Vn800b jets - Kawasaki Motorcycle Forums
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post #1 of 37 (permalink) Old 04-18-2016, 11:01 PM Thread Starter
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Vn800b jets

Hi I just put new pipes on 2005 vulcan classic 800 on but got a little bit of backfire I'm thinking about rejeting but I am not sure what size of jets I should get or if I should try something else first. Does anyone have any suggestions?
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post #2 of 37 (permalink) Old 04-19-2016, 12:56 PM
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Usually it's not necessary to rejet unless the stock intake has been replaced with a more breathable after market air box

Dave
95 Vulcan 800A-"Pump Hopper"
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post #3 of 37 (permalink) Old 04-20-2016, 01:01 AM Thread Starter
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What about the backfire? Does it really makes a difference having the jets changed with air box
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post #4 of 37 (permalink) Old 04-20-2016, 09:54 AM
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if you change the air box will have to rejett
hmm, just a suggestions
check pipe / cylinder connection, sometimes the crush washers need replaced
also, has the carb been off or losened up from the rubber boot? the rubber boot between the carb & manifold will cause backfire if not seated good

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95 Vulcan 800A-"Pump Hopper"
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post #5 of 37 (permalink) Old 05-02-2016, 12:05 PM
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Quote:
Originally Posted by lapereda View Post
Does anyone have any suggestions?

If you keep the stock intake, remove the pilot mixture screw cap underneath the carb and open up the screw counter-clockwise another 1.5 turns, that should stop the backfiring thru exhaust pipes. If you change stock intake to an aftermarket intake, you need to increase pilot jet size and main jet size as well as open up pilot mixture screw.
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post #6 of 37 (permalink) Old 06-22-2016, 11:01 AM
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Sounds like it's running a bit lean, that's causing backfire, removing the security cap and adjust the air mixture screw will fix that up, if car has not been off I doubt you have leaks at the intake backing to carb but you should still check. If the pipes were installed just for sound ( and that would be a shame) then just adjust the carb and you will be fine, however if they were installed to get MORE POWER then an airbox mod, and carb rejet are required, I just did mine rejetted my carb, did the scooterize mod on my airbox and removed baffles from stock exhaust, cannot believe the increase in power and sound, also installed a 18T front sprocket and a new chain to lower RPM on highway, I highly recommend you do the airbox and rejet, can supply some pics and info on parts if you need help. Here's a pic of the final results on the scooterize mod, in all it cost me about |$150.00 for the K&N air filter and the needles and jets I used,( a combination of HD jets and Dyno-Jet needle)

029.jpg
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post #7 of 37 (permalink) Old 06-23-2016, 01:31 PM
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What main jet and pilot jet sizes did you put in? how many turns on the mixture screw? did you keep the stock needle in or use dynojet needle and what notch? what about shims
if you used a dynojet needle did you use the DNO313 for the 1500 or the DNO106 for 800

Last edited by wsim; 06-23-2016 at 01:36 PM.
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post #8 of 37 (permalink) Old 06-23-2016, 01:44 PM
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I put in a 168MJ 50PJ DNO313 dynojet needle no shims e-clip on 3rd notch from top, 2.5 turns on screw, and its idling very poorly with occasional hiccup thru exhaust, I think it's too rich and in neutral I roll on the throttle slowly and it begins to bog down, I think the problem is the needle and it's not seated properly
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post #9 of 37 (permalink) Old 06-23-2016, 05:57 PM
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-Harley Davidson Main #165 with Harley Davidson Emulsion tube
-Harley Davidson Pilot #50
-Dynojet needle DN0160, e-clip 2nd notch, 2 washer spacers on top.
-Air Mix Screw 2 1/2 turns out +/- 1/8 turn my screwdriver tip wasn't an exact fit.
-De-baffled stock exhaust
-Scooterized air breather

Note: Breather MUST be replace with an aftermarket free flowing unit or an air breather mod must be done, otherwise all this time and money is wasted., and you will never get engine to run correctly. Mine is running like a top and no longer need choke to do first start on cold motor.
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post #10 of 37 (permalink) Old 06-23-2016, 05:59 PM
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I bought the Dynojet kit #2147 for the needle, spacers and e-clip alone the rest went into my motorcycle spare parts bins.
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