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1500 Vulcan Carb tweaking

7004 Views 17 Replies 2 Participants Last post by  whiskeyrockr
So I'm helping a buddy of mine Dial in the carbs on a 94' 1500 Vulcan 88 (BUBF). It has the most airflow possible with a "ear shave" mod which basically directs one free flow K&N filter to each carb(two filters total) instead of the restrictive stock system.

Now previous owner installed a Dyno jet kit and just like our bikes his ran like crap (its actually the reason my buddy got such a great deal on the bike) $500! what a steal bike only has 30k miles on it with regular dealership service papers. infact guy had the bike serviced just a few thousand miles ago before he installed the K&Ns and did the intake free flow which is when he started having all the problems.

We installed a FP Stage 3 kit and the bike now has a very smooth power curve, Pulls REALLY strong, I mean like a beast! FP didn't send any pilot jets and sure enough we are lean at idle and they are sending us two new pilot jets free of charge( Go FP!).

Anyways, Besides the popping/backfiring on low RPM decel and hesitation on a roll on throttle which the new pilot jets should fix we have another problem. The engine shakes really bad. I'm hoping that trying a carb sync will help with this but was wondering if any of the experienced folks around here might have some insights on this problem? The engine shows no signs of mechanical problems, has hydraulic lifters, not sure about how to time it if at all?
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what size pilots are you putting in to the carbs? a carb sync will help, but remember a kawi shakes more than a honda straight from the factory and they usually idle about 100 rpms less than a honda as well...
i have a shop manual, but can't remember if it covers the 94 model or not, i'll check in the morning when i get up due to it being down in the shop and the winds are up and it's sprinkling rain :)
1994 is an A model classic i think, but either way, i'll check the shop manual in the morning

that's a nice looking ride and with low mileage on it to boot...good score
it shouldn't be much to get it synched...i rode a '96 classic during the spring rally and it shook your bells off without hesitation :)
52 i thought was the factory, but it's been a while since i've messed with one older than 99 (most in my area are newer models now a days)...either way, 55 is a good starting point but i don't think i'd go over 57/58 with it without increasing the main. i'll be around for a short time in morning unless it's raining (i have a poker run planned for tomorrow)...either way, i'll still check the shop for the book and will help with it all i can if i have the book and what i can from memory if i don't have the book :)
that 88classic is a staught bike before being dialed in, but once dialed in, it will stroll with some of the biggest around today (which the late model classics dialed in has no issues with that either :) )
i'll touch back in the morning either way bro!
Stck main is a 190ish and we went all the way up to a 248...... So yeah the main jet is considerably larger and the pilot is still stock, huge gap in the jetting from idle to main. But once off the pilot this beast is hard to keep up with

Hmmm was just re reading this. Think the mains were 118and we went to 148's. Yeah that's more like it
LOL...yeah, that's be more like it :)
the last dual carb vulcan i synched had 160 main and 58 pilot, so, you can imagine how it ran :) :) :)
i went to a 180 with a 52 on the 1500 i just sold about a month ago...yeah, it was single carb, but she would scald the dog and she shook pretty darn good as be honest, i think the little 800 Classic i just bought shakes more than the X :hmm2:
i'm getting ready to head down and check on the manual. my poker run (if it doesn't rain) will start at 11am my time and 8 am your time....if i have to, i can 2 day the manual out to you monday if it includes the A model in it (i'm thinking it covers the A thru the E model, but i'm going to check in a few)
ozzy, sorry about the late reply! couldn't find the book to start with, then my computer was down all day saturday when i got back and most of sunday morning...i found the book late sunday doesn't go back to's a 1996-2008. if it will help, let me know. getting ready to head out to football practice about 5pm (east coast) and it'll be about 730 (ECT) when i get home...
again, sorry about the delay
ok, i wasn't sure if it'd work or not...for some reason i'm thinking the reason they are different, is that may have been the year they went to one carb (and i'm sorry, my book is a 98-08). i've never owned the 94 model, but i've ridden and worked on them more than once...once you get the pilots in, try it and if it still does it, play with the a/f..i can't remember the last setting directly, but i'm thinking they were both out at 1 1/2 turns or 1 1/3 turns...once you get it dialed, it will fly!!!
yep, it's the keihin cv40 which is easy to dial in....
go with the 58 pilot if you put in a 170 main or larger, you won't regret it...
i just got through making the rear lights run/turn on the 800...
there's a motorcycle repair shop down from my house that i stopped in today to see if he had some "kick out pegs" i could use to make my own foot resting pegs (i don't like crash bars)...we got to talking and i asked him if that was his 1200. he said yes, it is..i replied nice bike, i like it...he said thanks, but it runs like chit...i asked what was wrong...he said and i direct quote which i think is cool
"i can work on any part of the bike i want to but the damn carb"...i said to him, that's ok, we all have our weaknesses on bikes..he said, but i feel like i'm not a good mechanic due to that and it takes some work away from me...told him not to worry about and asked if i could hear his bike run and he said sure...fired it right up and let it idle up (super rough i must admit) then he asked me if i knew anything about carbs and i told him a little...he said take her down the road and tell me what you think...
i said sure, i'll do that...left and went about 2 miles out and 2 miles back...
pulled it back in and shut it off and said to "runs like chit, weak on the low end, sluggish on the high side, and she's sucking some serious air somewhere"...he gave me a raised eyebrow look and said, you asked :)
i asked him if i could take a look and we began to tear it down to get to the carb....
there she sit, a 40mm keihin with a broken enricher tied off and loose as crap at the carb entry point...took that out blocked it off, slide the carb out of the manifold boots, open up the a/f 2 turns and i asked him, you got in jets...he said nope...told him i'd be back in 15 minutes...
went to the house and got 1 main and 1 pilot and went back down...we opened up the bottom and i took the old jets out and put in a 170 main with a 58 pilot and we put it back together...
i looked at him and said, "ok, fire her up and head down the road"...he fired her up and he looked at me and said, "SOB, it ain't sputtering and spitting no more"...i smiled and said i'll be here when you get back...he came back in about 15 minutes with bugs in his teeth (i chit you not)...dude offered to pay me or give me a set of forward controls (for an HD, but i could have made them work :) )....i turned him down on both and told i might need a favor one day...he said you got it, anytime...gave him my cell number and we're gonna ride this saturday in a poker run together if it's not raining...:)
i love making friends, especially the mechanical way :)
damn good mechanic (i know him though) but as he stated, he just can't do carbs and undoubtly neither can the other mechanic in town since he was the one that had him running like crap
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yeah, i'm sitting here thinking the whole time i'm typing it's dual 36 no need to go over 150 or so main in each and the 58 pilots will work great LOL...
36's are stout when running dual, no question about that :)
like you said, still do the 58 in them and i believe you'll have her set straight....i have a guy that traded his wife's volusia today for an 1100 ACE...he wants me to rejet it sunday afternoon....maybe i should go to the other guy's shop and work with him on the side LMAO
good job you're doing for your buddy my friend! cheers

oh, yeah, i don't think i'd go over 4 turns on the duals...i think 3 1/4 is the limit on the single carbs on the kawi, but i don't go over 2 3/4 then i start looking at other issues to straighen it out :)
cool deal on the coasters for sure
Oh yeah I'll have to snap a pic of the carb sync tool we built for a whopping $2.35 :) that, i might need to make one myself :icon_mrha
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