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Another Vf500 Engine's Demise


YoshiHNS

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Someone asked if it's the exhaust valve that drops first in a VF500 engine. The answer to that is apparently.

IMG_3350.jpg

IMG_3351.jpg

http://www.vfrdiscussion.com/forum/index.php/topic/76067-cornercarver-got-better-head-than-me/

Maybe I should go for three in a row :wacko:

Guess I'll just start taking everything apart. Anyone want a VF500C with clean title, but missing an engine?

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Do you need your head back?

Dunno yet. I have to sit down and do the cross-referencing of all the parts. I don't think I'll be able to sell it without an engine. Need to go through and make sure if I do a full teardown that I can get all the parts I need to rebuild. Should try and hand crank the engine over to see how the bore is first.

One main issue is that I think the head is scrap because the valve seat is too chewed up to be recut without really cutting a chunk of material off. The only good thing about that at all is the valves all look to be in pretty decent shape. The other spare head, the valves look pretty toasty.

The next step SHOULD be to take the VTR250 engine out and take the heads off of that so I know what all three problem engines have wrong with them. All three engines share enough parts.

The really scary thing is that I had this engine RUNNING for at least a minute before I realized that there was a serious problem and not a carb/fuel issue.

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Wow...what a mess!

I was surprised to read how a significant number of these engines have suffered from the effects of broken valves. Back in "the day" (mid-to-late 80's) I was under the impression that the baby V-4s were pretty stout, as long as the engine's red line was respected. Camshaft wear issues were a problem for all of the 1st gen V-4s though.

I owned a '83 V65 Magna for a few years back in the 90's and enjoyed riding "the beast". I called her my "point and shoot" bike, for there was so much torque available it didn't matter much which gear you were in, if you pinned the throttle you'd better hang on. About 5 years after I sold my V65 I had an opportunity to try out a friend's 1st generation V-Max ('86). While Max's reputation for tire shredding acceleration when V-boost was active proved to be well deserved, I thought my old V-65 pulled harder at low revs.

My Dad purchased a '85 V-30 Magna w/just over 1k miles in 1990, and he only rode it another 6k miles before giving up on 2-wheeled transportation. Unfortunately my dad is 82 now and suffers from dementia. So barring a medical miracle he'll most likely spend his remaining days in the McGuire veteran's hospital where he's resided for the last 2 1/2 years.

About five years back he signed the title to his V-30 over to me in exchange for some work I did for him. By that time the little Magna had been stored unused inside his garage for over a decade-and it still sits there today. As I recall the little V-4 was a really nice engine with a smooth nature, & excellent carburation. She was surprisingly quick over 8k rpm, but didn't have much grunt down low in the rev band.

I'm hopeful that my dad prepped the little Magna well for the years of hibernation. I do know that he removed & drained the tank and I'm hopeful he did the same with the carburetors. I'm also hopeful that I'll be able to locate the (thankfully few) parts which he removed and failed to re-install over the years, including some of front brake and clutch components when I finally have the motivation and opportunity to attempt to hopefully coax her back to life.

Thankfully, I do know that she was well-maintained & not abused while my dad was still riding back in the 90's. So I'm hopeful the engine's internals s/b in much better shape than the images provided in this thread.

I just remembered that I borrowed the little Magna from my dad when I signed up to take the MSF Experienced Rider Course for the 1st time back in 1991. At the time (nearly a quarter century ago) one of the other students was on a Kawasaki's ZX10, which for a short time was top dog in the horsepower wars in those (pre ZX11) days.

Man, I feel old....

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Do you need your head back?

Well, dunno lost my head long ago... :biggrin:

- I had a VF700 Sabre and it was a great bike when it wasnt being fixed. It had cam issues, cam chain problems, CCT crap. And finally a big metallic crack happened, and I yelled...... UNCLE! Pretty sure a valve let loose. Sold it cheap, and moved on.

--- Never will I touch a gen 1 bike again.

Damn, it was a sweet ride, but what a headache too.....

Adding a pic for grinssssss........

Sabretonia1.jpg

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Maybe it's time to make it a custom build using a more reliable engine.

Let's assume that I have three bad engines (cause with the streak going, that VTR250 engine is going to be the same). The 250 is actually the easier one to deal with. Frame has no title, so I would probably just toss a CR250 motor in there and the CBR F1 front and rear on it for track day giggles. If I did get the 250 engine running, I would probably want to hunt down a titled frame for it and put it back on the street with the rest of the OEM parts (well, that front end still might have to go).

Now the 500's. What am I going to swap into a Magna frame? SV650? CBR500? Ninja 500? Possible, but probably loads more work than replacing a valve and piston. The 86 motor is actually in the hot seat now. Do I just crack that open and take a piston from it to put in the 500C, since that's the sellable bike? Or do I fix both of them and attempt to recoup something from the spare? Either of those two involves splitting the case, and both engines are pretty much in the same exact position, except the C has an entire bike with it while the F is just an engine.

I've never split an engine case before, but can't imagine it's anything super difficult. Need to read through the manual to see if there are any mandatory replacement parts that I can't get anymore. Piston, rings, con-rods, and rod bearings seem to be the big items that you can't get new. I did find someone with NOS pistons and rings. Maybe some more stuff.

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I'll check and see if one of the pile of Honda V4s at the shop is a 500. you game to try another one?

Brave souls....

