1982 1100g stock ignition rev limiter?

[prsiler]

I got a 1982 Gs1100G recently. I've been working on it and getting it up and running. It came with a 4 into 1 header and individual air cleaners on it and no stock air box. I've been working with the main jet's trying to get them in the ball park. When I try and make a pull from about 6 or 7 grand up at about 7 grand it act's like I'm hitting a rev limiter. I've gone up and down main jet sizes one size at a time from as small as 115's up to 142.5's. I'm not seeing a difference above 7 grand with the jet changes. Below 7 grand it I see changes but not above. Because I've made so many jet changes over a wide range with out much difference I'm going to check the ignition over carefully. Another factor is I don't trust the tach. It is slow to get back to idle and doesn't respond as quick as I think it should. So I'm curious if anyone knows if the stock ignition has a rev limiter? If it does what might be happening is My tach is lying to me and I'm hitting the rev limiter not jetting issues. I have chased what I thought were jetting issues before on different bikes and it turned out it was problems with coils and plug wires. I'm curious if anyone has any thoughts.

 

[Steve]

There is no rev limiter.

One thing to check is where your pods meet up with the carb intakes. Some of them have been known to block the ports at the 8 o'clock and 4 o'clock positions, which will affect how the engine runs.

Main jets are important, but are not the only thing you will need to be changing. Depending on the header (and muffler) that you have, I would expect something in the 130-145 range for main jets. Your needle circuit should also be richened up a bit. At least lift the needle a bit, but you might need to change the needles, too. The pilot jetting should not need to be changed, as there is no additional air flow at idle and low-throttle settings.

Have you verified proper fuel levels? Not just the float height, but the actual fuel level, with the carb mounted on the bike.

Have you cleaned the carbs and replaced the o-rings in the carbs and the intake tubes?

Have you checked valve clearances?

Have you verified ignition output and clean spark plugs?

.

 

[Nessism]

Dynojet jetting kits come with the appropriate jets and more importantly needles to run properly with pod filters. They also recommend opening up the vacuum port hole in the slide. Well worth the money to do the job properly. And speaking of that, real K&N pods are vastly superior to the cheap junko emgo fakes. APE makes some decent clones if money is tight.

 

[prsiler]

I'm using a Dynojet kit and I drilled the holes in the slides to the size they call for. The pod filters are not K&N's but I made sure they are not necked down and covering any of the inlet of the carbs. It has good plugs. I have not checked the valves yet but that is on the list. I have not used clear tubing and checked the running float levels. Mainly I was curious about the rev limiter. I didn't think it had one and now I know that's not a possibility.

 

[Buffalo Bill]

Maybe your engine needs internal work? Lifter shims, cam timing, valve job & new valve springs, piston rings.
My own1100G revs beyond 7000, but the mechanical tach goes crazy, can't handle rpms above 6000.
In fact the cable just failed last September, so I'm working on a digital tach install. That project is waiting in line behind another.

 

[Rob S.]

As far as I know, no factory rev limiters on the big bore fours.

My '83 style tach clock revs right to the 9k redline, with nary a cough or stutter anywhere from idle to redline. It revs quick up or down, and the needle follows closely.


If It's really important for you to get it perfect find a guy with a reputation and a dynamometer

And the APE pods seem to be just as good (and good looking) as the K&Ns.

 

[prsiler]

Thanks for all the replies. I wondered about the rev limiter because it runs so good up to that point. Everyone that said it is correct, I need to check the valve clearances, I need to do a compression test and I need to check the running fuel level. I bought this bike thinking it would be a parts bike but then I started messing with it and it's too much fun to dismantle. Right now I've replaced a couple missing body panels and I'm figuring out what needs to be fixed, fixing it and when I get it all lined out it's going to come back apart. I'm going to paint the body work at that time and pull the engine and do any work to it at that point. It seeps oil in a couple of the usual places so it needs some gaskets at the very least.
Has anyone else noticed that they are needing to run bigger main jets due to the alcohol in the fuel? If I recall correctly 15% alcohol might need a 5% increase in main jet. I honestly think that if it's set up for it you can take advantage of the alcohol in the fuel. I'm sure that statement will be controversial. I built my 79 gs850 last year and ended up with bigger mains than I thought it would. It's got a new top ended, Dynatek ignition, coils and wires, 4 into 1 and pod filters. Right now I've got the timing set at factory spec but I'm curious if you couldn't advance it just a smidge because of the alcohol. Also with an air cooled engine the cooling effect of the alcohol might be good. These are just idea's not statements of fact, I'm just thinking out loud.

