needle jet question

[sand rocket]

I have a set of 34mm tm mikuni carbs that are tapper bored to 36. Im haveing problems with the pilots. My bike will bog when your just out of the powerband. But it is close enough that it shoud hit it were i pit the throttle. I have worked all the way down to a 35 pilot. 30 is the smallest i can find. The only way i can get it to run good is have the screw bottomed out and backed out about a quarter. Cleans almost all the bog but still has alittle. My question is, should i get some small needle jets and try them. the main jet is good, mabe 1 or 2 sizes fat.

 

Bike is dune ported on stock cyl with cpi pipes.

[AKheathen]

your pilots want to go bigger when the airscrew is that close to bottomed out. do a plug chop and get the mains dialed in.

[sand rocket]

took the out of the stickyed post "troubleshooting your jetting".

 

The pilot circuit can be adjusted while the bike is idling and then test run. If the engine is running poorly just off of idle, the pilot jet screw can be turned in or out to change the air-fuel mixture. If the screw is in the back of the carburetor, screwing it out will lean the mixture while screwing it in will richen it. If the adjustment screw is in the front of the carburetor, it will be the opposite. If turning the screw between one and two and a half doesn't have any affect, the pilot jet will have to be replaced with either a larger or smaller one. While adjusting the pilot screw, turn it 1/4 turn at a time and test run the bike between adjustments. Adjust the pilot circuit until the motorcycle runs cleanly off of idle with no hesitations or bogs.

 

Screws on these carbs are more to the front side, so that would be screwed in is leaner.

[AKheathen]

Eh, that's backwards. tward the cylinder is a fuelscrew, and tward the filter is an airscrew. 2 strokes always use an airscrew, to the best of my knowledge.

[sand rocket]

anyone have any other view on this. Could these carbs be just to big for my app. Dune port cpi pipes, the riding that i do is dunning and trail riding.

[AKheathen]

anyone have any other view on this. Could these carbs be just to big for my app. Dune port cpi pipes, the riding that i do is dunning and trail riding.

dude, TRUST ME, i know what i'm talking about. there are a couple of mistakes on stickied threads on here. they are, after all, made by people, and people make mistakes, and mix things up on accedent. especially when doing a long writup. the stator colors are backwards in the electrical troubleshooting, too.

 

ok, the way the airscrew works, is by allowing air into the pilot jet passage, before the pilot nossle. the more you open it, the more air it lets in, leaving less fuel in the moixtur, and visa-versa. that being said, if the airscrews want to be that far to closed to make it run, then it's wanting more fuel. keep going up in pilot size untill it will want to run in the 1 to 2.5 turns from seated range on a warmed up engine. first, get your main right with a plug chop, or by feel. if you really are 2 sizes fat on the mains, it will sputter/break up a little @ wot. then get your needles right, and last, pilot and airscrews. personally, i would probably run 33's, but it really depends on where you tend to use your power. you might like those carbs better and not need what smaller carbs have to offer. you will never really know untill you get those dialed in right and see how they feel.