Valve Problems.

[jporter12]

Today I decided work on putting the timing chan tensioner in the Hon-duh. I'm glad I looked at things a little better before throwing it back together, as I found the source of the tapping that I had been hearing for quite a while. The tip of one of the exhaust valves is mushroomed. It's worn through the hardened surface, and is wearing rapidly at this point. Putting it back together would just be setting up for catastrophic failure in short amount of time.

The plan as of now is to get a gasket kit, pull it apart, and send both sets of heads that I have to the machine shop for them to put the best combination of parts that I have together for me.

Here's a pic of the culprit, and the good one adjacent to it:

Edited January 23, 2010 by jporter12

[ReconRat]

dam, I wouldn't give you spit for the valve spring on that one...

[jporter12]

dam, I wouldn't give you spit for the valve spring on that one...

I'm just hoping that with both sets of heads they can come up with enough to make it hold together for a few more years.

I'm also going to check in over at www.vfrworld.com and see if Jamie D. over there ever got anything lined up for an upgrade. He knows all about these bikes, and how well they are know for dropping valves!

[jporter12]

Why not put a fresh valve and spring in and call it a day? Maybe replace the rocker if you're worried it is compromised' date=' but paying a machine shop to do all that work seems a bit premature. Taking the head off is the "hard" part. Once you do that it's all gravy.[/quote']

Are bikes different then cars? Every valve I've replaced on a car had to be ground, or at least the seat ground to match, and I don't have the stuff to do that! The valve swap is easy, and the head seems pretty easy as well. Hell, I've had the crank out of this motor, how hard can it be to pull the head? Pull the carbs (which I need to do anyway to get to some coolant tube o-rings that need replaced) pull the front exhaust pipes, then a few head bolts. I already have the cams out, as can be guessed from that photo.

[jporter12]

I thought you had access to all that stuff.

Nothing for valve grinding and stuff. We don't do that sort of stuff, we send it out to be done as a more complete job, with resurfacing, tanking, pressure testing, etc....

I actually miss doing valves and stuff, almost! It's been quite a few years since I have done any valves on my own.

[serpentracer]

you can do a hand grind valve job. but it's way better to have new seats put in the head and use a new valve.

seeing how that valve you have need replaced anyway.

they make valve lapping compound for hand grinding and a $9 tool for holding the valve as you spin it.

or you can put the stem of the valve in a drill and lap it that way.

you can get the grinding compound it at any auto parts store.

http://www.permatex.com/products/Automotive/specialized_maintenance_repair/rebuilder_aids/Permatex_Valve_Grinding_Compound.htm

[dustinsn3485]

I've got an old valve grinder I'd sell for somewhere around $100 if there's any interest.

It's an old Sioux.

[jporter12]

you can do a hand grind valve job. but it's way better to have new seats put in the head and use a new valve.

seeing how that valve you have need replaced anyway.

they make valve lapping compound for hand grinding and a $9 tool for holding the valve as you spin it.

or you can put the stem of the valve in a drill and lap it that way.

you can get the grinding compound it at any auto parts store.

http://www.permatex.com/products/Automotive/specialized_maintenance_repair/rebuilder_aids/Permatex_Valve_Grinding_Compound.htm

I have that stuff, but what about getting the seat to contact the valve face in the middle? It's def a case of needing ALL of the right stuff to do the job, really, unless it just so happens to be close enough that it can just be lapped in.

I've got an old valve grinder I'd sell for somewhere around $100 if there's any interest.

It's an old Sioux.

Pics?

[dustinsn3485]

Pics?

I'll get some this afternoon.

[jporter12]

Dude' date=' it's a Viffer 500. Lap a new one and slap her back together. [/quote']

I gots to get some head gasketage first!

[ReconRat]

I've done it both ways. At home and out to a shop. If it's cheap enough for a rebuild on a head you carry in, I think it's cost effective to do so. Providing it's quality work, of course.

If you can check/inspect the other valves, it probably isn't bad to do just the one valve, lap it in, and reassemble. Bottom line is whether all the other valves are holding compression, and since you'll have that one valve out, the condition of that valve seat. It would be nice if you had a spring compressor that fits, and a spring tension tester. Then you'd know for sure what the condition is, and would be able to see all the valve seats and parts and judge them.

Short cut --> I'm old fashioned, and will pore gasoline down the inlets/outlets and let it sit for a bit, to see if it leaks into the combustion chamber (with the head off). It shouldn't leak through at all. If your head isn't a leaker, fix the one valve only.

