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Discussion Starter · #1 ·
Hey guys, hope this isn’t too long, but I’m going to drop in my notes from the past couple days. Currently the bike is a little outside of town and I’ve been troubleshooting an unknown issue. I’m running out of ideas, so hopefully this makes sense to someone.


Rode fine in twisties. Pulled into highway speeds, first time over third, and engine started overheating and losing power.
Then it would idle and rev fine but would return to no power after clutch lever let out.
A day later it will crank but rarely turn over. Spark plugs say the front cylinder is rich, rear looks okay. This should be because I degoated before this ride and the rear pipe is a lot shorter.
Spark plugs were wet when checked, engine flooded from starting all day. Oil res smells like gas.
I figured a roadside fix for the rich condition would be to chop the front pipe at the same length, so I did that instead of rejetting.
Next day will fire after oil change and cleaned plugs but very rough idle, max 15 sec.
Plugs have a little carbon buildup, but they’re the same and dry


(This is the bikes first big ride in months and first ride since degoat)

(earshave with uni filters, 40/42 no shims, riding at 5000ft plus)
 

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2003 VN750
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Hey guys, hope this isn’t too long, but I’m going to drop in my notes from the past couple days. Currently the bike is a little outside of town and I’ve been troubleshooting an unknown issue. I’m running out of ideas, so hopefully this makes sense to someone.


Rode fine in twisties. Pulled into highway speeds, first time over third, and engine started overheating and losing power.
Then it would idle and rev fine but would return to no power after clutch lever let out.
A day later it will crank but rarely turn over. Spark plugs say the front cylinder is rich, rear looks okay. This should be because I degoated before this ride and the rear pipe is a lot shorter.
Spark plugs were wet when checked, engine flooded from starting all day. Oil res smells like gas.
I figured a roadside fix for the rich condition would be to chop the front pipe at the same length, so I did that instead of rejetting.
Next day will fire after oil change and cleaned plugs but very rough idle, max 15 sec.
Plugs have a little carbon buildup, but they’re the same and dry


(This is the bikes first big ride in months and first ride since degoat)

(earshave with uni filters, 40/42 no shims, riding at 5000ft plus)
Where you said it would idle and rev fine but lose power when you let the clutch out. Were you able to get moving? That sounds like the kickstand switch if you couldn't get moving.

Sounds like it's flooding.... Does the vacuum line for the petcock have gas in it?
 

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Discussion Starter · #3 ·
I couldn't get moving, I thought it was maybe a failed kickstand switch but I think I was able to rule that out. Its definitely flooding, I'll check the vacuum line. If it has fuel in it what would that mean?
 

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I couldn't get moving, I thought it was maybe a failed kickstand switch but I think I was able to rule that out. Its definitely flooding, I'll check the vacuum line. If it has fuel in it what would that mean?
Gas in the vacuum hose means a bad diaphragm in the petcock. It will leak gas into the throat of the carb, then gas will run into the cylinder and fill up the crankcase with gas., even when not running.

Since the petcock vacuum is usually connected to the front carb, the front cylinder will be rich.
 

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Discussion Starter · #6 ·
Got the bike trailered back. vacuum line didn't have gas flowing through it or anything (petcock was left in off position if that matters). the side connected to the petcock was dry, but the carb side had some gas around it, and the brass fitting on the carb was wet too. cant remember if thats normal or not.
 

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2003 VN750
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Got the bike trailered back. vacuum line didn't have gas flowing through it or anything (petcock was left in off position if that matters). the side connected to the petcock was dry, but the carb side had some gas around it, and the brass fitting on the carb was wet too. cant remember if thats normal or not.
No, there shouldn't be any gas in the vacuum port. Though I'm not sure that's causing the running problem.

You might check the line again after trying to get it started. It shouldn't be wet anywhere.
 

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Got the bike trailered back. vacuum line didn't have gas flowing through it or anything (petcock was left in off position if that matters). the side connected to the petcock was dry, but the carb side had some gas around it, and the brass fitting on the carb was wet too. cant remember if thats normal or not.
Probably some dirt in the carb bowl has the float stuck open. Whack it a couple of times.
 

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Discussion Starter · #9 ·
tried to start it the other day, no gas in vaccuum, but it floods really easily. stuck float makes sense, I'll try later this week, might pull them just to be sure
 

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2003 VN750
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tried to start it the other day, no gas in vaccuum, but it floods really easily. stuck float makes sense, I'll try later this week, might pull them just to be sure
Much of the time, gentle tapping on the sides of the carb can free a stuck float.
 
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