About to pull out what little hair I have left

[Guest]

This bike. I would love to set it on fire.

Where in at right now:

Air filter and air cleaner box lid were gone when I got the bike. Filter was replaced with a 4" round paper element. Original was a foam element.

Stock jetting was 42.5 pilot 110 main. Bike would idle great, but surge and hunt at steady state low throttle cruise.

Went to a 47.5 pilot and 112.5 mains. Surge was gone, running super rich on low throttle, wouldn't run past 6k WOT.

Went back to 110 mains and 47.5 max revs increased to 7k, still rich on cruise.

Went back to stock pilot, 112.5 mains, lean cruise, revs still stuck.

Now 42.5 pilots (stock), 120ish mains (drilled, flow checked against the 112.5 to make sure they were flowing more, because at first they weren't because I neglected the entry and exit radii, and balanced with the other drilled jets) lean cruise, will rev to 7k and then very very slowly pull higher.

All grounds checked, coils grounds redone, coil signal and ground wires position swapped, new plug wires. I've tried running with the "choke" on, with and w/o the air box lid, with and without the filters, nothing seems to be getting me even close. Want to beat my face against broken glass.

Does it sound like it needs more or fuel up top or less?

Still haven't tried going with a smaller main.

Next thing I'm going to try is wrapping the filter in an old t-shirt.

[recycled64]

IMO, FWIW, not likely to get much of anywhere without obtaining a proper, original, cone-shaped foam air filter for it, and bringing all settings back to stock.

[bonanzadave]

IMO, FWIW, Not likely to get anywhere without obtaining a proper, original air filter for it, and bringing all settings back to stock.

Id try that too. Does it have a pipe ? and we should also ask which bike is it ? Any other mods ? Valves adjusted ? Good, clean fuel supply ? Decent plugs / wires ?

[rapidray]

If no one has ever told you this before, it helps us EMENSLY if you would tell us WHAT BIKE YOU HAVE!!!
Ray.

[bonanzadave]

Gotta be his 1982 650. Reading back on some of his old posts. Does NOT appear to have a pipe in his album photos.

[Rob S.]

Bike would idle great, but surge and hunt at steady state low throttle cruise.

From the July, 1982 Cycle World (about my GS1100e):

"Throttle response is good but there is a small amount of lean surge at steady-state cruising speeds and low throttle openings. It feels as though the carb pistons are undecided as to where, exactly, they want to position themselves."

You didn't mention your model, but just saying, a small amount of surge is normal.

The article continues:

"At higher road speeds, during hard riding, or in the fast-slow transitions of daily riding no carb problem is evident and the throttle is quick and responsive."

[chef1366]

If you have leaky intakes you are wasting you time trying to jet.

[yank]

From the July, 1982 Cycle World (about my GS1100e):

"Throttle response is good but there is a small amount of lean surge at steady-state cruising speeds and low throttle openings. It feels as though the carb pistons are undecided as to where, exactly, they want to position themselves."

You didn't mention your model, but just saying, a small amount of surge is normal.

The article continues:

"At higher road speeds, during hard riding, or in the fast-slow transitions of daily riding no carb problem is evident and the throttle is quick and responsive."

Rob, The bikes where tuned to pass emisions back in the day,they run much better now thanks to the folks on this forum who where toying with them 30 something years ago.

[Rob S.]

Rob, The bikes where tuned to pass emisions back in the day,they run much better now thanks to the folks on this forum who where toying with them 30 something years ago.

How?

Last I heard, they still have to pass emissions tests. Are you saying the small amount of surge that was considered normal can be completely eliminated on a stock 1100EZ?

How, exactly?

[chef1366]

How?

Last I heard, they still have to pass emissions tests. Are you saying the small amount of surge that was considered normal can be completely eliminated on a stock 1100EZ?

How, exactly?

Shim the jet needle or get a Dynojet kit.

[Rob S.]

Got DynoJet stage III, professionally jetted on a dynamometer. I don't really notice any of that "surge" on my bike, just saying a little bit was considered normal.

[Old guy]

1981 GS650GL. O rings, boots, new. Carbs cleaned (stripped, dipped, probed, and blown out), valves in spec, new plugs, new wires, etc. etc.

Motor hits a wall at a given RPM, jeting only changes where the wall is. I figure if I can move the wall to 10k rpms, all is good.

[Big Rich]

Mr Old guy: let me start off with that I know next to nothing about your particular bike. But I didn't see anything about turns in / out on the mixture screws or that you had shimmed your needles?

While the main jets will have an effect everywhere off idle, cruising rpm's are usually based off your needle heights. But pardon my ignorance if I'm way off base.....

[mmattockx]

Last I heard, they still have to pass emissions tests.

Depends on where you live. I am in Alberta and there is no emissions check of any sort done on any vehicle, two or four wheeled. OP doesn't say where he is located so we are all guessing on that part at the moment.

Are you saying the small amount of surge that was considered normal can be completely eliminated on a stock 1100EZ?

How, exactly?

There is no reason for the bike to surge, correct jetting will completely eliminate it. Stock bikes of that era were jetted very lean to pass emissions standards and driveability was compromised to that end.


Mark

[Sci85]

I'd shim the needle as well as suggested. I'd also try going slighty smaller on the mains. When I got my bike rebuilt, I thought I needed more main and needle and it too would not rev past 6-7k. After many tuning sessions I finally went leaner on the main and back to stock needle and bingo!, she finally ran like it should.

A suggestion is to take plug readings. After guessing by feel for awhile and not getting anywhere, I got some fresh plugs and took some readings and that's how I realized I was too rich. What do your plugs look like after a full throttle plug chop?

Good luck!