VT1100C front cylinder not running at high speed - Honda Shadow Forums : Shadow Motorcycle Forum

Monterey10 · 11-06-2012, 08:57 PM

New to me, used 2004 VT1100c Spirit. Got it for a low low price because it looks like it was run through a cow pasture. Each part I clean shines, so there is Some hope.

The guy I bought it from thought said the front cylinder wasn't firing. He said he cleaned the carb. The bike starts easy, runs at low RPMs very well..(even up to 65 mph) As soon as the throttle is opened for hard acceleration (and higher revs), the front cylinder quits firing. It acts like the throttle is being closed on the front cylinder.

Both cylinders seem hot. At idle, the front cylinder has an occasional cough. The front spark plug was black.

I cleaned the carbs and fixed two minor issues. A restart and the bike runs smoother, but on hard acceleration the front cylinder still shuts down.

The only other thing to mention is that the front cylinder has a little more tappet noise than the rear cylinder.

I am open to suggestions on what to check next. I would guess the fuel pump and filter, then check the coil. This bike has the evap smog. I should probably check the routing of the 6 vacuum lines. What confuses me is how willing the bike starts, and pulls away from a stop. As long as I'm chugging, it runs. Open it up and Nunnnnn (Back cylinder running by itself).

Thanks in advance for your ideas.

knucklebuster69 · 11-06-2012, 09:44 PM

The first thing I'd check is compression. Check both cylinders and make sure that they are no more than 20 lbs. apart. If that checks out, then i'd have to say verify the coil issue. Then move on to the carbs. Make sure that the fuel enrichening valve (choke) is working properly. You may need to go through the carbs again. Also, it may be beneficial to run a can of seafoam through it. Hang in there and good luck.

finjoey · 11-06-2012, 10:28 PM

After you check the carbs ( float ) You may want to check your out put on your fuel pump...

Monterey10 · 11-06-2012, 10:54 PM

The first thing I've checked is the carbs. Next will be the fuel pressure. I'll check the coils, but the bike gets good ignition up to high speed, then it drops. The bike is generating a lot of power even with the problem. Hard to imagine that it has a compression problem. But, I'll check it.

marcham · 11-07-2012, 12:41 AM

Agree, check compression first. Engine needs to be at operating temp before you check it.

Have you checked and swapped the plugs?

Swap the ignition coils front to back. If it was fuel pressure, you'd have problems with both cylinders.

Remember to only test/change 1 item at a time between rides.

Spark plug troubleshooting guide: http://www.aa1car.com/library/cm1196.htm

Both or just 1 front spark plug was black? Was it wet or oily?

Please measure the battery voltage at varying RPMs and report back.

Has the carb ever been re-jetted?

Do you have the OEM service manual?

Do you have a tach, torque gauges, multimeter, compression tester, etc...?

Monterey10 · 11-07-2012, 12:52 AM

I have the testing tools and two shop manuals. I'll see how much I can check tomorrow.. Then I'm working for a week.

93gc40 · 11-07-2012, 11:48 AM

Carbs in sinc? Test ignition resitance and charging system output, inspect coil for cracks.

Monterey10 · 11-07-2012, 09:12 PM

I followed the gasoline down to the filter, replaced the filter, followed the gas up to the Y and then checked the flow at the carbs. The fuel pump filled a wine bottle fairly quickly on each branch of the Y. So, I know the gas is making it to the carbs. With the carbs exposed, I started the engine and watched the CV pistons. Both rose equally. BUT, the front carb had gas hissing out the main jet. The back carb HAD NO GAS coming out of it. It was dry. I tried opening the carb drain on the back carb and gas came out. So, I know the gas is getting to the float bole, but not coming out the main jet. (?)

The funny thing is that I cleaned this carb yesterday and I swear the Main jet was wide open. It's an easy one to clean in that It's a big one. I've pulled the carbs and will scrutinize the main jet on the back carb tomorrow.

Is there any other reason the main jet wouldn't produce gas? I want to do a thorough job tomorrow when I open it up (again)

Thanks in advance.

Kitulu · 11-07-2012, 11:21 PM

I thought the main jet only had gas flowing when the throttle is opened?

Sent from my DROID RAZR using Motorcycle.com Free App

Monterey10 · 11-07-2012, 11:41 PM

I cracked open the throttle and the carb CV pistons jumped evenly as the big cylinders breathed.