 

[Nessism]

You shouldn't have to changes jets to compensate for alcohol in the fuel. The most noticeable alcohol-fuel issue most people face is the tendency to gum up the system if the vehicle is parked for months at a time. This obviously won't affect a daily driver, but if you have a large collection of bikes and some sit a lot it can be a real issue.

 

[prsiler]

No offense, but yes alcohol does change jetting and to get the best performance you do need to change your jetting. It might not hurt things if you don't but it's worth checking. The stoichiometric ratio is different for alcohol than gas. As you can see by the chart just 15% alcohol drops the ideal ratio a percentage point.

Fuel	Stoichiometric AFR
Pure Gasoline	14.7:1
10% Ethanol Gas	14.04:1
15% Ethanol Gas	13.79:1
E85	9.75:1
Pure Ethanol	9:1

Yes, if you don't ride your bike much or store it you should put an additive in the tank, even if it's no alcohol gas.

 

[Nessism]

No offense, but yes alcohol does change jetting and to get the best performance you do need to change your jetting. It might not hurt things if you don't but it's worth checking. The stoichiometric ratio is different for alcohol than gas. As you can see by the chart just 15% alcohol drops the ideal ratio a percentage point.

Fuel	Stoichiometric AFR
Pure Gasoline	14.7:1
10% Ethanol Gas	14.04:1
15% Ethanol Gas	13.79:1
E85	9.75:1
Pure Ethanol	9:1

Yes, if you don't ride your bike much or store it you should put an additive in the tank, even if it's no alcohol gas.

E10 is the overwhelming favorite formula. E15 is generally limited to some midwest states where there is a lot of corn grown. Put E10 in a Suzuki GS and it will run just fine. No need to worry about jetting changes and in fact, in all my years here I've never heard of even one person changing jetting because there is ethanol in the fuel. What is a common discussion here though is carbs getting gummed up, which happens far more frequently with the E10 formula.

 

[Steve]

Thanks for the numbers. :encouragement:

I have known that alcohol would probably require some richer jetting, but had no idea how much, or if it would be worth investigating.

My jetting has changed due to an aftermarket exhaust system, but it hasn't changed very much. I don't remember right now whether I have 117.5 or 120 mains in my carbs, but 115 is stock. Whatever I have, I am going to be leaning it out one size in an effort to fine-tune. My bike starts easily and runs well, I am now trying to improve the fuel economy a bit without leaning it too far.

Virtually all of the jetting questions and reports on the forum have come from riders that have installed aftermarket systems in the intake and/or exhaust. I can't remember ANY questions about jetting that were based on pure gas (E0) vs. E10, and very few that have stock bikes have reported differences in the way the bike ran on E0 vs. E10. We don't have E0 available in my area, but I have tried it in other places where I have ridden. I can not tell any difference in performance or fuel economy. As Ed mentioned, the biggest difference is what happens in storage.

.

 

[Rob S.]

BTW - what you call "weeping oil" we call "sweating horsepower". A newspaper on the floor solves it.

 

[bwringer]

Not to veer away from the original question, but a carbureted air-cooled motorcycle on the street should not be running anywhere near stoichiometric AFRs, and E10 makes not the slightest difference in power or running characteristics.

If you're running a race bike on a dyno all day with an AFR sniffer up the tail pipe, you can creep up on stoichiometric, but you'll still tune a little richer to keep reasonable ridability and exhaust temps, especially with an air-cooled engine.


Anyhoo, no, there's no rev limiter on a GS. You have some other issue.

It's also quite possible to have an electrical issue that's causing the ignition to get all confused at higher RPM. Lots of possibilities here; I've seen things like bad connections that get intermittent under vibration, or interference from the stator wiring.

Another possibility is a bad tach. These are not the most reliable units. Then again, you're sort of running into a wall, so I doubt it's the tach; a GS will happily pull well beyond redline, not that it's a recommended practice.

 

[londonboards]

I would take it to a mechanic who can rig up a test wire on the HT lead to analyse the correct rpm figure. That way you know for sure that what you are measuring in correct. (remember it's a wasted spark system so it fires every 360 deg)

To measure is to know - but you need an accurate measuring device to start with.