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Discussion Starter #1
My Ace Deluxe has gotten about 33mpg on each of my last fills. That sucks pretty hard compared to the 50ish I'm seeing folks posting on similar bikes.

There are two things I'm pretty sure have been going on:

1) carb might be gummed up. I put some seafoam in (ok, a lot) about five miles ago and am already feeling a lot stronger at medium rpm, where before it really only seemed to pull at low rpm.

2) It's started popping a lot when decelerating, I know a little can be normal, but it seems excessive. Was going to tune the pilot screws the next time I have some time.

Would these explain a drop of that much? Anything else I should try?

Thanks! This forum is beyond helpful.
 

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1999 Shadow 750 ACE VT750CD3 Modified
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The only time my 750 ACE has seen fuel consumption that bad was when I was riding like a mad man on the highway against the wind or when I had made the wrong jetting choices.
Normally I would expect low 40's for miles per US gallon and I ride fairly aggressively, if I didn't I could probably nurse it above 50 mpg, but where is the fun in that.

To me it sounds like your carbs and/or air filter are gummed up and messing up your bike's efficiency.
There is only so much magic one can expect from pouring in additives and wishing.
At some point you have to say "enough" and pull the carbs and clean them out.
It is a pain of a job the first time with all that needs to be removed and then put back the same way after, but it is not really difficult and once you have them sitting on the table in front of you and there is plenty of how-to info to go by.
Just take pictures of where the cables and hoses go before you pull things, it removes the crap shoot out of getting them back together right.

And if you do have problems you can always ask here, because you can guarantee almost everything has happened to somebody here before.
 

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1983 Honda vt750 Shadow
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14,484 Posts
Air filter clean? No obstruction like a rag sucked into the intake snout?
Critter nests?
 

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1995 VT1100C2
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3,666 Posts
Gumming in the carbs is almost always due to improper storage or inferior fuel so I have to ask has your bike been stored? What fuel do you use? I recommend a Top Tier (almost all brands but discount). If your engine was running well and then it didn't what has changed? Have you done any recent maintenance or mods? I would not adjust A/F unless something has changed (altitude or mods). We will find the root and address that. As a last resort (and usually as a result of neglect) the carbs can be overhauled as CSRoad mentioned.

G.
 

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Discussion Starter #5
It's new to me, first motorcycle purchased used a month ago. I know the previous owner didn't ride it for longer stretches, so yeah, wouldn't surprise me if things are gummed up. The mileage has been consistently low since I got it.

As far as recent maintenance, I did some brake work, swapped the turn signals for LEDs and did the associated electrical crap to make that work, had a shop do their half hour checkover on it (didn't mention engine issues, but I don't know how in depth they went in that time frame), replaced the spark plugs and messed with the idle a bit, and it didn't change much of the feel.

The three things that changed right before I noticed the popping noises were:
1) The shop changed out the sprocket, chain, and rear tire, and reinstalled a little secondary air intake filter that'd fallen off that everyone agreed wasn't super important.
2) I got a little cheap inductive tach and set the idle lower, around 1100. I also realized that I was sticking in some pretty low revs and experimented with going a bit higher. This felt bad until I dumped the seafoam in, then started feeling better. Rode a bit later on, and it felt worse again, but that might just be that it got a lot colder.
3) I started using engine braking at stops instead of pulling the clutch and stomping to first. I haven't driven a manual before, so I'm still getting used to best practices. It's possible that the popping on deceleration was there before and I didn't notice because of this, but I honestly doubt it. It's pretty obvious.

I've also noticed a bit of intermittent ticking since they put the tire on, but can't tell if that's just a hose clamp or wire tapping against something somewhere or the engine itself.

One reason I wanted to put my hands on the A/F is because I noticed that the "don't mess with me" caps have been drilled out and I'm not sure of the previous owner's attention to detail. I also noticed a really erratic idle speed and trouble starting without raising the idle and saw folks saying that adjusting the mixture could help with that.

That said, I'm super open to exploring other options, especially if I don't have to pull the tank ;-)
 

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1983 Honda vt750 Shadow
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You might inquire if the valves have been adjusted - should be every 8000 miles.Can give an erratic idle.
It won't hurt to adjust the mixtures screws. Warm it up and go back and forth between the two carbs to get the fastest smoothest idle.
You can first screw them in gently till they stop and count how many turns they were as a reference. Back them out 2 turns and go from there. Turned in all the way the engine should die.
 

