Scooterized, re-jeted, de-baffled WOW, throttle touchy now - Kawasaki Vulcan Forum : Vulcan Forums
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post #1 of 20 (permalink) Old 06-25-2016, 09:39 AM Thread Starter
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Scooterized, re-jeted, de-baffled WOW, throttle touchy now

OK i Just finished a bunch of maintenance and mods, valves adjusted, oil change, antifreeze change, de-baffle exhaust, re-jetted carb (Dynojet needle DN0106, 50 idle, 165 Main with emulsion tube all HD) and scooterized intake cannot believe the difference in power and highway cruising but as with anything there is a drawback at least for me and maybe you guys can help me out. I have my dyno-jet needle set at 2nd notch from top with 2 washers and air mix screw is at 2 1/2 turns, plugs after 400 KMS are nice and tan and there is absolutely no backfire from exhaust, occasionally I get a cough from intake when at a stoplight or intersections where I must completely stop and I blip the throttle (habit I suppose) but that is rare and the only hiccup when running, I know moving up a notch on the needle leans out the mix and down makes the mix richer, but not sure how that would effect throttle response, right now the bike is super responsive, maybe a bit too responsive, on the highway it's perfect but in town it seems that the throttle is way too touchy. I am very aware of over throttling and I am talking about fractional movements on the throttle and the bike wants to launch, hit a small bump at slow speeds in 1st, 2nd or even 3rd gear and that is transferred to my hand resting on throttle rocker and bike surges forward really touchy but very smooth on highway, make driving in traffic a real pain and I would like to dial that down just a bit, any suggestions would be most appreciated, BTW I have already done a 17T to 18T front sprocket swap and intend to do the rear swap to 40T at a later date, this will calm it down some but just put a new chain and sprocket set on last season and it's only got 1200K on it so far so it's not going to get changed for a while. Any carb tuning tricks I might employ would be appreciated.

2002 VN800B, 6" DYI forward controls, EPA system removed, baffles removed, DYI lowered 2 inches in rear , 2" riser, mustang solo seat, re-geared to 18T/42T, scooterized and re-jetted carb, chrome rear fender rack, led headlight, old school leather saddlebags, billet chromed foot pegs, ISO hand grips

Last edited by jfl1960; 06-25-2016 at 09:45 AM.
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post #2 of 20 (permalink) Old 06-25-2016, 10:46 AM
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I have an '03 1500 and tried about every jetting combination within reason. FWIW, I finally settled for a 48 pilot 2 1/4 on the screw and a 165 main. As far as the needle goes, I stayed with the stocker, but used 2 washers to raise it up 30 thousands. I am running a TAK and 3" Roadburner pipes. I ended up going into the carb 4 times before I got it dialed in. Ride for a while and you will feel what needs to be tweeked.

Road Burner 3" Exhaust
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post #3 of 20 (permalink) Old 06-25-2016, 11:43 AM Thread Starter
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I have an '03 1500 and tried about every jetting combination within reason. FWIW, I finally settled for a 48 pilot 2 1/4 on the screw and a 165 main. As far as the needle goes, I stayed with the stocker, but used 2 washers to raise it up 30 thousands. I am running a TAK and 3" Roadburner pipes. I ended up going into the carb 4 times before I got it dialed in. Ride for a while and you will feel what needs to be tweeked.
Thanks for that insight, I know it's a tweaking thing but didn't want to start changing too much at once and start a yoyo effect, I have exhausted my mod budget for the year so I am hoping to get this dialed in without buying more jets and I definitely do not want to remove the dyno-jet needle as it's the only part I used from a kit that cost me $80.00, at least not unless I have no other choice, I did forget to mention I also did the top side mod where you drill out the slider with a 1/8" drill, maybe a smaller hole would have been better any other suggestions are welcome, thanks.

