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Discussion Starter · #1 · (Edited)
Ok guys this thing has the best of me at this point. Bought the bike from a co-worker in non running form. He bought it new and hurt his back and it has sat ever since until last weekemd. It has a whopping 1004 miles on it. It sat outside but covered and he drained the gas when he parked it (thank you). Tank was clean!

I have cleaned literally over 100 carbs in the last 5 years. I'm pretty familiar with them. If you've ever had to RnR shadow twin carbs you know they are no treat!

Anyways the problem is the bike starts, idles perfect, revs great....all when not under the load of actually riding it. When you ride it and put it under a load, it just kinda barfs. Acts like a cylinder is cutting out. I'll list what all I have done to it below. I will also post a vid of it starting, idling and revving stationary. The second video is a short vide of me taking off on it and it barfing. Its only 6 seconds but it's too dang cold to get a better vid tonight. But you can see it take off and as I get in the gas you can here it barfing. If you dont see the vid yet its still uploading. I'll adjust post when they are available.

Here is what I have done so far:

Installed brand new battery has about 14.2 volts under all running conditions as expected.

Cleaned carbs..twice. Second time was just to verify I didn't miss something. All jets clean. Everything moves as it is expected. Frankly I've seen worse carbs but both the main and pilot are now clear as is everypassage that can be cleaned. Chokes work as they should. Both plugs for idle air screws are removed and screws adjusted to best idle.

Air filter like new.

Changed oil

Checked all electrical connections to make sure nothing was corroded. Everything looked good. Front cylinder coil had a slight bit of moisture where coil wires went in. I did trim both ends and reinsert and lock down.

Changed oil and filter.

Brand new plugs at all four.

Brand new OEM fuel pump. Original was just dead. Verified pump is pumping.

Brand new fuel filter.

Bypassed kick stand switch to take it out of the loop.

Put a timing light on it and rode it to make the problem occur while observing the spark pattern. Have to admit when problem was happening it did seem as if the spark was not consistent. This was the same for both front and rear cylinders. I would have thought if I had a problem with an individual coul I would only see oddness on one coil, not both. Regardless at no time when the problem occured did I lose spark completely.

If you have ever ridden an ATV with a really dead battery (that would at least fire off with a pullstart) it is acting like that as if it has enough spark to run without load but not strong enough to fire properly under load.

I have read there is a pulse generator, and I have a manual from this site but don't know what years it covers. I am yet to see the pulse generator. Does the 2003 Spirit have one? Where is it at? Under cover with stator?

So anyone have any ideas? Ears open!! Videos to follow. Internet is slow.

Here is vid of it falling on face:

http://youtu.be/RQfcCLKjUf0

Video of it starting and reving

http://youtu.be/exL7G4VXQ5g
 

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no you removed the carbs they NEED to be resynced. its allows them to run together equally. it needs to be done trust me.

The main symptom is poor throttle response off idle. Also --irratic idle / racing or stalling.
 

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Discussion Starter · #5 ·
no you removed the carbs they NEED to be resynced. its allows them to run together equally. it needs to be done trust me.

The main symptom is poor throttle response off idle. Also --irratic idle / racing or stalling.
I didnt split them. Kept them intact. I did this on my first shadow a few years ago when I rejetted for pipes and didn't have to re-sync at all.

Both vids up now.
 

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you said you cleaned them right? took them apart? just cause you didnt split them doesnt mean they wont go out of sync. really it cant hurt its a few minute job. and hell it just could be your issue. better then guessing whats going on honestly :)
i pulled carbs and cleaned them without splitting before and ended up way lop sided in sync and never touched the sync part.

if you dont have on build one me and my friend built one similer to this and it works awsome
 

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I'm not sure if your manual is the same as mine but section 19 shows and describes how to diagnose bad pulse generator/coils if that's what you suspect.
 

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Also bad carb boots could cause that. Sucking in air where it shouldn't be. Spray starter fluid around the boots and see if the idle picks up or changes in any way. That would be an easy place to start.
 

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Moisture in the primary coil connections you say? Have you checked the primary coil blades for oxidation and clean them and make sure the wire leads are firmly connectected to the coil male connection blades? Even with a bad coil connection the bike will idle but will need an increase at the idle speed screw, but will lack acceleration since it's running on one jug. If you haven't done so check for spark and check your exhaust pipes for temp variation. Just another thought from my experience to add to your list.
 

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the OP has extensive experience in that department. However, a bad diaphragm in the petcock has been known to cause similar issues under load.
 

