Babelfish

I've been searching both the forum and the workshop manual without finding the answere, even though I seem to remember a picture showing how to.
I have a vibration on high revs on power that I suspect can be due to ueaven wear. The front cylinder had a valve train crash and one valve replaced.
I suspect that this may have streched the chain as well causing this strong virbration. It has been building for more than 10K km now but I feel that I should do soeting about it now

Wicky

Rather than cam chain wear you should investigate for deeper down damage caused when CCT failed which caused valve to meet piston. Potentially an engine rebuild....

Babelfish

Well I guess I take may chances on that one.
I Don't have the time or facilities to do a rebuild the engine my self and workshop hours are way off budget here. So buying a used engine would be the obvious option. That said there are no noises or other symptoms that indicate damaged bearings about to fail.
I'm not sure but the my best guess is that the engine has done 30k km after the CCT failure. That's a lot of Ks for damaged parts.

Anyone who know how I can measure the cam chains?

If they need replacement, anyone tried the chains with connector link?

thetophatflash

The cam sprocket would show an odd wear pattern I would think. Pull the valve cover and check.

Wicky

Checked spark plugs? balanced carbs? Is the timing correct - if you suspect the cam chain is loose has it jumped a tooth or three?

The VTR's duplex cam chain is not readily renown for 'stretching', possibly damaged by CCT failure if it flapped around but if you've done 30k without a problem...

http://www.wemoto.com/bikes/honda/vt...in_borgwarner/

Babelfish

No the timing is "correct", or as correct as i gets. It doesn't align 100% for the front cylinder. Spark plugs has been replaced a couple of times. Valve play is slightly tight on the intake valves. Carbs has not been synced for a loooong time and I plan to do that as soon as I get the boost joint from my Honda suplier.
Can unsynchronized carbs really mess up the engine that bad when hard on power? I thought that only took care of a smother run at idle and low rpm/low power running.

Babelfish

I can see bright "polished" spots where the cam chain engage but I wouldnæt know how that odd wear pattern would look.

thetophatflash

Check the sprocket for "hooking" or other damage at the sprocket tooth. This is similar to checking your rear drive sprocket. Look for signs of metal chips in your oil.

Babelfish

Are you telling me that I have to look for a damaged sprocket to decide if the chain is stretched outside it's limits?
I thought that replacing chains were rather common while replacing sprockets were not as common. Wouldn't the smaller bottom sprocket be even worse off as it is smaller?

thetophatflash

I'm telling you that this is probably the easiest way to get an indication of an abnormal situation, if it exists.

HRCA#1

To me it seems unlikely that it's a cam chain problem, I do question having only replacing one valve! Normally in a 4 valve head they both hit the piston, usually the intake.

Wear isn't really an issue for the sprockets although if you see any damage as in cupping or abnormal wear I could be wrong but I've never heard of it.

PS Just read your last post. The cam chain is a HyVo chain not a roller chain like the drive chain. You could try lifting the chain from the sprocket if it moves more than a 3/8 ths of an inch you may have an issue but again I've never heard of it!

E.Marquez

If the chain is worn (stretched is a misnomer) you will see it in cam misalignment.. IE retarded and advanced cams.
If the cam chain is worn you will see it in a CCT that is extended a long ways.
If the cam lobe is worn, you will see it in extreme cases visually, in less extreme cases you'll need to measure the lobe height .

Caffeine

I had the same issue when I replaced my front head. the F.E. looked perfect.. all 3 times I tore it down, the 3rd time I just moved one tooth, as it was boarder line.. lined up a little better with the mark the first way I had it but the bike wasn't running right. Figured I had Nothing to loose as I was going to part it out.. damn thing fired up and is running like a champ! put 15K on it since then.. running strong.. I'm betting it's out one tooth.. PS.. compression looked fine as well, so you can't use that to judge..

Renderw

here's a few pics and the story of when I found my cam out by one tooth..
https://www.superhawkforum.com/forum...replace-28997/

Babelfish

How was the engine running with one tooth off? Mine is running perfectly normal except for that vibration that comes strong at about 6k rpm. It does the same wheelies and power the same way as always. At low rpm I guess the extra vibration is there but it's harder to distinguish from the normal vibrations.
Oil consumption is normal, nothing to very little metal particles in the oil.
I do some track days and usually do clutchless shifts upwards so a very small amount of metal "dust" on the oil plug is, I think, what to expect.

