Finally have a (kind of) running blaster after combining two (carb / air filter questions)

ERM9683

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Mar 22, 2024
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Finally got a running blaster…but it SMOKES like crazy. I know why - it has a 260 main in it. Here’s the mods: pro circuit platinum full system, stage 2 uni filter, and airbox lid is off. Thing is - I rode it a couple times with my stepson; it ran like sh*t at 1/4 throttle…RIPPED above that. I have the necessary jets in the mail to tune it, but the couple of short sessions I had were without filter oil (and on asphalt).cleaned it, but As soon as I oiled it, it wouldn’t start without holding the throttle in a bit. I SWORE I only oiled it lightly…do I need to soak some of that up?? I have these main jets coming (will do a plug chop, but wanted to see if I could get some input): 235 through 250. OH - running 32:1; 93 octane. PO broke it in at 25:1. Apologies for my ignorance, this is my first 2-smoker. Thank you!!


Eric
 
Sounds like a pilot jet issue to me. If it is ripping 1/4-3/4 throttle (needle) and WOT (main), make sure the pilot is super duper clear as it starts the bike and controls the fuel up to about 1/4 throttle. There are tiny holes in the jet that allow the fuel the vaccuum into the venturi of the carb. May also be the reason your machine wont start after oiling the filter. Would also double check your mixture screw, typically likes to be around 1.5-2 turns out from bottom.
 
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Sounds like a pilot jet issue to me. If it is ripping 1/4-3/4 throttle (needle) and WOT (main), make sure the pilot is super duper clear as it starts the bike and controls the fuel up to about 1/4 throttle. There are tiny holes in the jet that allow the fuel the vaccuum into the venturi of the carb. May also be the reason your machine wont start after oiling the filter. Would also double check your mixture screw, typically likes to be around 1.5-2 turns out from bottom.
THANK YOU for the input! Would the bigger main jets explain the heavy smoking, though?? I know 2-strokes obviously do that, but this was NUTS…clouded the whole culdesac from my yard! Also - any suggested brand of screwdriver to get those pilots out?? I had a mishap before with my bike, and I had to drive a small screwdriver THROUGH the pilot just to get the damn thing out. Those carbs sat a while, but they were carbs for a 4-banger.
 
I wouldn't start making main jet alterations as you state that it rips from 1/4 to WOT. You issue is on the idle/pilot circuit. Make sure the pilot jet and it's circuit in the carb body is clean and clear, also make sure the idle air circuit is clean and clear. Sounds like you may be rich down low which could be due to a pilot jet that is too large or a stopped up idle air circuit. Either will cause heavy smoking and poor performance on the low end.
 
I wouldn't start making main jet alterations as you state that it rips from 1/4 to WOT. You issue is on the idle/pilot circuit. Make sure the pilot jet and it's circuit in the carb body is clean and clear, also make sure the idle air circuit is clean and clear. Sounds like you may be rich down low which could be due to a pilot jet that is too large or a stopped up idle air circuit. Either will cause heavy smoking and poor performance on the low end.
Update: I took both of the carbs into work (I’m a millwright / industrial mechanic in training, and there is a TON of tools / materials that I can use), and soaked the jets in parts cleaner. Sprayed the sh*t out of the carbs as well. Both carbs had a 32.5 pilot in them; the one I was using had a 260 main and the extra carb had a freakin’ 360 in it! I’m going to try to put them on and give’er a go later today.
 
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Ohhhh yeah, I forgot - the needle on the carb that’s in better shape (the one I plan on using that had the 360 main) has a needle with 6 notches…it’s clipped on the 3rd notch down. Is that an aftermarket performance needle?? Figured it was, because the stock only has 5 notches, yeah??
 
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Either that or possibly some AM brand of carb rebuild kit that came with that needle. It may or may not be a good thing, needle taper and profile matters quite a bit and if there was an AM rebuild kit used that was of questionable quality (read Chinesium) it may give you issues.

I always run Keihin jets and needles in my Keihin carbs. And would do the same with Mikuni if I had any of those.
 
Another update: was about to put the new (better shape OEM) carb on, but the slide from the old one (still connected to the throttle cable that I got it with) is getting caught / stuck at full throttle?? I tested it before I actually secured it on. Am I screwin’ up here?? Every machine I’ve had (mostly old Japanese bikes) has had CV carbs, so I am completely ignorant towards the slide part of these. Can I pull it up too far somehow?? How do I adjust the cables going INTO the slide?? I feel like an absolute DUMBASS / missing something pretty detrimental. That being said, You all have been the best fuggin’ help, and you’re helping out with making my son PSYCHED on getting out and ripping around. It’s much appreciated!
 
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Could be a couple of things. I know you already cleaned the carb up, make sure the slide and channel it sits in is nice and smooth. Also, make sure the slide is in the channel correctly, not sure if you can put the top on if it is backwards or not, but could cause a sticking issue. Check out the springs between the slide and cap and make sure you arent binding up there. Check your thumb throttle to make sure it is not the culprit that is sticking. If allof those check out, i would be looking at your throttle cable if it is older. May be able to get away with just greasing it, but if it ends up being the problem its cheap enough to just replace.
 
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Agree with everything acdiez said.

But would like to add that every round slide carb I've had, the slide can indeed be put in the housing backwards which will hold the slide about halfway open or so. When putting the slide in, always ensure it easily and smoothly seats all the way down against the stop before screwing the slide cap on.

That said, I never messed with the stock carb with the TORS apparatus on top of the throttle slide cap on my daughters Blaster, so there could be different mechanics at work there. I Promptly removed it and swapped in a brand new Keihin PWK28 🤘🏻
 
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Thats exactly what I did with mine, actually. @ERM9683 our thoughts above should still apply, but I yanked the TORS out immediately and swapped to PWK28 as well so there may be other spots to look within the TORS cap.
 
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