11-06-2012, 08:57 PM	#1 (permalink)
Monterey10 Junior Member Join Date: Nov 2012 Location: Capitola Village CA Posts: 22	VT1100C front cylinder not running at high speed New to me, used 2004 VT1100c Spirit. Got it for a low low price because it looks like it was run through a cow pasture. Each part I clean shines, so there is Some hope. The guy I bought it from thought said the front cylinder wasn't firing. He said he cleaned the carb. The bike starts easy, runs at low RPMs very well..(even up to 65 mph) As soon as the throttle is opened for hard acceleration (and higher revs), the front cylinder quits firing. It acts like the throttle is being closed on the front cylinder. Both cylinders seem hot. At idle, the front cylinder has an occasional cough. The front spark plug was black. I cleaned the carbs and fixed two minor issues. A restart and the bike runs smoother, but on hard acceleration the front cylinder still shuts down. The only other thing to mention is that the front cylinder has a little more tappet noise than the rear cylinder. I am open to suggestions on what to check next. I would guess the fuel pump and filter, then check the coil. This bike has the evap smog. I should probably check the routing of the 6 vacuum lines. What confuses me is how willing the bike starts, and pulls away from a stop. As long as I'm chugging, it runs. Open it up and Nunnnnn (Back cylinder running by itself). Thanks in advance for your ideas. Last edited by Monterey10; 11-06-2012 at 09:04 PM.

11-06-2012, 10:54 PM	#4 (permalink)
Monterey10 Junior Member Join Date: Nov 2012 Location: Capitola Village CA Posts: 22	Carbs The first thing I've checked is the carbs. Next will be the fuel pressure. I'll check the coils, but the bike gets good ignition up to high speed, then it drops. The bike is generating a lot of power even with the problem. Hard to imagine that it has a compression problem. But, I'll check it.

11-07-2012, 11:48 AM	#7 (permalink)
93gc40 Senior Member Join Date: Nov 2008 Location: Visalia, CA Posts: 4,360	Carbs in sinc? Test ignition resitance and charging system output, inspect coil for cracks. __________________ 93 VT1100C Harley Killer (1150cc), VH Exhaust, 2mm sleeved and bored, Modified Heads and Valves, Adjustable Timing, Touring Seat, Baby Apes, Metzlers

11-07-2012, 09:12 PM	#8 (permalink)
Monterey10 Junior Member Join Date: Nov 2012 Location: Capitola Village CA Posts: 22	Day #2 I followed the gasoline down to the filter, replaced the filter, followed the gas up to the Y and then checked the flow at the carbs. The fuel pump filled a wine bottle fairly quickly on each branch of the Y. So, I know the gas is making it to the carbs. With the carbs exposed, I started the engine and watched the CV pistons. Both rose equally. BUT, the front carb had gas hissing out the main jet. The back carb HAD NO GAS coming out of it. It was dry. I tried opening the carb drain on the back carb and gas came out. So, I know the gas is getting to the float bole, but not coming out the main jet. (?) The funny thing is that I cleaned this carb yesterday and I swear the Main jet was wide open. It's an easy one to clean in that It's a big one. I've pulled the carbs and will scrutinize the main jet on the back carb tomorrow. Is there any other reason the main jet wouldn't produce gas? I want to do a thorough job tomorrow when I open it up (again) Thanks in advance.

11-06-2012, 09:44 PM	#2 (permalink)
knucklebuster69 Member Join Date: Jul 2012 Location: Stanwood, WA. Posts: 83	The first thing I'd check is compression. Check both cylinders and make sure that they are no more than 20 lbs. apart. If that checks out, then i'd have to say verify the coil issue. Then move on to the carbs. Make sure that the fuel enrichening valve (choke) is working properly. You may need to go through the carbs again. Also, it may be beneficial to run a can of seafoam through it. Hang in there and good luck.

11-06-2012, 10:28 PM	#3 (permalink)
finjoey Member Join Date: Oct 2012 Location: Baltimore Maryland Posts: 77	After you check the carbs ( float ) You may want to check your out put on your fuel pump...

11-07-2012, 12:52 AM	#6 (permalink)
Monterey10 Junior Member Join Date: Nov 2012 Location: Capitola Village CA Posts: 22	I have the testing tools and two shop manuals. I'll see how much I can check tomorrow.. Then I'm working for a week.

11-07-2012, 11:21 PM	#9 (permalink)
Kitulu Senior Member Join Date: Sep 2010 Location: Tennessee Posts: 576	I thought the main jet only had gas flowing when the throttle is opened? Sent from my DROID RAZR using Motorcycle.com Free App

11-07-2012, 11:41 PM	#10 (permalink)
Monterey10 Junior Member Join Date: Nov 2012 Location: Capitola Village CA Posts: 22	I cracked open the throttle and the carb CV pistons jumped evenly as the big cylinders breathed.

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