toomey plug chop
- Thread starter snake61047
- Start date
Plug chop with the #300, a #250 will fry your piston!
Your mods call for a #290 or #300 main with the stock needle on the middle clip.
Adjust the idle before you do the plug chop run.
Your mods call for a #290 or #300 main with the stock needle on the middle clip.
Adjust the idle before you do the plug chop run.
Runs like a top now. Plug looks great. Just trying to get ahold of joeak47 for a rechambered head.
View attachment IMG_20130615_130125_604.jpg
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View attachment IMG_20130615_130211_655.jpghey guys. finnaly got around to doing another plug chop. I think im running a little rich. it is 77 degrees with 78% humidity. the engine is air tight and float has been set. I have the 300 mj in right now. im thinking of going to the 290. When it is warmer it feels abit bogy unless I hit wot.
View attachment IMG_20130615_130140_107.jpg
View attachment IMG_20130615_130211_655.jpghey guys. finnaly got around to doing another plug chop. I think im running a little rich. it is 77 degrees with 78% humidity. the engine is air tight and float has been set. I have the 300 mj in right now. im thinking of going to the 290. When it is warmer it feels abit bogy unless I hit wot.
That plug looks just fine to me, a little on the rich side, but that is insurance.
I would happily run that #300 main and I pre mix bean oil at 25:1.
Before it gets to WOT, you say it is boggy, what is the needle clip set at?
You may need to plug chop the needle at 1/2 to 3/4 throttle to confirm that it is correct.
I would happily run that #300 main and I pre mix bean oil at 25:1.
Before it gets to WOT, you say it is boggy, what is the needle clip set at?
You may need to plug chop the needle at 1/2 to 3/4 throttle to confirm that it is correct.
So by bogging do you mean hesitating as in lack of fuel, or is it like pulling the choke out and sounding like a 4 stroke.?
like if you hit a certain rpm it doesn't like to rev past unless you give it wot. you pull the choke out and it is dead. ive had this problem before in the midrange and it was because my mj was to big. couldn't compensate enough with the needle.
when the temps are around 50-60 everything is good. crisp throttle all thru the powerband. no bog or hesitation
This does not gel!
The main jet does not come in play until after the needle gets past 3/4 throttle.
You could effectively have a 500 main jet in there and the needle would limit the passage of fuel until 3/4 throttle and would run fine until that point.
Then and then only, after 3/4 throttle the main jets job is to control the amount of fuel.
It must be remembered that carburetor jetting
is determined by the throttle position, not engine
speed. If the engine is having troubles at low rpm
(idle to 1/4 throttle), the pilot system or slide valve is
the likely problem. If the engine has problems between
1/4 and 3/4 throttle, the jet needle and needle jet
(most likely the jet needle) is likely the problem. If
the engine is running poorly at 3/4 to full throttle, the
main jet is the likely problem.
The above is cut and pasted from \/ \/ \/
http://www.motorcyclecarbs.com/carbs101.pdf
you should never try to compensate for one jetting range being too rich or lean, by compensating with other jetting ranges.
thats a recipe for disaster.
start at the bottom and work up thru the jetting ranges....
1. the fuel/float level first,
2. adjust the airscrew/pilot,
3. needle and clip settings,
4. main jet plug chopped.
in that order.
I completely agree with the above posts. Being said. I could not adjust for warmer temps on my sled with the needles and ended up having to change mains then adjust the needles to get the proper performance and plug color. I will chop mid
This gells, if the main jet is not passing enough fuel to supply the needs of the needle jet and jet needle, then adjusting the needle will not make any difference.
