carbs running rich rejet or drop needles?

[mrbsyammy]

I just bought a 79 1100 special that sat for 6 years. So it needed all the usual stuff, got it running. runs great till you hit 5000 RPM and chokes out (running too rich) so I took the mains out which were 140 and put stock back in and still does the same thing, unless you take the air cleaner element out then it runs great all the way to redline, which it also did the same with the 140 in it. The air cleaner that was in it was pretty much gone so it was getting more air then it would have with a good air cleaner in it, so this is why the previous owner said it ran fine when it was running the last time which was 6 years ago. So do I drop the needles or rejet it? it has the old RC 4 into one headers on it. HELP HELP!!! GREAT SITE ..YOU CAN EMAIL BACK AT 70rtse@milwpc.com or leave a message here...Thanks Mr.Bill

[TopCatGr58]

Hey Mr. Bill,

What you said about the filter doesn't quite make sense, saying that the old filter was "gone", but that it was getting ?MORE? air with it "in" instead of when it was removed?

Your symptoms like you said sounds like richness, but more like CHOKING down, not being able to breath as it needs, which a dirty CLOGGED filter will cause. When you take it out, it's able to breath properly, and performs as it should with both the OEM 137.5 jets as well as the slightly richer 140's.

Before you go changing jets or needle positions, you need to get a GOOD FILTER, and also ensure that the SNORKEL is free of debris, many things have been known to clog it, from sockets, to rats nests, etc., even being kinked between seat and frame!

After the new filter, then check performance and your plugs, and then report back if it's not behaving, but I would expect it to be good!!
T.C.

[mrbsyammy]

Thanks for your help...the filter is new and the plugs are black. the original filter which I never used was deteriated to the point that it would have let the air flow, .I asked the former owner how it ran when it ran and he said great that is where the deteriated filter comes into play, because I don't know how it would have ran good if the filter was good because It sure don't want to now.. so back to the problem?

[mrbsyammy]

I will back up here and let you know what I have done to the bike since I bought it. I completely removed the carbs completely taken apart cleaned in professional carb cleaner(in basket NAPA type cleaner) carefully set all settings and double checked everything, took tank off and cleaned it so it is free of all rust and varnish gas remnents, new UNI foam type air filter that I put a light spray of oil on it as recommended, cleaned plugs and checked on my oil furnace ignitor box to check there firing to make sure they were good removed air box and cleaned it, removed the octopus system, stared it up ran good till you drove it then it would just almost stop the minute you hit 5000 RPM so I went back home took out the air filter and tried it again and it ran perfect right to redline, so I thought that it had too big of mains in it so I put the stock ones in it and the bike does the same exact thing, if the fiter is in 5000 RPMs is it remove filter and it will hit red line with no problem, so everything is clean nothing has a mouse condo in it .. I am seriosly thinking it is the exhaust. 4into 1 RC exhaust if I could get the baffle out I bet it would run great but it doesn't seem to want to come out and I don't want to wreck the exhaust because it is good. I just sold a Honda CB 900 custom that I had the same problem with, I rejetted it a dozen times and could never get it right, the day before I sold it I took the baffle out of the exhaust and it ran perfect (same type situation) so !!! ??? HELP!!! The bike starts instantly and runs smooth till 5000 rpm then it is like you removed 3 plug wires. there is no doubt in my mind that it is running rich but how could it of ran right back 6 years ago and it won't now?? of course this is what I was told but I know the guy pretty good and I see no reason he would lie about it?? I hate working on carbs especially when its mine because they are the only ones I have problems with...so now you have the info so back to the drawing board.lol.lol

[mro]

You say it fires right up.
Do you need to pull the choke to get it started when it has sat for a few hours???


mro

[81xsproject]

check to make sure that your filters are not blocking the air jets where they mount on to the carbs.

[mrbsyammy]

single filter and its not blocking

[mrbsyammy]

yes I have to use the choke if it sat for a while

[DiverRay]

I would dump the UNI filter and get a K&N. I DO NOT like the foam type filters, and most of the XS1100s don't either. They will restrict airflow at higher RPMs, and that is what you are saying.
If it will rev without the filter, and stops at 5K WITH the filter installed, the filter is your problem. As you try different things, change ONLY ONE thing at a time. try the bike, if it does not help, go back to what you had, and then change the next item. IF you try to change too many things at once, you WILL get lost, and never find the cure.
JMHO
You may also want to drill a few 1/2" holes in the bottom of the air box. They go in the CENTER, as the XS1100 draws the air into the center of the airbox, through the air filter, and then into the engine. If you look at the "Tech Tips" on the left side, you should be able to find a diagram.
Ray

[mrbsyammy]

Thanks I couldn't find the item on drilling the hole in the air box but I just ordered a K-N filter and I hope you are right and it works but won't know till it gets here and if you could find that article on drilling the holes I would really appreciate it I looked and can not find it...Thanks again Mr.Bill

[DiverRay]

Mr. Bill;
Here is one reply on a different thread,

Personally i like the way my bike looks with the stock airbox...and i'm not afraid of the rain ..or washing my bike..i've got a k&n in stock airbox with four 1" holes underneath..i cut off most of the rubber inlet on top(about an inch behind the turn) it greatly simplifies removing or re-installing stock airbox..have kerker 4 into 1...i have 142.5 mains in carbs...i can pull throttle wide open in high gear at low r's (under 2grand) with no spitting or stuttering..pulls smooth up to about 3500 or so ..then pulls like a rocket to 8500 ..i don't make a habit of running it that way but when you can pull away smoothly like that you know your carbs are pretty well synced...i'll stick with my airbox stevo

The holes are drilled in the MIDDLE OF THE AIRBOX LOWER HALF. You will see a line that the air filter fits, and the dirty air is on the INSIDE of the XS11 filter. You don't really want to drill the entire area, just add a few holes to flow a little more air. The air picked up from the bottom is HOT off the engine. If you add too many holes, the inlet air is too warm, and power will suffer.
Ray

[mrbsyammy]

I am sticking with the original air box just going to K-N element which I don't think will make any differance but we will see as of tomorrow

[mrbsyammy]

K-N filter did not make any differance at all. If you remove the filter it also makes no differance ..If you remove the bottom of the air box it runs great. Ok , I originally removed the octopus and the lines that are the over flow, so I don't know what differance that makes but I have a strange feeling it makes a big differance. So I have rejeted it with no changes I have droped the needle which made no differances so I am going to put everything back to the way it was when I bought it including the octopus and I hope it is going to run correct if not?..I am going out now to find out what differance those overflow hoses make.. I will get back to you all and let you know ...cross your fingers.lol.lol

[mro]

Don't know if you've tried lowering float level???
Will help lean it out.


mro

[TopCatGr58]

Okay, reread the thread,

79SF, the octopus won't have any affect on how it behaves since it's already getting plenty of fuel. However, are you sure you have the hoses for the carbs setup right. The lower hoses and T's are the fuel supply hoses. The upper T's and hoses are the bowl vents, and are NOT to be blocked, just vented. They usually plug into the stock box on those nipples on the front of the box. I'm wondering IF the hoses, or the nipples are clogged. With the filter off, the bowls may be able to vent, but with the filter in and cover in place, they may not be breathing right!?!? You're sure the SNORKEL isn't getting pinched?? The air box is the key!!
T.C.