New Jets?

[Racer51]

Hey I'm a little new to the jetting specs on blaster carbs can any one tell me what the stock main and the pilot jet sizes are. I currently have an AB148 and 50 in an OKO 30mm carb that i just took apart this afternoon and is pretty clean now. I need to know what they are cause I have almost no power in 1st and 2nd and can only putz around unless I'm on the pipe so in 3rd and higher it's about normal. I did a compression test was a bit high might be a flat top piston dought it's bored. Did a leak down test. It has a Toomey B1 pipe kit, no air box lid, stock reeds, 30mm carb, put new plug in after I rode it and thats it.

If any one can help me it's you guys thanks.

 

[Luni]

OKOs use Keihin jets. Nothing relative to stock, so you wont get much help there.

So it sounds like your carb has a 50 pilot and a 148 main?

How does it feel? You said it has no power in first or 2nd, is it kinda boggy, or does it sputter in those gears?

Usually boggy indicates a lean condition, and sputtery is rich. Have you pulled your jet needle out of the cable end to see what position the clip is in? If you havent, do that. Take note of where its at. The positions toward the TIP of the needle are richening the mixture, the positions toward the TOP of the needle (toward the throttle cable) are leaning it out.

So, if the needle isnt in the middle position, put it there and try it. See if it gets better or worse.

Also, another trick you can try to see is try riding it with the choke on. If youre too lean, having the choke on will increase fuel and make you run better. If it gets even worse, then youre too rich, and Id see about pulling your main jet back.

And finally, the ONLY real way to tell if your jetting is on, is using a combination of the butt dyno/ response curve and a plug chop.

So, to do a plug chop, get the bike up to temp, and install a fresh spark plug. Start it, and immediately go WOT through the gears if you can. At the end of your WOT run, turn the key off, push the clutch in, and hold the throttle open. Then remove the plug. Youre looking for a dark center electrode with a mocha brownish porcelain insulator. If your plug is wet when you remove it, youre too rich.

Also does your quad idle? If you have a cold engine, can you start it without choking it? If the answer is yes to the choke question, usually that means youre too rich on the pilot jet. You should have to choke a cold engine to get it to start.

 

[Surfrjag]

thats not a stock carb so its doesnt help you to know what stock jetting is. have you tried adjusting the air screw? have you tried looking at the plug or doing a plug chop? you should be in the ballpark with those size jets but obviously needs some fine tunning. maybe a smaller pilot jet?

 

[Racer51]

It's enough to get around on but it shure as heck dosen't raise the front wheels off the ground when you hit the gas hard like any other blaster should as my dad says. It feels like it's going to bog like it's sluggish when I let off the gas to shift. Yes the ring was on the grove nearest the tip. When it's a cold start yea i hold the throttle between idle and 1/4 open when it's running. To start it I just flick the gas a second. As to the choke Q&A probably. I dont really think about it. I press down on the kick starter gently until it gets stiff let it back up and kick it over hard and it usally starts up on the first or second kick every time I've ever had it. But can be a little difficult to start if I happen to stall it by accident I don't use the throttle when starting it.

 

[Luni]

Well, try what I mentioned. Did you reset the needle? Did it help? Make it worse? Did you try riding with the choke on? Make it better? Worse?