Tappet Loosening on its Own

T

tacoking

New Member
So, I've had this 73 honda 350 for a little over a month now and I've been getting down and dirty to make sure it runs as best it can. However, after about 5 different adjustments I've come to realize that one of my tappets is loosening all on it's own. I've got split washers in there to make sure this doesn't happen but it still does. Has anyone here experienced this before or know why it might be happening?

I have checked my oil level and it's good, which means it's probably not a lubrication problem. I've also put a lock washer on but it's not effective. The tappet that is loosening is the 4cyl exhaust tappet. Thanks for the help!!
 
Just checking your oil level is not a good way to know if your top end is getting oil.

Mark the adjuster, the washer, and the locknut. See if they are actually getting loose. If they are, the threads on the screw or in the rocker may be bad. Check by removing and inspecting.

If they arent, either your cam lobe, your valve tip, or your rocker for that valve is wearing out fast.
 
Thanks DohcBikes! The only way I know how to mark metal is with soapstone and I'm afraid that will wash away. How would you recommend marking the adjuster, washer, and locknut?

Also, considering how much I really doubt it's loosening on it's own as I've inspected the threads on the screw before. What would you suggest I do if any one of my cam lobe, valve tip, or rocker for this particular valve are wearing out fast and why might that be??
 
You can scratch the metal any number if ways, I use a carbide gasket scraper to make a mark just enough to see, it doesn't take much. Most importantly, mark the top of the adjuster screw with a line right through the middle, and either make another mark on the rocker or simply visually index it. Run the bike for the amount of time it takes to see the adjustment change, go back and check your marks. If the screw hasn't moved, some material is being shaved somewhere.

The cam and follower are hardfaced. If at any time these surfaces fail to receive sufficient lubrication for an extended amount of time, there is a risk of damage. Usually this can be easily seen by inspecting the parts visually.

As far as your valve tip, sometimes they just wear out. Crack, mushroom, lose material, it happens from time to time

The overall objective is to find WHERE the clearance is getting bigger. Then you'll have a better idea of what's happening. Once you find the part that is worn of wearing out, replace it.

The normal affect of a worn valve FACE or a worn valve seat in the head is to make the clearance tighter and tighter. Normal valve wear will also cause the clearance to tighten, but not quickly.

Your problem is the opposite, so the culprit is likely viewable from under the rocker cover. Unfortunately if it is the valve tip, there's some pretty major work in your future.
 
edit: good info dohc i dint see that when i slo typed this
the tappet screw is pretty darn hard metal the threads in the rocker end itself are the ones likely to be egged-out
with the tappet screw in place and the jam nut backed off can you feel wiggle in the threads ? it needs to be a really good fit,very little play it is a precision thread not loose like an average screw and nut
if the threads are too loose split washers wont do any good you need a new rocker arm
as far as a marker you could try paint like a paint marker for metal ,right there on the counter at the local welding store
you would want to clean off the oil and then let the paint setup
but like dohc says the other possible fails are the cam and follower wearing lets hope it is just the threads
 
The screw is probably damaged from over tightening.
Bit of a PITA to change as rocker box has to come off and adjuster screwed through from top (unless your lucky enough to have the 'small adjuster?)
Get a NEW adjuster screw and locknut, honda probably has them in stock (if not, 'borrow' some from a Chinese pit bike ;) )
Another common problem is rocker pad wear
 
.

is the nut loose when you check it?

if the nut is not loose, but your adjustment is increasing, your cam and rocker are wasted as DOHC mentioned.

if the nut is loose, remove the lock washer and tighten the crap out of it, if it strips then you know it was, and is, bad.
 
