Jetting an 1100

[earlfor]

I finally got the 83 1100E back together and running. It has a bore kit in it and I am told it is 1197cc. Engine is fine, carbs rebuilt, idle circuits and midrange are about pefect. I have a stock airbox and filter on it with a NOS 4 into 2 exhaust system (the factory one) There are no visable numbers (with a bright light and magnifying glass) on the main jets. The bike at aprox 75 mph is running out of fuel on all four carbs when I twist the throtle farther. The plugs at that point are burning way too clean with only the slightest hint of a whiff of tan on the center ceramic. I am sure the mains are not large enough to meet demand. Also, upon shut down, the bike will crackle lightly for a minute.........to much heat. Anyone know, or running a 1197 kit with stock exhaust and intake......what the appropriate main jet size is? Considering the degree of lean I have, I'm thinking I need at least 2 full steps in jet size.

Earl

 

[Jethro]

Suprised it still has a bore kit and still has the stock airbox and pipe. My jetting won't be anywhere close to yours, not to mention it still isn't right.

 

[Anonymous]

Won't be much help, but with 1148 pistons, stock air box with lid removed, and V & H pipe, 127.5 worked real well. Never seen jets with no markings. ????????????

 

[KEITH KRAUSE]

I know you Earl, and I have to assume everything else has been considered that could cause fuel starvation. Failing petcock, small fuel line, tank venting, floatbowl venting, float level...
75 mph in top gear is still under 1/4 throttle, correct? If the starvation happens as soon as the throttle is opened slightly more, then it could be the needle circuit. We all know the main doesn't really regulate flow until about 3/4 throttle. Of course, if the unmarked mains are WAY too small, I suppose they could be the cause.
If it is the mains, I think your idea of two full sizes up is a good starting point. Adjusting the float levels to the richest setting within their "range" can help with a piston kit.

 

[RacingJake]

I'd start at 140 (Mikuni) and work my way up. Heck at 1197 I might even go with 150's first.

 

[earlfor]

Gonna intersperse replies with your comments............. easier that way.

I know you Earl, and I have to assume everything else has been considered that could cause fuel starvation. Failing petcock, small fuel line, tank venting, floatbowl venting, float level...
**************** Yeah, you can count on that. heh Short vents on the bowls, etc. Float levels set at high fuel level spec. I havent hooked clear tubes to the bowl drains to visually check actual level. I guess I should do that to verify settings before making jetting changes.




75 mph in top gear is still under 1/4 throttle, correct?
**********At most, it is about 1/4 throttle.



If the starvation happens as soon as the throttle is opened slightly more, then it could be the needle circuit. We all know the main doesn't really regulate flow until about 3/4 throttle. Of course, if the unmarked mains are WAY too small, I suppose they could be the cause.
******************** I am thinking larger mains would result in a larger area around the partially withdrawn needles resulting in more fuel flow. Considering the relationship of the needles moving up and the resultant increase in jet throughflow area, I'm inclined to think raising the needles is not a solution.




If it is the mains, I think your idea of two full sizes up is a good starting point. Adjusting the float levels to the richest setting within their "range" can help with a piston kit.

*********** When I got the bike, it had no lid on the airbox and no airfilter, it was just an open box. The exhaust was a 4 into 1 drag header with a VW car muffler U bolted to the header. I dont know how well/ if, the bike ran like that. I replaced/installed the correct lid on the airbox with the stock filter element. I had on my parts shelf, a NOS factory 4 into 2 exhaust system for an 1100, so that is what is on the bike and why I have a big bore engine with stock intake and exhaust. LOL I'm not after top end HP. I tune for crisp, smooth throttle response and good midrange. I dont like excessive noise either.

My Clymer doesnt list (that I can find anyway) the stock jet sizes and there are no discernable markings on the jets installed. The surfaces are clean, there just isnt any number on them. I need to go a couple sizes bigger than what I have, but a couple sizes bigger than what?

