1985 VF500F - Making it Run Again - Need advice!

I have an 85 VF500F that I just got done rebuilding the carbs on. Pretty sure I have them done correctly.

I had to rebuild because a chipmunk or other small rodent set up camp in the air intake and was peeing down the #1 carb, ruining it. I bought a new carb body for #1 and all new float valves, pilot jets, gaskets, fuel and vent tubes, vacuum slide boots etc from Billy's Outback.

I have the floats set correctly, bench sync'd the carbs etc.

The bike starts and idles well. The problem I have is it doesn't rev for crap. It will get to the higher RPMs, but it seems rather "soggy". I have not yet done a compression or leakdown test. That is next.

All of the plug wires and coils are original, but I did re-terminated one of the wires just to check if it made a difference. I also replaced the front two spark plugs so far.

As for the soggy revs, it doesn't seem crisp. All of the vacuum slides are working correctly BTW.

Could there be something in the ignition that I need to address? I don't know crap about this bike.

Can't tell if it's electrical or vacuum related.

Here's a video of it running:


Any feedback would be appreciated!

 

Hello, seams to me you have a vacume leak because the revs come down too slow. What is the condition of the carb boots?
also, a proper introduction would go a long way with this forum group

 

Also, with stock jetting, VFs really dont run properly with out the air box and filter installed.

You can't truly evaluate anything running it like that. It is ultra lean.

 

Ha, I guess I should've started there!

New to the forum, obviously. New to these bikes. Very familiar with carburetion in general, but only single cylinder/carb bikes.

I did replace the carb boots as well, assuming that the hose clamps don't need to be overly tight? I will put the air filter housing on and see how that affects the running condition.

 

Literally hose clamps or are you just referring to the OEM insulator clamps?

 

Air filter housing WITH a good filter

 

Here is with the air filter housing on:

Has a hanging idle and bogs.
Starts pretty easily without choke. Generally idles well.
It's about 70 degrees F.

 

Sorry I meant the OEM carb boots and OEM clamps!

 

No idea why the video is upside down!

 

What are your air screws set at ?


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Are all 4 exhaust getting hot. Sounds like 3 cylinders. 500 V4s are electric smooth.

With stock exhaust and airbox on, the original jetting should be good.

Have you REPLACED the spark plugs?

 

I fucking CHASED MY TAIL recently on a VF1000R. I knew my jetting should be perfect, I've done enough of them. Was about ready to jet up again and already bought the jets. Then I replaced the plugs.... fuck. Idiot. This is a fairly new to me bike and I knew the previous owner, but I didn't do my due diligence. And paid a summer of dealing with not-quite-right because of it. The last real ride I went on it was a completely different bike, and it was already pretty damn good.

 

Good suggestion Cap… i believe he did the front plugs but not the rear


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Yes. Did you account for all of the parts when you had them out? Still sounds like 3 cyl to me.

 

you know better than that. fuel screws, not air screws on VFs and VFRs.

if nothing gets it running on all 4, time to consider a faulty "CDI" box.

 

I can't recall now on the screws, but it was what the stock setting is. either 1.75 or 2 turns out. I will get the rear plugs finished and also double-check the wires.

I am 99% sure that all cylinders are firing but will measure the temp on all 4 after replacing the rear 2 plugs.

 

I didn't have my coffee yet....

 

OK - I removed the coils to test them out... I am a little confused on the resistance testing of the coils... I believe that the two tests are ground to each of the two tab connections and also ground to each of the spark plugs. When I test ground to the tabs, I get nothing. Same for the plug wires.

I am using a good multimeter with auto range.

 

I was speaking to the guy that I got the bike from. He had it in the shop to have some (3) seals replaced, due to oil leaks under the bike. He says that it never ran right since. Had no power, probably similar to what I am experiencing. Could he have damaged the stator in some way? I bought a service manual yesterday so I can stop asking dumb questions!

 

What’s a dumb question?
Always good to ask ….


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