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87 off idle hiccup

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bike runs great .....but off idle it has a hiccup.  

 

Great idle

clean tank

fresh fuel

petcock doesn't shut off... drips out when in the off position

 

Any ideas?

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There's a ton of variables here.  Assuming the obvious stuff (air cleaner, plugs, caps, etc), have you properly gone thru the carbs?  And when you do, you should "split" them to replace the fuel crossover o-rings.  They are a ticking time bomb at their age unless you are 100% sure they have been replaced.  Every single set I've done in the last few years nearly crumbled in my hand and they all were cracked.

 

Also perhaps some ether while idling to check for intake leaks.  The rubber intake boots can be bad by now too. 

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12 hours ago, Captain 80s said:

There's a ton of variables here.  Assuming the obvious stuff (air cleaner, plugs, caps, etc), have you properly gone thru the carbs?  And when you do, you should "split" them to replace the fuel crossover o-rings.  They are a ticking time bomb at their age unless you are 100% sure they have been replaced.  Every single set I've done in the last few years nearly crumbled in my hand and they all were cracked.

 

Also perhaps some ether while idling to check for intake leaks.  The rubber intake boots can be bad by now too. 

 

look at the O-rings with a 10X magnifier to see the real imperfections. seems like they always leak through the rusty crusty buildup.

 

 going through the manual's "idle drop" adjustments might be necessary.......after all and a plug color comparison.

 

 

oct_15---18_059.JPG

 

 

 

oct 15---18 061.JPG

 

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Thanks guys I plan on the carb clean up.  Just curious to get input on what others have experienced.  It came with a Uni-Pro filter in it and the snorkel removed from the airbox.  I've never used them before

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I have never run a Uni in a street bike.  You could change out some parts and see if it gets better or worse as a guide to what is going on (lean vs rich).  Maybe your buddy's bike has a snorkel and/or a stock air filter to try out.  My guess is lean, likely somebody did the filter and de-snorkel without any jetting changes.   Or maybe even tape off some of the airbox inlet as a test too.

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my sad experience with uni filters is that they crumble to dust after just a few years, seems like the filter oil eats 'em up. 

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that's what I thought on the filter combo.  

 

Idle was around 1100 to 1200  seemed low... I raised it to 1500  no hiccup so I'll get a new filter and snorkel to try first.  Took it for a nice ride at that idle and no issues

I'll redo the carbs later, wheel swap is first and working on the exhaust.

 

You guy rock  thanks

 

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Got a snorkel back in and does seem a little better, need to fiddle with the carbs a bit.  But I still need to grab a K&N for it first.

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All of my VFRs automatically get at least #40 pilots (from 38).  I put #42 in the RC26 (4-1, K&N, no snorkel) and it is great.  I'm sure #40 would have sufficed just fine, but I have no regrets, it starts, idles and performs perfectly.   I also shim the stock needles .5 - 1mm

 

 

 

 

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Captain ,  thank you sir!  As always great info

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Captain, would you point me towards a Keihin carburetor jet source, please?

Brian

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I use eBay usually.

 

99103-MV9-0420    -Changing the "0420" to "0400" doesn't work on that part number to get the Honda part # for a 40 though. 

 

Or just search on eBay

 

KEIHIN Carburetor Carb Pilot Jet 40 Slow Jet  (insert whatever size you're looking for).

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