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Old 08-14-2011, 09:47 AM
Listic Listic is offline
Join Date: Aug 2011
Location: St.-Petersburg, Russia
Posts: 3
Default Introduction to gentle tuning


I have recently started riding Yamaha Jog C Coolstyle. As surely many before me, I now wish for more speed and I started thinking about tuning. I see that ideally I would be better off with slightly bigger ride like Axis or Zuma/BWS because of their larger power, wheels and passenger-carrying ability. Alas, this is not an currently an option because it's more expensive, I already got one and I need a driving license for that.

The thing is I am not mechanically inclined (maybe mechanically challenged, even); I want to go on long trips out of town on my scoot and I wish for it to go long without failing. I can buy the necessary components and find a good repair shop to do the job, but I can't do anything myself.

What "safe" modifications can I do that will not significantly impair the scooter's reliability, or maybe even increase it? (e.g. now it takes 100% power to go 60 km/h and I'm afraid going for long rides like that is a bad idea, but if it will be taking just 80%, it might work more reliably, right?)

What modifications are better be done with each other?

1. I have an idea that using an alternate CDI is bad for reliability (they say Red Daytona is the "best") because it just takes the cap off the engine's rpm.
2. What about tuning the variator: if we let the gear ratio go higher, it shouldn't impair reliability, should it?
3. What about changing the exhaust: I was told that Leovince SP3 is good (I would appreciate the noise profile and looks that don't show off). But how exactly does exhaust influence engine's work?
3a. I'm offered a good deal on Yasuni Z exhaust. They say it's miles ahead of Leovince SP3 and works fine with stock engine. It's shiny, but I think of spray-painting it black. How well you think I'll be off from reliability point of view?

Last edited by Listic; 08-14-2011 at 11:20 AM.
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Old 08-14-2011, 03:47 PM
Listic Listic is offline
Join Date: Aug 2011
Location: St.-Petersburg, Russia
Posts: 3


It's a Japanese model. Specification for it that I believe is correct:
Model year 2005 (manufactured 2000-2008)
Frame. SA16J
Engine. A125E
Length, mm. 1670
Width, mm. 640
Overall height, mm. 1005
Wheelbase, mm. 1160
Ground clearance, mm. 100
Seat Height, mm. 650
Gross weight, kg. 69
Maximum speed km / h. 60 *
Engine type. SA16J
Number of cylinders. 1
Number of cycles. 2
Displacement, cc: 49
Bore and stroke, mm. 40,0 40,2
Degree of compression. 7.3
Power, hp / (r / min). 7,2 / 6500
Torque kg-m / (r / min). 0,67 / 6000
Oil tank. 1.4 l
Petrol tank. 5.7 l
Front wheel. 90-90-10
Rear wheel. 90-90-10
Front brake. Disc
Rear brake. Drum
Here's the picture of my younger brother on it, speedometer, rear view, one more view.
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Old 08-14-2011, 06:13 PM
mpathus mpathus is offline
Join Date: Mar 2010
Location: Baltimore
Posts: 329

27,750km = 16,650 miles, seems very reliable!!

Proper maintenance is enough to assure best reliability, so "upgrades" that stress the engine more will compromise engine longevity some. Proves there is something to be said about Yamaha's original design specification.

I'd check cylinder compression to see how close the cylinder is to needing to be rebuilt (rings), if worried about being stranded. How far are those trips you plan?

NICE original(?) scoot!
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Old 08-15-2011, 06:00 AM
Listic Listic is offline
Join Date: Aug 2011
Location: St.-Petersburg, Russia
Posts: 3

Originally Posted by mpathus View Post
27,750km = 16,650 miles, seems very reliable!!
Yes, to think of it, it must be not a little, especially given that some scoots' odometers only go to 9999. Let's hope that it will last a lot if it lasted thus far.

Originally Posted by mpathus
Proper maintenance is enough to assure best reliability, so "upgrades" that stress the engine more will compromise engine longevity some.

I'd check cylinder compression to see how close the cylinder is to needing to be rebuilt (rings), if worried about being stranded.
I'm looking for a good repair shop right now. I'll be sure to check compression.

Originally Posted by mpathus
How far are those trips you plan?
I'm not sure how much to wish for? How much is reasonable?

Still would be great to receive answers for my original questions.
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Old 08-17-2011, 07:12 AM
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BWSman67 BWSman67 is offline
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Join Date: Jul 2008
Location: Stratford ON Canada
Posts: 934

The engine is designed to run at 100% for the majority of the time. Changing the exhaust to something less restrictive will help a little as will a performance variator & clutch without seriously impacting the reliability.

The only real way to get increased power is with a BBK and if set up properly; can be just as reliable as the stock cylinder.

As for taking long trips and what is reasonable; that depends on each individual. Some people think just riding the scooter outside town limits is unreasonable. It depends on how comfortable you feel riding among traffic that is likely to be going faster than you. There is the fact that the fuel tank is not very big and that you will only have a range of 80 - 100 km before you need to refuel.

I myself have ridden in excess of 150 km in one day going to the nearer larger cities and back on my Zuma(BWS) and felt comfortable doing it (but the top speed of my Zuma is close to 80 km/h)
2001 BWS/Zuma, Athena 70cc sport cylinder kit, Tecnigas Silent Sport exhaust, Athena Speedmatic variator, Athena belt (coming soon: 17.5mm Dell'Orto carburetor)
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Old 10-09-2011, 02:56 PM
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veedubh20 veedubh20 is offline
Join Date: Feb 2005
Location: honolulu
Posts: 425

The japan blk jog that, you got is the 5bm motor. It has bigger intake reed valve. The big bore kit will fits good! 5bm stamped mark is located on the rear shock bushing on a block, just below.

Nice scooter! I would love to get one of those .

Last edited by veedubh20; 10-09-2011 at 02:59 PM.
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Old 06-27-2012, 10:49 AM
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Gabe502000 Gabe502000 is offline
Join Date: May 2008
Location: Clayton
Posts: 1,018

Hello Listic, & welcome! To answer your questions: 1) Since you're beginning just keep it simple. There are good aftermarket ignition systems, but they don't give them away, & it means paying a mechanic to install one,and get it sorted out. Yamaha's factory system is a good one, and gives few problems.2) If you'll go to a site where many of the members ride,& tinker with Yamaha Jogs,you'll be able to get an idea about the simple mods that can be done to your variator, to improve performance, without affecting reliability. This may point you in the right direction... http://www.mopedarmy.com/search/?cx=...%2C1694%2C1708 Provo has an excellent store, where you can purchase your parts it you wish. 3) When you install an aftermarket exhaust, you increase the airflow through your engine, which also requires a change to larger jets in your carburetor, to keep the fuel/air mixture from being too lean, and burning a hole in your piston....There are some vids on Youtube that show you how much noise some of these exhausts make. You'll have to search for them...(A Jog Owner over at Moped Army, may be able to assist you here.) 3a) Again, find some Joig Owners that have done some serious modding, before you part with your not easy to come by $$$... It may save you both $$$ & aggravation! Hope this answered your questions! Again, Welcome to Provo! Gabe
2007 Yamaha C3 Scooter

2010 Ural-T Motorcycle

"You never need a loaded weapon, until you need one Very Badly!" Sfc Hugh Lispcomb- Senior Drill Instructor, "Charlie 4-2" Ft.Leonard Wood, Mo. April 1974...

Last edited by Gabe502000; 06-27-2012 at 11:39 AM.
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50cc, gentle, jog, tuning, yamaha

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