Where to get larger main jet for stock HS carb?

[lemont1]

I changed the air filter on my latest bike from stock to the one from sick bike parts. Now have too much air for the size main jet (found this info on this forum, thanx guys) so I went back to stock filter till I can re-jet. Thought about re-sizing with small drill bits one size at a time but am not really sure. Can some one recomend a place to buy maybe a set of different size jets for the huasheng 142 F stock carb? Thanx in advance for any help!

 

[gothicguy64]

try spooky tooth

 

[back2theborstal]

sick bike parts has 10 different jet sizes for the regular old NT carb...

 

[Htown]

was told that no such jet exists, and that you would just have to live with opening up the idle screw as much as you can without it dropping out. I guess that is why some sites sell extras.

 

[Silvaire]

This is an OLD motorcycle racer tuning trick - an EMERGENCY method used in order to have the correct size jet when you just cannot obtain one.

To increase the jet size, you can drill out a jet with the next size larger NUMBER drill.
(If you EVER drill out a jet, mutilate the number stamped on it so that no one will later confuse it with an unmodified jet.)

But what to you do if a jet is too large?

Get some flexible insulated stranded copper wire. Poke one or more strands of wire through the jet until you get the engine running right. Secure one end of the wire by wrapping it around the top of the body of the jet (or whatever else is in the area may be handy) and then poke the loose end through the jet. Not all stranded wire has the same size strands, so find wire of a size where each strand of wire will reduce the cross-sectional area by only one percent or so. (Measure, and then use a little math here.)

I know that this sounds like a REALLY funky idea, but I have successfully used it many times.
(I have occasionally used it as a "semi-permanent" solution - holding the wire strands in place by soldering them to the top of the jet after finding the correct number of strands to use.)

 

[4950cycle]

What to do ?

I like the wire strand idea. But what do you do when you have the needle on a motorcycle carb going down through that hole in a main jet as the carb piston/plunger/slide goes up and down ? It will jam against the side wall of the main jet. How do you get around this ?

 

[Old Bob]

You really don't want to drill the jets. Drilling can leave spiral marks in the hole which will creat turbulence that can actually reduce flow volume.

The holes should be reamed with a straight flute reamer.

 

[4950cycle]

I have a 1978 750 parallel twin (side by side) with twin carbs. It was made in the 1970s gas crunch. The first one ya know ! Soo Kawi wanted to boaste great gas milage for this bike. So as a result they jetted it way lean. The end result being, most of them went to an early grave because they ran hot as a result of being air cooled an mainly always running lean. They didn't make a whole lotta jets for these big twin carbs so finding richer (bigger hole) jets was hard. Anyway, to make a long story longer,lol I drilled my two main jets one" number drill " larger then the original size of the jets as Silvaire indicated above. Needless to say I have one of the only 1976-1979 (only years they made this model) Kawi 750B model that runs great in the US. The Britts seem to have a lot more Motorcycle savy / machanical guys so they have more that run right. Bottom line, Drillin jets works ! Just go no more than one number drill at a time. It is easy to over do it so be patient. Cheap fix if lean is your problem.

 

[lemont1]

I added two wire strands with no problems so far and no real plans of changing any thing cause, well, if it aint broke dont fix it, right? When I drilled the jets I ran the bit from both sides and turned clockwise while pulling the bit out, thinkig that this would reduce any rifleing (if that is the right term) and as I said It works so far.

 

[4950cycle]

I believe rifleing would be the perfect word for it. I don't believe it would matter anyway. Unless it was so eregular you could almost see it with a 20/20 naked eye. Were not talking nuclear reacters or rocket science. We are talking little Industrial internal combustion engines. As long as the air / fuel ratio is somewhere around 14 to 1 and the timeing is where it should be and ofcoarse spark it WILL run gauranteed. As long as you are in an atmosphere like earth has period.