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1995 VT1100C2
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As a new rider your fuel consumption will be not great. I would not worry about it until you have a season behind you. Plus riders include highway miles in their results and you may not be riding on the highway.

Decel popping is common with these engines and difficult to tune out. To completely get rid of it you actually detune the engine slightly. I wouldn't worry about that now. Ignore the popping unless it gets loud more like a backfire. No one notices your popping.

If you can contact the previous owner I would ask if there was any carb rejetting or a kit. That's the usual reason for the plugs being drilled and that affects the A/F screw setting.

I would recommend you change all the consumables unless you have service records:
oil and filter (every year) JASO- MA certified oil. Nothing wrong with Honda GN4 and a Honda filter
Brake fluid (2 years)
coolant (5 years) I use Prestone premix
air filter (5 years)

G.
 

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Discussion Starter #8
-Makes sense, I won't worry about the popping sound itself.

That said, I'm still concerned about the erratic idle and ticking. I'm going to confirm that the mixture is correct and think really hard about overhauling that carb. Is it nuts to think about adjusting the valves myself if I've used feeler gauges before?
 

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1995 VT1100C2
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Adjusting valves is a maintenance item (8,000 miles) so if you are going to DIY you may as well attempt. You need to remove the seat, fuel tank, air cleaner housing, thermostat and then the cylinder head covers. Since you are removing the thermostat you will need to drain coolant so you should plan on replacing coolant and valve clearance at the same time if possible. You will require a torque wrench along with the usual metric box wrenches. Honda says you need a special tool for adjusting the valves but someone will probably tell you what fits. When you decide to do the valve adjustment start a new thread and you will get precise instructions.

Sometimes erratic idle (not the guy from Monty Python) is due to the SE (choke) not being fully closed or some gumming so maybe try working the choke engine on and off. Don't overdo the Seafoam dosage and don't adjust anything while you have Seafoam in the tank

G.
 

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1999 Shadow 750 ACE VT750CD3 Modified
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Seriously if you are taking everything off to check the valves you are already down to the carbs and may as well clean them up too.
A JIS screwdriver (looks like a Philips #2) is the only weird thing you need for that.
As for the valves other than the usual, everybody has them, metric tools, a torque wrench, I use a 4mm open end wrench and a set of feeler gauges.
You do not need to drain the coolant if you can get enough movement after unbolting the thermostat housing from the single bolt on the right side of the frame, the one where all the green wires come together. Used to work for me that way.
In your case with a bike that may have the original coolant in it I'd change it.

Take a look in the attached book at Service Item 19.
The book is originally from 750ACE.com and so we say thanks to PlaneCrazy.
 

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1995 VT1100C2
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3,666 Posts
CSRoad: What a great document. That's so much better than any of the official manuals. I wish I would have found that years ago instead of scrolling through the complete service manual.

G.
 

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1999 Shadow 750 ACE VT750CD3 Modified
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It was already there when I arrived at 750ACE.com, so I don't know the whole story.
As far as I know it was a remix of User Manual info, Service Manual info and working notes by PlaneCrazy.
That was a heck of a great web site and good people, the website slid beneath the waves of the Internet, but hopefully people and bikes are doing well.
 

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06' VT1100C/99' GL1500C Valkyrie
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Keep Seafoaming it until it go's away? Took my Valk 2.5 mi. to clear up and that was 7 yrs. and 33,000 mi. ago. I used a half a can to 5 gal. of fresh fuel as I have 6 carbs to feed. For regular seasonal additive I use Berry B12 every 2500 mi. or so @ suggest rate on label.
 

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Discussion Starter #15
The seafoam has continued to make noticeable progress over the last couple gallons, I gotta say, I did not think it'd do anything when I dumped it in ;-)

When poking around I found some cracks on the plastic L-joint between the fuel cleaner housing and the rest of the bike... I think from when the previous owner dropped it, so I'm gonna double check the fuel mixture when I install that, since removing it is part of the procedure.

I may hold off on the valves a little, have the mechanic listen when I do the 500 mile new chain adjustment. I've narrowed it down to "if I'm in third at 27 mph +/- 1 mph, it makes that same sound", so at least he'll be able to hear it.
 
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