RS125 1 Posted October 4, 2019 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? Quote Share this post Link to post Share on other sites
Captain 80s 179 Posted October 5, 2019 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. Quote Share this post Link to post Share on other sites
squirrelman 102 Posted October 6, 2019 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. Quote Share this post Link to post Share on other sites
RS125 1 Posted October 13, 2019 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 Quote Share this post Link to post Share on other sites
Captain 80s 179 Posted October 13, 2019 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. Quote Share this post Link to post Share on other sites
squirrelman 102 Posted October 13, 2019 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. Quote Share this post Link to post Share on other sites
RS125 1 Posted October 14, 2019 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 Quote Share this post Link to post Share on other sites
RS125 1 Posted October 29, 2019 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. Quote Share this post Link to post Share on other sites
Captain 80s 179 Posted October 29, 2019 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 1 Quote Share this post Link to post Share on other sites
RS125 1 Posted November 20, 2019 Captain , thank you sir! As always great info Quote Share this post Link to post Share on other sites
Smack 5 Posted November 20, 2019 Captain, would you point me towards a Keihin carburetor jet source, please? Brian Quote Share this post Link to post Share on other sites
Captain 80s 179 Posted November 20, 2019 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). Quote Share this post Link to post Share on other sites
BluRoad 41 Posted December 31, 2019 +1 on the #40 low-speed jets: https://www.ebay.com/itm/EBC-Keihin-RD-N424-21-Slow-Jets-Pilot-Jet-Size-40/141500460272?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649 ...that's your stumble. Be careful, jet prices on eBay are all over the place. 1250 RPM is a good idle speed. Petcock rebuild kits are available from ALL BALLS: https://www.ebay.com/itm/Honda-VFR750F-1986-Fuel-Gas-Petcock-Repair-Kit-VFR-750F/382516232576?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649 ...or the entire assembly from Father Honda: https://www.partsfish.com/oemparts/p/honda/16950-mb2-013/petcock-assy To see what you're facing with the carbs, you may want to reference my site: http://v4dreams.com/maintenance.html A running sync is a necessity. Joe V4 Dreams (.com) 2 Quote Share this post Link to post Share on other sites
RS125 1 Posted January 2 On 12/31/2019 at 10:41 AM, BluRoad said: +1 on the #40 low-speed jets: https://www.ebay.com/itm/EBC-Keihin-RD-N424-21-Slow-Jets-Pilot-Jet-Size-40/141500460272?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649 ...that's your stumble. Be careful, jet prices on eBay are all over the place. 1250 RPM is a good idle speed. Petcock rebuild kits are available from ALL BALLS: https://www.ebay.com/itm/Honda-VFR750F-1986-Fuel-Gas-Petcock-Repair-Kit-VFR-750F/382516232576?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649 ...or the entire assembly from Father Honda: https://www.partsfish.com/oemparts/p/honda/16950-mb2-013/petcock-assy To see what you're facing with the carbs, you may want to reference my site: http://v4dreams.com/maintenance.html A running sync is a necessity. Joe V4 Dreams (.com) Thanks great reference and points of interest Quote Share this post Link to post Share on other sites
