikes use that size, so they are easy to find) for shim under bucket, assemble head with shim under bucket.

so none that drop straight in? gotta bore? lame. sounds like more work than i really want to do. i'll stick with shim over bucket. Thanks again guys for being so attentive.

bountyhunter wrote:

gumby prichard wrote: oh great that makes me feel great about this. so do you think they couldnt find the correct size they needed so they threw in some larger ones?

No, clearances gradually get tighter over time. The previous owner probably never checked them. The service interval for checking clearance is 3000 miles.

ahhhhh, i've never owned dohc im used to rockers and for some reason i was thinking the lobes and shims wear down causing you to have to put larger shims in. :S

OK GUYS hopefully i can get some clarity in this.

checked the shims, exhaust 1 shim was 150, exhaust 2 shim was 165, bot intake were 160, any idea why the two exhaust valves would have .15 difference?????? also either way a .002 feeler gauge would not fit in any of the valve clearances...... suggestions about the whole situation? and what shim should i move to? should the exhaust shims not match?

actually it may have been 250 265 and 260s ,but you know what i mean.

Typically, valve heads gradually sink deeper into their seats inside the engine head, thereby requiring periodic replacement with gradually thinner shims in order to maintain valve clearance within specs.

Such routine shim replacement usually continues until the thinnest available shim won't provide the needed clearance.

When the thinnest available shim won't provide the needed clearance, it may be feasible to "tip" the valve, which is a precise process -- not for the do it yourselfer -- whereby a minute portion of the stem end of the valve is machined or ground away in order to achieve a "shorter" valve stem, which thereby adds clearance.

After "tipping," it is of course necessary to determine and install the newly required shim size.

Good Fortune!

yeah, i know that, but does it make sense that the exhaust valves are two completely different sizes?