1985 VF500 maintanence/tune up

Hey everyone,
starting a thread to try and keep myself organized with the work I will be doing to this bike. So far I have removed the seat, side covers and tank. The PO told me the gas in the tank was old, so I will be draining it and disposing of it. The problem with the bike is it will start instantly and will idle (albeit at a pretty low rpm) but as soon as you give it some throttle it dies. I decided that the carbs were most likely to blame so I'm in the process of removing them. Also, I would just like to say that compared to my vintage air cooled Yamaha, this bike is a total bi%@# to work on! I was able to remove the airbox cover and access the air filter, which looked pretty good. Am I supposed to just pry up on the airbox to get it out of the way or is there some hardware holding it in? I cant see anything and the clymer manual I downloaded doesnt seem to point out anything holding it in. Any tips or pointers are greatly appreciated. I also have just ordered a new air filter, oil, oil filter, coolant and spark plugs. Should prob change all the fluids and get that done as long as I have the carbs off. Will also adjust the valves while I have the ease of access. Thanks in advance for any help.

 

The air box is held on to the metal base by two screws just behind the filter lid. Unless you plan on a complete carb disassembly (necessary to replace the fuel and air tube o-rings) , do not remove the metal air box base from the carbs, pull the base and carbs out as a unit. If you do a complete disassembly, you will need plenty of patience, a good measure of manual dexterity.

 

thanks for that. Yeah, I finally got the airbox out of the way and saw those half-circle shaped brass pieces that are sandwiched between the metal airbox and the carbs. Boy, did I try to get them loose. But luckily, I decided it would be better to remove the carbs with the metal part still attached, then I saw this post. Guess I dodged a bullet and actually did the right thing! In the end I got the carbs and all the linkages and smog crap off and sitting on my work bench. Tomorrow, I will pull off the float bowls, check all the jets, and pull off the top caps and make sure the diaphragms arent ripped and are working.

 

cleaned the carbs, then got them back on. what a pain. Tried starting it, but it doesnt want to. I think I read something about the jumping the fuel pump to prime the carbs for startup? Oh well, will check on it tomorrow.

 

Yea, basically you just unplug the relay and short the two wires with a paperclip or something. Once the pressure builds up, it will automatically stop pumping.

 

OK, so I got it to start, but it won't run without the choke, even after ts warmed up. And the rpms are pretty erratic which makes me think there is a leak somewhere. The idle speed screw was bent so I had to readjust it, but I can't seem to find the sweet spot.

 

just got done working on it some more. I drained all that crappy gas out of the tank and put in some brand new 91 octane which it really seemed to enjoy. I was able to back off the choke a little and it would actually idle for more than a few minutes. so far, I still cant get it to idle without the choke on even when it has warmed up. Will not connecting the smog lines and whatnot correctly cause these issues? The idle still likes to bounce around. Any suggestions are welcome.

 

If you plugged up the smog correctly, you should not have any issues. basically let the vents vent to open air, and the vacuum plugs on the top of each of the carbs can be linked together. Then just plug up the bottom vacuum port, and you're golden.

I know the carbs need to be synced in your case, if you have not done so already. The pilot circuits are probably still clogged. How in-depth did you get with your carb clean? These pilot circuits are some of the hardest to clean I have seen. Does adjusting the idle screw help change anything? Have you messed with your pilot screws?

 

well, I removed the carbs and pulled all the pilot circuits. I sprayed them with carb clean and blew them all out to get rid of any gunk. I did notice when I was cleaning them that they seemed to hold onto anything you put in them. Like the surface tension of the cleaning fluid or old gas was really stuck in there, so I ran a wire through them to get it all out. I'm thinking maybe I should just pull them again and make sure they are completely clean. Would I need a carb sync even if I didnt mess with the tuning screws? I will go through all the smog stuff as well. Will search on how to remove it, as well as removing the fuel pump and get a new filter on there. You wouldnt happen to have any pics of the smog tubing or how its routed would you?

 

Took off the carbs again. Blew out all the slow jets with carb cleaner and then ran a wire through them. Blew them all out with compressed air, got them all back together and reinstalled. Changed the fuel filter and got rid of the fuel pump. Changed the oil and filter. Swapped out all the plugs. I also decided to get rid of all the CA smog crap and i capped all the lines coming out of the float bowls exept the vents. What a difference, bike started up and ran really well throughout the rpm range. I even put the seat on it and rode it around a little. Now I have a new problem. When it starts to heat up, it doesn't like to hold an idle. It will want to stop unless you keep giving it gas, but eventually that won't even work anymore and it will die. Trying to restart it does nothing. Any ideas? I was thinking that maybe I didnt cap off the smog stuff like I should. I took some pics

The first two pics are off the lines that I capped. The last two are of the line that I left open. From what I have read in the manual and off the site, this must be left open so the floats will be able to vent and allow fuel to enter.

 

so, since my last post I have put about 20 miles on the bike with no problems at all. I think that what was happening was that as soon as the engine got hot at idle, it was vapor locking the fuel in the line. I got all new fuel lines with the filter and ran them a little too close to the left rear cylinder head and it was getting too hot. I let it cool for the night and the next day it started right up. I wrapped the line in some heat shielding material and so far, I'm loving this little bike! Definetely alot peppier than I expected. Was thinking about flipping it for a quick profit, but now...I dont know....maybe if I can flip it for another vf700 or vf1000 that needs work. Or I could just keep this one. Decisions...

 

Glad to read about your successes in get a vf500 running smoothly. I'm in the final process of putting the engine back into a vf500 that had the engine and radiator removed. I'm having some trouble figuring out how some of the final hoses, cables, and wires should be connected. Maybe you can help me since you have a running bike. The first issue is I can't for the life of me figure out where the negative battery cable (ground) should be connected to the frame or engine. Would you post a pic or describe where the cable is connected? The other items I can't figure out fully are the hoses for the crank case ventilation system and whether there are two hoses connected to the coolant reservoir tank or just one. I'll post some pics or a video of some of the issues I am having later tonight to make it clearer for anyone trying to help me

 

yeah I will try and get some pics up for sure. I dont think the breather lines are the same on your bike, as mine is(was) the CA model which had all kinds of stupid smog crap on it. I got rid of all of it, so maybe that will make it easier for me to help you. I think the negative cable connects to the engine crankcase on the right rear side of the engine as your sitting on it. Not 100% though, but I'll check.

 

Thanks, I just started a new post that has pictures and descriptions of the three final details I'm stuck on. The post is titled, "1986 VF500 Rebuild: Please Help Me with Final Details" Check it out if you have a chance and please give me your insight on the final 3 details.