j head repair

i just wond a j head on ebay for my drag bike build. It isnt in the best shape, but i got it really cheap. It is a bare head, which is better as i will be needing new internals anyways. It has two fairly good sized spots where the cooling fins broke off. Is it possible to fix this without the two pieces that broke off? Any ideas? Here is a pic of the two bad spots.

I've repaired a few broken cylinder head fins on my Zs. Simply use some flat aluminum sheet of the proper thickness, cut to fit, clean the repair site and the repair piece with something like mineral spirits. Figure out a way of holding the piece in place before you mix JB Weld in a 50/50 combination and assemble the repair piece to your cylinder head. Let dry for a day or so.

How long will such a repair last? I fixed two damaged cylinder head fins on my '73 Z1-900 in 1977 after I had to abandon my Z1 on US 101 in San Luis Obispo, CA one afternoon - okay, me fall down. Those fin repairs are still just fine.

In fact, you can repair it so well that many folks will not even notice the non-OEM fin piece(s) .

wow, thanks alot for the help. Where can aluminum like this be purchased at?

ive got some busted up kzheads i save to chop fins off of but aint got no extra j heads im ready to take the grinder to yet

Did you get the cam caps? If not, don't waste any time fixing fins.

why? are they hard to come by?

No there not all that hard to get. But I think what Jay is saying is that when the head is built is the cam caps are bolted on and the the bores are aligned bored. So if you put caps on the head that were not matched your cam bearings will wear quickly, I have seen this done on drag motors where the cam bearings are changed often But for a rider I wouldn't recommend it.

Really? that seems odd that all the kz builds are using cam caps that came with their head. Especially since most of the heads that are sold on ebay dont even come with the cam caps. I have sold two early kz1000 heads myself that i did not have caps for.

What Jay said is rudimentary knowledge. Same as Con-rod big ends, or Crank-shaft mains. If you question APE Jay, why ask the question at all. I've been doing this from 1978, and knew this from the very beginning. Why do you think that Kawasaki goes even so far as numbers each cap individually, so they don't get rearranged, and get placed on the same journal as they were honed.

2 more cents

Actually....it's very probable that cam caps from another head will work on that one. Guys run 'em like that every weekend.

The thing to watch out for is too tight of a clearance. All the bearings are the "same size" when new.

Get some caps, clean & lube the cams and the bearings, bolt the cams in and see how they spin. If it's tight, wet sand the bearings until the cams spin freely.

You can make yourself a hone out of some round stock that will use wet paper if you want to or you can just sand them with your finger.

If they're a little loose, the cams may walk a bit at idle and make a little noise. Who cares.....How long are you idling your drag bike

Is this the Kawasaki OEM Service Manual way....No. Then again, most people wouldn't believe some of the "non public" fixes that used to come from the Kawasaki Hot Line when you called them up about a problem...

I never assemble a motor with new cams without first spinning them in the head to see how they "really" fit. NEVER trust any aftermarket part to be correct! I've had brand new cams that were sent back because they were NFG right out of the box.....

JMO

Larry C

great info,thanks for the input.

leon holmes

Fixing broken fins isn't that tough. Done the JB Weld repair and also had a skilled welder fix heads in the past.Finding flat aluminum stock shouldn't be that hard and it's easy to work with to get the repair piece you need.

I concur with Larry C. - My experience in 35 years of owning Z's and about 30 years of dragracing, & that of many other people as well ,is that the caps from one head can be used on another. I know Mother K says not to do this but I can show you many motors with replaced cam caps.

I wasn't about to throw out my big$$ GPZ head when the cam chain broke at the top of 1st.gear and took out a couple of caps and broke the cams into 12 pieces NB. His advice to check for tight fit is the most important point to note.