Small world! I was in MHS class of '83, did 6 years in the Army but moved out in '91. I miss the place, nothing like waking up and being able to see the mountains.

Sounds like you are off to a good start. I called the folks in Denver and they said there wasn't anyone they would recommend up that way - which is pretty bad news for you because it means that there's no place that they would trust - BUT if you can find someone that can run a dyno correctly, at least you can get some good data from it. Just don't let them touch the carb. :-)

I forgot the link in my last post for the instructions. Here they are. It's written for a Sportster but the instructions for setting the IMS are the same.

 

Sorry to interject your post - but I am in Denver and my '86 evo is running rich - and I would like to put her on a dyno....how much are they and who should I go to? It is stroked 96CI s&s build.

 

Hey 91 Ultra

Still on the first tank since the needle change, so I dont have mileage data yet. But I'll post it once I do.

Mike

 

I decided to dive into this again yesterday, spent a good 6 hours "tuning" the carb and here are my conclusions thus far. The 42 slow jet with a 170 main seems to be the combination I am looking for. Bike runs good with 3 1/4 turns out on the air mixture screw. It is slightly on the lean side (VERY light tan on the plugs). I kept going back and forth between the 42 and 45 and the 45 slow jet runs too rich. I have ordered a sporster needle which I am thinking will put me where I want to be jet wise. I have also ordered a 44 slow jet so I may tinker with that a bit. The other issue is the gas mileage. I have ordered a rebuild kit as well, I am going to pull the carb apart when I get the needle and replace all the gaskets and adjust the float. If the gas mileage is still bad I may end up replacing the carb.

 

The folks in that part of the country that I trust are NRHS Performance, 303-702-1600. Note that the phone number on the home page is wrong, this is the correct one (although I think the "Contact" page has the right info). I'm not sure if they do tuning for bikes they do not build but I know for sure that Aaron Wilson and his folks are among the very few people I would trust implicitly with my tuning needs. If they cannot do it for you, a recommendation from them is worth it's weight in gold.

If you call, tell Dan (he answers the phone) that Lee Bussy sent you. It won't save you any money but he'll know all the excellent service they've given me in the past has some benefit besides my thanks. :-)

 

The low is possible but the 170 sounds really lean. A 1200 at sea level likes around 185 (slightly rich but safer and cooler running). Up there I'd think a 175 or 180 would be the lowest you want to go. Still though, that's a WFO thing and doesn't affect normal driveability too much.

The screw is actually fuel not air so your setting is a bit richer than most people would use. This leads me to believe that either you didn't have the butterfly closed all the way when you adjusted, or that you might have some damage to the carb body. When you drill the IMS plug out it's really easy to barely nick the top of the screw, driving it forcibly into the carb body - permanently damaging it. Also check to make sure that you have an o-ring, washer and a spring on there. Sometimes you can get an air leak that affects things. Have you checked for leaks as well? A small one might cause some differing readings.

It's not way off what I would expect, but enough that if you spend 6 hours to get it right it should be better.

First, with modern gasoline blends, any color on the plugs is likely too rich. You can't go by those old Clymer manual pictures of plugs anymore. Also, you cannot go for a ride and then look at them when you get back unless all you want to check is the conditions right before you shut the motor off. What you need to do to check various areas of your fuel delivery map is a plug chop. Here's a pretty good explanation, with some good links to other sources:

http://faq.f650.com/FAQs/SparkPlugFAQ.htm#Plug%20Chop

To mimick some of what the N65C needle will do for you, get some #6 brass washers at the hardware store and slip a few of them (start with 2-3) on the needle so it raises it up a little bit. If that improves your idle-part throttle transition then the N65C will probably be a good match. Sometimes I shim the N65C or NOKK needles too depending on what the bike wants.

Check the throttle shaft for leaks, also carefully go over the slide diaphragm for burn marks, hard spots, tears or holes. If you end up looking for a new carb, look for one that has not had it's IMS plug drilled out. No sense in getting someone else's headaches.

