1986 vs. '84-"85 VF500 Heads

I have dropped the intake valves on cylinders 1 and 3 on my 1986. I have a parts engine that is either 1984 or 1985 (any easy way to tell year of engine?). Can I swap the whole heads onto the 1986. I know that the valves are different, but would this work? I will explain more later.

 

I would GUESS that as long as you swapped cams and carbs with it, you would be ok. I have no hard evidence to back that up, just putting together pieces of info that I've heard. I'm also not sure if the cams are any fifferent even.

In my situation, I'm fortunate enough to have a spare 84-85 engine for my 85! Can't wait to get the thing back together, either!

 

Is there a part number stamped on the cams that I can't find? Does anyone know the engine serial number ranges for each year?

Here is my problem: I picked up a project bike in a 1986 vf500. I had a 1985 new back in the day and still love the looks of the bike so I thought it would be a fun project to restore one of these.

It was running rough, but running. I got a parts engine with it ('84 or 85 I believe) plus a bunch of parts including the older carbs in very clean, but cob-webby condition. The previous owner stripped the 86 engine completely to rebuild it due to a bent connecting rod on the 86. He and his mechanic father-in-law rebuilt the 86 bottom-up by combining the best condition parts of the two engines, tranny on up. They kept the 86 heads but judging from the pile of parts they used the cams from the older engine. They used the 86 heads, cylinders, etc. Oops! I don't think they realized that the intake valves are different between years or they thought both engines were 1986's.

I determined that the rough running was due to the bike running on three cylinders (sound familiar?). I pulled the plug on cylinder 3 and was able to almost block the sparkplug hole with my finger on start up = no compression. Not good. I pulled the cover and the rocker arm screws and nuts were gone on all four intake valves on cylinders 1 and 3! The valves appear to have dropped somewhat. I pulled the front cylinders cover and all the valves are intact. I am wondering what would cause all four intake valves on 1 and 3 to fail and no others. Why only the intake on 1 and 3? Any ideas? Misaligned camshafts / chain on re-assembly?

I have pulled the oil pan and between the parts I found up by the valves and those down there I have found almost all of the nuts and rocker screws. I hope to locate the last few parts when I get the thing apart.

The spare engine heads look nice and clean and little wear, so I am hoping to swap the heads along with the older carbs. So, I REALLY need a way to know which parts go with which engine.

Note: my assumption that the spare motor is not an 86 is based only on the fact that the spare carbs are the larger size. I could be wrong. Help?

 

My understanding is that the only difference between the 86 and previous models is that the 86 had slightly more aggressive cams. What I've gotten from this board is that the "hot" setup for these motors are 86 cams and 85 carbs on any v30 block...

 

According to my shop manual, the 86 model has less camshaft duration (10 degrees less intake, 5 degrees less exhaust), lift is reduced slightly. Journal dimensions are the same.Carbs are 30MM on the 86, 32MM on the earlier models. I read a magazine article back in the day and they said this was an attempt to improve midrange torque on the 86 model at the expense of a few top end ponies. They werent exactly torque monsters after all. I think the intake ports are different, but you can compare the two and determine for yourself. Cams are tougher because I believe there were a few variations made in attempt to fix the weak top end. Lobe height on 84-85 models is 1.387-1.393 intake, 1.383-1.389 exhaust, 86 models are 1.369-1.376 intake, 1.377-1.381 exhaust. That might help you in identification. I replaced the cams in my 85 about 10 years ago and they improved the oiling by drilling the lobe ramps so they are pressure fed oil from the cam gallery.

 

Thank you for the post. Could you go into a bit more detail on this modification?

 

Has anyone successfully reused head gaskets on these bikes? I could have a set made for about $50, but otherwise don't see other options (aside from a complete gasket set for $$$$.

Does anyone know if the valves, springs and rockers are the same between the 86 and previous?

 

'86 heads are unique to that year. Parts are not interchangeable from '84-85 and '86 as the heads, valves, cams, cam caps and head covers are different. Lifters might be the same, I don't know. I wouldn't recommend running one bank with an '86 head and the other with an '84-85 head either. Head gaskets are not reusable unless they are of the copper variety (which aren't recommended for the VF500F anyway).

-Jake

 

This was a factory modification to replacement cams. I have never seen it done before. She is due for a valve adjustment so a picture might be the best. The oil path is through a bearing on the intake cam. The cams are hollow, so this passes the oil to all of the other bearing surfaces. In addition, they drilled holes in the lobes for additional lubrication directly to the rocker face. This is not a cure-all. There are too many other problems with the top end. This was just an attempt to slow down the inevitable cam wear.

 

Thank you for the post. If you have a chance to take a few photos, when you are inspecting the valves, this would be most appreciated - any chance you remember if the dealer referenced a Service Bulletin for this?

 

Not that I know of. When I overhauled the motor at 35K, I ordered new cams rockers chains etc & that's what I got.

 

Help! I need to determine once and for all what the years are of my two engines are. I have not found any differences yet. I have not done any measurements yet, but the heads are off and they seem the same. Here are the engine serial numbers:

PC12E - 2100311
PC12E - 2018581

Great news! Only one of the valves actually dropped. The others just broke near the keepers and stayed up. The one that dropped barely touched the piston, hardly even scraping the carbon off.

 

Nevermind. It looks like I have an 84 and an 85. Found this:

VF500 498cc 4-cycle V-4 - Magna [more]
1984 VF500C
- Frame: JH2PC1300EM000028
- Engine: PC13E-2000040
California Models:
- Frame: JH2PC1317EM000004
- Engine: PC13E-2000066 [more]
1984 VF500F
- Frame: JH2PC1206FM100001
- Engine: PC12E-2000001
California Models:
- Frame: JH2PC1214FM100001
- Engine: PC12E-2000001 [more]
1985 VF500C
- Frame: JH2PC1307FM100001
- Engine: PC13E-2100001
California Models:
- Frame: JH2PC1316FM100001
- Engine: PC13E-2100001 [more]
1985 VF500F
- Frame: JH2PC1205FM100001
- Engine: PC12E-2100001
California Models:
- Frame: JH2PC1214FM100001
- Engine: PC12E-2100001 [more]
1986 VF500F
- Frame: JH2PC120XGM200001
- Engine: PC12E-2200001
California Models:
- Frame: JH2PC1219GM200001
- Engine: PC12E-2200001 [more]

at this site:

List of Honda Models with Frame and Engine Numbers - Z1 Enterprises, Inc.

 

I just noticed that the one of the pair of heads are stamped F1 and R1 and the other pair of heads are labled F2 and R2. Is everyone sure that they are the same between 1984 and 1985?