my mz project

[riversbikes]

Sorry for the pic size. Here's some snaps of my supermono project. Still not yet decided if it is going to be a streetbike or track bike. Skorpion frame with rg125 swingarm, r6 forks.

Rear KTM supermono wheel fitted. Have a matching front, currently waiting on spacers to be finished to get them centred in the forks and the swingarm.

It's -40C right now in my part of Canada -- cold for even us this time of year. Work time in an unheated garage is limited, but here's the modified subframe and mito tank. Shock will be an R6 model, offset to the right a la EX650 and Aprilia Shiver.

Projection components will be sending me alloy copies of the mdf template for fitting gsxr rearsets to the muz frame. I'll need to allow the RHS peg to fold UP, as I will be using an XT/TT 600 engine with a kickstarter, which might foul solid pegs.
Plan for the oil tank is an SZR660 one, mounted to the front left of the engine. Going to go with flatslides eventually. I have a bare xt engine for mock up purposes, as well as a "good" one (allegedly) to use.

Seat pan from alloy, seat hump is from a 2005 zx10R. Have a new OEM red one on order.

The hoped for end result...

[edfmaniac]

Cool. Reminds me a little of my project if you haven't seen it. I still need to have a rear shock built, replace the braking components and wheels, and do all of the final body work/tear down/paint/powder. But it's had a lot done to it already. The engine has already put down 60hp on rich stock carbs and a stock ignition so 65 at the wheel should be a safe bet with the Mikuni's and programmable ignition and the bike is down to 310lbs even with the super heavy wheels. Should be a real riot when it's done.

Good luck.

[edfmaniac]

Oh and be very careful when you design the upper shock mount. This isn't your average motorcycle frame and the original engineers probably didn't think about the offset forces created in the frame by a non symmetrical shock design modification.

[edfmaniac]

If you go with Mikuni's, get them directly from Topham. They are very experienced, will build exactly what you want and will get the jetting pretty darn close if you tell them what mods are done to your intake, internals and exhaust. I ended up with a TM34/38 and the jetting was close enough that I can't really tell if it's off without taking it to a dyno again.

[edfmaniac]

And one last thing. Have you worked out the difference in weight when you switch to the air cooled 600 mill? I bet there's another 10 or 15 pounds easy including all of the coolant, the radiator and the starter. Maybe more?

[riversbikes]

Thanks Ed. I've built and raced (and won on) a supermono frame built by Dave Pearce -- a copy of the MuZ frame actually. I adapted it to work with a DRZ400 engine, but I do realize this offset shock design will pose some engineering challenges. I also want to build in some adjustability as well, in terms of length.
As for the carbs -- I was planning on buying them from PowerBarn in the states. I did check topham, and they don't actually have a carb listing for the tt600, although they do for the 660 liquid engine..

I'm hoping the lump will be lighter, but I've also read here that the aircooled engine isn't much lighter. I've hefted 2 now, and my ex650 race engine was far lighter, if my back scale is accurate. I was also thinking kicker vs. electric start, no rad, etc... but we'll have to see.

I anticipate the rear spring being too soft at 9.6kg, and the front springs being too stiff at whatever they were set at for a heavier OEM R6. Getting it on its wheels, with the suspension in place, running, is only 50% of the battle! A huge amount of setup is likely next!

[edfmaniac]

When I said get them directly from Topham, I meant contact Stephen Topham. He will certainly be familiar with the air cooled 600 and will assemble a carb just for your particular needs.

Be careful when ordering from domestic distributors for Mikuni. They have steered a few MZ guys, including myself, down the wrong path. Fortunately I realized their price was too good to be true and did a little more research. The high performance flat slides should be about $150 to $200 more than the ones they can just order out of a book. The only way I've found to get access to them is through a European distributor like KEDO, Topham(the main source) or through a domestic US distributor after having them order it from a European distributor. I decided to go straight to the source and it worked out great for me. Don't know what the difference is between the cheaper ones and the more expensive, possibly the pump that adds extra fuel when you twist the throttle, but there's a difference. I was even able to choose a bore size combo for the weird 5 valve set up on the water cooled 660 that wasn't available anywhere other than Topham. They are the people to deal with if you are building a track bike or any engine that has modifications done to it.

