'85 Vf500f Engine Noise

Hey all,

I'm new to this group although you have helped my son with his '86 VFR700 a few times. We recently picked up an 85 VF500F for my daughter. It seemed strong when we got it, revved well and didn't seem to have any serious mechanical issues with 33,000 miles on it. Well we've ridden it about 1 tank of gas and now we have problems.
The first is this knocking noise, which came on rather suddenly and has me worried. When I listen to it with a screwdriver touching various parts of the engine, it's loudest at the front cylinders near the head. Are these engines known for this type of failure, as in rod bearings, or maybe piston slap?
The second problem which may be related to the first and which I haven't thoroughly investigated, is that it seemed to overheat during the same ride that the knock became apparent. This all happened on a relatively short ride and we got the bike home pretty quickly. After the bike was parked overnight I checked the coolant reservoir and it was full, but when I checked the radiator it took about a pint of water. I'm going to do a cooling system leakdown test, it may be a head gasket, but once again I'm just curious if there's a typical issue with this model and overheating.
I really didn't intend on becoming a first hand expert on VF500 engines, it's a little more complicated than what I'm used to working on. If someone has a known good engine for this bike I'd be (very) interested.

Thanks for reading, sorry for the long 1st post!

Frank

Nope, it's probably not piston slap. I'd pull the cam cover and check the valve clearances. It sounds like you have a valve getting ready to drop. That's REALLY common with the 500's, so you should take it seriously. If you find one out of spec you should scrutinize the condition of the valve stem. Any damage at all will be a positive indication.

The repair is more than just replacing that valve and keeper, you also need to replace all of the valve springs because they are what caused the failure in the first place. The worst part is that you need to pull the head... and head gaskets are discontinued. The only source I know of now is www.coppergaskets.us .

Let us know what you find out.

Nope, it's probably not piston slap. I'd pull the cam cover and check the valve clearances. It sounds like you have a valve getting ready to drop. That's REALLY common with the 500's, so you should take it seriously. If you find one out of spec you should scrutinize the condition of the valve stem. Any damage at all will be a positive indication.

The repair is more than just replacing that valve and keeper, you also need to replace all of the valve springs because they are what caused the failure in the first place. The worst part is that you need to pull the head... and head gaskets are discontinued. The only source I know of now is www.coppergaskets.us .

Let us know what you find out.

Thanks, I was going to go through the valve adjustment procedure but then thought it might be a waste of time if there was a bigger problem, but it sounds like I need to go step by step anyway. I'll definitely post what I find, I'm sure I'll have more questions once I'm into it.
Cheers.

Well I finally had a chance to check the valve adjustment. Some were pretty tight, most needed some adjustment. I couldn't see any specific problems with the tops of the valves, at least with the adjusters backed off enough to look at 'em a little bit, but I guess I wasn't sure what to look for anyway. But the valve stems appeared to be ok.

I put it back together enough to run the engine to listen again and also to get it warm to do a compression check. The noise is still there, coming from the front bank, mostly #2 cylinder if I had to pin it down.

The compression test wasn't very revealing, 160-165psi across the board. Nice, but I was kind of hoping I'd see some drastic indication that something was wrong somewhere.

I'm thinking that I'll have to remove the engine and start taking it apart till I find damage. Not my idea of a good time, but I don't think we can run it till it blows up either. How's availability on rod/main bearings for this engine? Or rods/pistons?


Frank

Is it a ticking sound? All 500's make a weird ticking-type sound that is totally normal. You can hear with the bike idling and sometimes even while riding. It's not a huge sound but noticeable. I guess it's hard to describe what it sounds like!

Is it a ticking sound? All 500's make a weird ticking-type sound that is totally normal. You can hear with the bike idling and sometimes even while riding. It's not a huge sound but noticeable. I guess it's hard to describe what it sounds like!

No this is definitely not a normal sound. It wasn't there when we got the bike. It's loud enough at idle to be a concern, and when you rev up to 8-9k it's pretty bad. I'm fairly convinced that it's lower end, crank/rod knocking. The thing is, it would be nice if I could just get into the bottom end without taking the heads off but I don't think I can take that kind of short-cut with this engine.
I guess I'll find out when I get the engine apart....
Thanks

You can pull the oil pan and look up there. I'm not sure if you'd be able to see everything, but you might be able to stick a screwdriver up there far enough to see if one of the big ends is loose.

If that's the case it's a bummer, the 500 engines are not easily rebuilt because of parts availability issues.

Sounds like it could be a cam chain tensioner to me.

I had one go bad and ended blowing the motor, then parted the bike.

Jamie, did you ever do any exploratory surgery on that motor I gave you?

Sounds like it could be a cam chain tensioner to me.

The 500's are not nearly as prone to this as the VF700/750F's are. They are more likely to have bottom end issues, but you bring up a good point as something else to look into.

I had one go bad and ended blowing the motor, then parted the bike.

Jamie, did you ever do any exploratory surgery on that motor I gave you?

Not yet, way too many other things going on right not (mostly shock conversions with a few wheel swap kits and fork rebuilds thrown in just for fun). I thought you mentioned that it just starting making noise, did it actually let go? It really helps narrow down the search when you know what you are looking for!

Could it be a cam chain tensioner problem? Honda's have had lots of problems with them from the early 60's till the current bikes.

I thought you mentioned that it just starting making noise, did it actually let go? It really helps narrow down the search when you know what you are looking for!

Mine actually let go, whatever it was. It was making an awefull intermittant racket that didn't sound like piston, or rod and before I had a chance to figure out that it could be the cam chain tensioner something popped and one cylinder started smoking like there was a hole in a piston.