2002 VN800B, 6" DYI forward controls, EPA system removed, baffles removed, DYI lowered 2 inches in rear , 2" riser, mustang solo seat, re-geared to 18T/42T, scooterized and re-jetted carb, chrome rear fender rack, led headlight, old school leather saddlebags, billet chromed foot pegs, ISO hand grips
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post #4 of 20 (permalink) Old 06-25-2016, 04:10 PM
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drilling a hole in the slider could be the problem, that could be making the slider very sensitive. What pilot jet size did you end up going with? the stock 48?
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post #5 of 20 (permalink) Old 06-25-2016, 08:11 PM Thread Starter
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drilling a hole in the slider could be the problem, that could be making the slider very sensitive. What pilot jet size did you end up going with? the stock 48?
165 main with emulsion tube and 50 pilot all are Harley Davidson parts

2002 VN800B, 6" DYI forward controls, EPA system removed, baffles removed, DYI lowered 2 inches in rear , 2" riser, mustang solo seat, re-geared to 18T/42T, scooterized and re-jetted carb, chrome rear fender rack, led headlight, old school leather saddlebags, billet chromed foot pegs, ISO hand grips
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post #6 of 20 (permalink) Old 06-26-2016, 09:21 AM
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you had to buy a Harley CV carb main jet because the Harley emulsion tube threads will not accept a CV Keihin main jet, the threads are different, but your pilot jet is not exclusive to Harley like the main jet is, your PJ is Keihin
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post #7 of 20 (permalink) Old 06-26-2016, 09:33 AM
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I think your problem is with both the drilling of the slide making throttle movement touchy and also your install of a 18T front sprocket, that 18 is what is probably causing your bike to launch from a stop because your gearing is set lower now and the bike will want to go farther on less RPMs. If you keep the 18T front and decrease the rear to a 40T, your highway cruising will use less RPMs and save fuel but your 1st gear get-go will want to launch the bike from a stop even worse

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post #8 of 20 (permalink) Old 06-26-2016, 09:44 AM
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the only solution to a 1st gear get-go launch from a stop using a 18T/40 sprocket combo, is the manage the clutch in a way that eases the clutch lever out slowly from a stop until you get moving because that bike with a 18/40 is going to want to launch forward very quickly
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post #9 of 20 (permalink) Old 06-26-2016, 09:48 AM
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consider a sprocket ratio where the front and rear have same teeth, like 18T front and 18T rear, that combo will made a bike want to take off into outer space on a single RPM of the motor
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post #10 of 20 (permalink) Old 06-26-2016, 10:05 AM Thread Starter
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I think your problem is with both the drilling of the slide making throttle movement touchy and also your install of a 18T front sprocket, that 18 is what is probably causing your bike to launch from a stop because your gearing is set lower now and the bike will want to go farther on less RPMs. If you keep the 18T front and decrease the rear to a 40T, your highway cruising will use less RPMs and save fuel but your 1st gear get-go will want to launch the bike from a stop even worse
Yeah I agree with this observation, while swapping to an 18T from the 17T front it did make highway cruising better but it did not help out in 1st even before the performance mods, I have been running the 18/42 only because the previous owner did no maintenance on chain and sprocket, he replaced a worn rear (42T) just before I bought bike and left old stretched chain and worn front on, made what was seen look new and said entire drive and sprockets had been replaced, anyway I replace chain and front within 1 week of having bike last summer without this problem, well not as noticeable I suspect, but now that I have done these power mods (re-jet, scooterize, de-baffle) it has become an issue, I can ride the bike just have to be careful in traffic for now, thinking about going belt drive (which will essentially give me the 18/40 drive ratio and should help out this problem) so don't want to toss any more cash into the chain and sprockets, and they are basically new anyway, cheaper solution is buy a used slider that is not drilled and see where that goes I suspect. I feel that the bike is running great otherwise so am reluctant to make and further air/mix adjustments or needle adjustments, appreciate the responses and insight provided, will update when I solve this minor glitch, thanks again. Here is a pic of the scooterized intake:

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2002 VN800B, 6" DYI forward controls, EPA system removed, baffles removed, DYI lowered 2 inches in rear , 2" riser, mustang solo seat, re-geared to 18T/42T, scooterized and re-jetted carb, chrome rear fender rack, led headlight, old school leather saddlebags, billet chromed foot pegs, ISO hand grips

Last edited by jfl1960; 06-26-2016 at 10:12 AM.
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