Babelfish

I agree that it is a bit strange, however I had some help from a very experienced Honda mechanic. He replaced the valve after I did a leak test with gas (head upside down having a pond of gas covering the valves. He said this normal and I could use the other valve. Did the same leak test afterwards and put it together.
As I said, I've done tens of thousands km after that and would expect a development of something else than the vibrations by now. Bent valves or damaged bearings don't continue to work that long, do they? The bike has been through many track days, spirited driving and a daily power wheelie, so there is no lack of strain on the engine. I would expect something to brake by now unless it something like the cam chain.

msethhunter

Wait, what? You mean with the valves closed, there was gas leaking through them? While it might be "normal" it's not right, because the valve is not sealed. A simple valve lap would have fixed that, and should have been done. If he is telling you that that is "normal" and acceptable, find a new mechanic.

Babelfish

No the gas leaked only from one valve, the bendt one. That valve were changed, and the honda guy did a quick lapping before he installed the new one. I did the leak test again and all valves sealed with no leaks.
The "normal" or "not unusual" was according to the mechanic that only one valve got bendt when the chain slipped.

E.Marquez

Very true for a TWO VALVE motor,, but as the VTR is a 4 valve motor, and BOTH intakes are open the same time, same amount,,,, bending JUST ONE is neither normal, usual, or in all but some freakish case I can not even come up with.. it's not even possible if we are talking mis timed cams.

Your mechanic is, was mistaken in his opinion I believe.

Babelfish

When a +50years chief mechanic with a reputation as an engine wizard and experience over the last 30 years, including international racing and tuning at the top level I tend to shut up and accept what they say, but then again YMMV.
But unless you tell me that this suspected valve cause the vibration and do so over 30 000 km while all the time giving top performance, no oil smoke I can't see why this mechanic is up for debate.
I just got vacuum meters, compression meter and hopefully I can use a fork air relief valve to connect to the front cylinder vacuum outlet so I soon have some answers.

thetophatflash

When are we going to better describe the vibration?

E.Marquez

Please ask the wizard how only one valve in a two intake valve motor impacted the piston due to cam misalignment.

Thanks

Babelfish

As a parallel twin without balance shaft.
As an engine out of balance. I once had an Aprilia 250 and it has a Suzuki engine with a two piece pressed together crank shaft. This had moved and that caused an even harder vibration. The vibration follows the rpm although I cant be sure if it is 1 x rpm, 2 x rpm or .5 x rpm. It gets stronger through the revs.
It is hard to get a precise feeling for it but to me it feels like the vibration is gone 90% when I shut off the gas from high RPM. The second or half it takes to go from 9k to 5k rpm it feel like the vibration is minimal compared to what it is going up through those revs on power. I place the rest to natural vibration for this type of engine.

My theory, and why I want to investigate the cam chain is that with bad cam timing one of the cylinders gets bad filling and bad exhaust push out, causing this one to perform slightly worse than the other and on power that difference in power is felt like a vibration as the power pulse is not as strong.

thetophatflash

I had a '70 Honda 450 twin that had a vibration in the low end. Turns out one of the mains wasn't a good fit in the crankcase. That being said, I'm not so sure that there wouldn't have to be a major problem on one cylinder to feel a vibration caused by a difference in power developed. Simply said, I doubt you would feel a problem like that as a vibsoration. There's just too much gong on to feel the weaker cylinder. I would be rechecking motor mounting torque, etc. Where do you feel the vibration? Hands, feet , handlebars? What rpm? Is it a "buzz" or is it heavier? Based on the fact that you say it has been building for the last 10k, I would be looking for signs of rapid wear or loose parts under the valve cover and in the oil. I might even check the chain and sprockets depending on "where I felt the vibration.

msethhunter

Okay, that makes more sense.

7moore7

I'm with Marquez... how could two perfectly symmetrical valves hit the piston asymmetrically (one hit and one doesn't)? It doesn't really make sense...

On a separate note, I'd check valve lash again before looking into cam chain problems. You have one new and and three old valves in there... who knows if they're all wearing correctly.

msethhunter

Carbon deposits.

Caffeine

ya mine wasn't running right, it would start to backfire and simply not rev at high rpm.. so I guess that's out..
thinking about the one valve thing.. that is odd. the only way I could think this could happen is if one valve was lifting higher then the other.. meaning shims were not set right.. did you check the valve clearence before reasembling?

Babelfish

New DID chain and new sprockets. I've had misalignment in the drive train and know that one.
The vibration become more of a buzz as the rpms increase but in general I'd say it's heavier. I can feel it in the whole bike. Hands, feet, tank and it's defiantly rpm related. How strong is it? I can easily feel it on power at 3.5 - 4k rpm but it only gets annoying at the track when the revs are generally above 6k over time.
Both top covers has just been off and things look ok.
Synced the carbs but run out of battery before I could perform a proper cylinder compression test. Will do that today.

Babelfish

Suggestions to get rid of that short of removing the whole head?