XSessive tuning issues

[CodyLane]

Question for you wizards:

I'm attempting to get my 78 XS11 tuned properly. It's turning out to be a bit tricky. Basically the #1 and #3 cylinders run excessively rich on the low end no matter what I do. Even with the mixture screws turned all the way in it still runs rich. I'm using a colortune to tune it and I'm a bit puzzled by this.

Some important info:

I'm running pods and a kerker 4-1. The pilots are 45 and the mains are 210 amal style jets. I had put 145 Mikuni mains on but they were too rich. Currently I have the floats set at 1 1/8" to account for the extra length of the amal style jets. Also the mixture screws have been broken off and refiled.

Any ideas as to what would cause it to run rich on the two cylinders even with the mixture screws fully seated? Any help would be greatly appreciated.

[natemoen]

First off I would suggest putting the right style jets in so that you don't have to fight with those f'ed up bastard jets. Run it with what it was designed to run with. Is 145 was to rich the go down to 142.5. Makes no sense to run the wrong style jet.

[CodyLane]

Definitely part of the plan my friend. I'm a bit strapped for cash right now due to recently being laid off so I'm trying to just work with what I've got. I'll address the main jet issue in due time. Until then, I'll just adjust the float height to compensate. The main jets shouldn't be affecting the low though. From what I understand the pilots do the majority of the work up through about 3000-5000 rpm? Can't remember which.

[TopCatGr58]

Hey Cody,

I'm not familiar with AMAL jets, but setting the floats real high can cause fuel supply issues. The pilots do run first to about 3k, but they feed off/thru the mains, and if the fuel level is too low, it can affect the ability of the carbs to flow and atomize the fuel properly, not enough vacuum to be able to draw the fuel up properly,etc!

Also, you said PODS, what type, brand, style. The cheap Emgo ones are known to cause problems with the intake ports due to the large lip on the inside mounting portion!

Also, are you sure you have OEM pilots, and were they properly cleaned to ensure that the side aeration ports were open? Same for the main jet emulsion tubes/jet needles!

Have you eliminated any/all vacuum leaks, intake boots, intake boot synch caps, etc.?!

T.C.

[petejw]

Definitely part of the plan my friend. I'm a bit strapped for cash right now due to recently being laid off so I'm trying to just work with what I've got. I'll address the main jet issue in due time. Until then, I'll just adjust the float height to compensate. The main jets shouldn't be affecting the low though. From what I understand the pilots do the majority of the work up through about 3000-5000 rpm? Can't remember which.

dont go changing float levels to compensate for incorrect jetting,
thatl cause so much more hassles, ull be chasing ur tail.
dont know what amal jets are, but as the others have stated
go back to stock jetting and start from there, if ur low on cash
see if u can get sum 2nd hand ones from a fellow member.
the pilots work right thru the rev range but work more so from idle
to around 3000rpm.
if uve got broken tips on the mixture screws and filed them, ull never
get them to run right, ur better of replacing those as well.

also if u havent synced the carbs it could show up as running rich
on those cylinders, so try syncing the carbs as well.

[CodyLane]

Well thanks for all the tips guys. I know it's a goofy setup but I've been running those Amal (large hex) jets for several years. They are what was originally in the bike. They look like this:


They're also about 1/8" longer than the jets that are supposed to be in the carbs. The only reason I'm continuing to run them is because the button style jets I bought (145) are too rich and these work better.

I'm still perplexed as to why I'm so rich on 1 and 3. Mostly 3. So rich on the low end that I actually am only able to get it to fire on #3 by having the air pilot jet removed.

I'll just have to go through and clean the hell out of everything. Mayhap the float valve isn't closing all the way and the bowls are overfilling. I dunno... It seems like for what I would end up paying for full rebuild kits that have the mixture screws, jets, and all that stuff... I could just invest that money towards a set of ZRX-12 carbs and be better off.

I drive this bike everyday. I don't even own a car. I've put about 35k on it since I bought it about 3 years ago. This poor bike sure takes a beating.