How Hard is it to modify the jet?

Status
Not open for further replies.
Randog707

Randog707

New Member
I hear people posting about modifying your jet,well what does it acually do?,and is it hard to do.what are the thing you need to modify it?....Thanks for you time guys....Randy
 
I ordered a jet with some other things, because it was just a dollar or two thrown in-

I'm very surprised at just how miniscule it is- I've put the kit on and reamed an alloy billet to be installed, and I might ream the ports on the ends, but haven't much fiddled with the carb- I may try to slightly enlarge this andput it on- but in no hurry, and it will have to be wth something very small and very little more opening- i'd like to remove theidlescrew- because it seems to leak gas there- and maybe the slightest little port on the slide would let it idle otherwise, but that's a risk.

The new NTS carb comiong out for the 66 motors claims a slightly larger jet, and justmay wait until I eventually get one of those.
Motorized Bicycle Carburetor
 
Last edited:
thanks Kat for the reply,I also wanted to let people know what I have on my MB,I have a 80cc raw kit with a ada proformance air filter,36t sprocket,ngk spark plug,everthing else is stock on the motor,engine is fully broken in. running 25:1 ratio.top speed 31mph.what else do I need to do to get a high top speed?
 
Speaking of Grandfathers, here's my Grandpap, the Original Wild Man! (circa mid-60's, Canonsburg, PA)
 

Attachments

  • grandpap.JPG
    grandpap.JPG
    74.8 KB · Views: 183
Modifying the jet size is easy. Simply drill it out if you need to richen your mixture or solder it closed and then redrill if you need a leaner mixture. Tools required: flat head screw driver, appropriately sized spanners and drill bits.
 
Drilling a jet is a terrible idea. The swirls from the drill bit make the fuel swirl which actually slows movement through the jet and will just upset the mixture. Buy a new jet for a few dollars.
 
Gee it works for me. I haven't had any problem soldering them shut and re drilling to tune these engines lot cheaper than 120 mile trip(for me to go to a big enough town with a cycle shop) to try to find a jet that is the right size and will fit one of these carbs.
But if you want to not do it that is fine.
 
Larger hole more fluid the carb atomizes the mixture anyway. Done it it works! However, if you can buy an assortment of jet sizes for cheap why would you mess around w/ drilling them.
Beyond smoothing out ports and maybe an air filter, every mod will require rejetting for a truly tuned motor!

The only adjustment you get w/ most of these carbs is from 1/4-1/2 throttle by adjusting the needle. Idle circuit stays "about" the same on most motors independent of state of tune so not really missing anything there. But if you change something i.e. exhaust, air filter, port timing, compression etc and you need to adjust 1/2 to full throttle, i.e. the main jet, then you either find'em or drill'em. Cause if you don't you'll have one sticky piston!
 
Some folks like to DIY and some would rather buy their way out of a problem... Sometimes it's even the same folks, just in different situations.

"swirly fuel" o_O

Ya made me lol :D Thanks ;)
 
Nashville Kat said:
The new NTS carb comiong out for the 66 motors claims a slightly larger jet, and justmay wait until I eventually get one of those.
Click to expand...

I bought my 66cc engine about 5-6 weeks ago and it has the larger main jet. I think that previously they were 0.7mm and my stock jet was 0.79.
I found the 0.79 too rich. 0.76 or 0.73 work better.

... Steve
 
Buddy said:
Drilling a jet is a terrible idea. The swirls from the drill bit make the fuel swirl which actually slows movement through the jet and will just upset the mixture. Buy a new jet for a few dollars.
Click to expand...


LOL! Where do you guys get this stuff?
 
I don't know where they come up with it???
Everyone has their own ideas.
Has anyone seen where you can buy a main jet for one of these carbs in assorted sizes???
I think I'll just drill them, its been working for me. I think I'll go to the shop and abuse a few main jets
solder them then drill them bad ol main jets.laff
soldering them and redrilling to a different size IS trying to upset the mixture either more or less fuel.Right???
Just how does that hole get there in the first place. magic? do they buy a box of assorted holes?laff
 
Last edited:
don't know where they get the jet holes, but i have a whole warehouse full of post holes for sale. they must be installed in the ground with a shovel, only $2 a hole.
 
"swirly fuel" o_O

I knew a swirley in a turdlet was not a good thing but there is a product called a tornado that is supposed to increase fuel economy.

i have a whole warehouse full of post holes for sale. they must be installed in the ground with a shovel, only $2 a hole.
__________________
Home - Acme Motor Bikes

How much is shipping and do they come with a warranty? What do you do if parts are missing? What if I get the wrong size what is your return policy? I'm thinking of giving them as a Christmas gift to my X.
 
Status
Not open for further replies.
Back
Top