 

Update, I received my new gasket kit and jets for the carb and decided to dive into it tonight. I pulled the carb off and disassembled it and cleaned everything. I think I found the cause for my bad gas mileage. Someone has put a dynojet kit in this one which I have read can cause a loss of 10-12 mpg. It has a dynojet needle in it and looks as if there has been some drilling done on the slide.

For the time being I stuck a 44 slow jet in and 180 main for now. The needle is set 3 notches down. I tried 4 notches down but the bike ran real bad so I put it back to 3.

I am not going to mess with this any longer and am going after a new carb. I am most concerned with reliability and gas mileage at this point. Am I better off going with another CV or should I go S&S or Mikuni?

[IMG]local://upfiles/36715/3523B3EA187F4DF49BF990B3A957E0A3.jpg[/IMG]

 

To "Un-DJ kit" this carb you would need to purchase a new (stock) emulsion tube, needle, and slide if it's been drilled.

You can get a take-of CV for ~$50 on eBay. With a stock engine, and given that you want reliability and mileage, I don't really see a good reason to spend an a$$load of money on an S&S or Mikuni. Between those two however, Mikuni is my choice hands down. S&S is rather antiquated technology and a step backwards IMHO from the CV.

 

My S&S Super E works good, came on my bike, and I like the fact that I can adjust the accelerator pump shot with an externalscrewand enjoy zero lean surge without having to take the carb apart to achieve it. But I would never have spent the $350 or more to get an S&Sif I already had anOEMCV.A better running bikealmost always means burning more fuel over stockno matter what carbyou use because the factory sent them leaned out. We've all heard the miracle stories but, bigger jets andthinner or raised needles (at cruise, you're primarily running on the needle) all cause reduced gas mileage. At the Harley dealership where I worked, the techs were awesome at tuning CV's, and their advice was always the same: keep theCV on standard displacement bikes (or up to 85-90 HP) and go with a Mikuni foreverything else. That dealership depends on repeat business and gets it, so they don't treat customers as one-timers. If it were me, I'd try another used CV (probably not necessary) before I'd spend the bucks for a new carb. Like LBussy said, I would go back to standard parts and then start over.

I bought a minty CV througheBay for $50+ shipping. I'm going to throw it on this winter when I change out my cam and see how it goes compared to my present set up. At my elevation, I'll start with a #47 pilot, #185 main,shim the needle .05", and leave slide undrilled. I'll go up or down on the pilot jet until the idle air mixture screw is, hopefully, 1.25 to 1.75 turns out (I like the low speed a little rich if anything)from lightly seated at best running. This combination, or something very close to it,has worked well for me on several bikes (EVO's) in the past. At your elevation you may end up with smaller jets, but I'll refrain from making a WAG.

The dyno "expert" that "tuned" my S&S carb adjusted the idle air too rich, and it ran poorly until I changed it back to where it was. He also left my low speed (S&S calls it an intermediate jet)as-is, which at a .75 of a turn out on the idle air mixture screw,indicates that the intermediate jet was at least one size too rich. He changed the main jet, which is very easy to do , from a #72 to a #68, and said that he had saved me some gas. Wrong! I don't cruise at WFO so it made no difference at all, except it was crisper running hard up through the gears. In other words, unless a dyno guy is willing to really do something for his $100+ an hour fee, you're left with learning how to tune for yourself, and it'll take hours of reading and fiddling. Once you've been through it a few times, you'll get very close on your own. I thought I'd get some magic for my money, and hadn't worked on an S&S before, but in the end, I just needed to pay my dues and learn the carb. In other words, keep at it, you can do it, especially with your previous experience.Tells us how it runs in detail, symptoms and at what RPM's, and it will be easier to zero in on what to do next. Good Luck!

 

Thats what I am looking for, to get back to stock so I have a good starting point. I have my eye on a couple of carbs on ebay, my other option is to purchase a new slide and tube from bikebandit for my present carb.