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Discussion Starter · #1 ·
when i first replaced the jets in my carb. i had no exhaust past the h box and air pods instead of a filter box. I replaced the jets from 78/115 to 90/125. things seemed fine until recently the temperature dropped quickly around here and last night i tried to start it with mixed results and alot of backfiring. i added a straight thru exhaust with a couple of 90 degree bends. should i go back to the smaller jets since i have created back pressure? a guy i work with told me i should only go up 1 jet size at a time and i jumped 5 on the low side. any advice would be greatly appreciated because i'm not running like crap in colder weather.
 

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90 should be fine on the low end. Would just be a bit rich if it was overcompensating. But in this case you're probably right on track.



How old is your gas? Gas in the carbs in the cold for under a week can cause some crappy starts. Drain the carb bowls and refill for a test.
 

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Discussion Starter · #3 ·
gas is fresh. per your other suggestions i took the air pods off and made extra sure that the right chokes were not stuck shut. both are open and respond to the choke cable the same way. i was going to pull the bowls off and jet back to 78/115 to see what happens but its alot of work that i will have to repeat and put the other jets back in if it doesnt work. the right side air boot was loose. looks like the hose clamp has failed. i'll replace it tomorrow and make sure it seals tightly. that may have been it. i hope so
 

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Discussion Starter · #4 ·
i put the 78/112 jets back in. took a little bit of time to tune it in but at last attempt the bike started and went to the 1000rpms. i shut it down after a few seconds because i was watching Makena and the start up sound scared her and she started to cry. as long as i dont have a vacuum leak next time and everything else holds up.

the bike was so rich before i put the 78 back in when i got it to fire again i blew a golf ball size piece of sludge blow out of the pipes. its all over my garage floor. good times.
 

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Discussion Starter · #6 ·
it was black. looked and smelled like carbon build up. on another note dealing with the carbs. the plate that ties them together was getting in the way of my choke operation. I took it off and so far I don't see any ill effects. the plate towards the bottom front that holds the carbs from the underside is still there but the top plate that holds them together by the carb pistons is now gone. the choke will completely shut so i hope that means i can tune it correctly and start with a fully shut choke. I also think I have a vacuum leak because the few times i get it to start and idle correctly with the choke closed after a few seconds it revs about 4k and stays there. i'll be screwin with it more tomorrow when the wife goes out for a girls night with her friends. i'll have the kid but i can sneak out in the garage occassionally.



i haven't checked the oil level in about a month. i'll check it tonight. i don't think i'm losing oil but i should verify. i'll have to change the oil before i go for reg and tags. its fresh but it needs a replacement filter.
 

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Discussion Starter · #7 ·
i did a search on some theory of carburetor tuning. trying to read it was like being back in high school. i read it three times and still didn't comprehend what i was reading. what i did get from it was that if you have to turn your air screw out more than 2 turns then you should go to the next size jet. i have it turned out 2 3/4 out right now and it gets really close but my question that i hope someone can answer is at what point do i set the throttle adjuster screw? right now its turned all the way out so i know my butterflies are either shut or damn near it. when i turn it in the idle goes from less than a thousand to more than four thousand. is there a set depth?
 

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Discussion Starter · #9 ·
I think its all set. i have it on 78/112 jetting. idle sits right at 1100rpms. i was expericening a problem with the throttle being too sensative. the bike warmed up and sat at 1100 rpms but if i gave it 1/4 turn it spiked to 4k and stayed there for 10 or so seconds. i fattened the mix up and that seemed to lessen the issue. i'm going to keep the hotter jets in case i have to rejet in the scorching hot az summers but i'm pretty happy with the bike right now. i'm calling the project done. it took just under a year and right at a grand but i think the bike is pretty unique and cool, i look forward to taking it out and disturbing the peace.
 
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