1983 VF 1000F Problems

So I bought a VF I loved the engine sound so I pulled the trigger when a decent bike showed up.



It was running good, I was not able to test drive it cause of the weather. Was idling properly (according to tach), no backfire


However during transportation the bike fell on the left side and I guess something got damaged. When I was able to ride it I noticed slight lack of power, 2,5k RPM idle (tach) and backfire when off the throttle from left exhaust pipe. Once when I was breaking with the engine and closing to a red light the bike just died.

Later on I noticed a small oil leak which was not there when I was purchasing the bike.





I also noticed that two rear carburetor boots are slightly cracked and fixed with silicone. All seem to be pretty solid, probably need to be replaced.

After the drive the tacho stopped at 2k rpm and sits there, before it was going down all the way to 0. I was not able to get it to rev past 9k rpm when driving.


Any suggestions how to proceed appreciated. I am still to investigate the condition of the plugs (previous owner installed new set and provided me with old ones) and fuel system for debris

 

Partzilla will have OEM boots and most OEM rubber parts (brake seals & boots). Check your low voltage trigger wires to your coils, mine were slightly corroded and caused bike to run on 2 cylinders (one coil fires two cylinders). When running at 2K both coils probably working, then one cuts out dropping rpm's.

 

You have to replace all 4 of the intake boots before "diagnosing" anything else. Those are a real problem right now regardless of how much silicone was used, and will result in symptoms exactly as you describe. And you better go through the carbs when they are off, now is the time.

Might not be your only problem, but it is a problem for sure.

Mike.

 

Thank you for all the tips.

So the leak is coming from the water pump. I am wondering if a rebuild will do just fine or a gasket kit maybe? I will drain the coolant and investigate tomorrow.

Furthermore all the rubber boots for the carburetors are just cracked. I need to get new ones. Part number 16212MB6010. I also need new spark plug wires cause these look original. What is the cheapest source in Europe? 50$ shipping is a little much



I also made two videos. One showing backfiring and the other smoke coming from one side of the exhaust. When the engine warms up there is no smoke.

https://www.youtube.com/watch?v=HKAH3joHMZw
https://www.youtube.com/watch?v=dEAzUnIEDug

 

I seriously doubt the plug wires need replacement unless you can see cracks in them. Honda used very high quality plug wires and unless damaged somehow, they'll last for the life of the bike. The oil leak is possibly due to a bad O-ring around the waterpump drive shaft, and it's easy to replace.

First thing i'd recommend on any bike new to you is to drain and flush the fuel tank, checking for any signs of rust.

 

There is clearly not an oil leak but coolant leak. Coolant got mixed with old debris from the chain and it was black and oily, but now it is clear what is leaking. Check the video for the spot on the floor.

I can clearly see missing insulation bits in the high voltage cables. So you suggest just tape them with some high quality tape? Sounds good to me

 

NO ! Damaged insulation requires replacement, but be sure you use solid wire core, not resistance wires, maybe hard to find.

 

Usually the best source for solid core plug wire is a lawn mower shop

 

I took a look at the carbs today. All the diaphragms look worn, probably need to be replaced. They have no holes but it is very difficult to reinstall them and they look as shown.

Also I want to confirm that I have the correct jet sizes. Can anyone take a look and confirm? This bike originated from Germany and some models shipped there were rated at 100 BHP.

 

http://v4musclebike.com/forums/showthread.php?p=266667#post266667

link to discussion on different forums on modification of the carbs. Maybe someone here knows something regarding the matter

 

You might need to stick the rubber diaphragms in place with some silicone goop b4 putting on the cap.

 

Those carb slides are discontinued.

You'll need to make due with those or find another set ... or different carbs. Those aren't horrible looking to be honest. I've seen worse go back into a set of carbs, including my my '82 Magna V45 ... it still took modern 600's in a straight line.

 

This may help you with your endeavors ... the service manual for the VF1000F

http://honda.vf1000.com/resources/Honda_VF1000F_Workshop_Manual.pdf

Main Jet:
Front #150 / Rear #145 (Alternate Front #138 / Rear #135)

 

First off the VF1000F bikes came out in 1984, not 83. Here's a couple of lists of what carbs each country should have on the bikes. Then you can research for jet sizes. Could have been a float sticking closed or like half way. Backfires, if all else is ok, usually is from a lean mixture. Your manifold boots are shot. They are probably rock hard and they will never seal right, you need new ones. That's why the rpm stays up then drops slowly.

The slider rubbers looks fine. Most look like that after the first few years. Just make sure you get them back on properly with the hole on the top edge right. Remember different jets also have different corresponding needles that go with them. Don't mix and match unless you really know what you're doing.

Did this bike run fine before it feel over? You rode it and all was ok? Or was this your first real ride of it?

This site has a lot of info on those Keihin carbs. http://www.motorcycleproject.com/

Here is a site that should be able to help you better with VF1000 info. http://honda.vf1000.com/

 

The bike was idling and revving fine. I was not able to ride it due to bad weather. My guess is that rubber boots got some cracks from the shock itself

My bike is from the first batch, produced 83 buy sold in 84

 

I doubt the rubber intake books on the carbs or the diaphragms were damaged from a bike falling over.

They'd have to be really fragile for that - the boots that I've seen get hard over the years get hard and almost indestructible. LOL!

 

30 year old rubber boots = stuffed

 

The sun is out so I finally took care of my VF

I was able to buy a complete set of carbs which had the different style sliders that I was looking for. Except for the different height they were identical. If I cut my old ones they would have worked! I kept the old ones just in case and installed the other set. The diaphragm also looked a little thicker.

After I replaced the boots, installed new old sliders and fixed water pump leak (new OEM gasket) the bike runs quite good. It does not smoke as before, goes all the way to the red line and pulls much MUCH stronger. There is no backfire on acceleration however I still hear backfire on deceleration - probably because of the empty exhaust baffles (middle muffler is cut out). Now I can finally tell that it has some power


I have also purchased fuel filter online (white pictured below) but its completely different than the one installed. I will try to find some other one that would work. Is this correct filter or the PO modified the fuel system?

 

Back fire on decel means too lean. Adjust your idle screws properly or if they are turn out 1/2 turn and try it.

 

I dont want to start new thread so I just update this one

Carbs were cleaned, rebuilt and synchronized. New carb sliders were installed but I have the old set that limits bike power to 100bhp. You can just cut piece of slider to achieve full power anyways

I did about 10kkms and the engine started to rattle a little. I thought I overheated the oil on the highway (coolant went over half the scale after long 140kph highway run with 30C+ and I needed to add 0.5l of oil)

I figured that I need valve adjustment but it is camshaft replacement time. I was able to adjust the valves to make it run better but front intake and rear exhaust cams are pitted. It was not due to the design but the fact that both rear screws for the cam were replaced with a simple rod - no oil was getting there at all for who knows how long.

I was lucky to get set of good cams - this is 11/83 registered bike using narrow cams. So I decided to do something to make them last.

- sandwich plate under oil filer
- custom oil lines made locally - I am thinking of reuseing a section of old line to keep the stock look
- modification of camshaft race to F2 spec
- installation of oil cooler (already have the oil temp gauge)

I think these mods need to be sticky over here so everyone knows the deal - I am new to the game and had to learn the hard way

Still love the bike, even if its not a beauty queen it gives me unique expierience I was looking for.