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Post by pyrobooster on May 28, 2012 19:58:31 GMT -5
Problems:
First problem is the bike has to warm up for a full ten minutes on full choke before I can get into first without it dieing.
Second, which I think is related to the first but not sure, after about 20 or 30 minutes of riding really nice, the bike begins to loose power on acceleration, bogs at idle and in acceleration, backfires occasionally, and dies when accelerating from a stop.
Bike info:
My bike is either a 79' or 80' "special 650". The sticker says it was manufactured in Sep. or Oct. of 1979, so I assume its a 1980. I just got it back from the mechanic who did a carb service and got it running. I hear the 1980's had a restrictive main jet that made it run lean for emissions control reasons and this may be part of the problem. It is 100% stock other than that.
I'm lost and out of cash for the mechanic, anyone have an idea what is causing this problem?
Thanks in advance, love this forum.
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Post by XS Rod on May 31, 2012 13:40:56 GMT -5
I'll cast my 2 cents...
The carb dude needs to revisit the carbs... IMO
You may possibly have a battery charging issue too...
Need more info... do you end up pushing it home or what? Last thing you said was it dies on acceleration after 20-30 minutes of driving.
Need more story.
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Post by headcase on May 31, 2012 19:06:43 GMT -5
Too lean is only good for steaks and supermodels. Scope the plugs out, see what kind of pretty colors are showing up. Hopefully silver isn't one of them.
If you can manage to get the carbs off and apart without trashing the gaskets, you can probably cure what's ailin' ya at no cost except for the time you put into it. Does yours have idle mixture adjustment screws? Not familiar enough with them to know much other than the urinals on my '79.
Oh, and clean the tank. Then clean the lines. Then clean the carbs again. And put it all back together with a filter or two. Otherwise you'll get REAL good at popping everything off and on.
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Post by grizld1 on Jun 1, 2012 11:16:12 GMT -5
Why is it that the human brain seems to be hard-wired to blame everything on the fuel system when the engine misbehaves?
You may or may not have a carburetor problem. If you haven't checked and adjusted cam chain slack and valve clearance, inspected compression, and checked the ignition system for defects in wiring, connectors, switches, and coils, this would be a good time to do so.
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Post by Tom Graham on Jun 2, 2012 10:06:22 GMT -5
There may be more than one problem. When you start the bike from cold and remove choke does one cylinder cut out? Will the bike idle on one cylinder but not the other? What I'm wondering is if the idle jets have dirt in them. Don't think because they were clean once that a tiny speck of dirt can't get sucked into the jet. The '80 had BS34, if the plugs were removed from over the mixture adjustment screw you may be able to remove that screw and spray carb cleaner inside and blow the dirt out of teh idle jet. Check the carb mounts to be sure there isn't an air leak which will do sort of the same thing.
A plugged gas tank vent can have a bike acting a little funny after about 30 minutes as the vacuum in the tank gets to be strong enough to stop the fuel flow to teh carbs. I can't remember having that happen to me but a friend has been plagued more than once. Use as clean container to drain the tank through the petcock and see if there is a flow restriction. Use something like a MityVac to open the petcock just like the bike is running.
There are a few ways that the charging system goes bad. The most likely is the brushes are worn so the battery doesn't get enough current to charge up. It slowly goes dead. The rotor also shorts out it's windings. That is a common problem and the rotor needs rebuilt/rewound.
Those three areas are where I would look first given what you said.
Tom
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