[Shavvo]

When reviewing the cam/tappet lash wear issues, exactly what is wearing? What wear, if any, is attibuted to concaving the top of the tappet? Is it harder than the cam? If it does wear, does the tappet have a random rotation creating and evenly worn bowl pattern? I see a bevel on a new cam edge, would this begin to thin in a theoretical bowl, if this could be happening? I'm going to find out over the winter, just wanted to know if this might make replacing the tappets a good idea or not.

 

[BayouRuler]

When reviewing the cam/tappet lash wear issues, exactly what is wearing? What wear, if any, is attibuted to concaving the top of the tappet? Is it harder than the cam? If it does wear, does the tappet have a random rotation creating and evenly worn bowl pattern? I see a bevel on a new cam edge, would this begin to thin in a theoretical bowl, if this could be happening? I'm going to find out over the winter, just wanted to know if this might make replacing the tappets a good idea or not.

The shims wear, there designed too:deal:

 

[RustyG]

The shims wear, there designed too:deal:

So if you have no shims you have no wear?

 

[ElrodontheV-Rod]

Typically,the normal wear is at the seat and the valve face.This creates less tolerance.If you find excessive tolerance,then look for worn components.If you can't find anything worn with high measurements,don't discount the fact that some have left the factory not set correct.
You MUST perform a top engine clean before you do this check to make sure there is no carbon in the way causing an ill reading.

 

[rjrivero]

Typically,the normal wear is at the seat and the valve face.This creates less tolerance.If you find excessive tolerance,then look for worn components.If you can't find anything worn with high measurements,don't discount the fact that some have left the factory not set correct.
You MUST perform a top engine clean before you do this check to make sure there is no carbon in the way causing an ill reading.

Beautifully concise, Al. :thumb:

 

[Shavvo]

Typically,the normal wear is at the seat and the valve face.This creates less tolerance.If you find excessive tolerance,then look for worn components.If you can't find anything worn with high measurements,don't discount the fact that some have left the factory not set correct.
You MUST perform a top engine clean before you do this check to make sure there is no carbon in the way causing an ill reading.

OK thanx, good advice: clean the top. Now, no carbon or other affecting debris.

However and but, still the question remains regarding the relationship between tappets and lobes. An automotive tech said that some car's engines have offset tappets, inducing tappet rotation, by the swipe of the cam. This assures a non-bowling, eliminating pin point wear, but rather an evenly distributed wear upon the tappet top surface.

Anyone comment concerning this. I guess we are evaluating the hardness differences between the cam and tappet.

Now, if "shims wear because they are designed to", how are they wearing if no tappet rotation? Just being smashed?

 

[RustyG]

OK thanx, good advice: clean the top. Now, no carbon or other affecting debris.

However and but, still the question remains regarding the relationship between tappets and lobes. An automotive tech said that some car's engines have offset tappets, inducing tappet rotation, by the swipe of the cam. This assures a non-bowling, eliminating pin point wear, but rather an evenly distributed wear upon the tappet top surface.

Anyone comment concerning this. I guess we are evaluating the hardness differences between the cam and tappet.

Now, if "shims wear because they are designed to", how are they wearing if no tappet rotation? Just being smashed?

I would discount the comments about shim wear. More likely it is what Al said in post #4. There have been many reports of valve shimming not needed after the first or second check and some bikes are approaching 100,000 miles or better. My two have had quite a few checks and after the second or third no more adjustments are necessary. Still checking however.

 

[El-Bobbo-Cheapo]

I would think offsetting the tappets will cause the guides to wear prematurely.

 

[ElrodontheV-Rod]

I know what you are talking about.
The profile of the lifter face is what makes it spin.It is made to spin for wear reasons.Flat tappets used the same technology,so did solid lifters.
Metallurgy and machining has come a long way up since this idea was put into use and we don't use it much at all anymore,now we use roller tip lifters,or followers w rollers.
Keep in mind the system used in the Revo is not new either,it is very well proven.This technology has been around for 80 years or longer,and used in many different engines.
You should try handling the shims in a Takegowa racing head for Honda mini bikes,I use tweezers!
The Revo is designed by Porsche and HD. I believe the major weak point in the valve train comes from the Harley side of the stick.They went with a low grade vender for the cams and this is part of the reason they want the lash checked at such low miles.
The buckets don't wear from their own fault.The ones I've seen that wear are from the cams that have pits.Not all pitted cams cause this wear,just the ones w sharp,or high edges at the pits.
If the buckets rotated,like you are suggesting,in the Revo head,I believe this would cause excessive wear in the bucket bore from lack of oiling.I'm sure they rotate some but they don't spin.Remember,the lifters you are thinking of live in a giant oil galley and have a constant supply of lube.

Like I say,I doubt you will find any terrible wear in the valve train,especially on the bucket face.If you do,look at the cam as the culprit,not the bucket.

Also,they used an adjustable solid bucket for the Revo because of the high revs it's capable of.A hydraulic bucket would not allow high revs as efficiently as the solids.


Also,the shims are heat treated after they are machined,they are not deigned to wear at all.

A micrometer should be used to measure the shims,not a veneer caliper.

 

[Jan-Dirk]

the tappet is chromed, very hard, little wear
I also noticed wear on shims, the valve stem "punctures" the shim over the time.
Very little wear on the seats so far.

 

[Philthy]

I would discount the comments about shim wear. More likely it is what Al said in post #4. There have been many reports of valve shimming not needed after the first or second check and some bikes are approaching 100,000 miles or better. My two have had quite a few checks and after the second or third no more adjustments are necessary. Still checking however.

