My bike recently has developed a little valve tick. I pulled the inspection covers last night to check the clearances, and ran into an issue with the feeler gauges. The manual says to bring the left intake valve to full open and check the right hand intake valve. The manual says the feeler gauge should just "nip", what do they mean by that? All the rockers seem tight with no play, except for the left exhaust rocker, which seems to have some up/down play when the valve is closed. Should I be worried?
valve adjustment question
- Thread starter nortncom
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Just 'nip' is when the feeler is pulled there is some resistance. It will drag a bit when pulled out. The best description I can give is that there is friction but no 'bite'. It is also important to have the feeler at as close to perpendicular when checking clearance.
SteveA
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nortncom said:
Why worry, you just need to do the adjustment! A little 'excess play' is what would cause your 'tick'. Closing the clearance down to the recomened gap should solve that. which as the man says is when the correct feeler guage, held at a suitable angle, just 'drags' when it is pulled out. (more vague words, but maybe more understandable in North America than 'nip', you will know when it feels right, try tightening and loosening whilst pulling and inserting the feeler guage to feel the difference). This is just finshing the job you started.
But do be careful with your wording here, when you say 'tight with no play' we will assume that you mean that you can insert the feeler guage between the valve top and and the tappet, with no 'excess play'.....if there was 'no play', you would not be able to insert the feeler guage, and then you should worry a litte bit because this is 'too tight' and would eventually cause burning of the valves....
But I assume you mean, 'three valves have the correct clearance as referenced in the manual and as checked with the feeler guages'. If so then great, just adjust the 4th valve to the correct clearance.
No worrying needed.
If however they are 'tight', meaning there is no measurable clearance, make absolutely sure you have the cam in the correct position when checking, as described in the manual, then slacken them off to the correct adjustment, ride and recheck regularly. If the gaps were closing after only a few miles then you would have an issue with valve seat erosion. I am pretty sure you don't. But it is probably a good idea to check the clearances at regular intervals, rather than only when you hear a noise, which of course is what it says in the manual....
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One trys to hold feeler flat to the valve stem surface so the drag sense is from actual spacing and not the tipped binding of the blade. Basically ya wiggle angle it to find least resistance of blade or just eye ball to hold flat to stem, which means blade is angled downward almost touching the rocker box edges. I prefer the feelerless thread count method of adjustor bolt, nip down till just seated then back off some and lock down.
Commando soon beats a dent in valve stems so at some point flat blade don't work.
Commando adjusters are 9/32" - 26 tpi BS Cycle thread. ( 1 turn = 0.0385")
5/16" UNF is 24 tpi. (1 turn = 0.0417") Ok. Based on 26TPI 1 turn = 0.0385in.
0.006in~ 0.15 turns or 54°
0.008in~ 0.20 turns or 72°
0.010in~ 0.25 turns or 90°
Commando soon beats a dent in valve stems so at some point flat blade don't work.
Commando adjusters are 9/32" - 26 tpi BS Cycle thread. ( 1 turn = 0.0385")
5/16" UNF is 24 tpi. (1 turn = 0.0417") Ok. Based on 26TPI 1 turn = 0.0385in.
0.006in~ 0.15 turns or 54°
0.008in~ 0.20 turns or 72°
0.010in~ 0.25 turns or 90°
DogT
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I'm not sure what you mean by tight, but the rocker with the closed valves should have some play corresponding to the instructions.
I would put the feeler gauge in as close to parallel with the top of the valve stem. That said, if there are any dimples in the valve stem, a feeler gauge will never give you a correct reading. If you have or can get access to a dial gauge it will be more accurate, but may be overkill.
Some people do it while it's running and just adjust it to what sounds best. I wouldn't though.
Dave
69S
I would put the feeler gauge in as close to parallel with the top of the valve stem. That said, if there are any dimples in the valve stem, a feeler gauge will never give you a correct reading. If you have or can get access to a dial gauge it will be more accurate, but may be overkill.
Some people do it while it's running and just adjust it to what sounds best. I wouldn't though.
Dave
69S
When I referenced tight, I mean that three of my rockers have no up/down play (valve open or closed), but my left side exhaust rocker has up/down play when the valve is closed. The tappet on that one actually doesn't touch the valve anymore when I move it up. All the other tappets make contact on the rear of the valve stem when closed. These cannot be moved by hand off the valve.
SteveA
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nortncom said:
Then reference my eaarlier comment, you should worry a little bit and slacken them off.....
The worrying is about why they became tight, assuming that it is not because they were previously adjusted too tight. But the process is set them, run it, check them and discover if they are tightening down on their own. If not, stop worrying....
I accept the comments from others about accuracy being reduced by wear and that there are more accurate ways to set a gap than feelers guages. But damn, they are useful, and actually the critical thing is to have a gap!
On an everyday bike with normal usage a little excess gap is no problem, may just be a little noiser, you may just notice, maybe not. A couple of thou too tight is OK too. Very tight is the one to watch for and the one that might cause more meaningful damage if left unaltered. Basically the valve is moving into the head, normally because the seat is eroding, which can happen for a number of reasons, like lead free gas! Once they become so tight that the valves do not clode properly, hot gasses escape then eventually expect the valve will start to get so hot it starts to burns away....now you really should worry, you may then need a head rebuild....valves and seats as minimum...but probabaly guides and more depending on mileage.
