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Monthly Archives: March 2009

Performance 2-stroke scooter CVT transmissions need to vent and cool to run best. Otherwise you start getting “heat soak” causing springs and clutch to fade and worst of all breaking your drive belt.

Heat soak is an even bigger problem once you go big bore 70cc or more, since now the engine runs even hotter! The dio style Honda Elite scooters have a split case cover that allows you to take the back half off and instantly have tons of airflow cooling the clutch and CVT pullies.

Jog style covers aren’t so lucky, so you must go custom! Some people drill lots of holes, cut chunks out, etc.

My personal favorite is cutting huge 1.25in holes side by side, then rounding off edges with a dremel. Not only does it look cool but your transmission parts will want to thank you for the added air flow.

In preperation for my Jog’s next big bore, here’s how I did this to my case cover.
(click to view larger image)



Here’s some history about one of my current scooters, a ’98 Yamaha Jog. I am going to be upgrading it once again very soon and posting this up for yall to get acquainted, click any of the pics to enlarge and enjoy the post.

Yamaha Jogs from years 1992 and up are very sought after scooter for their performance potential. Read this wonderfully detailed guide Motor Scooter Guide – Yamaha Jog if you’d like to learn more about them and what makes them so special πŸ™‚

I was lucky enough to find one in a neighboring city, Austin TX back in May of 2008, which I bargained down to a cool $800 total including transfer of ownership and all legal papers (was dealer owned), $550 for the scooter alone. I was just super happy to now own a TRUE Yamaha Jog πŸ˜€

Freebies included a huge storage box, dirty motor, and retro paintjob!

Next up, some cleaning and serious TLC back at home

I promised myself I would keep it “stock” and just cruise, getting a gps verified 65 MPG going WOT (wide open throttle) everywhere at a brisk 45-47 MPH, not bad for a stock 50cc scooter. But..

That didn’t last long and the mod bug soon bit 😈

I decided to go on a budget route, and started piecing parts together in August 2008, completing the build in late September.

Why budget? Because after goals have been accomplished the fact that you spent a lot less than the other guy for similar results gives you an even bigger grin. πŸ˜‰

How budget am I talking about? The following was done with about $450 towards mods..

1998 Yamaha Jog Nextzone Complete Modlist:
+ 3.50-10 Michelin S1 Rear Tire (32psi)
+ 90/90-10 Michelin S1 Front Tire (31psi)
+ Airsal T6 aluminum 70cc full kit
(Smoothed ports, Knife edged exhaust, Aligned base ports)
+ Cut Fins on A/C cover
+ Duct tape over slit between A/C cover and engine shroud
+ NGK Plug boot
+ NGK B9HS plug (.029gap)
+ 17mm Vento Carburetor
(filled main jet ~105, custom support bracket)
+ Custom intake with Unifilter
(Note Polini filter I tried first, but didn’t want to cut panels)
+ Vento Triton larger matching manifold
+ Polini Carbon Fiber reeds
+ Tecnigas RS (Race Series) exhaust
+ Jog90 788mm belt
+ Keli variator with added belt spacer
+ 8.6g x3 rollers 25.7g total actual
+ 2k Center spring, stock 105mm clutch and grab springs!
+ 1:8.16 Jog90 secondary gears, (25% upgear)
+ 75w90 full synthetic gear oil
+ Castrol 2t in injector, castor927 1.5oz premix

Build-up pics:

This combo netted a 67 MPH flat out top speed! by Garmin GPS, with amazing acceleration and wheelies at will!

However, this build was short lived. Not even a month after completion, as I was crossing an intersection the bike crackled popped and shut off, forcing me to walk it home. Pulling the motor apart I discovered one of the piston clips flew out and caused critical damage to the cylinder GRRR I was bummed since this setup was tuned very well, but show must go on.

I decided to rebuild back to a 50cc top end with just a few engine changes, including: Airsal T6 head for better dome shape and no headgasket for more compression, keeping the rest of the add ons (RS exhaust, 8.2:1 gearing, cvt mods..) in place.

That is where I’m at right now, seldom riding the Jog but getting great gas mileage and a 56mph gps’d top speed when I do, due to the crazy gearing.

Stay tuned for my Jog’s next 70cc adventure 8)

Welcome to my first ever scooter tuning blog! My name is Yan, also known as burnt_toast on many scooter forums, and in this blog I will be discussing and reflecting on my previous and current experiences with modern 2-stroke scooters, tuning, fixing and modifying them to travel at warp speeds (or as close to as humanly possible πŸ˜‰

As time goes on I will be adding lots of info that has been scattered in many previous postings, as well as blogging about all my newest and latest scooter projects! All right here on

I would love to hear your feedback, comments and suggestions about layout content or anything else you’d like to see here at Scooter Toast. You can reach me directly by email atΒ

Stay tuned, check back often, and please subscribe* to receive all the newest updates! πŸ™‚

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