Magna V65 Wont Stay Running

[Nick56289]

Hey Everyone,

I just bought a 1983 Magna V65 and it is having some problems.  At first it will start right up but it does have some hesitation and runs a little rough and will only run with the choke on. However once you start riding it and give it some gas it will start to bog down, and then even when you give it full throttle the revs will slowly fall until the bike dies.

Here are the things I have checked:

Float bowls are full of fuel when bike dies

Reg/rectifier has continuity where it should

Battery only reads 12v at idle

Pulse generators read 540 ohms (book says it should be 480)

Anyone have any advice for me? 

Just for a little background im an engineer at a heat treat shop in california.  I love motorcycles and owned a v45 for 5 years and loved it.  So im really eager to get this thing back on the road.

Thanks!

[hootmon]

1st of all, Welcome from Tampa Bay, Floriduh...
I have a gen 3 v45, so I am not an expert on your bike... If it were a 3rd gen, I would suspect the idle jets are clogged..
Did the bike sit for a time before you got it?
Is this a new problem, or the way you got the bike?
More people will jump in...

[Nick56289]

Thanks for the welcome.  The person I bought it from said the carbs were rebuilt 6 months ago and it has been sitting since then.  I drove it home about 25 miles and it ran great at freeway speeds.  I ran some seafoam through it and that really seemed to help.  However on the ride home it started to lose power on the freeway ( even at 7000 rpm ) so I dont think that the idle jets are the problem.

It just sort of gently lost rpms until it stopped running.  Now it will start up but as soon as you actually start riding it under load it will exhibit the same problems and then not start for some time.

[Jigger]

I'm wondering if you might have a vacuum leak some were.

[Magnum Magna]

Just to eliminate something.  I believe the tank vents at the cap.
Make sure it is venting.

[Nick56289]

Ive ridden it around with the gas cap open and it still has the same problem.  However a vacuum leak is a definite possibility.  Would this cause the bike to shut down when being ridden?

[Jigger]

The more the butterflies open in the carbs. The more air she is trying to suck in. It can get to a point that the engine is going to run so lean it will conk out.

[Nick56289]

The more the butterflies open in the carbs. The more air she is trying to suck in. It can get to a point that the engine is going to run so lean it will conk out.

So are you saying that it may be a vacuum leak?

I took a look at the plugs and they are nice and brown.

  My next step is to see if the timing is off or not.  The manual says that I need a special flywheel cover to check the timing.  Is that true?

[hootmon]

I know on the gen 3's there is no adjustment to timing... If the timing is off, either you have a bad sensor or you need to replace the computer...

[Nick56289]

Right.  If the timing is off then I will know its either the pulse generators or the spark boxes.

[screamin meme]

There is no timing adjustment on the first gens.

[Nick56289]

There is no timing adjustment on the first gens.  So the manual says if you check the timing and it is out then you know it is either the pulse generators or the ignitor boxes that are failing.

I removed the carbs and the idle jets were a bit clogged.  I cleaned everything and put it back together and it ran much smoother.  No more hesitation in the low rpm's.  However after about 5 minutes of riding at load the bike still bog's down and then dies.

I have a buddy with a v65 as well.  So he is going to come by next weekend and we are going to exchange the reg/rect, ignitor boxes, and pulse generators one by one to see if we can figure out what the problem is.

[hootmon]

Any chance you have sediment in your tank and reclogged the carbs?

[Nick56289]

The tank looked clean(no rust) and I swished it out a few times with fresh gasoline while I had the carbs off.  I also installed new gas lines since mine were looking deteriorated.  But it is a possibility.  I am getting new float valves in the mail so I will check when I have the carbs out again.

But the problem seems electrical since it will run fine as long as it is idling.  It takes gas and sounds great.  As soon as you start riding it and give it some gas it starts to loose power and then shut off.  It also has a hard time starting after that.  As soon as it cools off it starts and runs great again.

[L J VFR]

Sounds like could be bad ignition boxes. (Ignitor boxes)

http://www.advrider.com/forums/showthread.php?t=437569