'99 Prebug Zuma Build

[billwill]

Welp, posted up the rear wheel on facebook marketplace to see if it gets any bites. If I get what I want for it, the Kiesler is a go.

What is a reasonable price for a single rear Aerox wheel in the U.S.?

[billwill]

Spent some time getting a decent fit with the Torsen arm tonight. I found some axle slider hardware I had laying around that was a near perfect fit to use as spacers instead of the janky aluminum bar I was toying with last night.

I cut the axle sliders down to the length needed. Because the Aerox wheel/longer axle nut pushed the Torsen arm out by a little over an inch, the exhaust didn’t mount exactly as it would have with stock wheels so I couldn't use the Polini hardware to attach the exhaust to the Torsen arm.

I ended up using some rubber washers to create my own mounting setup so we’ll see how it holds. Then I noticed the silencer was coming into contact with the Torsen arm due to the differently angled setup, so I just popped it off and cut down the tail end of the pipe before the silencer down by about 3/4” so that it would fit.

What a roller coaster of fitting, finagling and mocking things up. All for a potential boost in rigidity. We’ll see how it goes on the first ride. The wheel spins freely and clearance on the wheel, arm and pipe is tight. But I’m happy with where things are at for now.

[aeroxbud]

That looks a lot better than the previous idea.

[billwill]

Went back to the stock bars today so I could wire up and run this aftermarket cluster I had laying around that I picked up a while back. Nice because it reads higher than just 40mph and matches the blue theme going on (sort of, it’s really a different shade of blue). 

My lord what a bunch of work, and the kicker, I’m pretty sure I don’t like the look 😭💀

I'm glad to have tried it and proved it out, but there’s just something about the naked bars that has such a simplistic vibe. It took a while to figure out the wiring for the new cluster and I even had to ditch the stock wire connectors/terminals to match up to the aftermarket one. I tell you what, having a fuel gauge is nice though. Was looking at aftermarket fuel gauges but they are all so big and clunky. 

This was the first ride with the Torsen arm setup too so I was eager to see how it felt. To be honest, I didn’t notice any improvement there. I’m wondering if the spacer setup I have just allows it to flex as much as it normally would without it. Glad to have done each of these things to sus it out and to say I could, but might be reverting both soon here. 


Stock connectors:




All wired up in new terminals to the new cluster. 






New (old) look:








the modern amenities of a fuel gauge lol

[aeroxbud]

Now to get it off the speedo readings. 😁

[billwill]

Over the past few days have been fiddling with things and put some 14/42 gears in and a yellow malossi torque spring.

In prep for those changes I also lightened the rollers from 5.3g to 4.5g.

Started fiddling with the carb too since I never got it fully dialed. Really just slapped a 138 main in it and focused on everything but full throttle up until now. The carb was pretty on point this way with a 50 pilot and the needle clip in the middle position. Crisp response and smooth idle up until 3/4 or 7/8ths throttle.

I also (finally) got a proper air filter setup and have a unifilter foam filter on it now. No more open carb lol.

Temps with this setup hovered around 180 to 190 at idle once warm but never got above 250 or so running it good. Full throttle would bog after a few seconds of keeping it pinned. Doing some more research on this specific carb, the Polini PWK 24, had me realize that this actually likes way lower main jets than the other PWKs like OKO etc.

I saw this thread posted by (I'm assuming Brandon) Scooter Swap Shop: 49ccscoot.proboards.com/post/250116/thread

So, I dropped the main jet to a 120 and pilot to 48. This wasn't a vast improvement over the 138 but I did notice a bit of a change. Thinking I may need to drop even more and the temps I'm seeing are an indication of that. It never got above 265º.

Feeling a little disheartened as I only saw a top speed of 52mph with this setup but thinking once the proper carb and trans tuning is in place, I'll see closer to 65 or even 70. With a full overrange setup and 14/42 gearing, it'd be silly not to hit that.

[billwill]

Dropped the main jet to 105 and the pilot to 45. Seemed to run a bit cleaner but there is still a flat spot from about 3/4 or 7/8ths to full throttle where there doesn't seem to be any change or increase in power. The only change is a slight change in noise. If anything it loses power in this range, just slightly.

Temps were looking better with a temp of 310º reached after about a 3/4 of a mile of full or 7/8ths throttle.

