Pilot Screw Setting

Fixed a few things on the bike that have been nagging at me (valve noise, carb sync and now idle drop) but I wanted to pick your brains as far as how many turns out that screw should be.

valves clearances were a bit off so I brought them back to 0.006" and checked my carb sync and ever so slightly brought them all within balance.

I tried the idle drop and while I was able to find what I thought was the lean drop around 2 turns out, I couldn't find the rich drop so I set all four screws to 4 1/4 turns out from seated. The bike starts and idles great and has good throttle response so it SEEMS like this is good but when I rebuilt the carbs, I went up to a 40 from a 38 so there's a voice in my head that's telling me my screws are WAY too rich.

any thoughts?

 

WAY too rich. If you went up to 40 you should probably be around 1.75 to 2.25 (maybe 2.5) turns form seated, which is the sweet spot. Plus that many turns out, there isn't much spring pressure keeping your screws in place. I have retrieved a few customer's screws from the V of their motor when they were trying to compensate without going up on the pilot.

 

okay sweet, I'll dial them in past 2.5 and see how she runs. I'm wondering if the stumble at 2.5 was my rich drop and I was just compensating by adjusting the idle. it did always seem a tad rich so hopefully I can narrow this down without any lean-hang.

 

Are we talking the VF or VFR?

 

And what mods (if any) are we talking about.

In reality it really shouldn't matter. Either one of those bikes, even with a full exhaust system, shouldn't have ANY lean hang with a 40. If it does, your problem is elsewhere. Like old, cracked intake boots or a badly sealing airbox (read:VF750F). The VFR air box mounts and seals so much better.

 

gotcha, talking about the VF in this case, VFR is still in pieces. No mods, bone stock aside from the bump in jetting on the pilot.

intake boots were pretty hard, soaked them all in wintergreen and alcohol and it softened them right up but I'll spray around and check for an air leak just in case, hoping it's still just a fuelling issue though.

off-idle it runs like a champ, just finicky below 1500 is all

 

update: set the screws back to 3 turns out as I couldn't get it to start otherwise and I know it runs there so that's a starting point. sprayed some carb cleaner around the #2 boot to begin with and the idle picked up about 150-200 RPM.

so......looks like I have an air leak and was masking it this whole time with more fuel.

any recommendations on decent boots? the OEM ones run $33 apiece up here, I can get a set of four K&L boots for about $80 but not sure if they're any good or not......

 

Although I haven't specifically used K&L intake boots on a VFR, I find their replacement parts in general to be high quality, meeting OEM specifications. I bought a set of boots for my Hawk, but haven't installed them yet.

Better than what you have, that's for sure. I knew it had to be something like that, Hondas tend to be kinda finicky about their intake systems.

 

ordered the K&L's up, should get them next week so in the meantime, screws are going back to where they were before - got a day of riding to bang off tomorrow

once I get the boots swapped out I'll update with how the carbs REALLY are!

 

Cool. Have a nice ride. Ride fast, take chances.

 

On the carb boots I have replaced the ones on my NC24's & 35's with cheap sets from eBay (Chinese copies). They are not really a precise item and the fact that new rubber is far more useful when mounting than 30 year old rubber just means that spending $10 on them isn't an issue. Zero problems with any of the 6 sets I have bought.

 

That's good to know. I have been leary of dropping down to that price point.

 

Do you have a link to the carb boots?

 

Not really as the only ones I have bought have been for my 400's. I can tell you I have not paid over 11 GB Pounds for the 4 but I'll ck my eBay history and see if they do them for 750 / 800's..

 

Damn, I was looking at likely the same ones you ordered on eBay yesterday but pulled the trigger on a set of K&L's instead. Good to know for next time that they're actually decent quality. Thanks!

 

If I was really suspicious I'd almost suggest that they are likely to be the same just in different packaging.... After all, how many manufacturers do you believe are making these for 20-40 year old bikes. But I'm not like that lol...

Do I think they are as good as the Honda versions - Nope. But then again, at the price point I'm not expecting that. My oldest set is 7 years old (RVF400) and perfectly fine. I'd buy another set in a heartbeat, but then again if I could buy a Honda set for sensible money then I'd get them.