gs1100e stumbles at WOT

[chobint]

I am having trouble getting my new 1982 gs1100e running properly. The bike idles like a dream at 1100rpm dead steady. It rides fine as long as you roll on easy, but as soon as you get aggressive on the throttle it falls on its face. When you really get on the throttle the exhaust pops and snaps, and you end up going nowhere.

The bike as I bought it:

• 138 main jets. This matches the dynojet stage 3 kit that the previous owner claims to have installed.
• Oval pod filters (not sure what brand)
• V&H 4 into 1 exhaust
• Dyna ignition, but stock coils.

Stuff the shop and I have checked/tried:

• Fuel line and filter have been replaced, tank drained.
• Petcock diaphagm seems fine (runs the same on prime as is on normal)
• Plug color indicates slightly rich mixture.
• Prelim spark test seems normal. (Again dyna aftemarket ignition, but stock coils)
• Jets sizes tried - 138 thru 145. 145 seemed obviously rich to me. Crack throttle, epic bog. Retain throttle position, engine eventually catches up and rips HARD towards the end of catching up.
• Carbs are clean. Not squeaky, but again it idles like a champ and has had multiple new main jets swapped.

If it meant de-tuning the bike, I would be fine dropping 10 hp if the damn bike would just run smoothly throughout the rpm range. Any input would be greatly appreciated.

[Gonzo]

New jets doesn't guarantee that the passages they sit in aren't clogged. I'm having the same issue, but lower down the range. I pulled the rack today and I'm willing to bet that a soak in the ol' Berryman's will fix it.

[chef1366]

Take the needle jets out and put the clip on one notch towards the pointy tip.
Keep the DJ 138.
Then ride
Hard

[Bonehead]

I am having trouble getting my new 1982 gs1100e running properly. The bike idles like a dream at 1100rpm dead steady. It rides fine as long as you roll on easy, but as soon as you get aggressive on the throttle it falls on its face. When you really get on the throttle the exhaust pops and snaps, and you end up going nowhere.

The bike as I bought it:

• 138 main jets. This matches the dynojet stage 3 kit that the previous owner claims to have installed.
• Oval pod filters (not sure what brand)
• V&H 4 into 1 exhaust
• Dyna ignition, but stock coils.

Stuff the shop and I have checked/tried:

• Fuel line and filter have been replaced, tank drained.
• Petcock diaphagm seems fine (runs the same on prime as is on normal)
• Plug color indicates slightly rich mixture.
• Prelim spark test seems normal. (Again dyna aftemarket ignition, but stock coils)
• Jets sizes tried - 138 thru 145. 145 seemed obviously rich to me. Crack throttle, epic bog. Retain throttle position, engine eventually catches up and rips HARD towards the end of catching up.
• Carbs are clean. Not squeaky, but again it idles like a champ and has had multiple new main jets swapped.

If it meant de-tuning the bike, I would be fine dropping 10 hp if the damn bike would just run smoothly throughout the rpm range. Any input would be greatly appreciated.

-If that is an inline filter, take it out. Usually does nothing but slow down the fuel flow.
-Why keep the stock coils? [PO decision probably] but you should check out the Dyna ignition. Make sure it is connected correctly, the whole way through. Dunno how complicated it is, so that could be a possibility.
-I didn't see it covered but what are the Air/Fuel mixture screws at? (the ones that are usually plugged from the factory) Stock is around 2.5 turns out, but with jetting changes that will fluctuate.
-As chef pointed out, check the needle jet (the needle in the slide) and possibly move it up a slot to lean out the mixture.

A little carb theory for ya...

Throttle Opening: Jets used
Idle-1/4: Pilot screw/ Pilot jets
1/8-1/2: Slide Valve
1/4-3/4: jet needle/needle jet (If the full DJ kit was installed, you will have adjustable needles now which will be very useful in dialing in the correct jetting)
3/4-WOT: Main jet

[Katarat]

If you take a few minutes and mark the throttle in 4 places from start to WFO and 2 in between you can figure out what circuit the problem is on but the previous advise from Chef1366 probably has you covered. If it pops when you let off the throttle richen the idle circuit some more to maybe 3 turns out. Im no expert just telling you what works for me

[chobint]

I'm picking the bike up from the shop tomorrow. I will try raising the needle a tick to lean out the midrange, as per Chef's advice.

A little carb theory for ya...

Throttle Opening: Jets used
Idle-1/4: Pilot screw/ Pilot jets
1/8-1/2: Slide Valve
1/4-3/4: jet needle/needle jet (If the full DJ kit was installed, you will have adjustable needles now which will be very useful in dialing in the correct jetting)
3/4-WOT: Main jet

Question on this:
I have seen this info before. Do the fractions refer solely to the throttle position, or a combination of throttle position, RPM and load. I ask because at low RPM, you can only twist the throttle so much then anything beyond that has no effect. I have a hard time believing that the main jets are in full effect while I'm cruising at low RPM in 6th then decide to crack the throttle wide open. Please correctly my faulty intuition if it is indeed faulty.

[chef1366]

I've installed more than a few of these kits. They are either spot on or lean on the needle. I've seen them lowered two notches to get rid of the stumble but most of the time it's one.

[chobint]

Thanks for clarifying. I will try dropping the needle one notch to richen up the midrange.

[chobint]

I replaced all of the main jets with 138's. I found the clips in either the 3rd or 4th position from the pointy end. I dropped all clips to the 2nd position from the pointy end (which I realize now is 2 ticks down from dynojet kit spec)

The engine still hesitates and pops pretty bad around 5k rpms. 1st and 2nd gear can usually get over it, but any gear 3rd or higher will get stuck stuttering pretty badly unless I ease off the throttle.

After today's test ride I checked the mixture screws. They were all over the place so I reset them to 2.5 turns. Maybe this is the magic? Maybe not?

Edit: Here are some pics I took during inspection. All of the diaphragms are supple. The carbs seem pretty clean. The pilot jet cavity is plugged with a rubber stopper, which is normal from what I've read. The emulsions tubes are clean, which means all the brass has been covered.

[xxBenJamminxx]

Does it seem better after lowering the needle clips? If so maybe try another position lower like Chef said. Might be one of the turbo lean kits and needs 2, maybe more to get it right???

[Samsonite]

Have you checked the pilots at all. I had some issues similar with my 82 1100 until i upped the pilots.

[chef1366]

47.5 on the pilots works well
Are the slides drilled?

[chobint]

The slides are drilled. The pilots are brand new 47.5's, but are currently plugged by a rubber stopper. I guess that means you recommend removing the stopper then?

[chef1366]

The slides are drilled. The pilots are brand new 47.5's, but are currently plugged by a rubber stopper. I guess that means you recommend removing the stopper then?

Absolutely not

[Katarat]

When you crank it wide open at low RPM in a high gear the slides wont open until theres enough vacuum to open them. The throttle may be WFO but the slides are barely open if that explanation makes any sense to you.