Skorpion 660 Lightweight Build

[breakwellmz]

I didn`t realise Skorpions had plastic tanks. It must be some impressive paint used at the factory to get the finish they had. I quite like the look you`ve achieved by removing the paint though and that you can see the fuel level.
Been enjoying the Mastiff lately but will have to raise the gearing, second gear is engaged as soon as i`m moving and i`ve found myself looking for a higher gear than fifth on occasions, the gearing on a Mastiff is lower than on a Skorpion though.

[jpmsteadi]

I am sure it is geared that way for the off-road intent. I know on my DR going to a 14 tooth in the front from the stock 15 made off road so much more enjoyable. much less clutch work.

I got in the Kawasaki ninja 400 wheel, sprocket, brake rotor, and axle in today for the rear wheel swap. Just off the bat picking them up: WOW its light. incredibly so. Casting tech has come such a long way in 25 years. I will be doing the fitment of it in the next couple of days, but just glancing at the stuff seems to indicate that it shouldn't be too bad. Nothing a lathe can't solve.

[Puffs]

I'd guess the gearbox ratios will be inherited from the XT's, so wide-ish ratios aimed at offroad use, with a short 1 for difficult climbs. For road use a taller 1st/2nd (/3rd) might be more suitable, but you probably won't find that. For optimising the final gear ratio, I look at the top gears. Btw, on my SP too I put the biggest F sprocket I could find - only road work for that old bike.

As discussed earlier, wheels can be a good focus for weight reduction.

[breakwellmz]

Hi.
I`ve been running the same gearing (And still the original F and R sprockets) on it since new, but only since the carb, intake and exhaust mods has it felt as under geared as it does now, all down to the extra torque the engine produces at lower revs.
I think i`ll go to a 43t on the back.
Cheers.

[Puffs]

I see. Would a taller (tubeless?) tyre help?
You can calculate the impact on the final ratio, and big tyres also give a different look.

[breakwellmz]

I`m running a tubeless tyre with a tube, always have done.

[Puffs]

Good for you, but the point here was not if it's tubeless, but rather the size of it.

I was just pointing out that if sprockets & chain are still fine, but the tyre needs replacing (as happens to me frequently), you can choose to achieve a taller gearing with a bigger tyre.

[jpmsteadi]

The spark box from bill finally came in. Along with a new rectifier and new coil for the CDI. I am making brackets for it all and mounting them.

The CDI:

The Rectifier:

and my favorite, the coil:

[jpmsteadi]

I am going to do another rewire as well, hoping to make it cleaner and final this time around.

The rear wheel swap is going well too. The axle for the ninja is also a 17mm and is very close to the proper length too. And I like the look of the rims too. If I end up really liking it I might get a front wheel for it to match.

I have a 3d printed caliper bracket to check for alignment before making the part on the mill. Seems like its going to line up! (and the mount will end up extended over the swingarm and being thicker where the bolts mount.

[Puffs]

That all looks very nice!

That rim sure seems light, but I wonder if that bracket the calliper hangs on is strong enough?

[jpmsteadi]

I mentioned in the previous post, but that caliper mount is to just see if everything is going to line up. The final mount will be much thicker and in aluminum.

[droy]

looking great - two rear wheel questions:

You said the axle was close on length (and 17mm). would it work as a stock replacement (a little long or short)? I hate the stock axle - looks like its from the 50's

what machining did you do to get the 400 wheel to work?

[jpmsteadi]

the axle should work for stock as long as you keep the big washers: it is a bit longer and will need that space taken up by the two washers.

As for machining: so far none, but I will end up making to make the new brake caliper bracket and make a wheel spacer to take up the rest of the space. I don't think it will be a hard project, but certainly one that would be very difficult without machine tools.

[droy]

Thanks - I'll give one a try

[Puffs]

Printed for testing - yes I overlooked that, apologies.