MZ/MuZ Riders

Bill J.,

I'm about to pull the trigger on getting some work done to my Skorpion and I wanted to make darn sure that I'm sending the machine shop what they are expecting. The top end on my 01 Skorpion Traveler is the same as an 01 Raptor 660r, correct? I was concentrating on going with head work but the machine shop said that you get just as much gain with a bore to 686 and a nice piston at about 25% of the cost of doing all of the head work. Both would be best, but if I can't afford the $1200 or more for the entire top end, should I go with the cylinder work and a piston instead of the head work?

Thanks
Victor

I'm no expert so take this for what it is.

Higher displacement and increased CR are the path to easy power.

Higher RPMS and a better cam are harder to accomplish, but on top of yielding more power, they open up gearing and make the bike more awesome.

If you want highly increased power from a much higher CR, you are absolutely going to have to have a big cam and would benifit heavily from valvetrain work. It won't idle well or will have to idle very high (guessing 3000-4000rpms for a race cam).

I don't recommend these. It doesn't sound like you want to invest that much money or trouble into it. I would recommend the headwork because you could pull the engine, pull the block, and have it bored and install the piston yourself. It should be silly easy with a single piston. I upgraded the rods on a 4 banger from underneath, through the oilpan, around the crank, and if you aren't comfortable doing the work, don't attempt it. You could end up hurting yourself, the bike, or worse (having a shop fix it when you get lost/stuck.)

do both for maximum effect...i'd go 686 with a milder cam to increase the mid range,and port matching or light port work. no decrease in reliability,
also go with larger diameter headers( good luck finding them) convince Tim Barker to make more or have them made (33mm i think)and run duals if possible
You should have about 60hp using the stock carbs....

Can anyone confirm that the all of the specs and parts for a Raptor 660r will match up with my Skorpion engine. I don't want the machine shop to encounter any surprises or have to buy any parts twice.

Thanks

the barrel,piston,head are the same,cases are different. 01 to 05 Raptor.
crank and all lower items are different. the balancer of the 700 fits the xtz 660(per Bill J)
Hope this helps..
you may ask if it is possible to mill the head about .010 or use a thinner base and head gasket to increase compression...

just 1 MM off the head/gasket/etc would increase it to 10.2:1 CR or so. Doubtful the valves would be a problem even with an aftermarket cam.

(edit, this are fast numbers off the top of my head. if pi*r^2*h isn't right, or I have fat fingers or a stupid head, please excuse me! )

Also, it doesn't seem like this is going to do much for the motor, maybe a bump to 55hp. However with mild P&P, an appropriate cam, I think you could expect 65hp easily. Probably more like 70-75 with a good carb or fuel injection.

Megasquirt with spark and fuel control (maybe two 300cc injectors) and ITB's with a strong exhaust and the aforementioned stuff should be in the 75hp range. Another 25hp of nitrous possible with a good rod.

If I dump that kind of money into this bike, it will be for an electric conversion after I have another gasoline powered bike.

If I bore it to 686, it will get a 10.5:1 piston. Maybe I should just try that first and worry about the head later. As soon as it pulls the front wheel in second with just the throttle, I'll be happy.

edfmaniac wrote:If I bore it to 686, it will get a 10.5:1 piston. Maybe I should just try that first and worry about the head later. As soon as it pulls the front wheel in second with just the throttle, I'll be happy.

Right on!

I always recommend bottom end work before top end, but you really need the top, especially on a high rev engine. With the short stroke of this bike, it can definitely be built to rev much higher (safely) and those rpms + the power increase from cam and P&P will unlock a lot of usable powerband as well as give it a bump in power.

12:1 CR w/ MS fuel+spark and e85 would be so sick!!!

I agree, 2nd gear power wheelies are a must, but I'm willing to drop the gearing to 15/51 to help do it!

Mine will wheelie 2nd now, with just doing the Mikuni 42 HSR. It is in the shop now to have 11:1 piston and stage 1 HotCam. He is going to do some light head work, not a full P&P. I am hoping for 3rd gear power wheelies when it gets back.

I just ordered my cylinder, piston and gaskets for the partial rebuild. I'm assuming that the cylinder is cast as a larger bore because 686 is cast into it. I guess the purchase is kind of a gamble since I couldn't find anything about it online other than the ebay store where they sell them, but they sell lots of stuff and have a good rating so we'll give it a try. I ordered an 11:1 piston since almost everything that I read said that it will do fine on pump gas.

I guess a new CDI is in order now.

harold wrote:Mine will wheelie 2nd now, with just doing the Mikuni 42 HSR. It is in the shop now to have 11:1 piston and stage 1 HotCam. He is going to do some light head work, not a full P&P. I am hoping for 3rd gear power wheelies when it gets back.

I'm hoping with you!!

Better off leaving the motor alone and lightening the bike - wheels for starters..If you did some searches you would find that our esteemed Bill J always recommends wheels, chain and then the starter fly wheel before you go messing with the mill.

my method to go faster
is leave it stock
and go get a bigger bike
just requires a deep pocket book and a big shed in the back yard

dave

DAVID THOMPSON wrote:my method to go faster
is leave it stock
and go get a bigger bike
just requires a deep pocket book and a big shed in the back yard

dave

I think I'll just put a bigger motor on this one

I don't mind getting a bigger bike, but I don't know of any supermoto's with a much larger engine.

A KTM 950 Supermoto would do.

Al.