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At Wits End with This

13K views 91 replies 16 participants last post by  vabrokenarrow 
#1 · (Edited)
I have an 05 Shadow Aero and on my way home two weeks ago, my bike took a crap. I had a sudden loss of power on the freeway and had my throttle fully open and was barely making 60mph. I have spent the last two weeks troubleshooting and I am running out of ideas and need some help. I have gone over the carb twice fully disassembling it, drained the tank and refilled with fresh gas, checked and switched the coils, replaced the plugs, checked for spark.

My front cylinder is not firing and I have no idea why. I have noticed a short while before this happened that when I went to start my bike, it dumped some fuel, and was getting harder to start. I may need to mention that I have removed most of my baffles a few months ago. Any feedback would be appreciated.
 
#4 ·
I have checked the petcock and it is functioning. My rear cylinder operates fine; just the front cylinder. I double check everything each time. I get a gurgling sound (best way I can describe it), when the bike idols. I tried to connect a compression tester to the cylinders as well in order to compare. There is no change in operation when I remove a front plug, but since only my rear cylinder is working, my engine cuts off when I pull a rear plug.
 
#6 ·
I had an old Virago 920 that was doing that intermittently until, after a while, it wasn't intermittent any more. Turned out to be the CDI.
 
#8 ·
The cheapest (CDI), (ECM) I can find is $100.00 and it would have to be shipped. I have considered this option, but there is no way that I have come across to test mine to see if it actually the problem. I don't want to buy one and wait for it to be shipped if that isn't the problem.
 
#10 ·
jpr1968, I removed each coil and checked the ohms and placed them on the opposite from where they were originally mounted. The wires were set by length to which cylinder, coil, and placement they were intended for. I did check for spark afterwards on each wire after re-installation. After checking for wire spark, I checked the front plugs for spark again. I am running out of guesses. I can't afford to take it to a shop and have my motor overhauled so I am trying everything else and reserving that as a last resort.
 
#13 ·
I noticed you said you tried to hook up a compression tester- but did you actually get a compression test result?
And it sounds like you have spark on both cylinders now. But it still won't fire on the front cylinder?

That strange sound may be a clue of the front cylinder having a compression related problem.

Compression Test Kit 8 Pc
 
#14 ·
There is compression coming from the cylinder and I was getting a reading before I hit a button on the side of the gauge. The sound is coming from the tail pipe. Almost like it is flooding while running.
 
#15 ·
If it is flooded your plugs will be wet or sooty black. They are your feed back of mixture.
 
#16 ·
If the compression isn't at least 100 or more it may not run right. Usual specs show about 180 pounds to 200 pounds.
Do you have a reliable manual?
 
#18 ·
I would say go back to get a good compression test. Crank each cylinder for 6 or 8 puffs with the throttle held open. Make sure the battery is strong too.
 
#19 ·
Firstly, I may have done it wrong with the bike sitting at idle. I will try with it wide open and see where it gets me. If the cylinder pumps out, I will be back at a stop again. Thanks for the input. Do you know of any way to test the ECM?
 
#20 · (Edited)
For Compression test the engine should not be running. Pull the spark plug wires or turn engine Stop switch off. Pull the front plug. Put your tester in and use starter for 4 to five seconds.

Compression should be about 185 psi +- 25 . If much less, pour 4mm oil in the spark plug hole and recheck. If compression rises you have a piston, ring or cylinder problem. If compression is still low you have valve problem. If compression is OK around 185 and you are getting good spark at the plug you have a fuel problem.

May as well check the rear compression also to compare and post results.


G.
 
#21 ·
Since you have a newer system than my old bike I don't have hands on experience.But if you are getting spark on front and back now the ICM,ECM must be working.
 
#22 ·
I will look in o the compression and see what happens. Thanks for all of the advise. I will post when I have an update.
 
#23 ·
If you have spark and you have compression I would guess a fuel problem. Check the plug on the problem cylinder after running the bike for a bit and see if it's wet as has been suggested. You may have to pull the carbs one more time and check your float valve on the bad cylinder if your plug isn't wet when you check it. you could also open the bowl drain on the bad cylinder to see if any fuel comes out.
 