I think Luke's/Skip's 1150 is 1229 cc with pods and four into one. I belive Luke is runnig 135 mains. Considering my stock intake and exhaust, and slightly less displacement, I dont see needing mains larger than 135. I run 122.5 across the board in my 1150.

What is the stock jet size for an 83 1100E? I'm guessing it has to be at least 115.

Is there anyplace I can get decimal equivalents for mikuni jet sizes?

Earl

 

[Mr. Jiggles]

I don't know if there were any stock jetting changes from '82 to '83 but on my '82 1100e the stock jets were Mikuni 115.

Jeff

 

[kz]

On the -84 it's 120 f?r all carbs (like Sweden) , some markets 120 carb #1 and 4 122,5 f?r carb #2 and 3.

but you probably know that already.......

 

[earlfor]

In considering everyone's replies, my best guess is to start with 130's. From there, if I have to make a change, I'm inclined to think it would be to 127.5 or 132.5.

Earl

 

[kz]

In considering everyone's replies, my best guess is to start with 130's. From there, if I have to make a change, I'm inclined to think it would be to 127.5 or 132.5.

Earl

I drove my 1150 with V&H Megaphone, 1 K&N filter and no lock on the air-cleaner with 130, so i think not you are to rich with 130.

Give it a try.

 

[Joe Nardy]

Gonna intersperse replies with your comments............. easier that way.
*********** When I got the bike, it had no lid on the airbox and no airfilter, it was just an open box. The exhaust was a 4 into 1 drag header with a VW car muffler U bolted to the header. I dont know how well/ if, the bike ran like that. I replaced/installed the correct lid on the airbox with the stock filter element. I had on my parts shelf, a NOS factory 2 into one exhaust system for an 1100, so that is what is on the bike and why I have a big bore engine with stock intake and exhaust. LOL I'm not after top end HP. I tune for crisp, smooth throttle response and good midrange. I dont like excessive noise either.

My Clymer doesnt list (that I can find anyway) the stock jet sizes and there are no discernable markings on the jets installed. The surfaces are clean, there just isnt any number on them. I need to go a couple sizes bigger than what I have, but a couple sizes bigger than what?

I think Luke's/Skip's 1150 is 1229 cc with pods and four into one. I belive Luke is runnig 135 mains. Considering my stock intake and exhaust, and slightly less displacement, I dont see needing mains larger than 135. I run 122.5 across the board in my 1150.

What is the stock jet size for an 83 1100E? I'm guessing it has to be at least 115.

Is there anyplace I can get decimal equivalents for mikuni jet sizes?

Earl

Earl,

I'm confused (not that unusual). You have a NOS Factory 2 into one exhaust on your inline 4 cylinder? I'm guessing you mean 4 into 2 into 1.

I checked my factory manual and the stock jet sizes are:

Main jet: 112.5
Pilot jet: 45

By the way, has anyone ever told you that PODs make removing and installing the carbs much easier? HAHAHAHAHAHAHA!

Joe

 

[earlfor]

I tell ya, you just cant get away with anything around here. LOL I meant 4 into 2. I have personal moments of loss of ignition.

As far as PODs go, having nothing would be even easier. LOL although they make removal easier, once set up, its rare that I need to remove the carbs. They also do not lend themselves well to the engine characteristics I prefer. I prefer a more tractible throttle, lower noise levels, better mid range and better gas milage. I am certain the bike will pass 150 mph no matter how I set up the intake and exhaust and that is enough, at least for me on city streets.

Earl

I'm confused (not that unusual). You have a NOS Factory 2 into one exhaust on your inline 4 cylinder? I'm guessing you mean 4 into 2 into 1.

I checked my factory manual and the stock jet sizes are:

Main jet: 112.5
Pilot jet: 45

By the way, has anyone ever told you that PODs make removing and installing the carbs much easier? HAHAHAHAHAHAHA!

