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weird hickup

Old 08-16-2017, 07:12 AM
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weird hickup

so yesterday i was riding the interstate dropped it to fourth and pinned it everything seemed ok. when i was holding it just about an 8th turn on the throttle letting the engines speed come down i had two blips. this happened about 3 times. stock air box filter 48 pilots and 2.5 turns out front and rear with slip ons. any suggestions?
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Old 08-16-2017, 10:59 AM
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What were the revs? - as there's carb fart phenomena at low revs - when the carbs blow back into the airbox and cause a stumble in revs. No real solution on the largest diameter carbs fitted to a production M/C apart from balance the carbs, tps and raise the idle to 1200/1300 to help prevent stalling at low speeds.
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Old 08-16-2017, 12:40 PM
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not really sure what the engine speed was at the time id say around 5000 is a guess at best. i had it pinned through two gears then backed off went to get back on the throttle at about 5000rpms and it had two blips with the throttle held at about 1/8th of the way open. if i had it anymore than that i didnt notice any blips. thanks for the info it was helpful. i am going to try the tps thing sometime soon just have not got a chance. probably going to sell the bike locally not sure yet.
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Old 08-17-2017, 01:42 PM
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diagnosis from afar without exact info is tough... I followed ALL the advice of some learned forum and facebook page members, mine runs without fault.. Fixing is fun, modding is "funner"!
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Old 08-19-2017, 07:58 AM
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ok so when going full throttle for about 15 seconds or longer I let off the gas at 9 to 10 thousand rpms i will apply just enough throttle to hold speed when the bike gets to about cruising speed at say 85 mph and just at 5500 to 6100 rpms i will have a two bump delay or hickup whatever. i have not noticed it at lower speeds or at shorter intervals of wide open throttle so it seems to only do it when i have it at wide open for more than 15 seconds then it will do it. i have 48 pilots slip ons and the air fuel screws at 2.5 out idle set at 1200.
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Old 08-19-2017, 05:36 PM
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If you are experiencing a lot of decel when backing off on the throttle, don't know what gear you're in, it may be the carb vent hose issue. ?
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Old 08-20-2017, 08:36 AM
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Originally Posted by xeris View Post
If you are experiencing a lot of decel when backing off on the throttle, don't know what gear you're in, it may be the carb vent hose issue. ?
F
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Old 08-23-2017, 05:37 PM
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I agree with menace: 'F'.
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Old 08-25-2017, 12:29 PM
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thanks for your input guys. i am not a novice with carb tuning on the other hand i am very much a novice with a vtwin. in my opinion i think it is that i have the air fuel mixture screws turned out too far or its a needle setting issue since it only happens just after wide the **** open throttle at high speeds. normally with an inline 4 i would not think it to be a/f screws but this thing is funny because it has only the two cylinders and huge carbs also i never in a million years would i have expected to gain so much more of an increase in power by changing just the pilot jets i went to a 48 and it changed everything in a good way for wide open power and smoother throttle position while maintaning speed but i also didnt have this blip b4 i put in the pilots and it seems to have an odd reaction on cold starts that it did not have b4 it likes to die after running for 30 seconds and does not start right up it takes about 3 to 5 turns of the crank and it did not b4. after the bike sits in the sun and the temp gauge reads 100 degrees b4 even starting it i have no issues but when i start it in the morning when its cold it will die after running 30 seconds i think that most of the starting issue is from the carb sinc being off a bit also a/f screw settings because the idle sometimes fluxuates just a smidge. with a four cylinder you dont really have to be as precise they react differently plus it has 2 extra cylinders so your tune can be off just a bit and not notice a thing. i have replaced both the little foam filters in the corner of the air box so i wouldnt think it to be that. do you guys possibly think that the needles could be damaged or worn at the tip 33,000 miles are on it. we all know its a huge pain in the *** to install the slides for the carbs maybe i messed one of the tips up while doing this or maybe its just that they are not at the right height. any feed back is welcome thanks for your reading and forgive me for the grammer and puncuation.
Dustin
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