sudden loss of power

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Re: sudden loss of power

#31

Post by Rat »

You don’t mention the gas cap, a plugged vent can cause fuel starvation ... when it acts up, just crack the cap open and see if it settles down.
Clean the cap vent carefully if that turns out to be the problem
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Re: sudden loss of power

#32

Post by sickradsean »

Gord-
I don't know where the vent is in the cap? I'm assuming that it's just the center bit on the top where there seems to be a gap? Either way i hosed the whole thing out with carb cleaner and then took a wire brush to it to get off the external crap. Ran the bike for a while and it eventually bogged down, removing the cap had no effect. If it was a vacuum in the tank I'd assume as soon as I cracked the cap it would right itself. Is there a preferred aftermarket gas cap? If I'm going down the line to make a list of things this problem isn't adding one more wouldn't hurt.
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Re: sudden loss of power

#33

Post by ericheath »

It should correct itself as soon as the cap is removed if the cap vent was plugged.

Your description makes it seem it could be leaking float valves, maladjusted floats, a leaking carb fuel seal, or a leaky plenum seal.

A leaky plenum seal will show a wet plenum floor with the air box cover removed and a flashlight to see into it.

To see if it’s either of the other two (could be more than one carb) let the bike idle until it starts struggling to stay idling, turn the petcock off and listen. After about a minute if the idle picks back up and runs nice, before stumbling and running out of fuel, it is likely one of the above.

What’s happening is your fuel level is too much in the carbs. When you turn the fuel off, the running bike consumes the excess fuel to a point where it is just right. Then of course within a minute it will be low on fuel and start stumbling and die.
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Re: sudden loss of power

#34

Post by sickradsean »

I was reading up on the electronic ignition and was recommended to test the pickup. The thinking is that when the bike heats up the pickup shorts and causes the ignition to stutter. I’ve looked at the dynamics website but can’t make heads or tails of how to go about it. Anyone do this before?
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Re: sudden loss of power

#35

Post by Sidecar Bob »

Mr. Honda ('83 GL1100/Dnepr) summer How a motorcycle evolves thread
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Click: Colour schematics for all GL1000 & GL1100 and GL1200 standard models plus instructions on how to download the full size version
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Re: sudden loss of power

#36

Post by LuckyEddie »

Sickradsean,

Make sure the wiring termination at the ignition terminals are not grounding out inside the housing. A short will exibit those symptoms.
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Re: sudden loss of power

#37

Post by sickradsean »

After not finding anything wrong with the coils or ignition itself I decided to dig into the wiring. I cleaned out all of the, lets say, "creative" splices that were in there and replaced them with proper connections. There are still a number of pig tail connectors in the headlight bucket, but thats all accessory stuff (for another day).
ImageImage
I ran the bike in up to temp and didn't seem to have any sputtering. I'll take it out tomorrow for a shake down ride to see if this fixed it.

Side note: what fuel lines are you using? I got some clear 1/4" ones from motion pro and they seem just barely too big. I'd like to not have to ring clamp every joint along the line.
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Re: sudden loss of power

#38

Post by sickradsean »

Update time! I replaced the fuel lines with the motion pro ones and they seemed to leak a bit without hose clamps on them? so not ideal. I still couldn't pin down the intermittent loss of power but I did possibly get some more (albeit terrifying) insight the other night. I had recently taken my bike out of winter storage and did about 20 miles no problem, the next day I took her to work (less than 10 mi) and it stuttered a little bit but corrected itself. On the way home however I felt like I was running out of gas the entire ride. Had to keep the throttle way open to keep everything vaguely stable. At a stop light I smelled something awful and looked down to see it was the chrome burnding off the mufflers!
Image
(here is one right when I got home)
Apparently the exhaust was backfiring so bad I was shooting flames out the back! Must have made for a hell of a show in the dark.

So into what I think might be going on. There is some gas leaking around the petcock and with the clear tubing I can see that there is a lot of air in the fuel lines. Would a leaky petcock/loose fittings cause there to be more air in the system thus creating a lean environment that I would have to dump more gas into to keep everything running (and then causing the backfire)? I was also suggested to check the carb boots for leaks, but I think it's more in this fuel delivery problem (the fuel pump was replaced a few years back so I dont think it's that).
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Re: sudden loss of power

#39

Post by desertrefugee »

You are obviously getting ignition. Your carburetors are crying out for attention.
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Re: sudden loss of power

#40

Post by Sidecar Bob »

Air in the fuel lines is perfectly normal. The float bowls are vented to the plenum via the main jet so air in the lines or filter won't affect anything unless you have something screwy like a fuel filter with the outlet higher than the inlet.
FWIW, with the second tank on the sidecar I have a fuel filter for each tank, both of which are in the lines just before they connect to the selector valve that's mounted on top of the fuel pump so they are in plain sight (not where you would normally see them when on the bike but I do occasionally look). It is normal for the filter for the tank selected to be as much as half full of air at idle but the fuel level in it rises when running at speed (= drawing more fuel).

If it was afterfiring enough to shoot flames you should have hard the banging ("backfiring" is often misused but it specifically refers to firing back through the carbs).

Are you sure you weren't seeing the leaking fuel dripping onto the muffler and burning? If so count yourself luck that the whole bike didn't catch fire. Motion Pro does recommend clamps with their hoses....
desertrefugee wrote: Sun Feb 13, 2022 1:27 pm You are obviously getting ignition. Your carburetors are crying out for attention.
Sounds like the next step to me too.
Mr. Honda ('83 GL1100/Dnepr) summer How a motorcycle evolves thread
The Famous Eccles ('84 CX650EI/VeloUral) winter Never Ending Build (CX500forum)
Click: Colour schematics for all GL1000 & GL1100 and GL1200 standard models plus instructions on how to download the full size version
"A guy with two sidecars can't be all bad." - Cookie
Another guy with two sidecars..... Hmmmm... must be something to that....
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Re: sudden loss of power

#41

Post by redglbx »

Check that your fuel cap is venting ! They seem get to a point where they don’t vent well due to spiders/rust/dirt/whatever. So check that you vent is venting, quick check is to just remove the cap.
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Re: sudden loss of power

#42

Post by digger »

As ericheath mentioned back in October, you may be running rich on fuel, next time it acts up, turn the petcock off while riding and see if it starts to run better as the fuel gets used up. If it runs better, turn it back on and see if it looses power again.
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Re: sudden loss of power

#43

Post by cfairweather »

I believe the Dyna Ignition is the best and most reliable system for the GL1000. I have installed many of these. The problem you are having is most likely a float/float valve issue. Next time the problem occurs, shine a light into the plenum and see if you see fuel at the bottom. If so, a float valve is leaking or a plenum fuel seal is bad. You can connect four clear tubes to the float bowl to see the actual level.
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Re: sudden loss of power

#44

Post by CYBORG »

cfairweather wrote: Sun Feb 13, 2022 8:27 pm I believe the Dyna Ignition is the best and most reliable system for the GL1000. I have installed many of these. The problem you are having is most likely a float/float valve issue. Next time the problem occurs, shine a light into the plenum and see if you see fuel at the bottom. If so, a float valve is leaking or a plenum fuel seal is bad. You can connect four clear tubes to the float bowl to see the actual level.
The Dyna is good. I have gone thru several on my 78, but I now have a
c5, and feel it is much better then the dyna
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Re: sudden loss of power

#45

Post by cfairweather »

I just went to the C5 web site and they don't make them anymore. I have to admit, I am not familiar with this company but I can see they probably made a high quality optical unit. These are probably more accurate than the magnetic types.
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