84 Honda Magna 700 problem?

What's the weather like when this happens? Humid and 50's or cooler? Carb icing.

The venturi in the carbs cool the air down as it speeds through and can result in freezing the water vapor. This tends to happen at constant throttle (highway riding) more than changing throttle. Not a whole lot can be done about it unfortunately. In areas where conditions are ever present, you can buy carb-heater to keep them ice-free, but most areas of the US only deal with these conditions for a few weeks/month out of the year.

This Site Might Help You.

RE:

84 Honda Magna 700 problem?

i have a 84 honda magna 700. Ive been having some issues with it and im getting differents answers from people. i bought the bike about 3 weeks ago and untill about a week ago it was running fine. recently i have been driving it and about 10 to 15 mins into my ride it will bog down and act like it...

If the bike is going down the road it has been my experience that when there is an electrical problem the bike will just shut off,bam its done.When there is a fuel problem the bike will make a "baughhh noise when you twist the throttle and then slowly die. With what you described it almost sounds like a dual problem.Try opening the gas cap and go for a ride with it opened up,if it runs good then you have a plugged vent line or a plugged fuel filter which won't allow the correct flow to keep up with the demand. You can check the vent line by blowing some air into it and if it is ok you will hear it coming out inside the tank.You can check the flow of the filter by taking the hose off on the out going side of it and it should run out pretty good.If it doesn't replace the filter and if it still doesn't clean the screen in the bottom of the petcock.Now if the bike dies with the gas cap opened and then re starts 15 minutes later then I would suspect a ignition coil problem -when the coil cools down it will re fire .

Had about the same problem with my 82 Magna, Turned out the fuel filter, right next to the fuel pump (tucked way under the battery case) was almost clogged up with rust. Some how every time the bike stopped, and I waited a couple of minutes, enough fuel accumulated again in either the filter or the carb bowls that I could start the bike and go for a few kilometer and then it would shut off again. Went on for about ten times until I finally made it home.

When I finally figured it out, I back flushed the fuel filter, and problem solved.

A lot of answers, but I think guardrail jim is the only one that close and I think he's missed it as well. Not the ignition coil, but the pulsing coil (I think that's what Honda calls them). The letting it set for 20 minutes and then it runs fine for a bit before doing it all again tells me that's the problem. I've had the exact same problem a couple of times on my Kaw over the years (actually decades). Yes, I've had ignition coils start cutting out after getting hot, but more often than not, they also started hard before hand. My experience has been that I've had a lot more coils fail by misfiring than by dying completely, and just temporarily. Most often, once the coil died after getting warmed up, it was dead, never reserrecting itself again.

As to the tach quitting, that's actually quite simple. Electric motorcycle tachs read the ignition pulses of the coil, when the coil stops firing, the tach goes dead. As to having to give it choke, that can also be explained. The weaker the spark is, the more perfectly the fuel-air ratio has to be. A good healthy spark can fire some pretty crappy mixtures, both too rich and too lean.

Reads like an dirty in-line fuel filter or a venting problem. Try running with the gas cap opened.

Symptoms of a defective coil.

Immediately check for spark with a known working spark plug when the engine will not run.

gummed up valves, try to keep it running while spraying in a can of carb. cleaner.