how many times can you re-jet a motorcycle carburetor?

Question

Wanting to re-jet a previously re-jetted carburetor. Is that possible or even recommended.

Answer 1

Depends on the carb- what was it on and for what market? In US starting about 1980 the EPA made some rules about 'fixed' jet carbs, non hotrodable carbs, sealed carbs-- basic said didn't want some motor like on some street motorcycle to have user friendly to modify carbs. I know a Yamaha rider that had the 'pressed' jet fall out of his new Yamaha and the top of piston got holed- Yamaha waranteed it- but needed to wait a couple weeks for a complete new carb as the old OEM carb for the market was non serviceable, the jets were not screwed into carb housing in a area thicken for screw cutting - the carb had been redesigned with thin case and slight tapered hole drilled for a cold pressed jet without threads. The cycle got the new piston and a older model carb for testing, ran good with it- but it was illegal for the dealer to release it for road use by customer until newe sealed/fixed jet carb came. Some of that kind of carb is on a lot of small engine sold in US market and some other markets- can't fix or repair, modify easy- has to be replaced. Some of them get a thread tap and a new jet screwed in, some get a glued and pressed in jet good for one change- you might have this kind of carb repair already on yours. Lots of 'replacement' carbs for out of waranty cycle engines, other engines- Mikuni sold a lot of the old pattern replacements for many cycles- they had thick castings and screw fit, plenty of mixture adjustments jets for idle and main available. Some of Kiehans were non servicable for a few years/models- but if you pulled the welch plug with a pick you could get to jets and change them, put in new plug- dealers were the ones supposed to do this for various legal reasons but most shops outside of factory dealers soon knew about it and most dealers would sell the plug kits since they didn't do the work so weren't in danger of fines-- about like the parts stores that sold the catylitic converter 'test pipes' for cars- the law said the car dealer would be fined for replacing the cat- but the owner could do it without a big fine since law didn't specify owner repairs illegal- and the parts store were only selling a 'test' part. And since over 1/2 the states DIDN"T have vehicle inspection the owner in those states was safe in running the no cat exhaust on street. Off road cycles tended to have servicable carbs- the EPA was concentrating on street vehicles at the time. California was first for off road emission laws for chainsaws, outdoor power equipment, offroad vehicle like snowmobiles and motorcycles, ARVs- CARB requirements meant another restricted market, but a large one in some cases. A carb for that market might be a sealed unit, you might have one or a easier to fix replacement---but you didn't post what kind of carb or what it was on by make, model , year..

Answer 2

A "jet" is traditionally just a small bolt with a very precise hole through it. The hole diameter is the # given to it. This lets you control the fuel/ air mixture on carbs. If the bike is not stock and you have a few or a bunch of after market parts, you may have to buy a couple richer jets to get it right.

Answer 3

Jet as much as you like. I race CC with my yz250f. I carry a small box of jets and scale for temp, and elevation. I'll put a pic up on. Hold on one sec. I used to build drag bikes so that is where I acquired it from. I'll bet you can get one, anyone can get one. Now it's for main jetting, but at certain elevations I change pilot too. Really if I have it apart I'm changing pilot as well.

Here is a pic.

Answer 4

If your plugs are light brown the jets are about just right.Required re-jet would be in order if you moved say from Bakersfield,Ca. to LA,Calif.where the air is thinner you would jet leaner in that case.

Answer 5

As most carb main jets are screw-in, as many times as you like.

Though make and model of carb would have been useful information, just in case it's a weird one.....

Answer 6

Until you wear it out.



Many, many, many times. It is a pain to get the rack of carbs in and out of some bikes, so it's recommended to get it right in the first few attempts.

Answer 7

you mean : rub the main jets :

-once...drill out all the main jets in the same size,or you`ll get later problems with synchronizing the carburretors !!-

it`s called in german "zwischengröße" between size:

-bigger than the original main jet size and smaller than the next availabel bigger main jet size.

-i`d that done that with my kawa zephyr 750,because i wanted that the choke works better..got more hp`s and more torgue (could use the 5.gear upon 30km/h till nearly 230km/h).

Answer 8

As many times as you want.



I did 5 rejets on the last set I was dialing in.

Answer 9

As many times as it take to get the fuel/air ratio correct .

Answer 10

are you thinking of or from a perfomance,point?