Hunley fuel milage is awful

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pidjones

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'75 GL1000 engine, stock carbs (rebuilt myself). Only ~100 miles on it so far, but the first time that I filled it up (last night) from a pump so I could figure the mileage, it was only 22.8 mpg. Now, there may be some inaccuracies in my previous fill to this one as the previous was from and can using a funnel. She idles well, accelerates hard but doesn't like low RPMs - wants to stay over 3500. Still on 13 year-old tires with marginal front brakes, so not getting ridden much but I did wind her over 7000 RPM yesterday and she felt quite happy with it. Much of the past 50 miles was 55 - 65 mph on a four-lane. I did re-adjust the valves after the first 50 miles on her (not much change). I know that the left bank has darker plug insulators than the left, and the left is MUCH louder, but #1 cylinder had 20 psi higher compression than the others. I've not rechecked the compression since I put the engine back in the frame, however.

So.... 22.8 mpg. Should I expect it to improve? Worry about pulling carbs again (won't happen until the fall at earliest)? Really, I did not find mounting the carbs and cables that hard, but then I didn't have the shelter on it then, either. I worry more about scratching up the paint more taking them in and out.
 
Crappy mileage. Should be closer to 40.

Unfortunately this won’t improve much if at all on its own if the cause is mechanical, like float levels too high, leaking seats, low compression, stuff like that.

I had a flakey needle valve flooding #2 cylinder that put my mpg in the toilet. I found it by misting water spray on the headers. #2 didn’t steam like the others. The cylinder (plug) didn’t look burning rich because it wasnt even firing. Still ran pretty good on just 3.
 
[url=https://www.classicgoldwings.com/forum/viewtopic.php?p=204862#p204862:35tqh86o said:
dan filipi » Wed Jul 25, 2018 9:55 am[/url]":35tqh86o]
Crappy mileage. Should be closer to 40.

Unfortunately this won’t improve much if at all on its own if the cause is mechanical, like float levels too high, leaking seats, low compression, stuff like that.

I had a flakey needle valve flooding #2 cylinder that put my mpg in the toilet. I found it by misting water spray on the headers. #2 didn’t steam like the others. The cylinder (plug) didn’t look burning rich because it wasnt even firing. Still ran pretty good on just 3.
I have an IR thermometer that goes to high enough temperature. I'll try that (if I can find it).
 
Probably carbs. Brakes all seem reasonable temps (<50 C) Choke maybe but exhaust pipe temps are actually getting closer together the more I ride it. Air filter is brand new. Idle speed is creeping up, but could be just "running in" (or getting a 4th cylinder working?) Rode it about 45 this morning and might ride it again this evening. So nice riding a naked bike with the heat we've been having (I've not owned a naked since my RD400 in the late '70s)! I have been winding her up to at least 6000 when I can before shifting, but trying to keep cruise RPM to ~3-4 thousand.
 
[url=https://www.classicgoldwings.com/forum/viewtopic.php?p=204949#p204949:17jqvtlk said:
joedrum » Fri Jul 27, 2018 3:06 pm[/url]":17jqvtlk]
hmmm well one side seems richer than the other side ...use atf in the gas and see if things get better is a good start for the rebuild carbs ...
Beat you to that one Joe! I put MMO in it last week. Maybe that is why it is starting to even out.
 
Similar issue with my '77 GL1000 in that it would not really run below 3000 rpm. I had significant carburetion issues. It turned out that among many small details, someone in a previous life of the bike had removed the air bleed jets from the carbs. If you have any significant mods in the carbs, you'll likely never attain decent operation.
 
Carbs are as close to stock as I can get them. The left cam belt however, was off by one tooth. After correcting that, valve adjustments, timing correction, and re-balancing the carbs, I think it may be corrected. Now to get some miles on her and see if fuel mileage is better.
 
If I'm not mistaken the 1000 carbs have mixture screws you can easily reach. Unlike the 1100 carbs. I strongly suggest you start with the motor warm and idling at 1000rpm and adjust each to the highest rpm you can get. Setting the idle to 1000 each time. Do them all twice. You may find much better power and mileage.
 
slabghost":173f5kb9 said:
If I'm not mistaken the 1000 carbs have mixture screws you can easily reach. Unlike the 1100 carbs. I strongly suggest you start with the motor warm and idling at 1000rpm and adjust each to the highest rpm you can get. Setting the idle to 1000 each time. Do them all twice. You may find much better power and mileage.
They have idle mix screws. I've adjusted them, but fuel milage would be more dependant on other things, I would think. Anyway, getting the cams on the correct tooth seem to be the biggest help. She idles smooth as I could hope. I did as you suggested again today. Couldn't tell any performance difference. #2 plug soots up, so that carb will have concentrated efforts when I pull them this fall.

I can't get over how light this bike feels after riding an 1800!
 
[url=https://classicgoldwings.com/forum/viewtopic.php?p=204857#p204857:2g1o5jz7 said:
pidjones » Wed Jul 25, 2018 7:22 am[/url]":2g1o5jz7]
'75 GL1000 engine, stock carbs (rebuilt myself). Only ~100 miles on it so far, but the first time that I filled it up (last night) from a pump so I could figure the mileage, it was only 22.8 mpg. Now, there may be some inaccuracies in my previous fill to this one as the previous was from and can using a funnel. She idles well, accelerates hard but doesn't like low RPMs - wants to stay over 3500. Still on 13 year-old tires with marginal front brakes, so not getting ridden much but I did wind her over 7000 RPM yesterday and she felt quite happy with it. Much of the past 50 miles was 55 - 65 mph on a four-lane. I did re-adjust the valves after the first 50 miles on her (not much change). I know that the left bank has darker plug insulators than the left, and the left is MUCH louder, but #1 cylinder had 20 psi higher compression than the others. I've not rechecked the compression since I put the engine back in the frame, however.

So.... 22.8 mpg. Should I expect it to improve? Worry about pulling carbs again (won't happen until the fall at earliest)? Really, I did not find mounting the carbs and cables that hard, but then I didn't have the shelter on it then, either. I worry more about scratching up the paint more taking them in and out.
First of all, the early GoldWings got terrible MPG compared to today's bikes. 23 MPG is low, expect low 30's. I typically get 32-35 MPG depending whether I'm riding in town or on the Interstate.
 
Ok I’m thinking your best move is to mix atf in the fuel all riding season ...use the center stand mostly all the time you can ....and check the oil a lot as in if any gas seems to be getting in it ...it sounds close enough to me that aft may finish the carb job ...that how it worked for me on my 79 so many years ago ...it got to where the gas mileage was about 35 mpg ...these carbs were alway lean back in the day and now days gas is much worse and makes them really lean getting started ...I would take them off till things like this are tried ...in my opinion
 
Well, that was last summer. I ended up finding a pinched o-ring for a jet in #2 carb. Runs much better now, but haven't had a chance this winter to check mileage. BTW, I run nothing but 100% gasoline with Stabil in my carbed engines.
 
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