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 Tuning after BBK 
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Joined: Thu Jan 07, 2016 12:03 am
Posts: 16
Location: Ho Chi Minh City, Vietnam
scooters and mods: BWS-190cc, 63mm piston, 3.2mm stroker, racing cam, 30mm carb, open air intake, 2Bros pipe w/ silencer
Post Tuning after BBK
Hey guys! Thanks for all the awesome info on this forum. And a lot of thanks to Chris at RC for all his help and his attention to details. I wanted to get your advice on my tuning saga. I weigh about 165 lbs. I live in Ho Chi Minh...hot and humid most days.

I have a carbed 2009 BWS 125 that I started modding about a year ago. Right now I have a 63mm cylinder, 3.2mm stroker, roller cam, racing head, 2 bros pipe, open intake, TST with 11/13 rollers, PG clutch, OEM bell, 1000 spring, 30mm carb with 140 main and 48 idle jets. I have one washer on the needle. OEM gearing. New plug today. The latest engine upgrade was done about 3 months ago. Have regular oil, 20w-50 I believe changed about 3 weeks ago. Valves checked 2 weeks ago and lashed to 0.1mm per Chris' recs.

My sharpie only has about 2-3mm left on variator. I get up to about 7000+ rpm at WOT and can hit 105 km/hr reliably and pretty quickly, no tucking involved. At that point it kind of just hangs out there. The acceleration is great, but the top speed still seems like it could open up more.

I have been slowly going down on roller weights, to increase RPMs and following the sharpie tests. I'd like to be able to get my top speed up still.

1. Should I aim for RPMs of 8000? I've read that that is the power band of the engine.

2. I have read that a rough estimate of main jet size is 5 x carb size. I have a 30mm carb, so 150? Does that sound right? If so, I need to up jet.


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Tue Feb 02, 2016 7:02 am
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Joined: Fri Jun 25, 2010 6:56 am
Posts: 14284
Location: San Diego, CA
scooters and mods: FA$T Zuma 155cc
Post Re: Tuning after BBK
I had made this video for someone else that wanted to know what rpm's to shoot for
its not edited so if you skip to 1:00 and 2:50
https://www.youtube.com/watch?v=tFlkxNbnEvE

you will see when I accelerate hard my rpm's are around 8700

and slowly move up, yet my speed moves up much faster
and rpm's stay around 8700 until I get to much higher speeds
to me im in the powerband right when I accelerate hard, making the most power right away

of course if you ride slow then the rpm will be lower, but if I need to get on the throttle it will bump up to around 8700 right away and I can blast off


my top speed rpm on long flat road was 9700 and I hit the rev limiter


I remember when I big bored I went down pretty light in weights maybe 2 grams



this is why I always say use a tach when tuning
it will show you in numbers slight changes you wont see on the speedo




as for jetting its pretty easy
start large
run full thorttle, back off throttle a hair
if your rpm's go up and top speed goes up then your too rich

at least thats what ive found myself

or invest in an o2 sensor and gauge and you can just shove it into the end of the muffler
connect it to you battery and it will tell you exactly how rich or lean you are at top speed
http://www.zumaforums.net/phpBB3/viewtopic.php?f=54&t=26282&hilit=temp
will be expensive but you could get some friends to help pay for it then you all share it

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2010 Zuma 155cc
BWS X Digital Gauges<>Clear Smoke BWS 125 Turn Signal Covers<>Billet Bar Ends<>Front Brake Rotor 260mm<>Razor Cam Covers<>NCY Breather Assembly<>Polini EVO Clutch Bell<>Anodized Orange Dipstick<>RRGS Front and Rear Shocks<>Dual 5000K HID's 35w High/Low Beam<>Black Adjustable Brake levers<>Halo Led's<>TST 2 Stage Variator 9gL 10gS <>NCY Oil Cooler<>Yamaha Skid Plate<>NCY Contra Spring Bearing<>1000 Rpm RRGS Contra Spring<>Yoshimura Exhaust<>NCY Direct Ignition Coil<>Lightweight Cooling Fan<>Koso Cable Clamps<>High Lift Cam+Lightened Cam Sprocket<>Underseat Storage Bag<>Stage 6 (Koso) Clutch<>Accel Handlebars<>Koso Brake Light<>Lightweight Swingarm<>RRGS 4 Pot Caliper (PH80)<>Stainless Braided Brake Line<>Lightened F|ywheel<>OEM Headlight Screens<>Zubiku Wing<>Air Horn<>9 inch stretch<>Koso High Flow Filter/Cover<>RPM 10 Spoke Wheels<>Digital Camo Vinyl Wrap<>SEP Cvt Covers





