Take the long way home
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2002 magna(Read 4019 times)
2002 magna on: November 19, 2019, 10:23:16 PM
About a month ago I changed the air filter. I made sure I was low on gas to ease the task.
Since I bought the bike there's been a flat spot at about 1500-2000 rpms. After the filter change I was at a light and when it changed the bike died when I gave it gas. Got it to the side and it seemed to be flooded, but no gas smell. My gas vent isn't impeded and the fuel line is flexible. I thought maybe something got dislodged while handling the tank. So I put some Seafoam in it. Then drove 15 miles home. Put thirty miles on it today. Tank was full, put 3ozs. of seafoam in it. There is a miss that I can't detect all the time, but I think it may be in the right front cylinder from the sound of it.
All pipes will boil water after warming up. I reached 5200 rpms for a few seconds but it runs rough between 1500-3000 rpms. I have ordered a set of plugs.
Wondering what you guys might think of this situation.

 
2002 vf750c



Re: 2002 magna Reply #1 on: November 19, 2019, 11:17:10 PM
Double check the vacuum line on the right side going to the fuel shut off valve..
Maybe you have a leak and it is not fully opening the diaphragm, or the diaphragm might have a pin hole in it..
This is only one possibility, you could bypass the shut off and see if the problem changes...
The flat spot is pretty normal on a stock set up.. Adding a shim to each needle helps...
Does it run better with the choke on?? IF so, you might have gotten some trash in the slow speed jets.. Keep up with the seafoam..
"accidents aren't predictable, don't be a DUMBASS" - MD Dan



Re: 2002 magna Reply #2 on: November 20, 2019, 08:55:19 AM
 It's warm here so the choke isn't needed, but I'll check that.
It's odd to me but it idles just fine, but gets rough at 1500 rpms. That lasts 'til about 3000 then the problem is overridden by sheer volume. But it just isn't quite right, I can tell by the sound.
Waited for a while and cranked It and it started right up, but there's like a miss that's not consistent, but definitely on the right side.
Thanks for the help.
2002 vf750c



Re: 2002 magna Reply #3 on: November 21, 2019, 12:44:58 PM
I would suspect a clog in one or more of the jets/needles, or a leak in a diaphram.  When mine clogged up one time, I could start it and run at idle, but almost any throttle would kill it.  Keep trying seafoam, but may require a jet cleaning operation. 



Re: 2002 magna Reply #4 on: November 22, 2019, 08:25:42 AM
I've been helping a friend recover from knee replacement , so haven't been home. By fuel shutoff do you mean the petcock?
I'll be back home this afternoon and hope to get to it.
2002 vf750c



Re: 2002 magna Reply #5 on: November 23, 2019, 01:52:29 PM
40 degrees here, started with the choke. Ran fine at first after warmup, but was dying at 2k rpm. After staying with it I got it to run but still not good from 1500 to 3000 rpm.
I'm going to take the tank off and check all hoses and wires.
I haven't started it since Tuesday.
I also learned that knee replacement isn't fun. Seems to be a painful recovery.
2002 vf750c



Re: 2002 magna Reply #6 on: November 24, 2019, 08:50:25 PM
I've been helping a friend recover from knee replacement , so haven't been home. By fuel shutoff do you mean the petcock?
I'll be back home this afternoon and hope to get to it.
NO.. If you follow the fuel line from the tank it goes to a disc looking device (Vacuum shut off) on the right side of the bike. That device has a fuel in hose, fuel out hose, and a vacuum line that runs to the front cylinder right by the faux airbox on the right side.
"accidents aren't predictable, don't be a DUMBASS" - MD Dan



Re: 2002 magna Reply #7 on: November 25, 2019, 09:25:27 PM
NO.. If you follow the fuel line from the tank it goes to a disc looking device (Vacuum shut off) on the right side of the bike. That device has a fuel in hose, fuel out hose, and a vacuum line that runs to the front cylinder right by the faux airbox on the right side.
[/quote]

I found it. I ordered a diaphragm repair kit. I have a Honda Service Manual and owners' manual, but they ignore It  for the most part, and call it something else.
The bike starts fine and runs smooth with the choke out, even idles ok once it warms up. Something I've never noticed before is that as it warms up the idle speed picks up until it hits 1000 rpms, which is what always has been the idle speed.

I appreciate You taking time to answer.
2002 vf750c



Re: 2002 magna Reply #8 on: November 26, 2019, 05:09:47 AM
Other then the vacuum shut-off most everything fuel related is dirty carbs, I haven't read through these post, maybe I should, if this doesn't do  it pull the carbs and clean well including pulling the jets and cleaning them and all the circuits.
Terry

My mama always told me never put off till tomorrow people you can kill today.

Allen, TX.

74 GT750 - 75 GT380 – 01 Magna - 03 KX 250-01 – 04 WR 450 - 74 T500 Titan



Re: 2002 magna Reply #9 on: November 26, 2019, 07:36:31 AM
I 'm hoping to avoid the can of carb worms. But if I have to I will. I am not a big fan of wrench turning, but will do it when necessary. Guess I need to buy a carburetor tool anyway. I should have the diaphragm Friday.
Thanks for responding.
2002 vf750c



Re: 2002 magna Reply #10 on: November 26, 2019, 08:45:50 AM
What carburetor tool are you going for, Bobbalee?



Re: 2002 magna Reply #11 on: November 26, 2019, 01:14:36 PM
What carburetor tool are you going for, Bobbalee?
I have seen more than one, but motion pro is the one I may buy.
The tool is a 90 degree small socket wrench. The socket required is a "D" shaped one. If you search Amazon you should find them.
2002 vf750c



Re: 2002 magna Reply #12 on: November 26, 2019, 08:44:24 PM



Re: 2002 magna Reply #13 on: December 02, 2019, 10:40:06 AM
40 degrees here, started with the choke. Ran fine at first after warmup, but was dying at 2k rpm. After staying with it I got it to run but still not good from 1500 to 3000 rpm.
I'm going to take the tank off and check all hoses and wires.
I haven't started it since Tuesday.
I also learned that knee replacement isn't fun. Seems to be a painful recovery.
So, is it running fine over 3k rpm's?  If so, it's not the shutoff diaphragm, as that would affect high rpms even worse.  If it is running ok at +3k, then it really sounds like the needles or needle jets as the CV carbs fuel flow goes from pilot, to mid to main circuits.  Sounds like your mids are gunked.



Re: 2002 magna Reply #14 on: December 05, 2019, 11:07:16 AM
Before I jump into the carburetor cleaning, do you think I should have a carburetor rebuild kit on hand? The one I mean is the one with gaskets and o rings.
The bike has 43,374 miles on it.
I have a sonic cleaning tank and tiny brushes, along with carb cleaning spray.
Thanks to Greg for the tips he published here, that's helpful to someone who has never pulled Magna carbs.
Rejetted my Suzuki so not a complete stranger.
2002 vf750c