My opinion; Japanese springs (all of them) aren't the best, and whenever possible, I'll replace them all with aftermarket of better quality. Maybe Japanese springs are better now than they used to be, but I don't know that. Of course, some aftermarket springs will be rough on the camshafts and rockers.

[jporter12]

I've done it both ways. At home and out to a shop. If it's cheap enough for a rebuild on a head you carry in, I think it's cost effective to do so. Providing it's quality work, of course.

I have a couple machine shop connections that are VERY good, and both have no problem with doing bike work.

If you can check/inspect the other valves, it probably isn't bad to do just the one valve, lap it in, and reassemble. Bottom line is whether all the other valves are holding compression, and since you'll have that one valve out, the condition of that valve seat. It would be nice if you had a spring compressor that fits, and a spring tension tester. Then you'd know for sure what the condition is, and would be able to see all the valve seats and parts and judge them.

This is where I'm torn. Do I just do it quick, dirty and cheap, or go for the gusto and do it all. I don't have anything for checking everything.

Short cut --> I'm old fashioned, and will pore gasoline down the inlets/outlets and let it sit for a bit, to see if it leaks into the combustion chamber (with the head off). It shouldn't leak through at all. If your head isn't a leaker, fix the one valve only.

That's something we do from time to time, although we usually fill the chamber side.

My opinion; Japanese springs (all of them) aren't the best, and whenever possible, I'll replace them all with aftermarket of better quality. Maybe Japanese springs are better now than they used to be, but I don't know that. Of course, some aftermarket springs will be rough on the camshafts and rockers.

THAT is where the problem lie with these 500's. They're known to float the valves at high RPM's. One of the "guru's" over on VFRworld has talked about it a few times, and has seen it happen many times. The valve spring issues, coupled with the top-end oiling weakness, and the lack of sufficient hardening of the cam and rockers put the VF500's on the failboat express. Good luck finding anything aftermarket for the top end of these motors!

I shouldn't have much in getting it all done right. I'm thinking a couple hundred in the machine work (if I go that route) and less than $100 in the gasket kit, IF they have them in stock now, it's been hit and miss when I checked before.

Megacyclecams lists reground cams (using my cores) in the $500 range, and re-hardening of the rockers for something like $60 or so each. Add in the gasket kit, valves and springs, or even machine work on the parts I have, and it gets to be more than the bike is worth, and the springs are still an issue. Since I don't have the kind of money to be spending on something like that, and still have a weak link with the springs, I don't think I'll even consider that any further. The one thing that might make the cams worth it is that they will put a "race" grind on them. I just wonder what sort of HP they would make then! I guess the motor is rated at 76HP in stock form, which is pretty good for a 500 of that era!

[jporter12]

So, I pulled the head, and I also pulled the head off the parts motor, which is supposed to be the original motor for the bike. I found the SAME valve had the same problem, along with the cams and rockers being wiped. I talked to my friend that has a bike shop down the road, and he said to just bring everything over, he has all we need to do the valves, except for the valve spring tester. I'm thinking of just swapping everything from another cylinder of the parts head into that bad valve position.

One other interesting thing of note was the presence of grey sealer on the head gasket of the motor that's on the bike, as thoughn it had been apart before, and not had a new head gasket installed.

[jporter12]

Ok, time for an update, I guess.

I got the valve switched out, bought a gasket kit from partsnmore.net, installed that head and went about putting it all back together. I soon found another problem. It seems that I got the cam timing off to the back head when I put the crank in it last summer. No big deal.....yet.

I decided I had better look at the valve tips on that head, since I had to do work back there anyway, with the cam timing. Well, 3 or 4 of the exhaust valves are "not looking so good", for the technical terminology. I had to pull the engine off the bike to pull that head, and that's where it sits now. Engine on the floor, rear head off of it.

In the late 80's, Hon-duh had a service bulletin on this issue of the valve tips pitting, mushrooming, etc. If the valve tips weren't mushroomed, or have pieces protruding, they would install "caps", which I'm guessing was to make a fresh hard surface at the tip of the valve, along with a different adjuster, which I'm sure would be shorter to make up for the cap. I'm tempted to try and find some of these kits, as none of the valves are going to be in great condition. Otherwise I need to just swap out more valves out of the parts engine, slap it back together, and be conservative with how high I let it rev.

Aftermarket parts are pretty much non-existant, due to that bike only being made for 3 years.

Any other ideas?

[max power]

Any other ideas?

Part it out and upgrade?

[jporter12]

Part it out and upgrade?

I'm too broke right now. Also, I'm not sure I can convince the wife...