Peer Pressure 1986 VFR700

There are quite a few differences, some more apparent than others. But you can run 86 carbs on a 84/85 engine and vice-versa. My race bike with 85 carbs started with an 86 engine and currently has an 84. Floated a valve and mushroomed the stem on the 86. Still ran great and won a race on that engine, but it was pretty "ticky". Thought I needed to adjust the valves... got to what happened to be the very last valve before I found it. Well, shit.

Ran my fastest lap with the 86 motor, but the 84 sounds better (nastier) with my exhaust. The cam timing is different from the 84/85 to 86. The 86 has line-bored heads. Look for the half moons in the valve cover gaskets.

And any talk of certain year frames not taking other year engines is not correct. I've mixed-n-matched everything. Every frame is slightly different and you just need to be methodical.

Any parts bike VF500F that has some good shit on it for a reasonable price is usually worth it. I built my race bike out of parts bikes, some came with fairly trick parts on them too for the time.

 

Late to the party, but colddevil - if you’re having trouble sourcing something and don’t want to replace the entire carb, I can have a go at turning that brass piece on a lathe.

Will need accurate dimensions to work off of, but otherwise it’d be yours for postage.

Can always use the practice.


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That's great to know. I thought that because the intake boots on the 84/5 were different than the 1986 that the two carburetors would be incompatible with the opposite engine.

When you guys were racing these, were people putting in stiffer valve springs to try to limit the chance of valve float? That's something I've thought about that I should have researched further while I had the engine on a table. I know it'd sap some power, but if they do run a high chance of floating at redline, I could see the benefit. My worry is more about a poor downshift revmatch going into a corner than it is running a straightaway on the gas too long.

Ed, let me see if I can actually get the carburetor rack together and straight enough to operate correctly. The brass piece will still be visible on an assembled carburetor. If so, I may just take you up on that offer. Thank you!

 

"You guys"? Hah. Just me. And beating 600 Hurricanes, 600 Ninjas, FZR600s and even a RZ500.

There's been some talk of springs over the years. I don't think there's a compatible stiffer spring and custom ones aren't cheap. But interest in the bike in general just waned.

It can take brief runs to redline, like downshift over revs. It is exactly running a straightaway on the gas too long that does them in. And two of the tracks I raced on had very long front straights because they were also drag strips. But I raced a whole season on the 84 engine too and it's still cool. Even when they were "new" and the springs still fresh, they could fuck the stems from float. Ask my buddy. He did it twice, but he WRANG THE PISS out of his all the time, and the 84 ignition boxes don't have rev limiters. I never had a problem with my first 84 VF500F.

 

That's awesome. I've read some of your posts about racing the VF but didn't know you were the only one out there at the time throwing down with the Interceptor. I think I found those posts when researching rearsets--which is probably years down the road and a question for another day. Gotta make sure everything is working first. Thanks for the information about the springs.

____

Interesting development. I had the starter solenoid off the bike and was testing it because I'd never actually done that before, and I was curious. Everything seemed like it was working correctly, so I threw it back in the bike and just felt like blowing another 10A fuse since I bought a big pack of them. And then the bike turned over. So, it seems as though I must have a ground that (in my guess) is from one of either the clutch switch (Lg/R) or solenoid negative (G/R) extremely exposed, frail, and horrible looking wires. And I must have moved them out of harm's way temporarily.




So I'm looking at the "new" wiring harness that showed up, and for the most part it looks really good. Far better than the one on the bike. But it had an oddity--the red and red/black wires on one of the 6 pin connectors were just tied off together crudely. I'll be honest I'm not sure how the bike would run like this. I took the other blade terminals out. The 6-pin connector is trashed, but I found another one I can use off a spare rectifier. I just need to buy new blade terminals.



So that's encouraging. I'll need to buy some new terminals and do some cleaning up on this 'new' wiring harness. Hopefully that gives some rigidity to the electrical system. If the fuel pump proves to be viable, then we're one step closer to getting it fired. If the carburetor comes together.

I got the correct Speigler stainless brake lines on the front too.

 

The bike was hot wired. On those years bikes it gives total functionality. I saved somebody's day on a group ride with that one when their ignition switch on their Magna failed, not even close to home. I almost always have a jumper wire in my tank bag just for those kind of things. He was able to just pull one side out at the remaining stops.

