Basketcase 1075 Prostreet...ish

Hey Everyone! It has been a long time since I've been in the motorcycle game, let alone the KZ world, but so damn glad to be back. On to the good stuff. Well, kinda...

TL,DR: Questionable past of a "pro street" build, lots of miscellaneous mismatched parts, need to figure out best route to go for a decent street build. Pics will come tonight. Questions further down....

Traded a clean studded 5.3 LM7 and all my various parts for this KZ 1000. I feel like I got the better end of the deal, clean title, mostly complete parts bin, nice roller, etc.. The story I got was that he bought it running from a gentleman in WV who drag raced with it. No confirmation by way of pictures or time slips, so no reason to doubt up to the point. THEN he starts telling me how it being a 1075 with these carbs(I find out carbs are later model VM28's, non pumper, sometime from 1972-1975, based on info I found here) and it had some 300hp. Now I'm starting to feel like this is not what I think it is. 300hp on a 1075 with VM28's seems really far fetched. But as we continue on, he claims it to have an undercut trans, it does have an air shifter setup, Dyna limiter box at the top of the tree, Dyna ignition at the crank(I don't recall seeing a box that I thought they needed to run), excel coils, wires, +2 swingarm, J Head, KZ cylinders, KZ block, and some giant cams. Has all the trimmings to be a fun street bike with a little grunt for a fun few runs at the track, but I'm thinking more about 125 hp at best. Maybe even less. So I get it all home and did the research on the parts that did come home. 

Frame VIN (Thank the lord Zedder exists) shows it as a 1980 KZ1000-E2 Shaftie, Motor VIN shows it as a 1980 KZ1000-A4 MKII. He had 2 different cams, one is a web 231(.470 lift, 300 dur.) and a Cammotion Z10(.485 lift, 272 dur.). Cylinder bore is 2.835 or so, pistons measuring 2.825 ish, so 1075 seems correct. 3 of the pistons have no markings, shocker. One piston has the Wiseco emblem and the 4052 embossed underneath. So still not sure what was happening here, but I'm working under the assumption that a few valves were playing footsies with 3 of the pistons, and that's why a few of them are different and a new head appeared. The one Wiseco piston has a wrist pin sticking halfway out, it is 17mm, and it's 100% seized. I'm sure it'll press out fine, but I assumed they should be able to slide into the piston fine(assuming there are no burrs from the c clip moving in the groove). I figure the con rod will need to be heated to allow the pin to slide in and the piston will have a smidge of free space to slide in, but I have never done this before so correct me if I'm wrong. Also, he said the center gasket on the cylinders was milled out and epoxied where it separates the timing chain from the cylinders. Why? I assume it's an old school thing, but definitely threw me through a loop.

Goals. Fun street bike, I'll probably only use it to go back and forth to work for the most part, maybe take it to the track once or twice, but nothing crazy. Yet.

So, now you all have the information I have. Here is where I have a few questions, that I've not yet been able to find here. 
-I know I'll lose a couple points in compression using a J Head on KZ engine, but if someone were to make this head fit on this motor from a compression perspective, what would be the changes? Milling the head? milling the cylinders down? Need to make sure this wasn't some bastard child that was put together before I move on to other things. Would I be better off running a stock KZ head?
-I'm going to weigh the pistons to at least make sure they're all the same in that perspective, but can someone help clear up the proper way to install a wrist pin? Heat up Piston in the oven then heat up the con rod, then glove up and throw the pin in afterwards? Would I just be better off buying a new set of pistons, rings, clips, and pins? Trying not to do that yet, but will do what's necessary to keep this old girl alive. 
-CAMS. These cams seems to be insanely oversized for a 1075 and VM28's. Maybe I'm wrong, but that's what I feel with my limited knowledge of these motors. I've heard the Web 118's are perfect for a 1075 mild street build, but need to make sure the valves weren't under shimmed for the monster cams it came with. 
-VM28's Carbs. I have no problem rebuilding, balancing and tuning carbs, but I'm not sure if these will be good enough for this application. VM29 Smoothbores better? RS34's? CRS31's?
 

300HP rom a NA KZ1000....     I needed a laugh first up this morning !

wrote:

300HP rom a NA KZ1000.... 

   I needed a laugh first up this morning !

Yep! Even with 1075cc ,a turbo and 30 psi we only get 250 hp on the drag bike..

Yeah, that's about the time I realized he had no idea what he was talking about.

I guess he could run 2 kits of nitrous  , but would have blown the cylinder head off its studs..

wrote:

So, now you all have the information I have. Here is where I have a few questions, that I've not yet been able to find here. 
-I know I'll lose a couple points in compression using a J Head on KZ engine, but if someone were to make this head fit on this motor from a compression perspective, what would be the changes? Milling the head? milling the cylinders down? Need to make sure this wasn't some bastard child that was put together before I move on to other things. Would I be better off running a stock KZ head?
-I'm going to weigh the pistons to at least make sure they're all the same in that perspective, but can someone help clear up the proper way to install a wrist pin? Heat up Piston in the oven then heat up the con rod, then glove up and throw the pin in afterwards? Would I just be better off buying a new set of pistons, rings, clips, and pins? Trying not to do that yet, but will do what's necessary to keep this old girl alive. 
-CAMS. These cams seems to be insanely oversized for a 1075 and VM28's. Maybe I'm wrong, but that's what I feel with my limited knowledge of these motors. I've heard the Web 118's are perfect for a 1075 mild street build, but need to make sure the valves weren't under shimmed for the monster cams it came with. 
-VM28's Carbs. I have no problem rebuilding, balancing and tuning carbs, but I'm not sure if these will be good enough for this application. VM29 Smoothbores better? RS34's? CRS31's?

 

J head is 40cc compared to the kz's 36cc.
This equates to an approx comp drop of 2 points.
1mm of stroke is approx 4cc (depending on bore size) so a 1mm head skim will get the comp back up to where it should be.
Wrist pins should be a light push fit with no heating necessary.( DON'T heat the rods . You would only need to lightly warm the piston if at all and not in the oven )
Generally cams up to 410 lift are best for a fast road bike.
28mm carbs will be fine for 1075 street motor and depending on valve sizes and cams would be the minimum size.

Thanks Zed for the info. Do you know if there is a way to tell if the head has already been milled? Also, if the pistons are 10.25 compression for the 1075 kit that was installed, then the likely compression ratio would then be 8.25, is that correct? So milling the head would be necessary to take full advantage of the aftermarket pistons. 

After I got home, I found that the one wrist pin that was seized was seriously corroded, but the rest were properly fitted, moveable, but no slop. Double checked the fit on the connecting rods and determined they fit well. So no heat needed. 

Yes! the comp will be approx 8.25 with the J head.
Unless you can tell by appearance you will need to CC the head to see if it's still got 40cc combustion chamber volume.
Due to the curvature of the combustion chamber a skim closer to approx 1.3mm will be needed to correct the comp ratio to match the piston spec if needed.
The J valves sit 1mm higher in the head ( and have 1mm shorter stems ) so skimming the head doesn't close up the piston to valve clearance any less than using a stock KZ head.