Jet trouble

[choppareed]

Greetings! I have a twice generic chore master 212cc engine, almost fully built. I ordered a new chikuni (Chinese Mikuni) carb for it recently, but I'm having trouble finding which jets to use. It came with 10 extra jets. I figured instead of checking each jet 1 at a time I'd just ask if anyone knows off top. Ill list all parts I have to give a better idea..

Arc billet rod
Arc billet flywheel
570mm flat top piston
Dynocams super grind x cam
26lb valve springs
Champion roller rockers
Stock valves
I think that's it, if I didn't list it, it's stock
I live in central valley of california too idk if that matters or not, I'm thinking elevation wise
Also what makes your engine stage 4? Based off the info, what stage u think mine would be?

Thanks!!



Ps: I do have matching front tire...so be nice

 

[ole4]

Can you post a picture of the jets? There have been a number of folks that have gotten them with Kehin style jets (I think from GPS) most come with mikuni. Be sure to take a picture of both the pilot and the main jet. The majority of the carbs that came with mikuni jets will run ok with the stock 15 pilot and a 120 - 130 main. I would start with a 130 main. If you have the Kehin style I have no idea as I never had one to play with. Picture below are Mikuni jets

 

[Havasu Dave]

I use Jets R Us to determine which jets I have. I have ordered from them several times as well. Great people to work with. If you click on a MFGR, then a jet, they list the dimensions and holes and other characteristics of the jet so you can ensure on getting the correct one.

Jets R US by Carburetor Type

Also, there is no one size fits all jet size. Altitude, barometric pressure, (same thing really) humidity and temperature all play a big role, and the best we can ever do is find the jet that serves us "most" of the time. Sure, there are lists for starting places, but I have never built an engine of any type where the "recommended" jet tuning ended up being the optimal jet to use. Getting a carb with ten extra jets is a good thing. Also, I recommend checking out Ian Williams' site for some real solid Mikuni tuning advice.

Sorry if I have adopted a lecturing tone. It is not intentional.

 

[choppareed]

Can you post a picture of the jets? There have been a number of folks that have gotten them with Kehin style jets (I think from GPS) most come with mikuni. Be sure to take a picture of both the pilot and the main jet. The majority of the carbs that came with mikuni jets will run ok with the stock 15 pilot and a 120 - 130 main. I would start with a 130 main. If you have the Kehin style I have no idea as I never had one to play with. Picture below are Mikuni jets

Okay good I have the same style jets. I went ahead and put the 120 main in first because I found it before the 130. I could notice a huge difference just idling. I'll know for sure after a test ride.im debating going now at 11:30 or waiting til morning....I think I'll go now

Thank u for the information!!

 

[choppareed]

I use Jets R Us to determine which jets I have. I have ordered from them several times as well. Great people to work with. If you click on a MFGR, then a jet, they list the dimensions and holes and other characteristics of the jet so you can ensure on getting the correct one.

Jets R US by Carburetor Type

Also, there is no one size fits all jet size. Altitude, barometric pressure, (same thing really) humidity and temperature all play a big role, and the best we can ever do is find the jet that serves us "most" of the time. Sure, there are lists for starting places, but I have never built an engine of any type where the "recommended" jet tuning ended up being the optimal jet to use. Getting a carb with ten extra jets is a good thing. Also, I recommend checking out Ian Williams' site for some real solid Mikuni tuning advice.

Sorry if I have adopted a lecturing tone. It is not intentional.

Hey again,

I think I have a new problem..after installing the new jet, which was the main jet?? Which was the 120, gas started pouring out of the overflow on the bottom of carb, I didn't know why it was doing this because it's brand new and shouldn't do this. I thought maybe the jet was too big? So then I removed 120 jet and installed a 108 jet. Just a little bit of a big so I might go up to 110, however even with the 108 would still trickle out of the over flow rather than steady stream..

I took the carb off, took out all the jets, cleaned everything and came to the conclusion that the float was stuck in the down position,. Anyways I put everything back together. Now gas only trickles out overflow when the bike is leaned over too far. Any ideas? Never did this with "stock chikuni" jet. Carb still has 108 jet in it, might try a 110...the long skinny jet is the 38. The short little jet is the 108

 

[ole4]

the Nipple on the bottom of the float bowl is the drain. Overflow is a different vent tube on the side. Did you loosen the drain screw?