[edfmaniac]

These are probably the ones you want and list for 600 Euros, which is almost $700. If the place you are ordering from quotes you much less than that, you are probably getting inferior carbs. FYI If you don't want to do business with Topham, The Vintage Spoke is local and can order from the KEDO catalog if you know what parts you need.

http://www.kedo.com/products/31235.html

[riversbikes]

These are the carbs I've been lusting after...

http://www.power-barn.com/yamaha-tt600- ... retor-kit/

[samandkimberly]

I used those carbs on my first race SRX600 motor years ago and they worked great - easy fit, great response, and very tuning tolerant. Techncially the newer design mikuni and keihin flat slides may be better carbs, but i doubt you'd see a real difference on the dyno or at the track; if i hadnt gotten a deal on the Mikunis now on my bike I probably would have gone with the CR-S too.

Sam

[edfmaniac]

Cool. I've never read anything about those carbs other than the marketing stuff, and am curious what kind of characteristics the round slides have as opposed to the flat slides. Any idea what kind of HP you are going to have in the end? Engine mods? I noticed you mentioned Projection Components. They made the headers for my bike and I was very happy with the quality.

[edfmaniac]

Haaaaa. I was writing my post when yours went up.

[edfmaniac]

I haven't been to the dyno since bolting on the Mikuni's but the feel on the road vs. the stock carbs is night and day. Can't wait to go back to the tuner to get everything perfect, finish programming the ignition and get a final number. So far I've gone from a stock 45hp to 60hp with engine mods and stock carbs.

[riversbikes]

As you can see from my sketch, I am hoping to use pro-circuit headers (which I have) and get my friendly tig-welder accomplice to fabricate a mid pipe and reverse meg exhaust that exits under the tail. The steel subframe I'm constructing should be more than sturdy enough to hold up the rear of the exhaust. I have a few rubber mounted exhaust brackets from my TZ250 days I hope to use to isolate a bit of the vibes. Alignment is key. I have the ktm rear wheel centred, and need to align the engine CS sprocket with the rear. My hope is that the front mz downtube will align nicely with the engine, and the sprockets will also line up. Have done this enough times to know that this is a 50/50 likelihood.

As for engine tuning, I'd eventually want a hop-up kit of cams and a slightly overbored piston... maybe 630ccs or so. I'll still need to kick start the bastard, so nothing too high compression. A falicon/carillo rod, lightened crank, etc would also be fun to do.... once I get the thing running, ensure that the szr oil tank functions properly, and it stops, turns, brakes, etc.

My hope is that at my local track, around 50hp (remember this is the aircooled engine), in the light(ish) chassis, might embarrass a few of the minitwin/supertwin backmarkers. No way will I contest for a win in this class (unless it is raining???) with the frontrunners on 90hp sv650s.

I'm 90% certain this will be a trackbike... but I need to keep an eye on the state of our local club, as its taking a slight downturn right now with grid entries and etc. I do love going down to the states and doing trackdays with Ducati Omaha at MPH and MAM. A dream of mine would be to do an AHRMA round or vintage days... I think those guys still have SOS or supermono classes.

[zippy49]

I used those carbs on my first race SRX600 motor years ago and they worked great - easy fit, great response, and very tuning tolerant. Techncially the newer design mikuni and keihin flat slides may be better carbs, but i doubt you'd see a real difference on the dyno or at the track; if i hadnt gotten a deal on the Mikunis now on my bike I probably would have gone with the CR-S too.

Sam

I used the same Kehins on an SRX back in the 1990's. I had no trouble with them, unlike those Mikunis...