off idle - too rich or too lean?

[psycoreefer]

K&L carb controversy renewed...

Well I looked for leaks and check my synch today when I got home.
Synch was off by just a touch between the two banks. Just thinking about turning the adjust screw was almost enough to bring it back.
No vacuum leaks found.
Still fell flat with any kind of throttle input.

Decided to remove the carbs yet again and go through the idle circuits with a fine tooth comb. Compared old parts to new again and found this:




Click here for the full size

The jet on the right is the new K&L idle jet, the jet on the left is the original idle jet. Now I can clearly see that the hole in the original jet is larger then the new jet. Both are stamped 42.5. I can only assume that the K&L jets are not right. I've ordered a set of genuine Mikuni jets and I'll see if that fixes the off idle problems, but they won't be in until Thursday. I really suspect now that my problems have been caused by a way to lean condition because the K&L jets are so much smaller then the Mikuni ones.

Randy:
I suspected that I might need larger mains and I in fact have a set of 140 mains. I tried the 140's and they really stole my mid range but that was with the leaky old emulsion tubes. I intend to try them again with the new tubes once I get the bike ridable. As it is now I consider it un-ridable because taking off is so slow and difficult. You also have the free-er flowing air filter where mine is stock.

[ross]

hey there neighbor....

hey there psycoreefer....if ya need, i got the colortune kit.....it is not the fix all tool, but it along with a good set of ears and it sounds like that it would fix your problems....schmeerman helped me get mine straightened out and i bought the kit....busy this weekend, but drop me a line and let me know what i can do for ya.....talk 2 ya later.....ross

[TopCatGr58]

Hey Psycho,

It's not so much the hole size that you see in the END of the jet as is the location of that hole....see below borrowed from MikesXS site. The K&L pilot jets are the wrong style, the VM style, vs. ours/mikunis that are the BS style!!


But, yes, sounds like you're on the right track, getting the OEM mikunis, and putting the 140 mains in will probably help as well. Having the Pilot screws out almost 3-4 turns would normally indicate too lean a jet, but you'll probably want to reset to the 1-1/2 setting with the new pilot jets, and then adjust to desired response.

But, I still think that many folks are trying to ride these machines at TOO LOW an rpm. They are not Harleys, and even though they have the power and torque, they are higher revving engines and don't like to run below 2k, especially in any gear other than 1st.....JMHO!!!!
T.C.

[psycoreefer]

TC, I've got the right style, the BS30/96 style and on those the hole that meters the gas is right at the tip. On the K&L jets the hole is much smaller then the ones I took out. I'm not going to say for sure that the K&L is wrong, just that its different. When I get the Mikuni jets and can compare those to the K&L then I'll pass judgment. For all I know the old jets were drilled out by the PO.

[psycoreefer]

OK, well I got in the 42.5 mikuni jets I ordered and they are the same as the K&L's so no problems there. I looks like the PO drilled out the old jets.

I went up and found a local shop that had some 47.5's in stock. I was looking for 45's because I don't think I should need to go 2 sizes up, but they didn't have 45's, so I got the 47.5's. Put them in and it's better but still not right.

I guess I'm going to try and get some 50's and see what those do. Any ideas why I'd need to go up so far on the pilot jets. Any ideas what could be making it so lean at or just off idle?

[81xsproject]

Your on the wrong track. You shouldn't need anything bigger than stock pilots. Put your new Mikuni 42.5's in and start looking down a different path. There is no way with a 4-2 exhaust that you need larger pilots than stock.

[oseaghdha]

Psyco,
What are the chances that DrillBoy had a go on the air jets?
Obviously, drilling the idle jets was an attempt to cure something else.

[psycoreefer]

I didn't think so but I don't know what "other path" to go down. Do you have any suggestions? I feel like I've checked and double checked everything I can think of. I can't think of any reason that it would be "lean" at idle besides the carbs being off. I suppose its possible that one of the PO's put in a big bore or some thing, would that require larger idle jets? It does seem to have high compression for 40 some thousand miles. 160lbs all the way across.

Whatever it is it's something thats been wrong/different with the bike for a while because someone drilled out the stock 42.5's to something between 47.5 and 50.

any gurus in michigan?

[Winterhawk]

Throw the K@L pilot jets in the trash, they are wrong.

Use only OEM style pilot jets.

I think the needle jets come into play before the jet needles and the mains?

[petejw]

have a look at the needle jet and compare
the top half diameter of the needle to the old ones,

ive done a bit of reading of late, the top part of that needle
b4 the taper affects off idle to quarter throttle.

u could try also rev it to the place it starts to break down and give it a little choke, if its lean will pick up a little if rich will run worse.

mite help

[psycoreefer]

Current setup:
Stock 5GZ6 needles
NOS 266 - X2 Needle Jets
new K&L 137.5 Mains
Genuine Mikuni 147.5 idle jets
new K&L 180 Idle air jets

The original needle jets were replaced with NOS ones because I could see physical damage to 2 of the originals.

I'm using the original needles because the ones that came with the K&L kit were longer and different taper then original.

The K&L idle and main jets look identical to the original mikuni jets so I don't think thats the problem. I may order some original mikuni jets just to rule it out but I've not got much hope that thats the case.


oseaghda - I've got new idle air jets. It doesn't look like the old air jets were drilled, I may order some mikuni jets just to be sure but it will be about a week before I can try that out.

Winterhawk - I've read all about the K&L controversy but try as i might I can't seem to find anything wrong with there jets. They look and as far as I can tell function exactly as stock.

Pete - I'm using original needles, although they have 40k+ on them. I'll give the choke trick a try today and report back.

thanks and Keep the ideas coming...

[Winterhawk]

Maybe it was the K+L mains that are sized wrong. I've been away for a little while in Hog Heaven...LOL

pysically look at the K+L's mains verse the OEM and I bet the K+L's are larger?

Can't remember which ones are wrong out of the 2.

[DavesXS]

My 2 cents

I have read the thread all the way through.
You have a stock air box and 4-2 pipes. So your carbs NEED to be completely stock. If the PO installed a large bore carb or did any mods what so ever to the carb then I'd replace the whole set. In order to need any carb mods you first must increase air flow in(change box to filters). And air flow velocity out(4-1 headers).

Apparently the PO didn't have a clue and went modding things the wrong way. Since you've noticed what seems to be faulty mods, theres no telling what he's done to ruin these carbs. Buy another set, or put back all the factory jets, toss the K&L's. Even if you cann't "see" a differance. The fact there not mic's means there wrong for your set up.
Or buy filters and headers, cross fingers and hope that does it?
Start fresh, new carbs. Problem then solved, back to riding

[DavesXS]

How about your carb boots? Have you tried spraying carb cleaner at them while running to see if the idle changes? Have you removed them?

[psycoreefer]

I don't think the carbs have been modified, at least not visably. A friend suggested I check the "length" of the slide springs as the PO may have shortened them and I suppose that could be causing a problem and It is something I haven't checked. I'll be ordering new Mikuni idle air jets and mains on monday, just to rule that out.

When I said big bore I meant the engine not the carbs. I suppose if that had been done it would probably have been mentioned.

Dave - I have checked the boots several times for leaks, with "starting fluid" and with an unlit torch and never found any leaks. I have been watching for a new set of carbs but they always seem to go for 100+ on the bay and I don't want to spend that kind of cash on something that doesn't look bad to me. If I get down to the point of having nothing else to check (after I replace the jets) I suppose I'll be forced to pick up a set just to check.

Thanks everyone