RSTAR99 wrote:
My 99 is doing the same thing, even with the other engine. Where is the pilot jet located? Do you have to remove the carb to replace it?


If you have already been in the carb, and have replaced the bowl screws with the allenheads, you can do it with the carb on the bike. Shut the fuel off, drain the bowl, and remove the bowl like normal(ie loosen the carb heater etc.). You can see the pilot jet in the pics in this link....

http://roadstarclinic.com/content/view/60/96/

There are two different opinions regarding the stock jetting on the 99-03's. I'm of the opinion, that it is a tad on the lean side. I think the factory did that on purpose to help with emission standards.
When I bought my 95 Springer, the dealer told me right off the bat, I'd want to put a kit in the carb to get rid of the cough, because it was set up to please the EPA. When I put the barons kit in my carb, and took it out for a test ride, it coughed several times when shifting on corners etc.. I had the 37.5 from another kit, and went ahead and put it in. I don't experience any cough or sputter now at all. Granted, I don't go looking for it. I'm very pleased overall with the performance and throttle response.

There was also two different versions of how to tune the PMS running around when I did mine.

Keep in mind, tuning the PMS should be done on a 'burns your pinkies' warm engine, and with the idle set @ 900rpm's, or close to it.

One method, had you turn in to the lean stumble and back it out until it just ran smooth. The other, had you turn in to the lean stumble, and then back it out until you noticed a change on the rich end, and then go back to the halfway point. I couldn't get a rich stumble, and had the PMS out about 5 or more turns. Based on comments from several members, and what was written in this article, I felt like the 37.5 was worth a try. I did get a change in the idle on the rich end after the swap, and it allowed me to find a happy medium around three turns out.
The 37.5 is a small step, that gives just a bit more fuel in the pilot circuit.

http://tidyville.roadstarclinic.com/muckarb.html

WOW!! What a difference!!! This is an issue I have been fighting for some time! I had to order the 37.5 pilot jet from my dealer, but I changed the PMS to 2 1/4 and tweaked on the accelerator adjustment as you guys said and my Roadie is running amazing! I thought it was an issue with my carb on my old motor ( my bike was stolen and recovered but the motor was not recovered, so I purchased another motor) When I installed this motor it did the same thing. But now thanks to my R* brother's, she's running like a champ! Thanks fellas!!

RSTAR99 wrote:
WOW!! What a difference!!! This is an issue I have been fighting for some time! I had to order the 37.5 pilot jet from my dealer, but I changed the PMS to 2 1/4 and tweaked on the accelerator adjustment as you guys said and my Roadie is running amazing! I thought it was an issue with my carb on my old motor ( my bike was stolen and recovered but the motor was not recovered, so I purchased another motor) When I installed this motor it did the same thing. But now thanks to my R* brother's, she's running like a champ! Thanks fellas!!

You can run it a bit and see how it runs if you haven't dropped the 37.5 in yet. Plenty of people are still running the 35, and are happy. Glad this helped.

sputter is usually a sign of rich, hesitation lean. Yrs back when I first learned to tune the stock carb, I learned from the best carb guru at the time on the RSR forum, he was 99.9% on the mark. He worked part time at a dealer, only worked on cruisers, but at his house usually had people come to him even as far as 500 miles away. On avg he worked 50 to 100 Roadies a yr, so yes, I would say this man knew his stuff.
Any way, when it came to the Barons needle or for that matter the DJ needle, he would never change the pilot jet. He always said that if a larger pilot was needed, then there is an air leak. He also used 7 different filter kits on his bike. I can't even begin to say how much I learned from this guy. Unfortunately he knew nil on the 42, so when I got my 42, I did a lot of experimenting and did at least 2 dozen jettings for the "lets see what this does factor". As well had exhaust gas analyzer runs done here and there between the different set-ups.

I was think'n "sputter", and "rubber boot", have one thing in common. They can mean lotsa different things

I was going more off of what "tarcon" said about his issue, then the word "sputter". I was thinking that his lag and gasp, might possibly benefit from just a bit more fuel to clear up the hesitation coming off of idle.
With a slightly bigger pilot, and reducing the shot of fuel from the accelerator pump, you can almost kill two birds with one stone. The reduced fuel shot from the pump, might clear up any gag symptoms(an instantaneous rich moment in the carb from the pump), and the slightly larger pilot, would allow you to tune the carb slightly richer so you didn't need a big mouthful of gas right off to make the bike go. The slightly larger pilot might also allow you to stay out of the main a bit longer in the overlap for a smoother transition between the vacuum and venturi.
I was hoping that he wasn't sitting at the light blipping the throttle like a teenager on a crotch rocket ...but maybe
The other thing could have been an idle set to low causing him to play catch-up when he was rolling on the throttle. That little extra bit of vacuum with the higher idle, would probably help with some more fuel when rolling on the throttle at a light.

My other thoughts on this, are mostly based on the idea that if you can become to lean with the addition of pipes etc., and require a slight richening in the main, why does the pilot get a pass? When cruising at 65 or 70, we're still getting plenty of fuel from the pilot. With slightly more fuel available from a 37.5, we are not needing the main quite as soon. When decelerating in gear with the throttle closed, we're almost using the pilot all by itself.

