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Author Topic: Help with I/S Unstable Accel  (Read 2509 times)
John G.
Member
*****
Posts: 54

SC


« on: June 02, 2009, 02:26:08 PM »

I am experiencing an unstable acceleration problem at low RPM with the I/S and a flat spot when starting off.  This condition is getting my attention especially in slow traffic and 2-up.  I changed spark plugs today and very little help.  The flat spot is particularly bothersome when taking off as the RPM does not follow the throttle and if I give it too much throttle--well you know what that causes with a Valkyrie.  Bike starts easy but sometimes not easy to keep running until warmed up. Standing beside the bike and slowly advancing the throttle you can tell a little roughness in the RPM and about 1500 RPM it wants to go.  I am guessing this is about change-over from primary to secondary.  I have run some Sea Foam through it and no help.  I am wondering if this might be a candidate for a carb sync???  Also, wonder about ethanol.  The bike has 13K on it and yes, it does need more driving.  I went to my local wrench today, who is a Valk driver, and did not get the feel they want to be bothered with a sync job.  They have not done one is some time and may not have equipment.  I would not have asked them but I do not have a sync setup nor have I ever done one, but may be better off trying it rather than going to the wrench.    Any suggestions on this problem will be appreciated.  If I have to go to a wrench what do I expect to have to pay?  Any recommendations on where to get a good sync job I can travel--located in central SC.

 
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daytona
Member
*****
Posts: 209


Port Orange, FL


« Reply #1 on: June 02, 2009, 02:45:05 PM »

Hey NICE BIKE!!!  Does partial choke help? The gooroos will get ya fixed!   cooldude
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Just started!
MP
Member
*****
Posts: 5532


1997 Std Valkyrie and 2001 red/blk I/S w/sidecar

North Dakota


« Reply #2 on: June 02, 2009, 03:20:51 PM »

Dittos on the nice bike.  Good luck.
MP
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"Ridin' with Cycho"
John U.
Member
*****
Posts: 1085


Southern Delaware


« Reply #3 on: June 02, 2009, 03:53:17 PM »

Do the easy stuff first. Check all vacume hoses for leaks, plugs on the vacume nipples, O-rings on the intake tubes and the upper and lower clamps on rubber connecters between the carbs and the intake tubes. You may get lucky.
Based on your description, I think the slow jets may be clogged. Ethanol will do that if the bike sits for a while. Try some Techron in the gas, give it a big dose (whole bottle in half full tank). Let it work for a few days, run the bike with the Techron in the gas every day for a week (long enough to get the bike hot).
If that won't do it you'll have to clean/replace the slow jets. Many of us have gone to 38s, stock is 35 to reduce the ethanol clogging.
If the bike runs strong with the choke on or over 3000 rpm but acts as you describe below that # with the choke off the problem is almost certainly slow jets.
Let us know how things are going.
Good luck
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humshark
Member
*****
Posts: 172


Spring Hill Tennessee


« Reply #4 on: June 03, 2009, 09:15:51 AM »

I agree with John above. 
You didn't mention how much Sea Foam you used or in what strength.  When mine began to act up, it took about three tanks:
1 tank - full can
2 tank - half can
3 tank - last half can for good measure! 
This gave me all kinds of reasons to ride to the store, or to anywhere!  ( Not that i really needed it! )

Now is a good time however to check the things listed above for peace of mind.  Clamps seals and O rings can really make you worry that something else serious, is wrong, when in fact 30mins to and hour of time and a couple of basic tools will get the fix!

PS - I have not heard that "balancing" our carburetors will fix a poorly running engine.  I'm expecting when I balance mine, It will increase response and millage.

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99 Interstate
05 FJR
97 Vulcan '88' Hacked
John G.
Member
*****
Posts: 54

SC


« Reply #5 on: June 03, 2009, 09:46:22 AM »

I got some more carb cleaner this AM.  Did not use but half can of Sea Foam on first dose.  Thanks for the info on dosage.  I think the correct dosage of cleaner might help because the bike does not get ridden enough.  Will fix that this week.  Will post update after I run a few tanks through it.  Thanks for the help.

                                   
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humshark
Member
*****
Posts: 172


Spring Hill Tennessee


« Reply #6 on: June 03, 2009, 09:58:34 AM »

No Problem!
By the way, I agree with the others, you have a very nice bike.  My first Valkyrie Standard was very similar in setup to your Interstate.  The studded Corbin seat on a black bike, accented with chrome is timeless, and will ALWAYS be in style!

Now get out and ride her!  Look forward to the update.
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99 Interstate
05 FJR
97 Vulcan '88' Hacked
John G.
Member
*****
Posts: 54

SC


« Reply #7 on: June 03, 2009, 11:50:29 AM »

Thanks for the compliments----this I/S is cherry!  You guys are kind and make me feel bad about considering a trike kit for the Valk.  Wrench told me there should be a law against me even thinking about it.  Fixin' to go for a ride to wash the fuel system.   John

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John G.
Member
*****
Posts: 54

SC


« Reply #8 on: June 05, 2009, 12:57:38 PM »

Update!!  The Fat Girl seems to be coming around after a huge dose of Techron Concentrate.  Accel from starting out is a lot smoother and bike seems to run smoother overal.  Still got some miles to go but should get that done tomorrow weather permitting.

                       
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humshark
Member
*****
Posts: 172


Spring Hill Tennessee


« Reply #9 on: June 05, 2009, 01:21:07 PM »

 cooldude  Smiley  laugh  Cheesy  Grin  Shocked

Don't you LOVE the easy fixes!
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99 Interstate
05 FJR
97 Vulcan '88' Hacked
John U.
Member
*****
Posts: 1085


Southern Delaware


« Reply #10 on: June 05, 2009, 07:15:37 PM »

Glad to hear it worked for you. That ethanol "enriched" gas can mess up the carbs in just a few weeks if it sits. Use gas stabilizer if it won't get regular use.
A bike as sharp as yours should run as good as she looks.  cooldude
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