#24 ·
You may have to pull the carbs one more time and check your float valve on the bad cylinder.
The plugs are wet but not too bad. On the Aero there is only one carb and it has been torn apart and gone through twice. If it were bad, the both cylinders should be starved.
 
#32 ·
I don't want to keep harping on the compression but it may be low and that is all it would take to keep that cylinder from running. If you do a "finger compression test" it can tell something. Try to hold the pressure on each cylinder when cranking. Compare them.

Try this simple easy test=
Shut off the fuel so it won't flood.
Drain the fuel from the carb float bowl.
Clean and dry the plugs.
Spin the engine a little to clear the cylinders.
So now it should be dry of fuel.
Then put the plugs in and try to start it. If it pops and uses all the fuel in the manifold, etc good.
Then try to start it with a little carb cleaner - short sprays.
If it starts and runs on BOTH CYLINDERS, then you know the engine CAN run properly and go back to the carb and find out why there is excess fuel.
 
#33 ·
That is something I can try swifty2014. I have a couple other methods that were posted here that I am going to try this weekend.
 
#35 ·
Did a compression test this mornig and there is no registerable compression in front cylinder. I put a little oil in and no change which leads me to think it is a valve issue. I hope I can have it done today.
 
#38 ·
I suggest you always do the compression test on both cylinders so you know what the difference in compression is (closer is better) and that you are doing it right. As mentioned, you should have some compression even with a hole in the piston or stuck valve but don't go there unless the compression test has been done on both cylinders.

G.
 
#39 ·
This is really becoming a nightmare for me. I did my compression test and tried to determine if it was the piston or a valve. After checking both cylinders, and including a drop of oil, there was no change in the pressure for the front cylinder. So I tore down the top of the cylinder. Going through forums and seeing some things online and communicating with a friend who has worked on many bikes, I have come to the conclusion hat it must be my exhaust valve. The exhaust port going to my pipes is wet on the front cylinder which would be from the fuel not fully burning. I took off the crankcase cover so that I could adjust the valves and the crankshaft hole cap is stuck. I even tried an impact and it will not budge. I did order a crankcase stater cover on ebay for $20.00. No idea what Is behind the cover when I remove it.
 
#40 · (Edited)
To clarify there are 2 covers with similar names: there is a crankcase "rear" cover and this is a plastic piece attached with a single bolt and a clip and there is a crankcase cover that is attached with 11 bolts. You do NOT need to remove the second one (11 bolts) for valve adjustment. I guess the 11 bolt cover could incorrectly be called a "stator cover".


For valve adjustment you need to have pistons at Top Dead Centre. To do this there are timing marks on the flywheel. "FT" for front cylinder and RT for rear. The crankcase cover has a mark on it so you remove the Timing Hole cap and line up the flywheel "FT" with the mark on the crankcase cover. Check that the cam lobes are facing down or rotate again counter clockwise (you need TDC on a compression stroke) In order to rotate the flywheel, you remove the Crankshaft Hole cap and that will reveal the flywheel bolt (left hand thread) that you turn counterclockwise turning the flywheel.

Basically you are removing 2 caps: the front hole you will be putting a driver in and turning while the rear hole you will be looking in to align the markings. So remove spark plugs, remove cylinder head covers, remove Crankcase Hole Cap and Timing Hole cap. Move markings to align FT and adjust Front valves. Move markings to RT and adjust rear valves again making sure cam lobes are facing down.

Not sure why your Crankshaft Hole Cap would be difficult to remove as they are only torqued to 11 ft/lbs and should be lightly greased.

But ... if your valve is stuck, bent, not seating then no adjustment will work and you need to remove the cylinder head which requires engine removal and a few special tools. At that point you at decide to remove engine and take engine in to pro or remove engine and dismantle cylinder head and take head in to pro.

G.

Perhaps take a photo or 2 so we can see what the problem is? I am a little confused that you are using an impact wrench on something. My current 750 is a 1999 DC so may be different but not that different!.
 
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