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Discussion Starter #1
So I recently bought the above mentioned bike. It currently has the super G carb. Seems like it's getting too much gas, crazy quick from the start, then hit's a flat spot in the mid range. Also it appears to want to foul out spark plugs. I've had several people tell me that no matter how you try to tune that super G it will never perform right, that I should switch to the Super E. Any thoughts?
 

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What size jets are you using? Either will work, but jetting is more important.
 

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Discussion Starter #3
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What size jets are you using? Either will work, but jetting is more important.
I'm not sure, the guys were telling me they went through this issue, changing jets and adjusting, never was able to get it right, changed to the Super E, no more issues. I can get a good deal on a brand new Super E and was thinking about just going with that. Was hoping maybe someone also had this issue and what they recommend.
 

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E will have better low and mid range response, G will make more top end power. Unless you are racing you'll like E response better.

Sent from my SM-T350 using Tapatalk
 

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So I recently bought the above mentioned bike. It currently has the super G carb. Seems like it's getting too much gas, crazy quick from the start, then hit's a flat spot in the mid range. Also it appears to want to foul out spark plugs. I've had several people tell me that no matter how you try to tune that super G it will never perform right, that I should switch to the Super E. Any thoughts?
Doesn't matter if it is a G or an E, the tuning issue is rooted in the design of the carb not diameter of the ventury.

Several issues, but the two biggest ones are jet band width and the butterfly design. In its stock form, the Super X design has two jets with the main jet doing the bulk of the work. Here is where the bandwidth comes into play. The rpm range that the main jet is expected to operate over will far exceed it's capability. If the jet is tuned for higher RPM, the lower rpm area will be rich. If the jet is tuned for the lower rpm area then the upper rpm area will be lean. This can be overcome by adding a third fuel circuit, typically in the form of a Thunderjet from Zippers. There is a ton of misinformation and perceptions about Thunderjets. Most will equate their use with engine displacement. Not true.

The other issue with the design of the Super X carb is the butterfly. Unlike a carb with a slide that draws all of its air from a single hole under the slide, the Super X design draws air from over the top and under the bottom of the blade. This is an issue at lower RPMs because the fuel is drawn from the bottom. The air coming across the top of the blade has to combine with air after the fact. This causes tuning issues at low and mid RPMs and is one of the main reasons why a slide type carb seems to perform so much better.

Both of these issues are made worse as engine displacement is increased. Three courses of action; 1) accept it. 2) Add a third fuel circuit. 3) Use a slide type carb instead of a butterfly type carb. Most people simply accept it. If the the engine has high compression (>11.5), the engine really must be tuned for the higher rpm areas to prevent piston damage.

FWIW - My old 106" Evo ran a bored Super G with a T-Jet, and later switched to a MIk45 and a Mik48. The bored Super g made the most horsepower. The Mik45 seemed to be the most steerable but the Mik48 was not bad on the street either.

Good luck.
 

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the G is a bit large for only a 103,,, depending on if there is any performance work to the engine..

what turbo says is true,,, the thunderjet is remarkable,, I use them on many of my builds...
with the thunder jet mods,,, the low speed circuit now had a wider range,, the main can now be tuned for the mid range with fuel and air jets (part of the thunderjet mod), then when the motor gets up on top the thunderjet becomes active,, it also has tuning jets..
 

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Discussion Starter #8
E will have better low and mid range response, G will make more top end power. Unless you are racing you'll like E response better.

Sent from my SM-T350 using Tapatalk

Basically what those guys said, I'm not interested in racing, just want reliability.
 
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