Skorpion 660 Lightweight Build

[jpmsteadi]

Hello all,

I am new here, but I also just bought a MZ skorpion yesterday from one of my good friends. He had an Moto Guzzi V7 and traded it to guy for a Ducati 900ss and an MZ Skorpion. I had just sold a bike and was kinda looking for a project, given that we are all locked down for the foreseeable future. He was just going to throw the MZ up on craiglist, but after I rode it I figured it could make a fun project.

I am figuring to do a COVID-19 shutdown inspired build: only the essentials. Trying to get as much weight off the bike as possible. Should be a fun little project.

I spent today taking most of the bike apart and weighting everything. If anyone is interested in those weights I can list them.

There will be some fun 3D printing along a good deal of titanium and aluminum to replace a lot of the steel on the bike.

Not sure if anyone does build threads on this forum as I'm new, but I am guessing this will turn into something of the like!

Hello again and I look forward to searching through the forum and getting all the info I can from it!

-Jarrett

[breakwellmz]

This sort of thing? -

[Puffs]

Removed

[jpmsteadi]

This sort of thing? -

Kinda that sorta thing, but street legal and less aggressive in its stance. Something to putt around town on mostly, but also a fun project to get my though isolation times.

I already have a lithium battery planned!

Right now I have this list of things and their weights:
Part Removed weight Notes
Dash Cluster 1,713g
front fairing 3,816g
rear seat 933g
front seat 762g
front fairing hardware 36g
left side panel 855g
right side panel 855g
side panel hardware 61g
speedo cable 157g
front fender 562g
front wheel spacer (steel?) 28g 12.5 lg x 28 w x 20 id
Speedo Drive 226g 32lg x 32w x 20mm id
axle, steel, solid 653g
axle pinch bolts, steel 42g M8, 40mm lg
left controls, with screws 38g
clutch perch, level, cable 387g
fuel tank bolts 16g M5, 20mm lg
air filter 90g
battery tender cable 58g
BAttery 3,385g
fuel tank bolts (x3) 12g
rectifier, w/bolts 353g
CDI w/bolts 123g
rear axle/ w washer and nut 692g
Rear subframe bolts/nuts (x4) 150g
exhaust bolt/nut/washer 68g
oil drain bolt 38g M14 x 16.5
front srocket gaurd/with bolts 62g
taillight/w nuts,washers 263g
right heel gaurd 124g
rear fender 642g
rear braket master bolts 12g
lisense plate bracket w/turns 549g
subframe bolts/nuts 151g
toolkit 1,009g
wiring harness zipties 10g
wiring harness 949g
airbox bolts 43g
left radiator fan 236g
right frame cosmestic piece 74g
right side radiator fan 297g
left frame cosmetic piece 74g
horn 141g
left heel gaurd 123g
radiator bolts/washer/nut 26g
coolant sensors 82g
Throttle/cable/right controls 377g
handlebars 800g


Obviously a lot of those things will be added back on in some form, but I have a reference now as to the before and after weight.

I'm gonna see how crazy I get with a lathe. Maybe try and make my own hollow steel or solid titanium axles. Depends on how crazy I get. I am going to start with all the relative cheap stuff, then progress from there.

[Puffs]

Wow...

[jpmsteadi]

Things are going well on the build!

I have taken the bike almost all the way apart, cleaned it and removed everything I don't plan on using. I have gotten it back together and in running shape with new tires, new headlight and taillight, and some custom 3d printed parts (a new air filter for one).

This bike is so much fun to ride; light, flick-able, and not fast enough to feel like you aren't pushing at all at legal limits while being fast enough to feel fun!

Very much enjoying the project and the riding of it.

I have been searching around the forums and learning quite a bit on the bike as well. An interesting design and amalgamation of yamaha and MZ parts. Some of the MZ parts (like the air filter) are just not available anymore. I'm having trouble sourcing a chain slider right now, but have a feeler out and may just have to design something to replace it as well. My goal is to use as many OEM parts as possible, be them MZ or other-wise. Makes replacing stuff down the line much easier. The bike isn't pretty right now, but itll get there!

[breakwellmz]

Lets see some pictures then!

[Puffs]

Right - pics or it didn't happen...

'not fast enough to feel like you aren't pushing at all at legal limits'??????????? Even my 251 does naughty (and I don't mean within the city limits)...

[jpmsteadi]

Right - pics or it didn't happen...

'not fast enough to feel like you aren't pushing at all at legal limits'??????????? Even my 251 does naughty (and I don't mean within the city limits)...