Upper throttle range aside, seems like there is a TON of trans tuning to be done. 53mph max with the current setup and on this last run. I'm seeing rpms sit around 11,500 but it feels like it wants more. I swapped to a yellow torque spring but now thinking I might need to pull that back out and switch to white which seems awfully weak for this setup. Might go back up on the rollers too - right now I'm running 4.5g and could bump back up to 5.3g.

[billwill]

Sure enough, the pulleys are looking very underutilized.

It's also hard as hell to tell where the belt really is/has ridden with these ceramic coated stage6 pulleys, so take the markings with a grain of salt. It's not as clear cut as if it were bare metal.

[billwill]

Noticed my belt was looking a little worn so I measured it and it comes out at 16.8-16.9mm. I don't know if this is too worn or not but it comes from the factory at a width of 17.8mm.

I would think to remove some shims from the variator side but I am running exactly ZERO shims right now. Its kind of crazy to think I might have to remove some material from the drive boss?

One of the edges of the belt looks like it has some increased wear and taking a look at some of the areas in the case that I had ground down for the overrange to fit, it seems like it might be catching on some of those sharp edges. I might order a new belt and grind some more of the cases.

[Zino]

Your variator nut looks like it is not using all the threads .
So your drive boss may be on the long side .

Your temps sound closer to right for the main jet

[billwill]

Dec 14, 2023 19:06:08 GMT -5 Zino said:

Your variator nut looks like it is not using all the threads .
So your drive boss may be on the long side .

Your temps sound closer to right for the main jet

Dang good catch on the variation nut. Not even in focus haha. I’m going to double check that.

What’s the best way to shorten this boss, short of taking it to a lathe or machine shop?

I have a grinding wheel I could take to it but that wouldn’t give a true flat surface.

This carburetor thing is going to keep me stumped for a while I feel like. Really no idea what to do about this 7/8 to full throttle dead spot.

[Zino]

Does that variator set up
Have you removed the whole electric start assembly behind the variator .

when I remove the e-start to take weight off the crank so it revs higher and spins up faster .
I used washers from Lowes to make up for the thickness of starter clutch

here is from zuma thread
Electric starter delete
I did this a couple weeks back
The engine spins up a little faster with the extra weight off the crank .
So I did find I am running 6 grams on the variator for the same shift point
E-start 5.5 grams was 9100 rpms when I hit the throttle 6 grams was 8800 rpms
After Delete 5.5 grams hit 9400 rpms and 6 grams hit 9200 rpms

I did have to shim it for taking out Starter clutch
I used the Malossi shim that came with the variator on the backside where the starter clutch was
I used 2.5 mm total
2.5 to 3 mm would have worked you could use a 1/2 inch washer from a hardware store to space it out .

I just measured the starter clutch like this

[Zino]

this the malossi shim that I used it is 2mm thick

[billwill]

Dec 14, 2023 20:28:30 GMT -5 Zino said:

Does that variator set up
Have you removed the whole electric start assembly behind the variator .

when I remove the e-start to take weight off the crank so it revs higher and spins up faster .
I used washers from Lowes to make up for the thickness of starter clutch

here is from zuma thread
Electric starter delete
I did this a couple weeks back
The engine spins up a little faster with the extra weight off the crank .
So I did find I am running 6 grams on the variator for the same shift point
E-start 5.5 grams was 9100 rpms when I hit the throttle 6 grams was 8800 rpms
After Delete 5.5 grams hit 9400 rpms and 6 grams hit 9200 rpms

I did have to shim it for taking out Starter clutch
I used the Malossi shim that came with the variator on the backside where the starter clutch was
I used 2.5 mm total
2.5 to 3 mm would have worked you could use a 1/2 inch washer from a hardware store to space it out .

I just measured the starter clutch like this

Thank you for this write-up, awesome stuff and most appreciated but yeah I removed the starter and starter clutch. I had to in order to fit the overrange.

At this point, I've read a few things about folks struggling to get full travel out of the S6 overrange and I'm wondering if its just not in the cards for this setup.

At the time, I had found a great price on the whole kit on dynoscooter and it was significantly cheaper than other places AND the MHR overrange but I'm thinking it might be time to try the MHR. Sitting at 11,500 rpm on flat with 14/42 gears and only topping out at 53mph doesn't sit right.

My Vento Triton with similar gearing will do 60mph at 10,000 rpm. It just doesn't feel right.

[bigmatthew86]

I would still go down a size on the main. I shoot for peaking around 350 so you’re still a little rich to me. Try the white contra, I ended up like it more than the yellow.