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High Performance Bicycle Engine Tips and Motorized Race Bicycles We all want our bicycle engines to push our bikes faster. Get exclusive engine modification tips and suggestions from us. Also check out some of our racing members builds

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  #1  
Old 09-19-2014, 11:44 AM
FFV8 FFV8 is offline
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Join Date: Oct 2013
Location: Spring Valley NV
Posts: 552
Default 20mm Walbro on a China Girl

Tired of smelling like gas, and chasing jets, I wanted tuning & a fuel pump...



Then some threads



And install a hose barb




.
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  #2  
Old 09-19-2014, 08:01 PM
FFV8 FFV8 is offline
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Location: Spring Valley NV
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Default Re: 20mm Walbro on a China Girl

The intake mounts at the same angle as the cylinder port - you can look straight through the carb in to the cylinder



Add the crankcase pulse line



I laser cut the carb flange to include the bracket for the cable,and cold formed it to locate the cable & return spring



Even the stock intake nuts still fit.
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  #3  
Old 09-20-2014, 12:39 AM
skitchfish skitchfish is offline
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Join Date: Oct 2010
Location: Michigan
Posts: 222
Default Re: 20mm Walbro on a China Girl

FF, That is nice work and excellent pics! I hope you do a follow up on your linkage and throttle. I feel that this is the downfall of the Walbro carb, unless your racing, the feel of a less than 1/4 turn throttle doesn't get it with me.

The tuning aspect is unbelievable from bottom to top and in my own opinion is the best that can be had with such ease. I even used a old piece of excercise equipment to run my back tire under load in the garage. No four stroking anywhere, no screwing around!

I will be very interested to see what you come up with for your throttle as i can not seem to eliminate it's total crap feel. Thanks, Skitch
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  #4  
Old 09-20-2014, 11:06 AM
FFV8 FFV8 is offline
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Default Re: 20mm Walbro on a China Girl

The biggest problem with the throttle cable is a lack of a proper return spring.

Trying to use the OEM spring on the butterfly will only lead to frustration. Without enough spring pressure the cable drags in the housing & feels mushy.

I use a return spring with an adjustable preload, and fabricate the cable attach parts for the butterfly arm - smooth, consistent throttle operation is the result.

.
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  #5  
Old 09-21-2014, 06:01 PM
graydog8josh graydog8josh is offline
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Location: Starkville,MS
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Default Re: 20mm Walbro on a China Girl

where is the rest of your cylinder?
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  #6  
Old 09-22-2014, 08:32 AM
FFV8 FFV8 is offline
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Default Re: 20mm Walbro on a China Girl

Quote:
Originally Posted by graydog8josh View Post
where is the rest of your cylinder?
It's laying right here. I just took it apart to port it, makes it easier to reach the transfers.
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  #7  
Old 09-22-2014, 12:17 PM
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SpecializedMountainMoto SpecializedMountainMoto is offline
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Location: Scottsdale, AZ
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Default Re: 20mm Walbro on a China Girl

your kidding right
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  #8  
Old 09-22-2014, 08:16 PM
FFV8 FFV8 is offline
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Location: Spring Valley NV
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Default Re: 20mm Walbro on a China Girl

I don't think the saw kerf will leak much more than all of the damage from the broken rings & the missing chrome where the piston stuck. Should run as good as it ever did.

.
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  #9  
Old 09-22-2014, 08:27 PM
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Davezilla Davezilla is offline
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Location: San Antonio Texas
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Default Re: 20mm Walbro on a China Girl

it'll still work... just use a little ultra copper and you're good... lol
Anyway... Nice job on the intake you made
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  #10  
Old 12-30-2015, 10:06 PM
curtisfox curtisfox is offline
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Join Date: Dec 2008
Location: minesota
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Default Re: 20mm Walbro on a China Girl

This has to be the best idea i seen in a long time, with all the carb trouble people are having. Jet changing, moving C clips, trying two or three different carbs ( none fast then the other ). Don't have a china engine myself,but have others. And have used chain saws for years and never had trouble tuning like the guys do with china tuning, and they can be run on 4 stroke as well. Just turn the high and low jets a little for fine tuning. The big thing about 2 stroke is measuring the gas right and the same every time you fill ...........Curt
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