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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 :)

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 :D

Freebies included a huge storage box, dirty motor, and retro paintjob!
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Next up, some cleaning and serious TLC back at home
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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 :twisted:

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. ;)

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:
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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.
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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)

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4 Comments

  1. Hi,

    I just bought my very first scoot which just happens to be a 1988 Yamaha Jog! It is in pretty rough shape as far as looks go but the engine is still going strong. I was looking at your webpage on the Mods you did to your Jog and was wondering how a person like myself, who has very little MC/scooter engine knowledge, can attain speeds and gearing like you did? I can be satisfied with the current speed, but more is always welcome. :)

    Cheers from Vancouver, Canada!

  2. Hi Toast. Great jog. Sorry the piston blew up on you.

    When you switched back to the stock piston is the Technigas Rs still loud?

    • Yup, still loud but not as deep tone as with 70kit

        • Paul
        • Posted September 18, 2009 at Friday
        • Permalink

        Hi Toast,

        I have read all of your posts on provo and scootertime. You did a great job with your jog.

        I am planning to make a few modifications to a 93 jog artistic spec. Nothing to fancy.

        I am looking for quicker excel and a slightly higher top end (50mph)

        I want to keep noise down as much as possible.

        Here is what I plan to do. Any advice would be helpful.

        1. Larger tires. 3.50×10 front and back. I already have these from another project and they will be fat if they work. I think they will. My only concern is the front tire but I think it should be fine.

        2. Technigas R Chromed pipe.

        3. New Rollers. Maybe 4 or 4.5? I would like to use the stock variator. I am thinking about getting a tuning kit. What size rollers do the Jogs use and do you know their weight?

        4. White or yellow torch spring. What do you think about this?

        5. Clutch Springs. Not sure which ones to get.

        I plan to use the stock airbox and carb. I do not have plans to rejet at this time.

        Do you think this plan will meet my goals? Faster excel and top end? I think I only need to gain about 5-7 mph.

        I think this would be a great set up for normal riding where I live.

        Thanks Toast,

        Paul


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