 

I should put a Kia sticker on the bike, and it'd be right at home in Milwaukee.

Son of a bitch I was actually wondering to myself if that was a hotwire job since it was seemingly bypassing the Ignition and Battery. Learn something new everyday, lol.

 

CD, a few notes:

• Terminology: diodes are two-terminal devices that allow current to flow in one direction only. Low current diodes are commonly referred to as switching diodes. Higher current diodes are often referred to as rectifier diodes or silicon rectifiers. The Interceptor diode probably has a 10A rating and is approx. 10mm x 10mm.
  
  
• Wire insulation: the original factory wire insulation would not have failed (crinkled) with a 10A current. It's possible that your wiring was not original or the current was well above 10A.
  
  
• Diode testing: I noticed that your DMM has a diode test function. The diode can be tested with the procedure shown in this video:

• Electrical Components: Cycle Terminal is a recommended source http://www.cycleterminal.com/

hth.

 

Phil I gave it a shot testing out the way he does in that video, and from those tests neither of my diodes appear to be working. I do wonder if it's just an issue with the multimeter I'm using though since I think the silicon rectifier is actually functioning correctly. Well, functioning correctly insofar as that it's functionality is to keep the neutral indicator light from coming on every time I enable the clutch.

Quick video of testing:

 

I got the carburetor mostly reassembled today. I'm missing a thrust spring along with a few other items that need attention. I think my attempts are bending back the throttle linkage connection plates can actually work. I think synchronizing these might prove to be a bit of an experience though given the damage I only just now noticed on the carburetor #3 throttle plate.

FFS lol. How does this even happen?


I do see how some of the damage happens though. When I was trying to mount the rack to the plenum, I just kept thinking... there's no friggen way. It's just not going to fit. Once I loosed up the mid (2 to 3) carburetor connector plate and the choke linkage rods, it settled in.



The new metal fuel tubes and air vents look pretty neat. Tough to explain to guests why there's no food in my fridge because I spent all my money on 4" fuel tube replacements for a bike that I can't guarantee will run.. but I digress. I bench sync'd it as well as I could on the 3 carburetors and took an educated guess on the damaged butterfly.


It certainly looks nicer than the starting point at least.


But of course it couldn't end on a nice note. Carbs #2 and #4 developed an immediate drip when I pressure tested them. #1 and #3 were fine. So I tried changing the float height to on #2 and #4 from 7mm to 8mm and it almost eliminated the drips.. but they still very slightly leaked. So I'll try cleaning up the float valves and seats again. If that doesn't work, I'll pick up some new ones. I didn't see leaks anywhere else at least.

 

it's not right to change float settings to cure a leak consider replacing all the float needles.

your throttle shafts look corroded, need lube or they may seize up.



that bent throttle plate......OMG you wont be aBle to synch that carb or the others no way. it would be worthwhile to use appropriate force to try for some improvement or consider doing it right by replacing the part because the bike will never run smoothly like that.

another vivid example why some ppl just don't have the skill or patience to work on carbs and should send the carb repair work to a competent shop or carb guru.





`

 

On the float height--yep, agreed. I was just curious. I spun a Q-Tip through the float valve again and cleaned up the valve tip (quickly), but just out of curiosity. There's been some advice on here recently about freshening up float valves so I'll give that a real shot later this week. I just ran out of motivation for the evening.

I'm thinking about taking a flat knipex plumbers wrench to try to straigten out that butterfly valve. I honestly didn't even notice it this whole time until I was bench syncing with a piece of gasket paper and saw that.

**Edit -- regarding the throttle shafts: I left them on their side and tried to drip AC50 into them for lubrication since that seemed like the thinnest material with the best chance of penetrating deep into that bore. It was very crunchy before cleaning but everything appears to be sliding pretty well now.

**Edit #2 -- regarding the float valves and needles, I'm going to try Captain's method from Rogue's VF500F thread:

 

CD, the video is informative - my $0.02 fwiw...

Your Innova 3320's diode test capability should be the same as the Fluke DMM in the video. Your video shows that the first diode has failed and is OL (open circuit) in both directions - that's usually the result of an over current event, i.e. it's fried. It appears that the second diode has failed and is short circuited in both directions - that's usually the result of an over voltage event. If I have time, I'll pull mine and test it tomorrow to confirm 'nominal' behavior.

