Kawi2strokes.com Forum

I have been a little quiet on the board again so here is an update of the racing this year.

Been busting my Kawasaki's, Z1R broke a crank at Willow, and my H1R and BH had ignition problems. TZ750's ran great.

After a repair the Z1R had another crank issue at Road America, BH ran great, but the front brake disk on my H1R cracked

Lorraine also blew an engine at Willow, but had a good time at Road A and Grattan and picked up her first wins and a couple of minor crashes.

Although we have been to the track several times the focus has been on the IOM and the TZ750 I have specially built. Here is a link to the build process and plan from Scott Clough web site.

http://home.earthlink.net/~scloughn/id22.html

The bike is in a container heading to the Island with my A1R which I will also ride.

Dave

My hero! Go get em Dave!

_________________
Twist the throttle, tilt the horizon, and have a great time. What triples are all about...........

Early Z series cranks are very hard to get wrong. The first year ZiR's with the short cam gear. Later Z1R cranks had the longer chain, bigger sprocket, used a different type cam chain tensioner and were leaps and bonds better. They all need MIG weld on the crank pins, NOT TIG. MIG weld doesn't change the heat treat on the end of the pin, TIG does, which makes the weld area different than the rest of the pin, and I have repaired more than a few TIG welded pins that broke away. Since MIG adds weld material, and not at TIG heat levels, the welds hold far better than TIG welded ones do.

Early GPZ1100 cranks had shifting issues on the left flywheel pair. The two wheels on the let would slip on the main axle, and move the rod end forward, done from heavy downshifting deceleration only. Result was wiped out valves and a dead piston. Usually, simply doing the alternator end over, with MIG welding as you go, stopped further issues. Factory did a warrantee crank replace with a MIG welded pin set for them. I did a few crank re-phase and MIG weld repairs on the cranks that came out of those engines, after the factory stopped the warrantee program for them from the factory.

I remember doing a few cranks for rob Muzzy back then, for Lawson's EL race bikes, made Titanium rods, with shrunk in big end races, then, built the cranks. To make the inserts, I took stock rods and cut away everything that wasn't a rod race for the big end, making the big end races, then, cold/heat shrunk them into the Ti rods. I know one of those cranks went two years in one of EL's engines, then, became a front room lamp, complete with special painted shade.

I used to MIG weld all the two stroke cranks as well, never had one come loose, and they always pressed apart easily, no alignment issues when they went back together.

The #2 big end pin snapped into two on my Z1R crank at Willow, I cannot complain, I purchased the crank at the swap meet in Sandia and it lasted 3+ years and posted 30 race wins. The second one came from a Craigslist $250 engine, oh well....

Yup, the can do that. When they are apart, have them tested with two methods. First is the regular auto machinist's "mag check". This uses a magnet and iron powder to detect surface cracks as they are starting, and if you find them to be in question, go to test method 2, have the part X-Ray inspected.

It is rare to see a big end pin broken, but it does happen in extreme high stress situations.

Something else I did was to build press fixtures so I can literally press the cranks straight, and not hit them with a soft brass hammer to get them straight. It is easier on the parts if the wheels are "slid" on the pins, and not shocked into moving, with the hammering.

Might ask the drag race guys, like Baxter, what they use for those parts, might be some better ones in their particular realm in the world of racing.

Dave, any experience with the J engines and racing? I am just updating my P&M to a big J engine for Phillip Island and I am thinking of upgrading my Z1R. Lots of parts available since they use these in police bikes.

Scott probably knows the guys at APE, they do some really nice work on dragbikes and shouldn't be that far away from his shop, they are out by Willow. And I think Marine Crank does a lot of Z model stuff.

The guys around home here always used to use John Pearson in OH for all the KZ/Z1 cranks. I know he used to do all the cranks for Gast and Schnitz as well. (937)839-9723, he has no website as he has enough word of mouth.

Man, you ask an old, feeble mind to remember about stuff that has cob webs all over it.

J (M, 1000cc) engines are a bit better, 998cc, instead of 1015, smaller bore, different cranks, rods, pistons larger valves, cams, larger inlet and exhaust ports, not a bad start over the older early Z series.

The ONLY issue we ever saw when Muzzy ran them (and I built them when I was in charge of R&D at RC
Engineering) was the cam chains, cam guides, and cam chain tensioners. The early engines run roller cam chains, the later ones, link types (flat plates with connector rivit pins, like a timing chain in a car). The main problem with the link chain is that when it is in full operation rpm's, it tries to go round in shape, and doesn't change direction well at all. So, when the chain needs to "bend backwards" as it travels up, and back from the top end, it wants to literally force itself into the guides and tensioner parts, and is working against itself.

With the type of crank/cam orientation of these engines, old and new, that ain't good. When I worked at RC, the first J/GPZ crank I did was for an early GPZ1100, and I did a fast one with it. I used an old engine center pin, with roller chain sprocket, from the 1980 MkII engine (16 teeth, as opposed to early Z 15 tooth), machiined the cylinder and cam cover for rthe early cam tensioner/roller sprocket guides, and made a manual cam chain tensioner, eliminated the link chain guides, and made sprocket adapters for the later engine 2 bolt cams, to the early cam 3 bolt roller type sprockets. The owner was then a UPS driver in Cookeville, Tenn., and I spoke with him about a year ago, same engine is still going well, NO failures of anything, cam drive setup working just fine. The reason we got that engine in 1982 was, it tossed the cam chain and guides, broke the tensioner.

It is also NOT practical to attempt to graft a later J/GPZ head onto the early engines. The later engines have a lot more potential than the early ones do, and that is the series Muzzy did for the Lawson racers. With the exception of only that one engine I helped modify to roller cam chain setup, Muzzy used the stock J/M/GPZ link chains and guides, but changed them just about ever second AMA National race event, just to make sure they didn't get old enough to make problems.

I always wanted to do a different center in for the crank, and sprockets that were for gear drive, then make a drop in drive pod to do same, but, never got around to doing same.

Definitely look into doing a later engine if you can, they have a lot better potential from the start than the early ones do, and, when done right, about the only thing that beat them was the rider falling off the bike.

For cam profiles that work, you have an excellent source near you, Jim Doerr at Mega-Cycle Cams. His cams just plain work well in road race engines. From what I also remember, his wife Barbara, was/is super knowledgeable about cams as well, and is a nice lady to speak with.

Thanks Dave, great feedback. Dave