2005 Zuma 50mph+ "A Fat Guys Journey"

[TuneGoon]

I figured I'd just start a thread here in builds. Long story short: Im a large dude and Im doing everything Im capable of doing to this scooter to get it to 50mph+. I read plenty from folks who easily get 45mph stock -but Im assuming they arent 6'4 and over 300 lbs. This is where my journey begins:

Summer of 2022, I purchased a bone stock 2005 Yamaha Zuma with about 3800 miles on it. My first scooter!









It took me to all of about 36 mph over a very generous stretch of road. I opened up the case and removed the restrictor shim on the end of the boss. Gained 2 mph but at the cost of some off the line acceleration. My realistic goal was to hit 50+ not 38 mph so its time to buy some parts.

Purchased an NCY pipe along with a roller tuning kit & some Dr. Pulley sliders (15x12 5g) and (15x12 6g) for the stock variator from scooterswapshop. I also ordered a main jet kit. The stock is 80 so I ordered a 70-110 kit.

scooterswapshop.com/collections/yamaha-zuma-02-11/products/ncy-zuma-exhaust

scooterswapshop.com/collections/yamaha-zuma-02-11/products/dr-pulley-slider-kit-15x12

www.ebay.com/itm/192098611097?hash=item2cb9f82f99:g:QGkAAOSw1eBgU98f&amdata=enc%3AAQAHAAAAoA0lo3PfwGfcE9E%2BONXYqJSkQixG06RK0ocDrkmhSSvV%2BLb2QtAElJ3kJkItAahpZ5k4FEVNBtcKYHZMUQ8qRNKSHQfLijiVgyw%2FGOjHOC1%2BbPA39dxdNAcxjypgLn%2BOSfNkt4PCwtO6Uz1kuy7R7rSraVQOPYx6cj69MsjW0kCBDyzu%2FI%2FfJECgmeOuPTg5JO9ha6aYd%2B3KD%2FwWSNenCJ8%3D%7Ctkp%3ABk9SR665vMTSYQ

I received the sliders first so those got installed first and I didnt gain anything up top, but the acceleration was much nicer. The stock 6.5's were too heavy and the 5g seemed a little light on top end but got great acceleration. The 5.5's seemed like the perfect weight.
The NCY exhaust rolled in soon after and I got it all mounted up. Great fit, easy mounting and came with an exhaust gasket. This is much lighter than the stock exhaust and sounds awesome! Took it out and got it up to 42 mph on the same stretch of open road. A 4 mph gain on exhaust and rollers alone. Im impressed and hope other mods give the same type of gains.

I ordered a tachometer and a temp gauge and found that my power band begins right around 8200 rpm and from there it runs up to 8900 rpm at 42mph max speed.

Changed out the main jet from stock 80 to a 90 and it was too much. Bumped it down to an 85 and it was much better running on the top end and got a little bit cooler as well. Still seems a little rich. Since the kit I got only goes in increments of 5, Im going to order an 82 and an 84.
www.partzilla.com/product/yamaha/14T-14343-41-00
www.partzilla.com/product/yamaha/14T-14343-42-00

[TuneGoon]

I ordered a Polini 3 shoe adjustable racing clutch to replace the stock 2 shoe clutch as well as a new clutch bell.
scooterswapshop.com/collections/yamaha-zuma-02-11/products/polini-3g-race-clutch?variant=43345588425

The clutch came with 2 sets of springs (yellow and green). I went with the green springs being the lighter of the 2 sets and have them adjusted so that the clutch engages right before the belt begins to travel in the final drive. Im getting firm clutch engagement at about 5600rpm. I know its not quicker, but it sure feels like it off the line with the butt dyno.

I then decided to purchase a new cast iron NCY 72cc BBK and found one on ebay for $80. The box was torn and the copper head gasket was bent but I think I did ok lol.




I found that it is much easier for me to just pull the engine from the scooter and work on it on the bench top. Im too old n fat for crawling around on the ground to do it lol.

[TuneGoon]

After heat cycling it a couple times, I took it out and ran it about 3/4 throttle in bursts. What a difference in power on the low end! After getting it broke in I took it out for a longer ride and some higher rpms and soft seized it.





OUCH! Well I guess its a good thing I ordered a couple more top end kits lol.
Messed with the carb and jetting for what seemed like an eternity and couldnt get my rpm's down or an idle that wasnt above 2700 once warmed up. I made a diy leak down tester (CLICK HERE) and conducted a test & found nothing. After some insight from a few very knowlegeable members I found that I was too far in on my air screw so I needed to move up a size on my pilot jet. Stock on the Zuma is 44, so I went to a 46 pilot jet (CLICK HERE) and was able to get my air screw to a more adjustable range. Idle issue was corrected. Now that were into winter months here, "tuning and gooning" has been at a minimum.

[bigmatthew86]

Very nice. The 70 will pick up a good bit more power but won’t give you a lot more speed. You’ll need to change out the gears to match your new found power. 11:1 is considered the ideal on a Zuma I ended up going with a set of 15/50 on my Zuma around (12.2:1) it picked around 6mph. I’m a big guy to 6’4 260ish. Just some food for thought.

[TuneGoon]

I ordered and installed a Malossi Multivar variator kit (LINK HERE).



