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so I Had the fresh built motor fired, strobed and run around the block. Felt great to be on her again. few issues that I'm trying to figure..
-Before running, at the exhaust valves/pushrod/rockers, there would be a slight click as the cam would reach it's apex. Wasn't sure if it was full compression on one side or full release on the other as it would happen on both sides.
-There developed a terrible clattery sound when I would run it beyond 3-3.5k. it wasn't there while strobe timing. when I put her up on the stand and pulled the valve cover off I see that one exhaust valve is now SUPER loose at about .035. the adjustment was still tight however. I pulled the pushrods and they don't appear to be bent. I used some extrusion blocks and a height guage to verify as best I could.

I've pulled the head off but haven't pulled the valves/springs out to check those yet.

The other issue is I had the Bob Newby clutch set and working well. Ez engage and good solid bite. After getting it back on the stand and going to kick it over to check compression the clutch doesn't bite enough to turn the motor over now. Even after tightening the springs well beyond where they should be.

I will try to upload a pic but I'm curious if this bushing/sleeve shoulder is supposed to extend so far into the clutch basket assembly area and causing issues. Or if the gearbox could float and cause engagement issues. I don't know. Just guessing at this point..

https://photos.app.goo.gl/RKfNJUaUzoeX5PJ86

I don't know how to upload photos apparently but can link to the photo in my Google drive..

Thanks!

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Sounds like your valve springs are going coil bound.
Did you check it when you rebuilt?

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Or the pushrods were not properly seated in the cam followers when you originally set them
As the cam grind should be the same & the pushrods should be the same length pop them back in anc check that the rods lift & drop the same amoutn and that they sit at the same height when on the base circle
A bad follower that has worn through the hard facing will both click & wear rapidly .


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Originally Posted by NickL
Sounds like your valve springs are going coil bound.
Did you check it when you rebuilt?
Could be. I got some springs from a vendor who shall go unnamed. New springs from MAP solved this issue.


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Originally Posted by NickL
Sounds like your valve springs are going coil bound.
Did you check it when you rebuilt?

I thought I checked clearance but it's very very possible they still are and I was off..

The thing is. I don't see any deflection in the pushrod (cromoly). Valve stem isn't noticably bent. I still need to support it and check the runout on it for true with a dial gauge. Doesn't look like there's any damage to the cam. Followers look good. The adjustment on rockers for valve clearance was tight so I don't see anyway it could have slipped, especially that much.
I agree it seems to me like it's coil bonding but for the life of me I can't see where that .035 valve clearance came from..

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Originally Posted by BSA_WM20
Or the pushrods were not properly seated in the cam followers when you originally set them
As the cam grind should be the same & the pushrods should be the same length pop them back in anc check that the rods lift & drop the same amoutn and that they sit at the same height when on the base circle
A bad follower that has worn through the hard facing will both click & wear rapidly .

I'm sure they were seated properly. I will do that check when I reassemble it though.

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Valve spring fit in the hat and cup might be the issue. A fat spring might not seat in the hat or cup. After all the stress and wiggle of a running engine then the spring might find the seats and result in a wider lash.

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Originally Posted by Bustednukel
Valve spring fit in the hat and cup might be the issue. A fat spring might not seat in the hat or cup. After all the stress and wiggle of a running engine then the spring might find the seats and result in a wider lash.

That may be the case. I did have to machine the inner lip of the valve spring cup to accommodate the thicker springs. It certainly seemed as though the spring was fully seated but perhaps not..

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OR you've actually bent the rocker arm.
I've seen that before but only with lightened rocker gear.

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If your Bob Newby isn’t biting with the springs wound down to being flush with the top of the nuts on the four plate kit or flush with the bottom of the slots on the five plate kit then your problem is unlikely to be the clutch but more likely the fact you need to reset the centre adjustment screw. The screw thread is quite coarse so 1/8 a turn from being screwed in and all the components touching (not screwed so tight your busting the other side the clutch) is sufficient.