Joe

 

[KEITH KRAUSE]

Gonna intersperse replies with your comments............. easier that way.

If the starvation happens as soon as the throttle is opened slightly more, then it could be the needle circuit. We all know the main doesn't really regulate flow until about 3/4 throttle. Of course, if the unmarked mains are WAY too small, I suppose they could be the cause.
******************** I am thinking larger mains would result in a larger area around the partially withdrawn needles resulting in more fuel flow. Considering the relationship of the needles moving up and the resultant increase in jet throughflow area, I'm inclined to think raising the needles is not a solution.

A larger main won't increase the flow at 1/4 throttle. When the needle is rising up until 3/4 throttle, the space around the needle will still be smaller than the main, so the needle is still doing most of the work. Of course, if you have a very small main involved, the main would kick in a little sooner.
If you're really wondering what size the mains are, you could rig up a flow test into a marked container and compare with known jets. Hook up a fuel line clamped to the jet and see how much fuel flows in a minute. One of your spare jets may yield the same amount.

 

[earlfor]

Fuel starvation is not immediate, it accelerates well for about 3 seconds after more power starts coming on, then it acts exactly like I turned the petcock off and all four run out of fuel. No cough, no miss, just abruptly decreasing power.

I wish you would quit teasing me because Y'know, everytime you wave a carrot at me...........................

You said...................."A larger main won't increase the flow at 1/4 throttle. When the needle is rising up until 3/4 throttle, the space around the needle will still be smaller than the main, so the needle is still doing most of the work. Of course, if you have a very small main involved, the main would kick in a little sooner. "

Uhhh, lets talk about that. A larger main leaves more space around the needle as it raises. At 1/4 throttle the needle has moved up slightly, so a larger jet is going to allow more fuel throughout the range of needle movement. I know some approach the situation working from low end to high end when setting up carburetors, but my instinct is to size the main first, then adjust the needle for midrange, and finally to set up the pilots.

Earl

If the starvation happens as soon as the throttle is opened slightly more, then it could be the needle circuit. We all know the main doesn't really regulate flow until about 3/4 throttle. Of course, if the unmarked mains are WAY too small, I suppose they could be the cause.
******************** I am thinking larger mains would result in a larger area around the partially withdrawn needles resulting in more fuel flow. Considering the relationship of the needles moving up and the resultant increase in jet throughflow area, I'm inclined to think raising the needles is not a solution.

A larger main won't increase the flow at 1/4 throttle. When the needle is rising up until 3/4 throttle, the space around the needle will still be smaller than the main, so the needle is still doing most of the work. Of course, if you have a very small main involved, the main would kick in a little sooner.

 

[KEITH KRAUSE]

I can understand why you think a larger main will help in this case, but the carbs are just not designed that way. Any jetting chart or Mikuni info will show us that. Only if the mains have been switched to a too small main would your idea make sense.
The smallest opening in the main/jet needle/needle jet passage will regulate the flow. At 1/4 throttle (your problem point) to 3/4 throttle, the opening around the jet needle is still smaller than the main opening. At about 3/4 throttle, the opening around the needle becomes larger than the main and the main takes over.
If your problem is at approximately 1/4 throttle and a bit more as you say, then the needle circuit is causing the problem. I swear Earl. I wouldn't mess with ya'! Check any jetting chart or Suzuki carb info and it will tell you the same thing.
I would definitely suspect the mains in your case but only because they're unmarked. A bore kit will effect the mid-range a lot.

 

[earlfor]

I think I will see if I can match up the jet diameter with something I already have that is marked. The largest jet I have on hand is a 125, so if what is in the bike is bigger than that, I probably have a needle problem. If its much smaller than that, I'll expect a jet and needle problem.

The bike is pretty quick now even without proper fuel flow and will likely do a 50 mph, roll on wheelie. I may scare myself when its really right.