My thoughts on this also go off of what has been said in the past about the size of the main only being an issue if your always at WOT. The rest of the time, it's just what's slipping past the needle(more or less). If the main is to small, then when you reach its limitations you run lean...even if the needle is removed completely.
In theory, a 35 pilot could run out of capacity as well. The PMS limits the fuel flow at idle where the pilot can provide all the fuel it needs, but does the pilot provide enough at peak demand on the pilot circuit? If the PMS could talk, would it be saying, "Hey! I could use some more fuel here!" at certain times. As long as there is sufficient fuel because demand is not up, then the metering job of the PMS works as advertised...but, what happens when you over ride the potential of the 35 to flow fuel in the amount needed? Ideally, this is when the venturi starts to take over in the overlap, but it is also peak demand on the 35 pilot(yes...no?).

It just seems that a bit more potential, as long as its controlled by the PMS, is a good thing. As long as there is vacuum drawing fuel through the pilot, we might as well let the little dog eat

Okay, pick it apart!

I think what the guys said about normal occurrence fits me. The bike accelerates great. The gasp or blurp is seldom and only if I roll the throtle real quick.

Dang Peg! Somebody paying you by the word now that you hit the big 1K, or is that the free beer talking?

I hear what you are saying. If the pilot is slightly enlarged, it can help keep the PMS from being relied on as the adjustment point for filling in so many gaps. We tend to do that because it is the easy button by nature, since we don't have to pull the carb.
For some reason, luck maybe, I have never had any off-idle or hard accelerating stumble or cough, but that might be that little bitty main jet I'm running!
Gotta get that thing swapped out. Now ya got me wondering if I shouldn't drop a 37.5 in while I'm tweaking yp with the 167.5 or 170 Mikuni main.
Dangit! I just got back from Mt. Washington, watching bikes rolling everywhere, with mine nowhere close , then this?
You guys are killing me!

I lowered my idel thinking it was too fast. Noticed same hesitation when leaving stop light. This slight 1 second hesitation about caused a guy to hit my rear end. Raised idle back up to what I would call normal and alkl is fine now. Bofish

jd750ace wrote:
Dang Peg! Somebody paying you by the word now that you hit the big 1K, or is that the free beer talking?

I hear what you are saying. If the pilot is slightly enlarged, it can help keep the PMS from being relied on as the adjustment point for filling in so many gaps. We tend to do that because it is the easy button by nature, since we don't have to pull the carb.
For some reason, luck maybe, I have never had any off-idle or hard accelerating stumble or cough, but that might be that little bitty main jet I'm running!
Gotta get that thing swapped out. Now ya got me wondering if I shouldn't drop a 37.5 in while I'm tweaking yp with the 167.5 or 170 Mikuni main.
Dangit! I just got back from Mt. Washington, watching bikes rolling everywhere, with mine nowhere close , then this?
You guys are killing me!


Free beer??? This is just something I've been pondering. Some people get by with the 35, and others are running a 37.5, and or a 40 and are quite happy. When Tarcon started this thread I had already been thinking on it, and when Fireman spoke up, I figure what the heck! This is the "Technical Discussions" page after all

It's not so much relying on the PMS, as it is relying on the pilot being able to supply enough fuel to the pilot circuit. The PMS needs enough fuel to regulate, as the carb gets to the overlap, where the carb is combining and or converting to venturi from vacuum.
When your rolling down the road, this is a smooth transition. It's those times when your moving quickly from the vacuum to the venturi, that it'd make the biggest difference. Fumbling with a shift on a corner, starting off from a light in traffic etc., where you are on and off the throttle quickly.
The PMS limits the fuel(the nozzle on the end of the hose), but if there isn't enough fuel there, because demand over rides the pilots(the hose) ability to provide, and the venturi isn't drawing properly yet, then the pilot circuit is slightly lean.

Speculation....

With a borderline pilot to help accommodate and or satisfy EPA emission regs, and a bike that was probably tested with a rider who was 170 lbs soaking wet in his cloths(probably the biggest guy available ), and a newly designed motor and model coming on line in 99, I think(this is an opinion) the pilot is at the edge of its ability to provide fuel for the PMS to limit at certain extremes.
Some peoples riding styles can either get by with, or exacerbate issues with the factory setup.
Also, when the 04's came out, granted there were more CC's, but the factory almost seems to have gone from one extreme to another. From slightly or borderline lean, to slightly rich. I'm pretty sure, that it is the 04's and later that seem to suffer more from SVS, and you very rarely ever hear of somebody using a main smaller then the 165 Mikuni. Top end performance with anything smaller then a 165 mikuni, suffers. I'm doing some carefree extrapolation regarding the pilot. Kind of a "if the main is at the edge, then what about the pilot".

I'm switching gears here...

I'm thinking seriously about moving my clip on the needle(in the main) to the 3rd groove, with an extra washer under the spacer(two silvers)(I'm in the 4th with one, now), to maximize the potential of the 37.5 pilot and see if it works out. With slightly more fuel available from the pilot in the overlap, I can probably get by with a bit less fuel from the main until I'm really wanting throttle. If the pilot is still providing enough fuel at 65, you wouldn't be rolling the throttle so far into the main at that point.


"bofish"... The 900rpm's needed to properly adjust the PMS, is fast. After I tweaked my PMS at 900, I backed the idle down to 700. It just starts to get a lope at that speed. To low of an idle, probably contributes alot to stumbles at lights etc..

Erbman, I rode my bike to work today and about 40 miles in to the way home I got in to a corner doing about 50 mph. Coming out of the turn, I went to accelerate and it sputtered. Right now the PMS is out 2 1/4 turns. Should I go out another 1/4 or in 1/4 turn? Unless I need to make a different adjustment?