:cool:

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Back in their day, the little 500's were tough. I had an 86 VF500F and I bounced off the limiter quite often without incident. However, I have a feeling you will have issues with most VF500F/C engines going forward because of old tired valve springs. I doubt that you will find any NOS or aftermarket springs for them.

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Back in their day, the little 500's were tough. I had an 86 VF500F and I bounced off the limiter quite often without incident. However, I have a feeling you will have issues with most VF500F/C engines going forward because of old tired valve springs. I doubt that you will find any NOS or aftermarket springs for them.

KPMI should have them as well. I should be able to get everything from them if I wanted to. $7 for OEM valve guides. That means a load of work and probably $400 in parts and labor minimum though.

The question is, why do the exhaust valves fail?

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Back in their day, the little 500's were tough. I had an 86 VF500F and I bounced off the limiter quite often without incident. However, I have a feeling you will have issues with most VF500F/C engines going forward because of old tired valve springs. I doubt that you will find any NOS or aftermarket springs for them.

KPMI should have them as well. I should be able to get everything from them if I wanted to. $7 for OEM valve guides. That means a load of work and probably $400 in parts and labor minimum though.

The question is, why do the exhaust valves fail?

Because they are exhausted? :goofy:

I'm surprised the parts are still made for them. I thought I had read a few years ago that they weren't available any more.

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I have a good running '86 VF500F engine. If interested, shoot me a PM.

Well, that's the issue, the 85 and 86 are different enough that I'm not sure they will swap. Well, they should swap into the frame no problem. I'll keep it in mind. I want to see what the VTR engine holds for me.

That's a cool explanation on the cam problems, but the cams and followers look fine. The valve failed. So did the keepers fail? The spring wore out? Valve stretch? Perhaps just not keeping up with valve adjustments?

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I have a good running '86 VF500F engine. If interested, shoot me a PM.

Well, that's the issue, the 85 and 86 are different enough that I'm not sure they will swap. Well, they should swap into the frame no problem. I'll keep it in mind. I want to see what the VTR engine holds for me.

That's a cool explanation on the cam problems, but the cams and followers look fine. The valve failed. So did the keepers fail? The spring wore out? Valve stretch? Perhaps just not keeping up with valve adjustments?

I've read that the little Viffer's springs weaken over time and allow the valves to float or bounce.

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I've read that the little Viffer's springs weaken over time and allow the valves to float or bounce.

If that's the case I should be able to measure that when I take the head apart.

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Looking at the pics of youre engine, there is one thing wich set me thinking. The undamaged cilinder pair has soot on it, meaning a rich fuel mixture. The damaged pair has no soot and is completely burnt clean. Indicating a lean mixture, with a much hotter burning process. I have sean pics of complete piston meltdowns, ruining the complete engine, molten metal transferred troug the complete engine. Or the heat could cause high speed nock.

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I have a good running '86 VF500F engine. If interested, shoot me a PM.

Well, that's the issue, the 85 and 86 are different enough that I'm not sure they will swap. Well, they should swap into the frame no problem. I'll keep it in mind. I want to see what the VTR engine holds for me.

That's a cool explanation on the cam problems, but the cams and followers look fine. The valve failed. So did the keepers fail? The spring wore out? Valve stretch? Perhaps just not keeping up with valve adjustments?

I've read that the little Viffer's springs weaken over time and allow the valves to float or bounce.

+1 I have read it several times also ...

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It was me that asked about which valve it was. I have a growing collection of pictures of blown VF500 engines. This one makes 8 and of those it can be said that in 7 of them, it is an exhaust valve that fails.

As to the why, I can only conclude it's just a marginal design. Of the picture I have where I can tell, the valve always seems to fail in the stem towards the head, almost in the radius of the valve head. However this might not be the root cause as I can also see examples where the head has broken off and the valve has failed in the keeper radius. I suspect in these examples the valve as failed in the keeper radius and then the impact of the valve on the piston has broken off the head.

On the plus side there are plenty of high mileage examples of VF500s still running so it isn't guaranteed the valves will fail this way. (I have one with 20K miles so mine ins't in this category yet). As a back up plan I have two spare engines. In Europe at least new valves and springs are unobtainium.

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It was me that asked about which valve it was. I have a growing collection of pictures of blown VF500 engines. This one makes 8 and of those it can be said that in 7 of them, it is an exhaust valve that fails.

As to the why, I can only conclude it's just a marginal design. Of the picture I have where I can tell, the valve always seems to fail in the stem towards the head, almost in the radius of the valve head. However this might not be the root cause as I can also see examples where the head has broken off and the valve has failed in the keeper radius. I suspect in these examples the valve as failed in the keeper radius and then the impact of the valve on the piston has broken off the head.

On the plus side there are plenty of high mileage examples of VF500s still running so it isn't guaranteed the valves will fail this way. (I have one with 20K miles so mine ins't in this category yet). As a back up plan I have two spare engines. In Europe at least new valves and springs are unobtainium.

http://www.cmsnl.com/honda-vf500f-500-interceptor-1984-usa_model1110/14721km3000-valve-ex_14721ke8000/#.UpMaxCfUxl4

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I tried to buy from CMSNL. They have a few springs and valves but not a full set of intake or exhaust. They may look like they do but they don't, or at least they ddn't in May this year when I ordered from them, even though their website suggested they did. They told me they were unobtainium too.

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