Carb Details/jetting Advice - 3G

Too much "looking into" is netting me conflicting info.  Darn my need for thoroughness.  

The Tstat on my ride is kaputz, so I need to swap that out.  Doing that required removal of the carbs.  My bike has always smelled gassy.  So while I'm at it, I might as well jet her properly, as I do have a K&N and a V&H slipon.  But the more I look at stuff, the less clear it becomes.

My first option was a Dynojet Stage one, but one source specifies for stock filter with slipon and another says aftermarket filter or aftermarket exhaust.  The main jet size seems to be 124 or 126 (part #'s are D__124), different if you have a CA model.  I do. It makes less sense because these are smaller than stock (seemingly).  Maybe they are confusing 3G and 4G?

Of course there are other options, most that seem to be less complete, although I'm not sure if its necessary.

Things that I think I know:

Stock main jets: 130

Stock pilot jets: 38 on CA model

I have yet to open the bottom of my carbs (shame, shame)

My bike was purchased in "stock" form, so my jets should be as well

I don't know why she then smells gassy

Things I would like to know:

What kind of Keihen do we have? I want to look for options on Sudco.

Jets are only $3-4.  Does anyone have main jet/pilot jet, needle suggestions?

Do I need new needles?  I read a post suggesting it isn't necessary, just adjust height.

Any and all advise appreciated.

Thanks!

What do your spark plugs say? Before I even messed with the carbs I would look at the plugs. I got a K&N and a Supertrapp and did not mess with the jetting ever. My bike still runs great. I run irridium plugs I run the eh9's. They seemed to work better than the stock heat range. If you have to rejet I would get a kit with needles and jets. Your going to have to play with it some and check the plugs to see what's going on in there. You should be able to look at the numbers on your carbs to get the specs on them. My book is out of reach or I would look it up for you.....

:lurk:

There are several aspects to this.  Start from the bottom up.  Just what I would do unless you are set going to a jet kit and pipe.

When I worked in the shop in San Diego, I ran IDK how many bikes on the dyno.  IDK how many I jetted and tuned.  If you don't have access to a dyno, or are not going to go that route with the jet kit, put the carbs back to stock, what YOU know is stock.  Everything from ensuring the plugs are correct, correctly gapped, air fuel mixture settings are 'correct', and that the carbs are clean and sync'd. 

Are you running a stock air filter or aftermarket?  What about a crankcase breather?  They will all play into what you may or may not need to do. 

I'd go run the bike on a dyno a few times to see what baseline I come up with.  Each component of the carb will have a different affect on how the bike runs on the dyno.  Air fuel mixture is x rpms to x rpms, then the needles take over, then the main jets.  You can really tell a lot from a dyno run and where what dip in the curve is. 

The curve the dyno shows will tell you where your issues are and whether you need to drop the needles a notch (jet kit), raise them, or go to a bigger or smaller main jet.

A good shop will have an EGA as well.  You can probably get 2 or three good runs on a dyno for $25 or so, then make a decision on whether or not to mess with the carbs more, or have the shop tune it. 

My plugs look decent, but I do get deceleration pops and the gassy smell that I'm trying to remedy.  Some things I'm considering: I've read that the RC36 carbs are lean to begin with.  I'm running a desnorkeled airbox with a K&N filter, EVAC cannister removed, PAIR system to be removed shortly, and a Vance and Hines slipon.  My thinking is to move to 132 or 135 mains, 40 pilots, and a 84j needle.  I hesitate to move to a DJ kit because I've read here http://www.vfrdiscus.../page-2?hl=jets that the jet profile is different.

I know I have 36mm carbs, but I have yet to determine what type of Keihin carb, a question I'm sure sudco can answer.

Have a dyno run. Normally a bike with k&n and open end can wil run lean.

My plugs look decent, but I do get deceleration pops and the gassy smell that I'm trying to remedy.  Some things I'm considering: I've read that the RC36 carbs are lean to begin with.  I'm running a desnorkeled airbox with a K&N filter, EVAC cannister removed, PAIR system to be removed shortly, and a Vance and Hines slipon.  My thinking is to move to 132 or 135 mains, 40 pilots, and a 84j needle.  I hesitate to move to a DJ kit because I've read here http://www.vfrdiscus.../page-2?hl=jets that the jet profile is different.

I know I have 36mm carbs, but I have yet to determine what type of Keihin carb, a question I'm sure sudco can answer.

