full throttle bog

[anthony91]

Hi new to this hoping someone could help me out. So I bought a blaster and put a top end on it got a new carb with the kit also. So when I fired it up it would not rev past 1/4 throttle well come to find out the guy I bought it off left the header in a barn an rats made a nest in it so I found a used fmf header and it opened up after that. Well I went to Haspen the other day and really got on it after I broke in the new top end. Well when I go to gun it there is a innermitten miss when it has a full load. Well I found out if I take the whole intake boot off it goes away. My question is do you think rejetting the carb would help with this issue. It seems to me like it's choking it out with gas and maybe I should go down a jet size? I know most people will say go to a aluminum Air box but I was hoping I could use the stock rubber boot, remove the cover and use a better flowing filter is this possible

 

[bummer981]

When you increase the airflow to the motor you need to increase the main jet. I believe FMF call for a 260 and running without the lid should go up one more.

 

[Blaaster]

There is a few thing ps that you need to investigate.

The float level may be off.

The carb could be flooding.

The air filter could be dirty.

Generally your mods with the air box lid off will use a 280-290 main jet, one size larger if you pre mix at 32:1.

Plug chop to confirm the jetting.

Before you make the plug chop run it is important that the float level is correct, the idle is set
correctly and there are no air leaks in the system, otherwise the smoke ring may lie about the
AFR.
WHEN ALL OF THE ABOVE ARE CORRECT PROCEED WITH THE FOLLOWING.
Warm up motor to operating temp.
Fit new B8ES plug, ride WOT through the gears and hold WOT in 5th or 6th gear for 10 seconds,
or as long as you can safely.
Switch off the motor and pull in the clutch, apply brakes to come to a stop quickly.
Take the plug out and replace the old one for the ride home.
Carefully cut the threaded end off the plug to expose the insulator.
There should be a smoke ring of a cardboard or biscuit colour around the insulator.
If it is non existant or a very light colour, you are lean and require a larger main jet.
If it is a lot darker you are rich and may go down a size in main.
I prefer to run a little on the darker side, I may loose a little power but it is worth it for the peace
of mind that I won't need a rebuild so soon.

http://www.blasterforum.com/do-yourself-20/how-plug-chop-38674/

You have to get up a reasonable speed so that you can get the motor to pull strongly.
Then hold it Wide Open Throttle (WOT) for 10 secs or as long as you can.
The idea is not to get speed but to make it pull strong at full throttle to get onto the main jet circuit.
I find I can safely do it on a short run by applying the brakes some.