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Old 10-21-2011, 07:04 PM   #1
jturn
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Default 85 Magna 700 won't run/rev right

Hi,

I've got a 1985 VF700C Magna that I'm looking to sell, but first I need to get it running right. It sat for several months in the early summer while I was on a cross-country trip on my other bike. When I got back from the trip I put a new battery in the Magna, started it up fine, and put fresh gas in it since it was running low. The last time I ran it before the past few days was about a month ago when I rode it a few miles.

The other day I went out to start it up to make sure it was still fine before listing it for sale and it started up but I can't rev it. Normally when I start it with the choke all the way open it idles around 4,000 RPMs, and without the choke it goes down between 1,500-2,000 on the odometer. Now it is running at about 1,500 with the choke open and it won't run at all without the choke. If I try to rev it at all it dies immediately. If I coax it just right I can get it to rev up into the higher RPMs and it sustains itself as long as I have the throttle open, but as soon as I let it go it drops back to 1,500 and dies when I try to rev it again.

The plugs are all sparking, and it seems to be firing on all 4 cylinders. Any guesses or advice on what I should check next? I'm moderately experienced in mechanic work but haven't done much advanced stuff and don't necessarily have a full set of tools (other than the expected drivers, sockets, etc).

Any help would be much appreciated!
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Old 10-21-2011, 07:15 PM   #2
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Plugged slow/idle jets.

You can try Berryman's B12, but you're probably looking at Carb R&R.

Good Luck, you're gonna need it........
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Old 10-22-2011, 05:41 AM   #3
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You can try Berryman's B12, but you're probably looking at Carb R&R.
Having sat idle no longer than this one has, there is a very good chance that a double dose of B12 will fix him right up.

Keep the choke on longer and let it warm up good.
Do that a few times over a couple of days with the B12 in the tank.
It would be good to drain the float bowls at least once too.

There is a stock air filter in place, right ??
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Old 10-22-2011, 05:54 AM   #4
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So just put some of the B12 (1/2 a can, maybe?) in the tank and run it like that?

There is an air filter in place but it's pretty dirty so I'm going to replace it.

Thanks for the advice- hopefully it works. I'll report back.
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Old 10-22-2011, 08:18 AM   #5
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So just put some of the B12 (1/2 a can, maybe?) in the tank and run it like that?
Don't guess. Read the directions.......PAST where they tell you to dump in the whole can, for a car.

IIRC, the standard dose is one OZ per gallon; double that to two per gallon. The can I have is 15 ounces so half a can would be about right IF your tank holds 4 gallons.

And yes, run it like that long enough to get it warm/hot.
Let it sit overnight. Drain the bowls. Run it again.
After doing that for 3 days in a row, there should be marked improvement. (not necessary to drain the bowls more than once.)

If not, you're probably looking at a professional cleaning.
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Old 10-23-2011, 06:29 AM   #6
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Thanks so much! I'm heading out to Autozone now to pick it up and will work on it later today.
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Old 10-23-2011, 06:40 AM   #7
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Thanks so much! I'm heading out to Autozone now to pick it up and will work on it later today.
Please let us know how it turns out.....PLEASE.

So many riders don't and it gets to be a little frustrating over time.
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Old 10-23-2011, 08:47 AM   #8
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So far so good, seemingly. The place I went to did not have B12 so I got Seafoam instead (the store and some friends told me they would do the same job). Ran the bike for a while and it seemed to be running a bit better after 10-15 minutes (of course that could just be wishful thinking). I'll let it all soak in overnight and fire it up again tomorrow, and will definitely keep you updated. Thanks again, and hopefully this'll take care of it!
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Old 10-23-2011, 04:26 PM   #9
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(the store and some friends told me they would do the same job).
They lied.
OK, probably not on purpose.

WalMart and every auto parts store in my town has B12.
It is a much better cleaner and is about 1/3 the price.

I would not recommending using both at the same time though.
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Old 10-25-2011, 09:56 PM   #10
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OK, status update:

After the third day of running the bike until it gets warm there does not seem to be a big difference (it certainly is still not running right). Here are some new descriptions of what's happening:

Once warm the bike, with choke all the way open, runs smoothly around 2000 RPMs. If I ease off the choke it slowly sputters, and eventually dies.

If I open the throttle at just the right instant and rate I can get the bike to run smoothly at higher RPMs. If I hold the throttle open I can also close the choke off, while adjusting the throttle, and the bike runs fine. I can then slowly let of the throttle and the bike continues running fine until about 3,000 RPMs. It starts to chug a bit at that point. It gets very sensitive as I continue easing off the throttle, and I cannot sustain it anymore once it gets down to about 2,000 RPMs.

Any thoughts? Would it be worthwhile to drain the fuel out, fill it with fresh gas and try again with B12? Should I start looking into taking it to a shop at this point, or should I just try to sell it as a junk/parts bike and accept the loss rather than paying to fix it just so I can sell it?

Anybody want to buy an almost-perfect 85 Magna?...
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