HELP! Why does my RVF idle at 5000rpm?!

MBellRacing · Post by **MBellRacing** » Sat Mar 03, 2012 7:12 am

Okay, so my RVF400 has been sitting a little while. I've been busy elsewhere. I had installed an HRC ignition box, higher flow air filter, Tyga airbox, Tyge pipes, Factory Pro jet/needle kit, etc. The usual stuff to go fast. It dynoed very well, but I did so without the intake runners (NACA runners from fairing) and once reinstalled on the road, the bike ran poorly again-- too lean. I pulled the carbs to find that I had some o-rings going bad in the fuel unions so I replaced them. Upon reattaching everything and installing the carbs back in the bike, it has an idle between 3000-5000rpm off the choke, about 5000-6000rpm on the choke. What the fack?!?

I'm not sure how to adjust the throttle plates, so that could be it. No, the idle adjuster is not holding open the throttles. The throttle wheel sits against the stop when idling.

Any help would be greatly appreciated. I'm having a tough time with this one and have pulled and reinstalled the carbs about 15-20 times today. My hands are bruised and bloody and the bike still idles super high. It runs OUTSTANDINGLY, honestly. A couple jitters down low, but WOT the bike is unbelievably fun to ride-- lots of power.

Thanks for your help.

-Matt

Post by **Drunkn Munky** » Sat Mar 03, 2012 8:13 am

only advice I can give is read the jetting guide in the workshop section.

hannakournikova · Post by **hannakournikova** » Sat Mar 03, 2012 8:32 am

Vacuum lines?

Post by **lizard821000** » Sat Mar 03, 2012 9:39 am

check air screw positions.

MBellRacing · Post by **MBellRacing** » Sat Mar 03, 2012 5:34 pm

Thanks guys,

I checked the screw positions-- all where they should be, I think. The only vacuum lines are in the engine runners themselves, right? I don't see any others that I would call vacuum. What sort of leaks should I be looking for and where?

Post by **Drunkn Munky** » Sat Mar 03, 2012 5:41 pm

Cant see it being anything todo with the vacume line if its running fine at WOT.

IIRC the factory pro kit isnt regarded a good mod for these bikes, what exactly does the kit include? what jets are you using?

MBellRacing · Post by **MBellRacing** » Sat Mar 03, 2012 6:06 pm

Stock pilot, stock fuel screw, 118 fronts, 115 rears. Bike runs right at about 13:1AFR at WOT at redline and hovers between 12.7-13.5:1AFR WOT at lower RPM, sometimes with a little rich shutter. Bike sounds great, just idles really high!!!

How does one properly set the throttle plates?

Post by **Drunkn Munky** » Sat Mar 03, 2012 6:15 pm

Jetting is back to front unless your running UK carbs (UK carbs have metal slides) and also maybe a touch lean. I cant really see why the idle is so high given the mods you've made, are you sure the butterflys are closed at idle?

You can set the plates many ways, best way is to use vacume gauges but i and many others do it with a drill bit to sync them. The method is detailed in the workshop section.

Post by **lizard821000** » Sat Mar 03, 2012 6:19 pm

im sure that if the slides are vacumed ones then its purely air that adjustes them!? so its getting too much at idel.

been a while since i looked at mine so just trying to think in my head if thats right with vacum slides. adjusting the idel adjuster just opens the throttle more or less, adjusting the amount of air into the carb mouth, i think.

i could well be wrong mind lol you could try adjusting the butterflys but that will effect jetting through the hole range.

im gunna stay out of this one as tbh im not too cluded up on the whole vacume process on these bikes.

if youv increased the air intake , the stock pilots could be lean.

MBellRacing · Post by **MBellRacing** » Sat Mar 03, 2012 9:53 pm

So I bottomed out the fuel screw (what Factory Pro called it... the idle adjustment screw?... who knows) and made sure no throttle plates were being unduly held up by another. Idle falls between 1500-2000rpm, so not TOO bad, really. It can sort of get caught at 3000rpm briefly, but a squeeze forward on the throttle and it drops back to 1500rpm and hovers around 2000. I think my fuel leak is also part of the culprit. When it popped the o-ring back out on the fuel union, the idle went back up to 3000rpm. Before I can make a logical judgment on whether or not I've solved the idle issue, I'll need to fix the fuel leak.

On that note, I'm in need of the proper Honda o-ring for the fuel union (the t-pipe that splits fuel flow to each pair of carbs). I have an A/C system's rings in there now, but they are a touch too shallow and are too easy to misplace in the groove which pinches them and allows fuel to seep around them. I'm in the US and am having a hard time figuring out the right part number to even ask for! Any help would be awesome.

Here's a short video showing the idle now and the fuel situation. Excuse the sound, the bike doesn't sound as rattly in person!

http://www.youtube.com/watch?v=KqYUKzcVsK0