Well, compared to my street triple, I feel like gunning through the first couple gears only gets me to 60/70 as opposed to 110....

Ill go downstairs and take some pictures now!

[jpmsteadi]

Here are some pictures. As you can tell, it looks REAL ratty right now. My goal was to just get it back on the road ASAP so I can enjoy it while I work out how to make it look as good as it rides, haha

The headlight assembly while printing ran out of black filament and so I used some scraps I had just to finish it and test fit it. I have another all black one printing right now (just under 2 days print time though). I've got the angle of the light worked out and its super low profile and lightweight (only 8 oz)

The handlebars came on the bike, I have some on the way that have a larger pull back to make the seating position a bit more comfy. Thankfully the bike had already been handlebar converted, though the handlebar risers are brown for some reason.... I cleaned up the bars by using a motion pro kill/start switch, a motion pro slim throttle housing, and a 3d printed choke housing. I am borrowing the RSC clutch lever from a friend to see if it works in the low effort setting (it does!). It won't be purple forever, I promise. The key is a Sicas racing lightweight item with a 3d printed part to make it go into the OEM hole.

[jpmsteadi]

The radiator lost both of the fans and coolant temp sensors (as the fans didn't work, they were unplugged when I took apart the wiring harness. Plus the plugs were quite heavy). The two holes in the radiator got aluminum plugs and a tusk fan unit was installed. At some point I will probably do a 3d printed bracket for the fan to get rid of the metal parts, but for now it works.

The stock seat is pretty awful, so I added some foam and recovered it, but as you can tell from a previous picture, upholstery is not my gift. The bike is ridable again and much more comfortable, but I want a better looking solution. I just sat the street triple seat on the bike to take a look and it matches fairly well. In reality I think I'd love to just go with the stock skorpion long seat that exists on the tour, not the sport, but I can't find one of those anywhere. I am VERY open to suggestions on this; it is for sure the part of the build I am least happy with at the moment.

[jpmsteadi]

Just weighted it as well (using an admittedly less that ideal bathroom scale method) and it comes in right at 365lbs with about 3/4 tank of fuel. When I first got it home and weighted it the same way it was at 398 lbs. So 33lbs lost so far and non of the titanium or tab trimming has started yet.

I have held off on doing any non-reversible mods yet so I could return it to stock should I become disillusioned by the project, but I think I might take the dive soon.

[Puffs]

Removed

[jpmsteadi]

Thanks for those pics!

Yes, surely a modern sportsbike like the street triple has the ratio of the gears closer, and consequently a much taller 1st. The XTZ660 was by origin a trails bike, which had wider gear ratios to cope with difficult circumstances. Close-ratio gearbox vs wide-ratio, and I suppose MZ took the engine un-modified. And of course the triples (both 675 & 765) are substantially more powerful than the single.

The miracles of 3d printing!

I'd put a F mudguard, without it, 1 wet patch and your visor is dirty. It might also be a legal obligation.

Radiator fans: are you sure you wan to have those off?

For making a good seat you need stiff (closed cell) foam, and properly shaped, and that's a problem. If you have suitable foam, maybe shaping it with a steel brush fitted in a stationary drill might work? Or use thin layers?

A bathroom scale, first F then R, should be OK, but for accuracy you should lift the other wheel by the same amount as the scale does, so that the bike is horizontal. Piece of wood, tile, ...

On your weight savings, 33lbs is a good start, but at 154kg dry it is still not spectacularly light (for the 58HP/58Nm engine).

For sure the gear ratios are super close on the street triple. The wider ratios are quite fun on the skorpion.

There will be a small front mudguard at some point.

I may have not been clear: I took off the disconnected (not by me, some previous owner had disconnected them from the wiring harness) stock fans and replaced it with an aftermarket temp variable fan with controller. Lighter than stock and more peace of mind. It seems this bike runs VERY cool too.

I agree that having the proper foam and shaping it is key to a good seat. I am hoping to find a stock style seat pan that works well with some modifications or brackets. Be more comfortable and easier. We will see though. Its a bit of the fun experimentation with the project.

For sure its a good start. Its again sort of the process. Going slowly and replacing things as they come in. Id rather keep the bike somewhat road worthy while I do that so I can still enjoy it! Nothing as defeating as a project just sitting in the garage for months.

[breakwellmz]

Fun, fun, fun.
I`ve used an electric carving knife to reshape foam and covered it with smooth black exercise mat, i had intended to put vinyl over that but didn`t need to.