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Tue Feb 02, 2016 8:05 am
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Newb
Newb

Joined: Thu Jan 07, 2016 12:03 am
Posts: 16
Location: Ho Chi Minh City, Vietnam
scooters and mods: BWS-190cc, 63mm piston, 3.2mm stroker, racing cam, 30mm carb, open air intake, 2Bros pipe w/ silencer
Post Re: Tuning after BBK
sweet man! i'll give it a try this week and let you know! finding parts around here is always an adventure, but i'm slowly learning. I spent 2 hours the other day trying to find a needle washer for the carb. it's always a big thrill to find something! last time i needed rollers they took some i had and added weight to them, as they don't have aftermarket rollers around that are easy to find.


Tue Feb 02, 2016 8:14 am
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Joined: Fri Jun 25, 2010 6:56 am
Posts: 14284
Location: San Diego, CA
scooters and mods: FA$T Zuma 155cc
Post Re: Tuning after BBK
ive used washers for RC cars found at the hobby shops that sell them

I think I also have read people use aluminum soda cans and cut out washers since the metal is very thin


Ive also drilled out rollers using a step bit around 1.5 grams lighter but you have to cut a little and put into water so the heat wont melt the roller

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2010 Zuma 155cc
BWS X Digital Gauges<>Clear Smoke BWS 125 Turn Signal Covers<>Billet Bar Ends<>Front Brake Rotor 260mm<>Razor Cam Covers<>NCY Breather Assembly<>Polini EVO Clutch Bell<>Anodized Orange Dipstick<>RRGS Front and Rear Shocks<>Dual 5000K HID's 35w High/Low Beam<>Black Adjustable Brake levers<>Halo Led's<>TST 2 Stage Variator 9gL 10gS <>NCY Oil Cooler<>Yamaha Skid Plate<>NCY Contra Spring Bearing<>1000 Rpm RRGS Contra Spring<>Yoshimura Exhaust<>NCY Direct Ignition Coil<>Lightweight Cooling Fan<>Koso Cable Clamps<>High Lift Cam+Lightened Cam Sprocket<>Underseat Storage Bag<>Stage 6 (Koso) Clutch<>Accel Handlebars<>Koso Brake Light<>Lightweight Swingarm<>RRGS 4 Pot Caliper (PH80)<>Stainless Braided Brake Line<>Lightened F|ywheel<>OEM Headlight Screens<>Zubiku Wing<>Air Horn<>9 inch stretch<>Koso High Flow Filter/Cover<>RPM 10 Spoke Wheels<>Digital Camo Vinyl Wrap<>SEP Cvt Covers





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Tue Feb 02, 2016 9:22 am
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Newb
Newb

Joined: Thu Jan 07, 2016 12:03 am
Posts: 16
Location: Ho Chi Minh City, Vietnam
scooters and mods: BWS-190cc, 63mm piston, 3.2mm stroker, racing cam, 30mm carb, open air intake, 2Bros pipe w/ silencer
Post Re: Tuning after BBK
So just an update on my tuning odyssey. I have been slowly going down on my rollers, and I'm currently at 10/11, normally revving at around 6-6500, maxing our revs at about 8000 at 105km/hr.

At the same time I've been going up on main jet from 140 --> 160 (big bog) --> 150. Also, have been experimenting with washers under needle as well. Currently I run 42 idle, 150 main, and .5mm washer under needle. In the morning the bike runs great, and in the PM when it's really hot, it feels too rich to me. Also if I go up slow and steady on throttle there is no bog, but if I pin it quick there is a big bog that recovers quickly.

I also changed up my air filter. Before I had a modified inlet from the OEM snorkel tube, but now I put the filter directly on carb. No problems as of yet. I've read some feel this isn't a good setup as it doesn't allow the air enough time to "organize" or something of the sort. Thoughts?


Mon Feb 29, 2016 11:57 pm
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