GS1100E performance

[headsbikesmopars]

When you block off part of the airbox with tape you are changing the flow rate of the airbox, how it was designed to flow air to the carbs. That creates turbulence in the airbox which will reduce flow. Turbulence is resistance to flow. That can create all kinds of fuel distribution problems. Why not just install some Mikuni jets above what you have tried and work down from there. Try the easy stuff first. Good luck and keep us posted.

Terry

 

[headsbikesmopars]

Get some real jets like Mikuni 140's then come back and post the speeding ticket for 140 mph plus :twistedevil:

The best mod I ever did was to get rid of the dyno jets and needle's cause they will have you chasing your tail trying to fix a lean condition. Stick with Mikuni jets, go big for big power.

What he said..

 

[rasndas]

Weather cooperated and I had a chace to do a plug chop on the current setup. Did test as follows. Rode out to my testing spot. Put in new plugs and then did a full throttle pass through all the gears. Power seemed to start to fall off above 7000 RPM. Pulled clutch killed engine and coasted to a stop. What is probably no surprise to anyone here but me is the plugs were pure white. No color at all. You guys are right; high speed lean condition. Need to get some richer jets. Not sure how I got wrapped up in thinking the Dynojets were too rich. Right now I have 112.5 Mikuni's. I'm thinking of ordering up a set of 120's and 125's to try. Sound right?

 

[rapidray]

That should get you closer. Ray.

 

[headsbikesmopars]

RASNDAS,
I have 125 mains in my '81 GS1100EX with a nice street head , '83 cams with stock pipes and airbox without lid and k&N filter , 34 CV's . Runs super.

 

[rasndas]

Thanks for the replies guy's. I ordered both sizes yesterday and hopefully they will be here this weekend. I was truly shocked at how white those plugs were after the plug chop. I will also check the petcock to make sure there is no restriction there. I enjoyed the post on the Wards machine. Thanks

 

[headsbikesmopars]

Rasndas, Good idea to always start rich and jet down because plugs are cheaper and a WHOLE lot easier to change than pistons. LOL. Yes you were WAY too lean I hope you didn't burn the pistons. If run very lean long enough it can burn pits in the domes of the pistons. You are probably good if you didn't run it long like that. ALWAYS start on the rich side when working out a new combo. Fouled plugs are an easy fix. Good luck and let us know how it is coming along.

Terry

 

[rasndas]

I have never run the bike hard much. Most of the time just crusing it down country roads so I hope you are right about the pistons. It has never given me any trouble at all so I'm thinking for the most part it's OK. Have no idea how the PO ran it. I am still amazed that the factory jetting is that lean. Hard to believe the V&H header would make all that much difference. I will keep you guy's appraised of what the jetting changes do.

 

[headsbikesmopars]

The GS's were on the lean side from the factory (EPA), and a good scavaging pipe will lean it out even more. If it was running ok then you are good I am sure. If you had any holes in your pistons you would know it by now. Ever see bikes that had aftermarket exhaust systems and the head pipes are very blue ? Blue is hot and that means the mix is too lean. I see this a whole lot with the V twin bikes. A goldish color is much better , richer is cooler. Chrome will turn blue when it gets too hot. Looks like you are on the right track with your project.

Terry

 

[rasndas]

Jets came in and I decided to try the rich ones first ( mikuni125). Power was greatly improved on the top end. I ran another plug chop and the plugs are still white. I am assuming with brand new plugs a full throttle 1/4 mile blast is enough to put some color in them. If this is the case it looks like I will have to go even richer. I really thought that 125s would be plenty.

 

[Flyboy]

Good to see you are on the right track, looks like you should have it sorted in no time.
There is real good advice and a wealth of knowledge here, from people who know their GS's in side out, all you have to do is take it

RacingJake

Get some real jets like Mikuni 140's then come back and post the speeding ticket for 140 mph plus

1166cc 1/8 ET 6.09@111.88
1166cc on NOS, 1/8 ET 5.70@122.85
1395cc 1/8 ET 6.0051@114.39
1395cc on NOS, 1/8 ET 5.71@113.98 "With a broken wrist pin too"
01 Sporty 1/8 ET 7.70@92.28, 1/4 ET 12.03@111.82

With those kind of credentials, I would take note when advise is given, don't mess around, just get a set of 140's

 

[rasndas]

Update on the jetting. My 135 mikunis finally came in and I installed them on sunday. Power seemed about the same as with the 125s maybe a little softer in the midrange. Plugs are still not showing much color however I noticed another issue that may answer my top speed issue. On one of the passes the speedo was only reaching about 95-100mph but I noticed the Tach was still climbing. I backed out at an indicated 7000 RPM. At home I checked the gearing and found it was not stock. 15 tooth counter and 40 tooth rear. Given the circumference of the tire (82 inches) the speed would have been 119MPH. I believe the bike is a little faster in 4th gear as I think I made 8500 RPM in that gear (123MPH). Anyway as it now stands I am running 135 mains, 47.5 pilots and the mixture screw 3 turns out from seated. I may experiment with the meedles some but overall it runs pretty good. My speedo works good up to about 70 but seems to develop some issues above that ( not a big problem because I rarely run it faster than that). Thanks for all your inputs.

 

[rasndas]

Just thought I would post one final update. The 135 jets seemed to really soften up the top end and not make as much power as the 125's did so I went back to the 125's. This is probably about right as the vance and hines website says 122.5 are what is required given the pipe and air cleaner configuration my bike has. One further item is I re-ran the compression test and this time made sure the throttle was wide open. with the throttle wide open compression was 160 PSIG across the board. With it closed or partially open 100 PSIG was all I could get. Thanks for all the help.

 

[posplayr]

With the 4:1 he is probably running lean and needs to increase the jetting. With pods and the 4:1 he should be at DJ 132-138

1100E standard 4:1 and k&N pods with Dyno jet kit is 132-138 which equates to 125-130 Mikuni (see the conversions). Unless you have 1150 carbs or cams you would be on the low side (read 125). The next issue is did you change to a slotted needle? Rapid Ray has them for sale.

 

[rasndas]

The bike has the factory air cleaner on it not POD's so the 125's are probably fine. V&H stated for a stock bike like mine with just the 4 to 1 header 122.5 was the recommendation. I have not looked at the needles to see if they have slots but do not have any issues at partial throttle it runs great.

 

[posplayr]

The bike has the factory air cleaner on it not POD's so the 125's are probably fine. V&H stated for a stock bike like mine with just the 4 to 1 header 122.5 was the recommendation. I have not looked at the needles to see if they have slots but do not have any issues at partial throttle it runs great.

I got that part from V&H but am giving you first hand experience with jetting a stock and K&N podded 4:1 GS1100ED, (I have one sitting in my back yard with DJ 132's and pods)but I guess all that matters is if you are happy with it.