hey everyone, if anyone knows how to change the jet of a high performance carby, or knows a video that shows you how to change it, could you please helpme out? and if the engine is running at the leanest it can go, (0.6) does it bog? thanks, and happy new year!
how to change jets in a high performace carby
- Thread starter motorized kodiak
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We need to know what carburetor you have. "High performance" doesn't tell us much.
Most main jets simply screw in. Some have wrench flats, some have slots for a screwdriver.
Tom
Most main jets simply screw in. Some have wrench flats, some have slots for a screwdriver.
Tom
Oh, that's an easy one, there's only one jet you can change, the main one, its inside the float bowl, just take that off and uncrew it with a flathead. Finding the right jets for those is much more difficult, they have 6x1.0 thread whereas the genuine Dellorto its modeled after uses a 6x0.8 threaded jet with a wider screwhead. I ended up rethreading some real dellorto jets with a die and filing down the head diameter in my drill press like a lathe. Maybe DAX sells the correct jets for the Runtong or "RT" carb as he calls it on his website.
thanks for ur input mate, i bought the leanest jet they had i think it was a 0.6, would the make my bike bog?
Yes sir. If you went too lean the engine will 'bog' or starve for fuel especially near WOT.
Check your spark plug color. If too light or near white you are too lean.
Proper fuel flow to the carburetor is also important.
Tom
The cool thing about the smallest jet is that you can drill it out. Of course, the best way to jet tune is to run it rich with a big jet and step it down to clean up the top end pull, doing spark plug checks after short (warm) full throttle runs, and when you get a plug read that is too lean or lighter than a milk chocolate brownish gray, then step up to a richer jet for safety of the engine. Sometimes the optimal jet can be in between available jet sizes, but you have diy options; you can drill out a small jet with tiny drills, peen the hole slightly closed with a center punch to close it up slightly, or use a drop of soft solder applied from the screw-head side to close the hole up and re-drill.
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what if i mix up more oil in my fuel? would that do the same effect of getting a bigger jet? thanks for all the replies, this forum is great haha
The more oil in the fuel the heavier it is and the slower it will flow through the jet.
Adding oil will have a similar effect of a smaller jet.
Also the oil does not burn like gasoline and because of this, more oil = less power during each combustion cycle.
Adding oil to effect the air/ fuel ratio is sometimes used track side by racers to fine tune the ratio when a re-jet places the mixture either too rich or too lean by virtue of the available jet sizes. Sort of a fine tune by band-aid technique.
This is really "splitting hairs" super fine tuning though. It may gain them a few 10th's of a second on lap times.
Adding oil will have a similar effect of a smaller jet.
Also the oil does not burn like gasoline and because of this, more oil = less power during each combustion cycle.
Adding oil to effect the air/ fuel ratio is sometimes used track side by racers to fine tune the ratio when a re-jet places the mixture either too rich or too lean by virtue of the available jet sizes. Sort of a fine tune by band-aid technique.
This is really "splitting hairs" super fine tuning though. It may gain them a few 10th's of a second on lap times.
Not noticeable by the seat of the pants feel.
If you are bogging due to being too lean, then adding more oil will only make things worse.
More oil = less fuel.
If you are bogging due to being too lean, then adding more oil will only make things worse.
More oil = less fuel.