Earl
P.S. You know you would mess with me anytime you thought you could get away with it. LOL

I swear Earl. I wouldn't mess with ya'! Check any jetting chart or Suzuki carb info and it will tell you the same thing.
I would definitely suspect the mains in your case but only because they're unmarked. A bore kit will effect the mid-range a lot.

 

[earlfor]

This just occured to me. Some may find it interesting. I took some know values and played with my calculator. This is main jetting for stock bikes with stock pipes and airbox with the exception of Lukes 1229.

Luke 1229cc mainjet 135 ..............1229/135=9.10

Earl 1150E mainjet 120 ..............1150/120=9.58

stock 1100E mainjet 115 ...............1100/115=9.56


Taking that indexing and applying it to my 1197 .............

1197/9.58= 124.94
1197/9.56=125.2
1197/9.10=131.5

Knowing Luke is racing a bit and probably more to the rich side and knowing that stock suzuki has traditionally been to the lean side, I estimate the optimum jet size as midway between those numbers.

That would be 128.22 so, 127.5 or 130 should work well.

This also coincides with rphilipps post, which was..................
quote...
Won't be much help, but with 1148 pistons, stock air box with lid removed, and V & H pipe, 127.5 worked real well....unquote.

and

agrees with Karl Z on the use of 130 jets.

Earl

P.S. If this works out OK, then Keith and I can continue our needle debate.

 

[KEITH KRAUSE]

Debate? :? What debate? I see you're not convinced, which is OK.
I wouldn't give out bad info Earl unless there was an honest mistake or someone wasn't accurately describing their problem. If a larger main jet does cure your problem, it's only because those unmarked mains are unusually small. At the throttle position you describe when the problem hits, the bike is solidly on the jet needle. You may need larger mains, but you need to raise the needle too.
I still think you can rig up a timed flow test and figure out what your mystery mains are.

 

[earlfor]

I'm only messing with you Keith. I know you dont give out bad info.
I suspect the mains are undersize and either way, I expect I will need to raise the needles. If I find the mains are way undersize, raising the needles may not be necessary. I take books such as Clymer, etc. as a starting point and general appraisal of the situation. They point in the right direction, but are not always accurate for every situation.
The great thing about this forum is the information and feedback. I now know what jets some have found to work with various displacements and set up. Combining the various viewpoints allows me to make a more accurate decision of how best to solve the problem. Instead of doing this a dozen times searching for the right combination, I think I will get it right in one try. 130 mains and raise the needle one notch. At worst, I will have to do it twice if I need to go two on the needles.

Just a little side into............. I found that for mikuni round main jets as used in CV carbs. the jet sizes are described as percentages of 1 millimeter. So, a #35 jet is .35 mm. A #100 jet is 1 mm. A #130 jet is
1.3 mm. (1mm= .0395 inches) (a #200 jet would give 4 times the flow of a #100 jet)

For VM carbs which use the hex jets, the size designates % of flow, not the diameter of the opening. So, a #200 jet is twice the flow or area of a #100 jet.

Therefore, if someone is asking about jet sizes because they have changed their exhaust to a 4 into 1 and intake to pods, it is necessary to know if they have CV or VM carbs. The two types of jets do not use the same indexing system.

Earl

Debate? :? What debate? I see you're not convinced, which is OK.
I wouldn't give out bad info Earl unless there was an honest mistake or someone wasn't accurately describing their problem. If a larger main jet does cure your problem, it's only because those unmarked mains are unusually small. At the throttle position you describe when the problem hits, the bike is solidly on the jet needle. You may need larger mains, but you need to raise the needle too.
I still think you can rig up a timed flow test and figure out what your mystery mains are.

 

[earlfor]

Well, I got the 1100 out for a long test run and the plugs are burning a nice medium brown, oil temp has come down and the bike no longer expansion/heat crackles after shutdown. The combination of #130 mains and
and raising the needles 3mm seems to be about right. Gas milage is about 40 mpg which is probably decent for an 1197cc kit.

Thanks all, I really appreciate the help.

Earl