For the top end, might be worth checking all the pushrods are properly seated. I’ve had a cap on a chromoly rod chip a piece off after a period of time, it didn’t cause any problems, I just found it as such at the next service. Possibly also the tappet/cam follower was being held up at one point and not following the cam, what ever the obstruction was has shifted and now the cam follower moves freely across the full movement of the cam. Resetting the tappets might be sufficient.


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Originally Posted by Allan G
If your Bob Newby isn’t biting with the springs wound down to being flush with the top of the nuts on the four plate kit or flush with the bottom of the slots on the five plate kit then your problem is unlikely to be the clutch but more likely the fact you need to reset the centre adjustment screw. The screw thread is quite coarse so 1/8 a turn from being screwed in and all the components touching (not screwed so tight your busting the other side the clutch) is sufficient.

For the top end, might be worth checking all the pushrods are properly seated. I’ve had a cap on a chromoly rod chip a piece off after a period of time, it didn’t cause any problems, I just found it as such at the next service. Possibly also the tappet/cam follower was being held up at one point and not following the cam, what ever the obstruction was has shifted and now the cam follower moves freely across the full movement of the cam. Resetting the tappets might be sufficient.

I'm hoping your correct. I found one of the cam followers didn't want to move freely in it's cradle. Perhaps it was stuck from moving it's full travel while setting gap and at intial timing/runout. Worked free when engine got warmer then the crazy loose rocker made that god awful rattle/clatter.
Allen, were you able to look at that photo I linked of the clutch shaft? I can't remember if the bushing/collar is supposed to protrude that far into the primary side...
Thank you for your input. I really value your advise and experience!!

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Originally Posted by StephenM
Originally Posted by Allan G
If your Bob Newby isn’t biting with the springs wound down to being flush with the top of the nuts on the four plate kit or flush with the bottom of the slots on the five plate kit then your problem is unlikely to be the clutch but more likely the fact you need to reset the centre adjustment screw. The screw thread is quite coarse so 1/8 a turn from being screwed in and all the components touching (not screwed so tight your busting the other side the clutch) is sufficient.

For the top end, might be worth checking all the pushrods are properly seated. I’ve had a cap on a chromoly rod chip a piece off after a period of time, it didn’t cause any problems, I just found it as such at the next service. Possibly also the tappet/cam follower was being held up at one point and not following the cam, what ever the obstruction was has shifted and now the cam follower moves freely across the full movement of the cam. Resetting the tappets might be sufficient.

I'm hoping your correct. I found one of the cam followers didn't want to move freely in it's cradle. Perhaps it was stuck from moving it's full travel while setting gap and at intial timing/runout. Worked free when engine got warmer then the crazy loose rocker made that god awful rattle/clatter.
Allen, were you able to look at that photo I linked of the clutch shaft? I can't remember if the bushing/collar is supposed to protrude that far into the primary side...
Thank you for your input. I really value your advise and experience!!

Your welcome, the more bikes we can get on the road and people being happy riding them the better I think.

The bush looks fine but the seal is the wrong way around, though since the BNR runs dry.... it probably won't make any difference. but typically you want the "ugly side" of the seal facing the side which is to hold oil or has the most pressure - ie the crank seal would face ugly side towards the crank.

I've seen with cam followers that if the follower has dropped beyond the block faces and rotated a little bit, then put down, it puts the tinest ding on the flat face. It doesn't have to be much but its enough to hold up the follower. In that instance I'd pull the barrel and carefully dress the offending surface with a file, covering up the other holes as much as possible. If its a dry frame bike you might be able to just get the head and barrel off in one piece, I changed followers on one once (from one radius grind to another to suit a cam), though I just lifted it up enough to enable me to have access. Youd still have to remove the push rods to do this. Assemble with some engine assembly grease to hold them in place - works wonders.


