QuestionQUESTION: Jim I need some information to help resolve a problem , I have a 85 hondo Vt500c , two weeks a go I ran into an issue with the bike loading up ( I think ) this aprears to have started over night as the day before I was riding the bike , The plugs have are black and sooty , so I have been thinking choke or rich fuel , I have cleaned the plungers and I believe the choke plungers are seating . I lubed the cable and verified it's coming all the way out on chike end I have changed the plugs and the bike continues to blacken the plugs (dry sooty) ... I ran the bike this summer with no issues and this happened over night so to speak . this is on all four plugs ( v-twin ) two plugs per cylinder . The odd thing is in 1st and 2nd I have some power. I can get the bike up to about 40km when I open the throttle any more she loads up , all i here is Burr Burr Burr , but she will not shut off , when I let go throttle or pull in clutch , she will rev up I am thinnks a plugged up carbs ? poor air intake ? can you plug up carbs over night , I have cleaned out the tank checked the gas for dirt ect ...
my other question is crankcase blow off would you explain this process to me , I have taked to a few people with 83 - 86 Vt500 and they all seem to have an issue with oil in the breather , could this be part of the problem ?
ANSWER: Without knowing too much about this model I would check electrical system. Especially the condition of the battery using a voltmeter.
Crankcase pressure/blowby is normal. Usually the blowby is water vapor with a few drops of oil. I don't expect this is the cause of your problem but you can always try pulling the breather hose off the intake and plugging up the intake hole. If that fixes the problem then you have identified it.
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QUESTION: HI, thank you for the quick reply , how would the condition of the battery affect the bike while running ? There is some corrosion on the positive terminal. Additional info : The bike has no problem starting , and idles fine , The airfilter was blocked with oil, I am wondering if the carbs may be plugged up with oil/water mix , slug ??
ANSWER: If the air filter is a paper element there should be no oil. If it is a foam filter then oil is normal. The breather hose usually routes past the air filter so that oil will not usually clog the filter. I'm thinking electrical because a bike with a weak battery may idle ok but will misfire when the ignition wants to draw more juice. It's pretty easy to check. Corroded connectors can also cause this.
If you can eliminate issues with the air filter and the ignition then the carbs are suspect. Problem is that blocked up carbs usually result in a lean mixture rather than a rich mixture. It's possible that too much fuel is entering the carbs due to leaking float valves, but that would affect idle as well.
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QUESTION: The Crank case breather hose on these bikes enter on the bottom of the airbox , right below the airfiler , in diagrams that i have seen of this bike there is foam rapped around the paper airfilter , this bike does not have this , air in drawn in from under the seat throught the airfilter and then up into the air intake . there is a bit of oil always sitting on the bottom of the airbox , I was thinking that some "mess" has been sucked into the carbs and plugging up passages . However , when I purchase the bike this summer back in July I was told the battery was new last year , but that could be suspect ! Right now to get her to stay runing I have to take the airfiler out .
AnswerOK, if it runs without the air filter that's a good data point. I would start by replacing the air filter. It may be old and plugged up. Sometimes its hard to tell visually.
If that doesn't correct the problem then its most likely the carb idle mixture has been set too rich. There should be an idle mixture control screw on the carb (possibly two: an air screw and a fuel screw). You can lean out the mixture using these. On some models the idle mixture screw is recessed into the carb and covered with a small aluminum plug (to make it less accessible). Make small asjustment (1/4 turn) and wait several seconds to notice a change in RPM. Higher RPM is better. At some point more adjustments will not affect the RPM or will make it drop. You want to adjust for highest RPM and then use the throttle idle speed knob to set the RPM to a comfortable idle.
If you still have a rich mixture after this procedure, the next thing to check is the operation and setting of the carb fuel float and float needle valve. It could be the carb is filling with too much fuel and causing the rich mixture.