It came with a white contra spring/variator/ramp/boss/ramp guides/shims/and a set of 7 gr rollers. I've been able to find a few days here n there over the last month to try and get some idea of how its running and see if I can get a gauge on what speed Im currently hitting. The variator did seem to add maybe a tiny bit to the low end, but top speed was unaffected . For the tiny "gains" I got from this new variator setup, I woulda saved my cash and just run stock. I'll mess with this later.

I purchased some 5/6/8 gram roller sets in 16x13. After running all of them in multiple combinations along with the new contra Im finding that 6g is getting me the most on acceleration and top speed. They get me into my starting powerband of around 8200 rpm right from full twist and pull from there. My max speed at this point was 44 mph gps verified. Suprisingly, my speedo is accurate with the gps up to 40mph. 44mph is good for a fat dude of my size, but it still isnt the 50 mph goal Im trying to achieve.

[TuneGoon]

I found that I wasnt reaching full belt travel on the variator. I still had 5mm left with zero shimming on the face of the boss and with the supplied 3mm? shim that came with the variator kit that goes on BEHIND the variator to align it with the clutch pulley. After a few runs and some carb tuning, I was able to get it down to 3.5mm.








My top speed so far to date is 46mph.




The stock OEM belt is 738mm long so I ordered a new belt that is 747mm long (4mm shorter than Athena/Polini/etc). Hoping this will allow me to eat up some of that remaining 3.5mm of belt travel on the variator and let me squeak out a lil more top speed.



Thanks bigmatthew86 I also ordered a vForce reed kit and a set of Polini 13/44 gears that are showing to arrive today. Im hoping this will be the move to get me to my 50+ goal. Whats your top speed on yours?

(POLINI GEAR SET LINK)
(VFORCE 3 TOP REED KIT LINK)

[TuneGoon]

I kept finding oil slung up onto the bottom of my rear wheel well and for the life of me couldnt find where it was coming from. The last time I saw it, it looked like radiator fluid as it was bright green. Been needing to top off my rear tire since Ive had it too so i decided to get some new tires front and back to get rid of the stock nobbies that are on it.
I pulled the rear tire from the rim to find this:






I wasnt aware that guacamole was a tire sealant . Even cleaned off they were still nasty:



So I decided to wire wheel them, change the valves, and freshen them up with some rattle can love:

[TuneGoon]

I did a JDM rear signal mod:





Updated the bulbs with leds in both the signals and the brake. I have a thread (HERE) showing how I did it if anyone is interested in doig it themselves.

[bigmatthew86]

The multivar is a good variator. You should be able to get to 2mm or less. How old is your belt? With the stock final drive gearing your at pretty much the top speed. You might get 48 with full travel. At this point you need more rpm’s or longer gearing. With gears you should see 55+. The new Zumas came with taller gearing from the factory. Still low but better at least.

[TuneGoon]

Feb 27, 2023 17:36:59 GMT -5 bigmatthew86 said:

The multivar is a good variator. You should be able to get to 2mm or less. How old is your belt? With the stock final drive gearing your at pretty much the top speed. You might get 48 with full travel. At this point you need more rpm’s or longer gearing. With gears you should see 55+. The new Zumas came with taller gearing from the factory. Still low but better at least.

I got some .2 & .5 mm shims to mess with the variator a bit more. Thinking maybe put a shim or two between the starter gear and the variator and see if it helps any. I replaced the OEM belt with another OEM belt about 3-400 miles ago. I havent gauged it yet to see how worn it is. I imagine with the stuff Ive done so far, belt wear will probably be much faster now?
On my last run, I maxed out at around 9600 rpm @46mph.

[TuneGoon]

MAIL CALL!!!




I got my Vforce 3 reed kit and Polini 13/44 gears in. Gotta find someone locally to press in the gear for me since I dont have a press. I'll post results once I get everything installed and can get out on a day that it isnt snowing, raining or below freezing here in the Metro Detroit area.

[aeroxbud]

The JDM signal modification is so much cleaner looking.👍

[sinfull]

Doing a great job with the zuma 😀 👍 👌

[bigmatthew86]

Don’t expect much from the reeds, I did the same block. The gears will be quite noticeable.

[TuneGoon]

Thanks aeroxbud sinfull. Having a lot of fun with this thing!
bigmatthew86 Im running the stock carb, but will likely upgrade that in the near future so I figured I'd get a better reed setup vs just replacing the chipped pedals on my stock cage. So I probably wont see any gains from the Vforce even if I upgraded from stock carb to a 17.5mm Polini or something?

Progress on the Zuma has been slow between finding someone to press parts and the cold weather. I did however manage to bring home another scooter last night and not piss off the wife lol. 2004 Honda Elite CH80 w/ 3800 miles on the clock.




I had been looking for a "comfy cruiser" for when I have the Zuma tore down come nicer weather and still want to ride. With the lack of aftermarket, it will remain stock other than some sliders and an aftermarket rear shock. She sags hard with my big ass on there right now and is a total turd compared to my 2 stroke, but she is comfy and reliable.
***Im looking for the outer handlebar plastics (headlight/signal bezel) if anyone has one in good shape they want to part with??