After 42 years I'd say all the parts are wasted. Stem tips, guides, adjusters....everything.
 
i only mentioned the egged out rocker tip threrads because i lhave seen that issue on these boards at least once it was discussed ,if the cam and follower were in that sad a shape ,to be knashing wearing knurling and galling,and continually loosening then i would think the oil would shine like a bass boat under the bug light in a 7-11 parking lot
all sparkly like just sayin'
.so op is your oil all metal flaky ?even a little or not at all ? you may need to drain it to look close and bust open the filter , see if it serves as witness ,and check them female rocker tip threads,,,,....,,,,,..//.'
motogp, the penultyimate round,sepang, up next :D
 
MR915 said:
After 42 years I'd say all the parts are wasted. Stem tips, guides, adjusters....everything.
Click to expand...
? Whut

There are 42 year old bikes ( and older obviously) with all original parts that run perfectly.
 
DohcBikes said:
? Whut

There are 42 year old bikes ( and older obviously) with all original parts that run perfectly.
Click to expand...
I disagree. 99.9% are worn out if they have served a normal life cycle.
 
.
Oh my, this oughta be entertaining.

graphics-laughing-867787.gif
 
MR915 said:
I disagree. 99.9% are worn out if they have served a normal life cycle.
Click to expand...

Not even remotely close... if serviced correctly you can see zero wear on parts over 100's of thousands of miles. Motorcycles tend to have very low miles/hours, poor maintenance is the only contributor to failure other than the obvious "wear" parts such as chains that stretch, brakes that wear, cables that fray, sealed bearings etc.....

People tend to wash and wax way more than change oil, grease and adjust... how many times a year did you brake down the head stock and clean the stem, bearing balls and races on your bikes, whens the last time you pulled the swingarm and pivot points to clean/replace bushings... hell even brake and clutch levers need to be removed to service twice a year those old rusty adjusters stuck in the perch ain't the bikes fault.

No parts don't wear out as fast as people wear them out :eek:
 
Tune-A-Fish said:
Not even remotely close... if serviced correctly you can see zero wear on parts over 100's of thousands of miles. Motorcycles tend to have very low miles/hours, poor maintenance is the only contributor to failure other than the obvious "wear" parts such as chains that stretch, brakes that wear, cables that fray, sealed bearings etc.....

People tend to wash and wax way more than change oil, grease and adjust... how many times a year did you brake down the head stock and clean the stem, bearing balls and races on your bikes, whens the last time you pulled the swingarm and pivot points to clean/replace bushings... hell even brake and clutch levers need to be removed to service twice a year those old rusty adjusters stuck in the perch ain't the bikes fault.

No parts don't wear out as fast as people wear them out :eek:
Click to expand...
Once again....I disagree based on my experience with air cooled motorcycles.
 
If you guys feel like discussing the life cycle and metallurgic properties of tappets and rockers, feel free to take your electron mircroscopes and tricorders to a new thread.

If you want to talk specifically about this particular situation and not tangent off into hypothetical discussion that adds zero value to this thread, then by all means post away. If the OP hasn't given you enough info to continue commenting then don't bother. Doesn't help answer the question if this turns into a debate about just how old is old.
 
Tim said:
If you guys feel like discussing the life cycle and metallurgic properties of tappets and rockers, feel free to take your electron mircroscopes and tricorders to a new thread.

If you want to talk specifically about this particular situation and not tangent off into hypothetical discussion that adds zero value to this thread, then by all means post away. If the OP hasn't given you enough info to continue commenting then don't bother. Doesn't help answer the question if this turns into a debate about just how old is old.
Click to expand...

And that 100 plus word rant was on point?


Sent from my iPhone using Tapatalk
 
Tim said:
If you guys feel like discussing the life cycle and metallurgic properties of tappets and rockers, feel free to take your electron mircroscopes and tricorders to a new thread.

If you want to talk specifically about this particular situation and not tangent off into hypothetical discussion that adds zero value to this thread, then by all means post away. If the OP hasn't given you enough info to continue commenting then don't bother. Doesn't help answer the question if this turns into a debate about just how old is old.
Click to expand...
Bad day Tim?

The discussion of metal's resistance to wear goes along fine with the thread.

of all the stuff on DTT this gets a reprimand? Ha.
 
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