I have run a few engines with shims over the buckets rather than under them. Quite a few bikes were built this way, as are most Toyota engines. On such an engine the cam lobe rubs the shim, not the bucket. Shims on these do not wear. I mic them for re-use and they simply don't wear. There is more variation between new shims of the same size than there is wear on a well used one.
Cam lobes show some wear and pitting over time, but we are talking six digits plus on the odometer before noticeable wear is visible. At around 200,000 miles the cams in my first K bike engines showed minor pitting a couple of scratches and the tips of the lobes were pretty well polished. These engines spin the buckets but this does not seem to wear the bores the buckets fit into. Geez, the cams run directly in the aluminum head casting, there is no bearing and these don't seem to wear out either.
What wears are the valves and seats, especially exhaust valves. They wear and allow the valve clearances to close up. If you don't catch this wear by checking valve clearances and by changing shims to achieve the correct clearance, eventually all clearance is used up and you burn the valve because it no longer seats fully. Modern engines with hardened seats and valves, for unleaded fuels, do not wear quickly. On my old 1984 K-100 I have put over fifty grand on the current engine since the last valve needed a new shim. This is one indirect benefit of both unleaded fuels emission regulations. It forced engine manufacturers to use more durable materials to meet the required mileage a vehicle must be able to last without exceeding pollution standards.

 

[Philthy]

I know what you are talking about.
The profile of the lifter face is what makes it spin.It is made to spin for wear reasons.Flat tappets used the same technology,so did solid lifters.
Metallurgy and machining has come a long way up since this idea was put into use and we don't use it much at all anymore,now we use roller tip lifters,or followers w rollers.
Keep in mind the system used in the Revo is not new either,it is very well proven.This technology has been around for 80 years or longer,and used in many different engines.
You should try handling the shims in a Takegowa racing head for Honda mini bikes,I use tweezers!
The Revo is designed by Porsche and HD. I believe the major weak point in the valve train comes from the Harley side of the stick.They went with a low grade vender for the cams and this is part of the reason they want the lash checked at such low miles.
The buckets don't wear from their own fault.The ones I've seen that wear are from the cams that have pits.Not all pitted cams cause this wear,just the ones w sharp,or high edges at the pits.
If the buckets rotated,like you are suggesting,in the Revo head,I believe this would cause excessive wear in the bucket bore from lack of oiling.I'm sure they rotate some but they don't spin.Remember,the lifters you are thinking of live in a giant oil galley and have a constant supply of lube.

Like I say,I doubt you will find any terrible wear in the valve train,especially on the bucket face.If you do,look at the cam as the culprit,not the bucket.

Also,they used an adjustable solid bucket for the Revo because of the high revs it's capable of.A hydraulic bucket would not allow high revs as efficiently as the solids.


Also,the shims are heat treated after they are machined,they are not deigned to wear at all.

A micrometer should be used to measure the shims,not a veneer caliper.

Who is this cam vendor? I was under the impression the V-Rod's cams were sourced from Schrick, the same company BMW and Porsche use for their cams. This is hardly low quality.
Btw, why not use a vernier caliper to measure shim thickness? I've been doing it that way for twenty five years now, I'm curious why a micrometer is a better tool for that job. I have both, but the vernier caliper is more accurate from what I can see, it has finer calibrations.

 

[bikerider58]

Modern engines with hardened seats and valves, for unleaded fuels, do not wear quickly. This is one indirect benefit of both unleaded fuels emission regulations. It forced engine manufacturers to use more durable materials to meet the required mileage a vehicle must be able to last without exceeding pollution standards.

What, those old bronze seats didn't last long enough for ya? Once the lead was out those valves really wear in deep. Amazing how bad they can be and the bike still runs (old school, slow, tired, air head).

 

[ElrodontheV-Rod]

I was told the cam vendor was changed and this was the reason for the cams pitting starting in 04.
A venier is not as acurate as a micrometer because the venier reads down to .01 mm and a micrometer reads lower,that's all.If you want to use a caliper,do it.

 

[Shavvo]

Typically,the normal wear is at the seat and the valve face.This creates less tolerance.If you find excessive tolerance,then look for worn components.If you can't find anything worn with high measurements,don't discount the fact that some have left the factory not set correct.
You MUST perform a top engine clean before you do this check to make sure there is no carbon in the way causing an ill reading.

I've been trying to comprehend all the good advice here.
This one on carbon has me stumped, needing more help with it.
I need to ask these questions about the carbon clean issue and please help me out if you don't mind.

Exactly what carbon is "in the way" and where in the "top engine"?
And just as importantly, how is this carbon actually removed/cleaned for certain? Adding potions and elixirs is not too inspiring to me but I need advice if there are new chemicals out there. I do use BG44 additive from time to time.

If this carbon is upon the valve lap/seat/contact area, wouldn't it have to be absolutely even to seal properly? If this is what you mean, then a compression check might reveal this carbon and we'd have a low or erratic reading because of it. I'm wondering how carbon can remain any where near or sandwiched in a swiping and revolving lobe and the tappets?

I was told that an engine can run normally & strong with sloppy lash at higher RPMs?

Anyone know at what RPMs this engine might experience valve float? Maybe the limiter will not allow this but it would be interesting to know what R's this begins to happen with stock cams and valve springs.

 

[VrodG]

Check out this thread.

http://www.1130cc.com/forums/showthread.php?t=128734&highlight=cleaning+valves