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Discussion Starter #1
I've been working on a honda shadow i bought that wasn't running. I've replaced spark plugs, several hoses, and installed a brand new fuel pump. I've managed to get it kind of running. Enough to where I have road it a few times. My problem is that I cannot get the bike to consistently start. I can almost always get it to fire with starter fluid. I have gotten it on a couple times off of gas but its pretty much a miracle if that happens. I've already gone through and cleaned my carburators thoroughly and inspected my flat needles, floats, diaphragms etc. And is in all working condition. When the bike manages to start, it runs great. One thing is that it does like to backfire alot when I'm trying to start it, was thinking maybe I should pull the air/fuel plugs and adjust as maybe I'm just getting too much fuel?

One other things is that my battery will not charge, I assume I need a new stator. Could this maybe be giving me a weak spark also, and it causing my starting issues?

Thanks in advance to anyone that offers suggestions and knowledge :)
 

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You could rule out the weak battery issue by jumping off a car battery. If it starts every time like that, then that’s your issue.

Have you done a compression test? When you first go to start, the cylinders might not be developing the vacuum to pull fuel in, but usually at least one of the two cylinders would do this... How sure are you of that new fuel pump? Could there be some other blockage or restriction in the filter, tank, or any of the lines?

How are you using the choke? My bike is the same as yours, and my father had problems starting it cold since it was new. Enough that he’d use starting fluid to quickly light it off in the morning...
 

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1983 Honda vt750 Shadow
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Mine is hard to start under 50 degrees. It floods easily. So I had to learn the starting tricks.
I richened up the primary jets (actually too much) and now I always try to start with NO choke for a few seconds and then add some briefly if needed.
If i flood it then it bangs and pops til it starts.
Try the jumper battery as mentioned Then measure the voltage across the battery when you rev up to about 3000 RPM it should get up to 13.5-14.5 volts.
Look at the 3 yellow wire connector next to the battery. It is a problem spot for burning the connections.
You might try turning the mixture screws out 1/2 to 1 turns to see if it helps.
And don't open the throttle when cranking.
 

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Discussion Starter #4
You could rule out the weak battery issue by jumping off a car battery. If it starts every time like that, then that’s your issue.

Have you done a compression test? When you first go to start, the cylinders might not be developing the vacuum to pull fuel in, but usually at least one of the two cylinders would do this... How sure are you of that new fuel pump? Could there be some other blockage or restriction in the filter, tank, or any of the lines?

How are you using the choke? My bike is the same as yours, and my father had problems starting it cold since it was new. Enough that he’d use starting fluid to quickly light it off in the morning...
Brand new battery, and the thing is its getting fuel because i have clear fuel lines and I can see it going through. Along with it running fine if its started, so I should definitely mess with fuel air then?
 

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1983 VT500C, 1985 parts VT700C
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Ok, since we don't have any pics to look at yet,
let's find out if we need to rule a few things out.

1. Does it have the OEM pipes?
If Aftermarket or chopped off, that's usually indicative of nothing being right as far as the carbs jets.

2. Noticed you didn't mention the air box system...is the OEM still there??
If it's running off just screens/K&N/etc, that's a whole other issue as well.
And make sure there isn't a squirrel nest/dirt dauber nest/honeybee comb/etc in the oem...
it's truly shocking what you can find inside that thing.

3. Possible charging issue...i.e. stator/etc
I've got nearly a whole '86 Shadow 700 that I need to
dispose of in storage now ;) Are you near Pensacola?
Have I gotta deal for you!

3a. If you do have a stator problem, another way to solve it is to have an Alternator
Shop rebuild it. Probably cost around $100-150 these days...

4. You say you've gotten it on the road a few times, definitely pull the spark plugs
and see what sort of residue is on them now. Should give you quite a few clues.

Hope that helps, and we look forward to seeing pics of your bike :)
 

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Discussion Starter #6
Ok, since we don't have any pics to look at yet,
let's find out if we need to rule a few things out.

1. Does it have the OEM pipes?
If Aftermarket or chopped off, that's usually indicative of nothing being right as far as the carbs jets.

2. Noticed you didn't mention the air box system...is the OEM still there??
If it's running off just screens/K&N/etc, that's a whole other issue as well.
And make sure there isn't a squirrel nest/dirt dauber nest/honeybee comb/etc in the oem...
it's truly shocking what you can find inside that thing.

3. Possible charging issue...well, I do know of a Shadow 500 around Pensacola
that did have a stator issue that needed to be solved, and I know where to get
a replacement stator if you're the one who bought it. However, if you aren't
anywhere near Brewton, AL it does you no good because the guy doesn't ship.
You gotta come there and pull the part yourself. Upside, he's got like 8 Shadow 500's.
And a boatload of other Shadows in the weeds...

3a. If you do have a stator problem, another way to solve it is to have an Alternator
Shop rebuild it. Probably cost around $100-150 these days...

4. You say you've gotten it on the road a few times, definitely pull the spark plugs
and see what sort of residue is on them now. Should give you quite a few clues.

Hope that helps, and we look forward to seeing pics of your bike :)
Everything is oem, along with brand new spark plugs. Also I didnt think of just getting it rebuilt, I was just gonna buy a refurbished one, but getting rebuilt is close to the same price so that sounds like a better idea to me.
 

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1983 VT500C, 1985 parts VT700C
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Everything is oem, along with brand new spark plugs. Also I didnt think of just getting it rebuilt, I was just gonna buy a refurbished one, but getting rebuilt is close to the same price so that sounds like a better idea to me.
Altho it might be quicker to grab a multimeter and check the stator with that...
it'll show problem/no problem fast. :)
 
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Discussion Starter #8
Altho it might be quicker to grab a multimeter and check the stator with that...
it'll show problem/no problem fast. :)
Yah ill definitely do that first lol. So when I get it to like 3000rpm I should be ready close to 14 volts right?
 

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1983 Honda vt750 Shadow
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Yes 3000 RPM 13.5 to 14.5 volts steady
 

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My father’s had green plastic gauze wrapped several times around the OEM lower intake. When I laughed at him ‘Macgyvering’ it up like that, he said that’s how it came from the dealer! 😳

You can try richening up the mixture, but the key is the fuel needs to make it into the cylinder in the first place. One other thing to check, off-hand, is the overflow/vent tube running from the middle of the carburetors to the ground. Make sure it isn’t blocked.
 

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Something to consider. A pop at exhaust indicates too much air typically. Check plugs. Too oily means too much gas or not enough air to burn it all so some burns on the hot exhaust pipe on the way out.

Now a fuel pump on some bikes have a fuel pump relay that can go bad. Happened on my VT750. Gravity will get some to the carb but it struggles due to the pump nor going. The flow isnt fast enough.

If plugs are burn, dry almost white then too much air. Should be a golden brown. So start at checking the plug ends. Oily wet and black or light and dry. Then you know if too much fuel or too much air. Then adjust carb accordingly. To test your fuel pump, disconnect the carb end and over a bucket or towel point up, turn the key to on and see if it squirts out. Maybe hit the starter to be sure. Fuel should shoot out. Point away from face. If nothing happens then fuel pump or fuel pump relay is stopping fuel flow.
 
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