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Check for coil binding with feeler gauges between the spring coils at full lift, a 3 thou blade should pass through, I dont see how a badly seated spring will change clearances, the valve length and seat wear dictate tappet gaps, not spring pressure. When turning the motor over by hand using the rotor nut to drive it round ,coil binding will be obvious, if the crank gets very stiff at max valve opening that is coil bind,( there will be some resistance as the spring compresses but if you feel a steep hump at max opening thats coil bind, spring pressure rise should be fairly linear.) this is not a good thing, if the motor ran it would indeed be noisy as the forces on the valve train will be immense, to keep running something like Nick describes would seem inevitable. If you have spare rocker arms compare them to whats in the bike now.


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Gavin, you are right about the valve length and seat wear dictating tappet gaps, not spring pressure. So, hopefully the OP sorts it out and posts an update.

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Do the pushrods have pressed on ends? One may not have been pushed completely on and shifted.


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Originally Posted by Bustednukel
Valve spring fit in the hat and cup might be the issue. A fat spring might not seat in the hat or cup. After all the stress and wiggle of a running engine then the spring might find the seats and result in a wider lash.

Originally Posted by Bustednukel
Gavin, you are right about the valve length and seat wear dictating tappet gaps, not spring pressure. So, hopefully the OP sorts it out and posts an update.

Not sure if your disagreeing or agreeing with Gavin or contradicting your original statement?

Either way. Anything that will effect spring pressure (providing it is enough to keep the valve closed) should not change the gap. If there is insufficient tension on the springs that will not keep the valve closed then it’ll more likely to drop the collets and then the valve.


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Originally Posted by Allan G
Originally Posted by Bustednukel
Valve spring fit in the hat and cup might be the issue. A fat spring might not seat in the hat or cup. After all the stress and wiggle of a running engine then the spring might find the seats and result in a wider lash.

Originally Posted by Bustednukel
Gavin, you are right about the valve length and seat wear dictating tappet gaps, not spring pressure. So, hopefully the OP sorts it out and posts an update.

Not sure if your disagreeing or agreeing with Gavin or contradicting your original statement?

Either way. Anything that will effect spring pressure (providing it is enough to keep the valve closed) should not change the gap. If there is insufficient tension on the springs that will not keep the valve closed then it’ll more likely to drop the collets and then the valve.

Alan, agreeing with Gavin cause he's right. My idea that an improperly seated spring could result in a wider lash if it seats after running was wrong. On a past engine build I had an improperly seated spring which I discovered as I centered one of the valve keepers which was in contact with the other keeper. It slid around loosely with ease and alerted me that something was wrong. Made me think of the OP.'s issues.

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Okay, been a minute as I started a new job as a machinist with the local school district and getting sorted into that.
I've gone through the top end and not been able to find what the offending issue is. I pulled the head off and check the valves and valve springs, everything seems to be as it should. I put the push rods on v-blocks and checked for any deflection/bend and they still look good.
I then pulled the cylinder off and put an indicator gauge on the cam lobes, then rotated the motor over and checked that one of the lobes hadn't been shaved and created that Gap. The one thing that I did find is one of the cam followers ( I'm running on the assumption that it was the correlating one) did not want to seat all the way. I'm hypothesizing then when I set the valve gap the cam follower wasn't allowed to go through its full travel. As I took the bike out around the block the engine heated up and allowed the cam follower to then get its full travel increasing the gap.
I've got the cylinders back on, the head back on just need to set the Valve gap again, put the cover on then get the engine back in and fire it up.
I really have no idea if my hypothesis is remotely close. At this point I'm fairly disheartened with it as I found no definitive reason for that Valve gap to have developed. I'm about 3 months behind where I wanted to be with this bike and it's got me really tempted to just park it and wait for that new Goldie to come State Side.
I'll let y'all know how it sounds and runs when I get it fired up thanks for the insight so far guys.


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