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Post by lain on May 11, 2015 11:15:02 GMT -5
Might need jets in less than 5 size increments to fine tune it. Keep changing the idle, it sounds like idle circuit giving too much.
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Post by murkyapricot on May 11, 2015 13:27:41 GMT -5
The way its running now I'm only getting light popping on decel at low speeds and none at high speeds so I'm debating whether I should drop the pilot jet back to stock or if I should try a smaller main jet first
and you were right too many mods at once, makes for a little bit if a headache diagnosing issues lol
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Post by geh3333 on May 11, 2015 15:12:22 GMT -5
The way its running now I'm only getting light popping on decel at low speeds and none at high speeds so I'm debating whether I should drop the pilot jet back to stock or if I should try a smaller main jet first and you were right too many mods at once, makes for a little bit if a headache diagnosing issues lol If you are getting popping on decel then the pilot is to small. That means you are running lean on decel. My scoot does this when its not tuned in perfect. TBA if it is only slightly popping on decel it should not hurt anything. I have a big carb 32mm pumper carb. Some of the carbs do not have an acv " air control valve" and this makes it hard to tune without having then popping on decel. |
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Post by murkyapricot on May 11, 2015 16:26:16 GMT -5
Are you sure? This whole time i thought i was lean bc of the popping but the richer i made it the worse it kept getting. So i leaned out the mixture and that's when it all but went away. I currently have a 38 pilot in, up from the stock 35
Sounds like ive still got a bit of guessing and checking left to figure this out
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Post by geh3333 on May 11, 2015 16:37:53 GMT -5
Are you sure? This whole time i thought i was lean bc of the popping but the richer i made it the worse it kept getting. So i leaned out the mixture and that's when it all but went away. I currently have a 38 pilot in, up from the stock 35 Sounds like ive still got a bit of guessing and checking left to figure this out These carbs can sometimes be tricky. Supposedly the pilot doesn't only come into play at idle. The pilot is also active through much of the throttle range. Let's say your pilot is too small but your main jet is too big . the main and the pilot are both letting in fuel through the much of th throttle range together. So possibly you leaning out the mixture helped get a better mixture through much of the throttle range , but on decel when the pilot is mainly letting in fuel you are popping because you are still lean . hope you understand that. |
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Post by geh3333 on May 11, 2015 16:41:12 GMT -5
Are you sure? This whole time i thought i was lean bc of the popping but the richer i made it the worse it kept getting. So i leaned out the mixture and that's when it all but went away. I currently have a 38 pilot in, up from the stock 35 Sounds like ive still got a bit of guessing and checking left to figure this out These carbs can sometimes be tricky. Supposedly the pilot doesn't only come into play at idle. The pilot is also active through much of the throttle range. Let's say your pilot is too small but your main jet is too big . the main and the pilot are both letting in fuel through the much of th throttle range together. So possibly you leaning out the mixture helped get a better mixture through much of the throttle range , but on decel when the pilot is mainly letting in fuel you are popping because you are still lean . hope you understand that. Are u still running a 115 main ? If so I'd drop to a 110 and raise the mixture. This will give you the same mixture through most of the throttle range but keep you from running lean on decel. |
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Post by murkyapricot on May 11, 2015 17:53:52 GMT -5
These carbs can sometimes be tricky. Supposedly the pilot doesn't only come into play at idle. The pilot is also active through much of the throttle range. Let's say your pilot is too small but your main jet is too big . the main and the pilot are both letting in fuel through the much of th throttle range together. So possibly you leaning out the mixture helped get a better mixture through much of the throttle range , but on decel when the pilot is mainly letting in fuel you are popping because you are still lean . hope you understand that. Are u still running a 115 main ? If so I'd drop to a 110 and raise the mixture. This will give you the same mixture through most of the throttle range but keep you from running lean on decel. i think but honestly i don't remember it's either 115 or 120, either way ill drop it down and size and see where that leaves me |
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Post by lain on May 12, 2015 8:28:10 GMT -5
Are u still running a 115 main ? If so I'd drop to a 110 and raise the mixture. This will give you the same mixture through most of the throttle range but keep you from running lean on decel. i think but honestly i don't remember it's either 115 or 120, either way ill drop it down and size and see where that leaves me Go up a size in the idle or main jet without changing anything else. I suspect the idle would be the one to change like geh said. |
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Post by murkyapricot on May 14, 2015 21:44:01 GMT -5
Dropped the main to a 115 from a 120, hasn't done anything for the low speed popping but other than that it's fine
Now here's where I have a question that I dont know if anyone really has an answer:
My carb has a stock 35 pilot jet, its overall length is 24mm
when i purchased new idle jets i could only find a 38 and a 40 with a 28mm length so the 38 I have in there now sits higher than the 35 that was in there
I don't fully understand exactly how the gas flows to know if this has a negative effect due to the extra height or not but I'm suspecting it could be my problem.
I suppose next I'll put the stock pilot jet in, see what that does, and if still a problem try the 40,maybe order one in the right length if all else fails
Just wondering if anyone had any input on the length
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Post by murkyapricot on May 18, 2015 15:29:27 GMT -5
switched back to the 35 pilot and it significantly reduced low decel popping which leads me to believe the extra 4mm length on the pilot was the cause guess gas couldn't get through
I'll have to do since searching and find the 24mm length one and see if that works
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Post by urbanmadness on May 21, 2015 17:08:55 GMT -5
Generally, on 150's, if I'm running just a uni and exhuast, I leave the Pilot stock. I usally just move up a size on the main jet (if it was running good in stock config) and go from there.
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Post by murkyapricot on May 21, 2015 21:36:57 GMT -5
That's what i have in right now 115 main and 35 pilot and I'm still getting light popping on low speed decel, ive got the length 38.and 40 coming soon I'll see if that fixes the problem
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Post by murkyapricot on Oct 1, 2015 21:03:41 GMT -5
Removed the emissions finally, gave up on getting to fix the popping, turns out there must have been a vacuum leak because there is no longer any popping!
Sure did alot of pointless carb tuning along the way but atleast it was good practice
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