cant get jetting right

Justin Moore

Member
Aug 1, 2019
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Hi everyone so I'm back and still having issue with my blaster. she will start on the first kick, she will idle all day, she will run fine at low rpm but once you get to full throttle she bogs down. I just got the quad two weeks ago. The quad came with a twist throttle, after market Mikuni carb and a FMF fatty pipe gold series with stock silencer. She was smoking like crazy and leaking oil from where the fatty pipe connects the engine which I was told was normal. Since I got it I have done a new exhaust gasket, new crank seal, new crank cover gasket, new uni air filter, new ngk br8es spark plug, drained the tank and cleaned it and put new gas and oil mixture at 32:1 using amsoil. I have also changed the main jet from 230 to 260 which is what FMF recommended and have the needle set at 3. There is no air box lid on it and she still runs crappy at full throttle. I noticed that the spark plug is moist which means that she is running rich from what I was told. I am not a two stroke guy and it is getting very frustrating that this thing is right. I also did a new cdi box. I cant do a chop plug test because I cant even run thru all gears because of the bog. This has gotta be something so simple that I am over looking or not doing that's why I am here for advice. I will be getting a new main jet set and try starting high and work my way down but any advice would be greatly appreciated .
 
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270 thru 310 genuine mikuni mains, NO jet kits, as you mentioned start large and plug chop down.

that aftermarket carb may also be the problem .... what size ? mm's ?
rarely will aftermarket carbs have the correct slide, needle or jetting that blasters require :(
 
270 thru 310 genuine mikuni mains, NO jet kits, as you mentioned start large and plug chop down.

that aftermarket carb may also be the problem .... what size ? mm's ?
rarely will aftermarket carbs have the correct slide, needle or jetting that blasters require :(
Thanks brotha. Im gonna order some this week and see what that does. It has gotta be the jets because I have gone thru everything that I can think of. My question is do I leave the needle set at the third position? or drop it down. I felt that since the plugs are always wet when I check them that I may be getting too much fuel and it cant burn it off fast enough
 
If it was the stock carb and needle, middle slot is golden on most.
an aftermarket carb/needle is anyones guess.

I'd think you'd be fouling plugs if it was too rich ?
don't worry about a wet plug if it's not fouling plugs and pulls good thru the 1/4 - 3/4 throttle range
you can do 1/2 throttle plug chops to tune the needle.
 
once again Thanks so much brotha. I will be ordering new jets some time this week and I will play around with it some more once I get them. I feel that I am so close to getting it tuned right but it can be frustrating lol. I will keep you posted once I get them and play with it some more.
 
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If it was the stock carb and needle, middle slot is golden on most.
an aftermarket carb/needle is anyones guess.

I'd think you'd be fouling plugs if it was too rich ?
don't worry about a wet plug if it's not fouling plugs and pulls good thru the 1/4 - 3/4 throttle range
you can do 1/2 throttle plug chops to tune the needle.
Hey whats up brotha!! so I played around with the carb some more. I dropped down on the main jet to a 230 because I felt like the carb was getting too much gas. I dropped the needle down to the second position and she got much better. so after looking into it a lil more I noticed that the throttle cable is too long and it is fully adjusted out on all ends so I think that may be my problem on top of jetting it correctly. It has a twist throttle that I don't know where the guy got it or what it came off of but I feel like the carb isn't opening enough to send the right amount of gas thru. I can go thru all gears at 1/4 and half throttle but it feels like it doesn't get to full throttle because of the cable if that makes any sense . Let me know your thoughts.