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Discussion Starter · #12 ·
Moisture in the primary coil connections you say? Have you checked the primary coil blades for oxidation and clean them and make sure the wire leads are firmly connectected to the coil male connection blades? Even with a bad coil connection the bike will idle but will need an increase at the idle speed screw, but will lack acceleration since it's running on one jug. If you haven't done so check for spark and check your exhaust pipes for temp variation. Just another thought from my experience to add to your list.
All of the spade connectors were clean and tight but I did pull them all and verify.

The moisture was noticed where the actual spark plug wires go into the coil and I felt like he may have pressure washed it or something. None the less and re-clipped them and re-inserted them just in case.

For the pulse generator, the manual it shows the pulse generator on the left side of bike kinda underneath the starter but I didn't see it. I'm trying to visualize how the bike is set up meaning I'm thinking of a standard pickup coil that runs off of the flywheel but it seems this bike will have something different. Not sure what year models thie manual is for unless it doesn't matter that they all are the same because they didn't ever change the design. Seems I read one place that it was under the tank and then the manual says its under the starter or something. Getting a little burnt out on it at this point so it's all running together. Lol!
 

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Discussion Starter · #13 ·
the OP has extensive experience in that department. However, a bad diaphragm in the petcock has been known to cause similar issues under load.
I admit I did not go into the diaphragms in the carbs as they felt proper to me and I really felt I had no reason to go into them because when not under load they appear to function fine. Seems to me they either they work or they dont meaning same whether inder load or not but I could be wrong on this. The carbs I have seen with bad diaphragms typically will have a loose resistance feel to them when you raise them in the slide bores by hand due to the hole in the diaphragm if they have one.

The spirit is not vacuum operated on the petcock.
 

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For the pulse generator .... Seems I read one place that it was under the tank and then the manual says its under the starter or something.
Pulse generators are located under the clutch cover. Per manual, try Clutch/Gear Linkage chapter. In your quote above, the manual might be referring to points to test the pg's .... at it's nearest p-connector or another option at the ICM? Instead of the actual location of the pg's.
 

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Check the fuel filter. I had a car that did the exact same thing. At idle and short bursts of the throttle there is enough fuel. Sustained higher RPM needs more fuel, and with a semi-clogged filter they may not be enough.
 

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Discussion Starter · #16 ·
I did put a new one on. I don't feel like it is fuel delivery between the tank and the carb. Typically if that issue is going on it will be fine until the bowl gets low due to lack of delivery then it runs like crap but if you let it sit for a minute it will be fine again once the fuel bowl fills again. In my case it does it all the time regardless.

RonW, thanks. I re-read the manual and see how to test it. One thing I don't like about the on line manual is it only shows how to troubleshoot when there is no spark at all. I have spark. Just feel like it is weak.

Check the fuel filter. I had a car that did the exact same thing. At idle and short bursts of the throttle there is enough fuel. Sustained higher RPM needs more fuel, and with a semi-clogged filter they may not be enough.
 

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I did put a new one on. I don't feel like it is fuel delivery between the tank and the carb. Typically if that issue is going on it will be fine until the bowl gets low due to lack of delivery then it runs like crap but if you let it sit for a minute it will be fine again once the fuel bowl fills again. In my case it does it all the time regardless.

RonW, thanks. I re-read the manual and see how to test it. One thing I don't like about the on line manual is it only shows how to troubleshoot when there is no spark at all. I have spark. Just feel like it is weak.
Check the resistance at the primary and secondary connections of the coils to ensure they're well within spec. Same goes with the plug wires. Your manual should show how to to check the primary and then the secondary readings with and without the plug wires with a multimeter.
 

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Discussion Starter · #18 · (Edited)
Just following up. Had to wait for parts. I went ahead and replaced both coils, caps, and wires to eliminate them as the cause. They are now on and in place and the problem is still there. I have positively narrowed it down to the front cylinder.

I rode it with both back plug wires off and the bike has absolutely nothing (cylindet not firing at all) under load. Idle and light roll in fine. Try to do snything with any load and that cylinder flat out quits working.

In addition, I no longer believe it is anything to do with the ignition system. I put my timing light on that cylinder and ran it on just that cylinder. When the problem is happening there is solid, consistent, good spark. It's getting fire at all times.

I took the air cleaner completely off to where I could see the cvt slides and I can see both slides moving as I expect them to when I crack the gas. It just falls on its face.

All indications are that it is still starving on just the front cylinder. I have been in the carb twice so far and all jets are clear and the carb is pretty clean in there anyways.

Looks like I am going to go back into the carbs yet a third time and try to find what I am missing. Gotta be something I am overlooking at this point.

More to follow pnce I have more info.
 

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Open the drain screw on the carb for the cylinder that isn't firing and see if there is gas. If there isn't then something is wrong with that carbs float or float valve. Even if there is some gas is might not be enough which would indicate the float height is set wrong.
 
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