I would look real close into the cam chain tensioner on that bike of yours Frank, Honda can't seem to get those right.

Nothing has let go yet. I am going to pull the oil pan and see what I can see. Another friend mentioned that I might learn something from cutting open the oil filter, if the rod bearings are shot I should have bearing material in the filter. I don't know if I can replace rod bearings on that engine without a complete teardown. On most automotive engines you can, and this has babbit type bearings so in theory I could, but I need to look a little closer.
I'm fairly convinced that it is a rod bearing as opposed to cam chain tensioner, although I am going to check that as well, I just can't imagine a cam chain tensioner knocking like this.
It'll be a few days till I can investigate much further though. Thanks for all the thoughts, I'll report back when I have anything solid.

Got the engine out yesterday, had to fab up a stand once I got it on the bench. I'll start the tear-down this weekend.

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Surest way to find if a rod is knocking or not is to remove one spark plug at a time and run the engine on 3
cylinders... if the knock stops then you found the culprit... if the knock continues repeat test on the
remaining cylinders... if the knock doesn't go away after testing all 4 cylinders then you have eliminated the
rods... rods only knock under the rapid pressure of combustion...

A scuffed piston will knock like a rod...

Make sure the knock you are hearing is not the clutch basket... actuate the clutch while the engine is running
and note if the knock changes pitch or not...

Try to establish if the knock is crankshaft speed or 1/2 half crankshaft speed... this will pin point if it's the
lower end or the upper end...

Cam chain tensioner knock comes and goes with rpms... if the knock is steady then it's unlikely the tensioner...
the VF500 tensioners are not all that bad...

Yep, I wish I had remembered the spark plug lead test before I pulled the engine, it might have been helpful.
I did find some disturbing evidence though. There was antifreeze in the oil when I drained it. I'm guessing blown head-gasket at this point, which would explain the overheating. I'm hoping to have the heads off tomorrow (If it rains, if not I'm riding).

Well I got the heads off on Sunday, no sign or evidence of a bad head gasket. I'm really wishing I had done more tests before I took this engine out. A cylinder leak-down test, and a cooling system leak-down test would've been a great idea. The cam followers have some typical wear on 'em, and everything else looks pretty normal to me. I have to get out the mics to see what's worn beyond spec. The cam chains/tensioners all appear to be fine and didn't have any slack.
I still have to flip it over to inspect the rod/crank bearings. I'm hoping to find something that will be definitive for the noise anyway.
I was able to order the Athena engine gasket set from oldbikebarn.com, so I'm a little bit relieved about the head gasket issue. I may get a fresh set of rings from them too, if I don't have to spend too much on the lower end. The cylinders look great, I'll hone them if I do the rings.
I'll post some pics if anyone's interested in seeing the guts of this engine...

I was able to order the Athena engine gasket set from oldbikebarn.com, so I'm a little bit relieved about the head gasket issue.

Ooh, Athena gastet set huh? Those are know for being, shall we say, less than good. I had a set once and the holes didn't line up right. Hopefully you will not have any problems, or should I say "more" problems.

I was able to order the Athena engine gasket set from oldbikebarn.com, so I'm a little bit relieved about the head gasket issue.

Ooh, Athena gastet set huh? Those are know for being, shall we say, less than good. I had a set once and the holes didn't line up right. Hopefully you will not have any problems, or should I say "more" problems.

Yeah, that's why I said a "little bit relieved". I've had my share of problems with aftermarket gasket sets for 20+ year old engines. In most cases I've been able to modify the ones that didn't line up.

On closer inspection of the heads/valves, I'm thinking that the valves look too clean for the age and miles. I suspect that it was starting to leak antifreeze into the cylinders, either from a bad head gasket or maybe a warped head. That could also explain the knocking noise (I think). I still have to look at the bottom end, and the rod bearings are cheap enough to replace anyway...

Right now I don't know what's worse, working in the heat of the summer in a garage with no air and 90% humidity or doing the same job in the winter with lousy heat. Seems like there's no in-between. I went out last night after dinner, started to look things over and was sweating just standing there. Decided to leave it alone for the night.

Damn, the engine is out? Shot in the dark but recently rode with a buddy and his gs500 and was concerned we wouldnt make it back form our trip the bike was "knocking " so loud. I mean friggin loud!!!!!
Turns out a carb sync solved the problem!!!! I would have bet money the thing was ready to drop a rod. Like i said a shot in the dark but....
Good luck with your repairs in any case.

Well it's been awhile since I updated this situation. I got the crankcase split, checked the rod bearings. They're a little out of spec, not too bad, but I found out that I can't order new ones anyway, contrary to what my local dealer told me, so I guess it's going back together as is. The Athena gasket set didn't show up either, it's been discontinued.
The only good news is that I called Cometic Gaskets and they have the specs on file for the head gaskets and they'll make them as a custom order, about $55 per gasket, shipped in a few days.
This thing is going back together.

Well it's been awhile since I updated this situation. I got the crankcase split, checked the rod bearings. They're a little out of spec, not too bad, but I found out that I can't order new ones anyway, contrary to what my local dealer told me, so I guess it's going back together as is. The Athena gasket set didn't show up either, it's been discontinued.
The only good news is that I called Cometic Gaskets and they have the specs on file for the head gaskets and they'll make them as a custom order, about $55 per gasket, shipped in a few days.
This thing is going back together.

I certainly would not do that. You can get copper head gaskets for about half that much. Even so, it's nice to know there are other options.

So, what DID you find? I would never reassemble an engine without finding the problem. It's pretty unlikely that is magically disappeared!