 

Thank you for the explanation Phil. I guess I've got a couple bad diodes. I'll try messing around with them later this week to figure out if the bike will still work without them. And I'll try to source a replacement if/when I get the new harness together and bike fired.

 

CD, just tested the S3H-02 diode in my 500 with DMM. Measured 0.54V in one direction (forward) and OL/open circuit in the other (reverse). This is nominal behavior.

A functional diode has two modes of operation - it can either operate as an open circuit (i.e. open switch) or as a pretty good, but non-ideal, short circuit (i.e. closed switch). Your first diode was always open - the basic electric starter circuit diagram on Shop Manual p. 17-0 shows that this would prevent the bike from starting in neutral. Your second diode was always shorted (closed) - the diagram shows that this would turn the neutral light ON when the clutch lever was pulled. hth.

 

Phil, I tested out both diodes (and also my VF500F one which is the same), and found everything you said would happen is exactly what happened.

• Open circuit = Can't start in neutral without clutch, neutral light works fine
• Short circuit = Can start in neutral without clutch, neutral light turns on with clutch
• Working diode = Can start in neutral without clutch, neutral light works fine
• No diode = Same behavior as Open circuit

Thanks for clearing that all up for me. I had no idea how any of that worked, and now I know what the little electrical bit was that always puzzled me. I honestly can't remember the last time I ever started a bike without having the clutch pulled in. I have always pulled in the clutch ever since I was 16 and I pressed the starter button my my dad's Sportster while it was (unknown to me) in first gear. The bike started walking away from me and I damn near dropped it. So it's just always been burned into my routine to start with the clutch pulled in case anything goes wrong.

This picture was taken almost 30 years ago (jesus christ...) on the bike I'd eventually learn how to ride a motorcycle on and almost dump in the driveway starting it in first gear 10 years after that.

 

score one for the good guys

 

A question I've thought about before but never asked and have been unable to find an answer to.. how high of a fuel column do you need to test floats at to be certain they're sealing correctly? I gave the #2/4 leakers a wipe with lacquer thinner, polished the valve seats, reset the float height to 7mm, and re-tested if they held fluid. I filled up the auxiliary tank about a quarter of the way, and they still had a very slight leak. Out of curiosity I lowered the auxiliary fuel level a bit, and it's been holding strong here with no leaks for about 1.5 hours now.



If this was gravity-fed, I'd say boom--done. I'm testing a fluid column height well in excess of the tank height while on the bike.

But these pumps deliver, what, 3-4PSI? Let's say 2.85. Estimating gasoline at 75% the density of water, that 6.56ft water column would be 8.75ft of gasoline. Well I'm certain it'd fail at that. I'm guessing both sides would.


Am I overthinking this? Yea, probably. I'll wet test the heights tomorrow to verify this hasn't just been an issue with me taking incorrect height measurements. If they all look close, I'm calling it good enough for now. My worry is about running conditions overfilling the bowls while the pump is running. I'm not worried about leaking while cold and stationary because between the fuel pump being shut off and the petcock in the off position, I feel pretty confident it won't leak. Maybe I should have just set these a little less aggressive in the interim.

I'm sure as soon as I get it fired I'll find a water pump that needs to be replaced or something else will explode anyway.

 

whoa there, cowboy, you need to do something before you go further......

the bent butterfly will have your bike running erratically and never idle smoothly unless it's fixed. what's your plan ?

 

I have a Knipex plumber adjustable flat wrench that I used to try to straighten it. I can snap a pic tomorrow. It looks better but certainly not ideal when tolerances are so tight to run correctly. I wanted to pull the full valve plate out, so I tried undoing it. One screw came out no problem. The other (the one with the stripped looking head) spun with no action. I didn't want to try to force it out.

*edit-I'm not pretending this carburetor will ever actually work like it was designed. It's been knackered. And should realistically be replaced. If the remainder of the bike was perfect, I'd just buy another one.

**edit 2--I've got some reading to do here about butterfly valve removal (I just want the plate off) http://v4musclebike.com/forums/showthread.php?t=21900

Messed up carb #3 on top, fine carb #1 on bottom.