You took off the airbox snorkel? I thought of doing that but I realized that I may be only letting hot air in to the airbox. That could give you the smell of fuel through evaporation. The vfr carbs are cv carbs they need a little pressure to work correctly. I have tried to run my bike with the top of the air box off and no filter just to see what happens. The bike ran like poo. Put the filter in and it got way better. It might be that you need to adjust your pilot screws. The honda service manual shows you how to do all that stuff. The clymers ones are ok but the honda one is way better. If you do not have one  Iwould suggest buying one. Running on the dyno is a great idea if you have the money and time to do so. You might just need to take them off and clean them really good. I put a litte two stroke oil in my fuel now days. The fuel is so horrible for bikes today I ran 110 leaded with no ethanol 92 at 50% bike always ran good. They closed the fuel station that used to sell it here so I have had to stop that for now. My bike is stone stock except for the can and filter. CA version with pair valves still clicking away. Over 170,000 hard miles mostly stock.

On the '91 I used to have, I had a K&N and V&H, and it was lean, I was fighting the feeling of surging (felt like a constant head wind) and it had a recent tune up for a good shop.  I believe I did a Stage one kit, and it cured the lean surge, but I did the kit, more than just replacing the jets.

I have a 2000 Magna in addition to my VFR. The stock jetting on the Magna is lean and most every owner swaps it out. I did and it works great.

The jetting guru over on V4Musclebike.com is super helpful and I believe has a jet kit "calculator" on his website that steers you to the jet sizes you need. He has jets for the VFR too. Go check out the page. I highly recommend his service based upon my experience. He sent everything in a kit with instructions. The VFR carbs are exactly the same, just a little bigger.

http://carbjetkits.c...-1990-1993.html

You took off the airbox snorkel? I thought of doing that but I realized that I may be only letting hot air in to the airbox. That could give you the smell of fuel through evaporation. The vfr carbs are cv carbs they need a little pressure to work correctly. I have tried to run my bike with the top of the air box off and no filter just to see what happens. The bike ran like poo. Put the filter in and it got way better. It might be that you need to adjust your pilot screws. The honda service manual shows you how to do all that stuff. The clymers ones are ok but the honda one is way better. If you do not have one  Iwould suggest buying one. Running on the dyno is a great idea if you have the money and time to do so. You might just need to take them off and clean them really good. I put a litte two stroke oil in my fuel now days. The fuel is so horrible for bikes today I ran 110 leaded with no ethanol 92 at 50% bike always ran good. They closed the fuel station that used to sell it here so I have had to stop that for now. My bike is stone stock except for the can and filter. CA version with pair valves still clicking away. Over 170,000 hard miles mostly stock.

The snorkel removal seems to have zero impact positive or negative on performance, beside more intake noise.  Now I kinda like the intake noise, but it may not be for everybody.  The gas smell was the worst when the bike was stock.

I fully intend to clean the carbs well, but I figure if by almost all accounts the bike is jetted lean anyways, and if my mods lean the bike out more, it seems obvious that I should probably richen things up just a tad.  Worst case, clean jets and a little cleaning never hurt nothing.

I have a 2000 Magna in addition to my VFR. The stock jetting on the Magna is lean and most every owner swaps it out. I did and it works great.

The jetting guru over on V4Musclebike.com is super helpful and I believe has a jet kit "calculator" on his website that steers you to the jet sizes you need. He has jets for the VFR too. Go check out the page. I highly recommend his service based upon my experience. He sent everything in a kit with instructions. The VFR carbs are exactly the same, just a little bigger.

http://carbjetkits.c...-1990-1993.html

I found this calculator online last night, and I ordered my kit this morning.  Hopefully, these will come in this week, and I can get the work done while it's raining.

Sweet hope it all works out for ya.

Just to wrap this sucker up, the kit from carbjetkit was complete and had good instructions.  135 mains, 42 pilots, and 2 shims. Everything went in easy, found that my bowls were very clean, one pilot was plugs, one main was not tight.  Gave everything a once over, put everything back together, and boy did she run like crap.

But this was expected, I've totally changed the induction.  I still have some fine tuning to do, but after getting the idle settled in (and another carb balance is in my immediate future) and some other minor tweaks, she's starting to pull like a freight train.  Did my first power wheelie yesterday.  The front must have come up a whole 1/64", but still a first.  The gas smell is gone.  She still warms up slowly, but stays warmer longer.

At the same time as the jets, I also replaced my t-stat and removed my PAIR.  If I did it over again, I would have removed my PAIR first, and then everything else.  The PAIR was in the way of everything.

The one thing that hasn't been overwhelming positive is yesterday and today she stalled at the same light on my way to work.  Both were at idle, choke slightly on. 1200rpm to nothing.  She started back up, and other lights (both before and after the stall) were not a problem.  I'm guessing this is a setting/balance issue with the chilly (58Fish) air and an motor that is warming up, so I'm not overly concerned with it.

You really should not ride with the choke on. Choke is not you friend.

I usually turn it off within a mile from my house, but I will keep that in mind.