MuZ Skorpion Engine re-build or not ?

[xbrmz]

A few weeks ago I bought a MZ traveler with a rattly top end ,Expecting to replace a few parts to get it running .

Only to find a scored barrel in four places and scuffing on the piston and a worn out little end.

Luck as always on my side ,I have found a freshly re-built engine with a 102 mm high compression piston at a good price that has never been run

This is going in my sport for testing

This now leave me with an engine in bits ,Is it worth re-building
or should I just keep it for parts ?

[Bill Jurgenson]

I would say, break the engne entirely first to see what other damage there is before deciding. An engine so mistreated as yours is bound to have further damage, e.g. in the transmission and big end.
I have seen such damage in aircooled 600 SRX engines but never in a watercooled XTZ. Admittedly, I have not opened or rebuilt all that many of them, but enuf for a survey and that engine was run pratically dry, not by accident but more probably by neglect.

b

[keithcross]

I was unlucky enough to have an engine go bad on my Baggi. On initial inspection similar damage to yours was found. On further inspection found teh big end was compleltly shot (and no the engine didnt `knock'). I also found the oil pump rotors and internal surfaces badley scored.
On talking to others it is thought the trouble was caused by a big end failing, the debris taking out the oil pump and lack of oil taking out the piston and liner. Because of the oil pump failure, I didnt rebuild the engine as the rest of the moving parts were suspect.
I hope your engine damage is not as serious.

[Wonky]

...I have found a freshly re-built engine with a 102 mm high compression piston at a good price that has never been run

This is going in my sport for testing

This now leave me with an engine in bits ,Is it worth re-building
or should I just keep it for parts ?

Has the engine with the 102mm piston been rebuilt with a Carrillo rod? Higher compression pistons can cause standard rod to snap as they can't stand up to the higher compression on a bigger bore, they get overworked!

I would strip your engine down and keep the parts as spares. The cases are expensive to buy and should you have an accident and drop your bike it's always less hurtful to be able to go into the garage and replace parts without visiting the cash machine!

[xbrmz]

I'm not sure if it's had a Carrillo rod fitted ,he did say that it was re-built professional mechanic though and he had kept it as a spare race engine but never used it .

This part of the reason I asked if it was worth re-building the old motor , with the thought of swapping them over and knowing exactly what is inside it .

The old traveler engine had done 32000 miles ,this is if the clock hasn't been changed and ran OK except for the rattling , as the little end is worn out I'll have to remove the crank to have a new con-rod fitted .
This will mean I can get to all of the parts to inspect them for any more damage .
Hopefully before I spend any more money .

[Wonky]

Sounds like the engine should have all the neccessary parts fitted, time will tell. If you need any help with parts i will be pleased to help, or check out parts here:

https://teamslipstream.co.uk/sos

[steveweck]

Will a Yamaha Raptor conrod work in the MZ motor? What are the differences in the bottom end? Are the Cranks different? Does anyone know? The reason I ask is because Hot Rods (the same people as Hot Cams) sell an assembled crank with Heavy Duty con rod and one new bearing. The assembly plus the other side bearing retails for about $300 US. They seem to be holding up well in the Big Bore kitted atv version of the motor. If these kits fit into the MZ version of the motor there is a big savings. Once you buy a Carillo rod you need to have it fitted and hope your crank is good. With these kits you basically drop them in. I would prefer this option if I knew it would fit. If anyone knows the difference between the two versions of the motor, please, let us know.

Thanks

Steve Weckesser

[steveweck]

By the way, I have compared the Hot Rods Heavy Duty con rod for the Raptor (which is available seperately) to the stock MZ con rod. As the bottomend was still assembled I could only see the piston end of the rod but the Hot Rod was substantially beefier, especially around the little end.

Thanks,

Steve Weckesser

[keithcross]

As far as I am aware teh Raptor and MZ engines use a different crank. Looking at teh parts fishes, teh MZ crank has full flywheels, teh raptor doesnt.

Keith

[steveweck]

If thats the case. Clearance shouldn't be an issue. And if its a race motor wouldn't you want the smaller cranks?

Anyone?

Steve Weckesser

[basser23]

Steve,
I understand the lower ends of these motors have different cases,and are
not interchangable regarding parts..coud be wrong though...if the cranks
are interchangable,you are correct as to the savings!!!!
Chip

[steveweck]

Well, I ordered the Hot Rods complete crank kit for the Raptor. Before I try installing anything I'll measure everything. If it works or not I'll post the results. I should be getting the kit on Monday. Probably get around to playing with it later that week. I also ordered the Edelbrock single carb kit for the Raptor. I should have it by Friday. Again, I plan on measuring and checking everything before I install it for good. I'll post results afterwards.

Steve W.

[Wonky]

The 660 Raptor rod is the same as the XTZ660 rod, same part! The 700 Raptor rod won't fit as the big end is bigger!!!!

[steveweck]

Wonky,

Do you know if the 660 Raptor crank will work in the MZ 660 cases? Would any mods need to be done?


Steve W.

[Wonky]

It would work but you will need to modify the MZ generator to fit Raptor crank and use a different bearing for the starter gear as the shaft is smaller!