No point being anal with dial guages, not many Norton owners had one of those in the '70s!, calculating degrees of rotation for a gap is OK if you have a good memory for that shit and don't make mistakes!, how much do you trust yourself when tired from a days riding, a set of feeler guages goes in the tool roll and things can be rectified in the parking lot on a road trip, best get used to using them and how they 'feel' when it is 'near enough'.....
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DogT, Over Kill? No more that a water pistol is over a pea shooter l, Valve dents reqiure DTI, i guess the gap 
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. DogT said:
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For a fumble clukz like me doing by blade or by thread turn both ended up close enough so its a personal call with mood and whats on hand or in mind at the time. Unless adjusting will running of course, which is not really possible on a Norton d/t the adjuster moving with the rocker. I can only think of things that can open gaps not any that can close them w/o something getting jammedintheworks for distinct noises of a destructive show stopper.
First and foremost, thank you all for your input regarding my question--I am fairly new when it comes to working on this old Brit bike. Not to beat a dead horse, but from the information I have gathered from everyone's responses is that the tappet should not have contact with the valve when closed. Would that be a correct assumption? If so, I should back them off then slip the feeler gauge in and tighten to the feeler?
On a different note, I was reading about cam size and valve/tappet clearances. From what I gathered the stock engine is .006/.008 and the combat is .008/.010, respectively. However, my cam was replaced when the engine was built (not sure the profile, but it is supposed to be between stock and combat). So should I set it at factory spec, or something else?
On a different note, I was reading about cam size and valve/tappet clearances. From what I gathered the stock engine is .006/.008 and the combat is .008/.010, respectively. However, my cam was replaced when the engine was built (not sure the profile, but it is supposed to be between stock and combat). So should I set it at factory spec, or something else?
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I'd be all ears to know of a cam between standard and Combat 2S, as only ones I've seen listed as more aggressive than standard needed more than 2S clearances. I'd sure scan online the cam vendors listing the range of lash and mic yout max lift at degree point to judge which lash to aim for, other than trial error set and run and listen, as sure can't while running darn it. Also note the lash values are for cold engine IRRC>
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Set it halfway between the standard spec. and the hot combat cam spec. Dimples or craterings to stem tops render all advice useless as the tops should be flat. Any cratering here guarantees ticking valves. Back off the adjusters to ascertain condition with a flashlight to the valve tops.
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I hope I'm not stating the obvious. There must be some clearance with the engine cold to allow the valves to close completely and to allow for a change to the gap when the engine is hot. The gap can change after a rebuild as gaskets settle. The gap will also decrease as the valve seat wears over time. After awhile, you can tell by the sound of the tapping if the gap has changed. When checking valve clearance, you should be able to tell after a bit of experience how much of a tap you get when you wiggle the rocker if you are close.
Anybody favor mushroom adjusters?
Anybody favor mushroom adjusters?
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I must be a pretty crude mechanic because I haven't used feeler gauges on a motorcycle for years. The tappet adjusters are usually cycle thread, 26 TPI on British motor cycles i.e. about 25 threads in 1000 thousandths, so one complete turn of the adjuster is about 40 thousandths of an inch. If the head of the adjuster has four flats on it, one flat (quarter of a turn) gives a clearance of ten thousandths of an inch. So I slacken off the nut, and while the valve on the other port is at about max lift tighten the screw until it encounters slight resistance on the valve stem, then slacken it off the required number of flats,- and then holding it , carefully tighten the nut. If your valve adjuster has been used a few times, it should be relatively easy to screw in and out, if it is tight the job needs a bit more care. I often use the type of adjuster which is made from a hollow allen keyed grub screw, because they are lighter. It is easy to keep watch on how much you have rotated the key from the 'just tight' position. (Wassell brand used to be the go, came with dural nuts. )
The trouble with using feeler gauges to adjust valve clearance sometimes comes when the valves are old, and possibly have a dimple where the adjuster has been rattling against the tip. In Triumph 650 engines,with the older race cams tappets are set at 2 and 4 thou inch clearance when the engine is cold . You can just feel clearance at 2 thou, and 4 thou is half a flat on the adjuster . Nortons have much longer pushrods, and barrel height, so you can expect different clearances to be specified.
The trouble with using feeler gauges to adjust valve clearance sometimes comes when the valves are old, and possibly have a dimple where the adjuster has been rattling against the tip. In Triumph 650 engines,with the older race cams tappets are set at 2 and 4 thou inch clearance when the engine is cold . You can just feel clearance at 2 thou, and 4 thou is half a flat on the adjuster . Nortons have much longer pushrods, and barrel height, so you can expect different clearances to be specified.
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nortncom said:
Valve clearance can only be set when the valve is closed, but you have to ensure that the rocker arm of the other valve is on the highest point. Decreased valve clearance could also be a result of head retorquing, which is usually done after a rebuild. So I would adjust the clearance and check it after 1k miles. If it is still ok then, I would not worry much about it.
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