Dunc
XS650 Addict
Are you using the Porsche style tappet adjuster? Make sure it's not catching on the lip of the valve retainer. See if you can put a finger on the tappet to feel the click.
Large Spine Frame XS650 / Egli / Rau / Cafe Racer
- Thread starter rehar
- Start date
And you say that's with the cam chain tensioner removed?
There are points in the cam cycle where the valve spring force through the rocker forces the cam round. Throws slack from one side of the chain to the other, it will be more pronounced if the tensioner isn’t fitted or the cam chain is slack.
My Xs650 and TX750 have a distinct clatter at 3000rpm, I have tried various things to cure it to no avail.
My Xs650 and TX750 have a distinct clatter at 3000rpm, I have tried various things to cure it to no avail.
Yeah, that's a pronounced and odd noise with which I'm not familiar. The nature of it (slightly tinny) sounds like it may involve valve springs or retainers.
The keeper/retainer/stem doesn't look quite right to my eye (good pic previous page). Can you tell us about your valve train parts and their source?
The keeper/retainer/stem doesn't look quite right to my eye (good pic previous page). Can you tell us about your valve train parts and their source?
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Wasn't there a design change on the valves and retainers?Yeah, that's a pronounced and odd noise with which I'm not familiar. The nature of it (slightly tinny) sounds like it may involve valve springs or retainers.
The keeper/retainer/stem doesn't look quite right to my eye (good pic previous page). Can you tell us about your valve train parts and their source?
Yep, maybe mid-year '73 (256)-'74 (341)...looking for the Bulletin
rehar
rehar
Hi all -
Dunc: Porsche style tappet adjuster? Not sure what that is. This is a new CAM and I ordered the new Rocker arms from Mikes. The only difference between what I had and what is in it now - is the "adjuster". It was a square extruded (male) shape and now it is an allen (5mm?, female) shape.
Jim: Yes - with tensioner removed.
Rasputin: Interesting. It was making the nosie with the tensioner there and valve covers in place. I removed the valve covers and the tensioner to see I could still here it, and I believe it became louder. But, that could also be due the the removal of the covers... But, maybe it is actually louder. I'll test that tonight.
Jpdevol: The valves themselves, including the springs and being assembled in to the top head - was not touched nor disassembled. I did not hear any noise like this when the engine was all together.
Total miles on the engine are maybe 50 miles - PRIOR to me starting the 277 crank conversion. The engine ran well with the exception of: Vibration (normal amount, but detrimental when mounted as a stressed member), clutch slippage, Oil leaks and starter motor not disengaging as quickly as it should.
So I did not see any need to touch the valves. As to the source - I can only say that they appear to be stock. Valves are stock size, etc. The lifters appear to be stock as well. The old CAM appears to be stock. Brand new CAM is a megacycle, 277, mild flavor (250-20).
I wonder - could there be an issue with the old valves/retainer and the new CAM / Lifters? (The Lifters, other than the aforementioned adjuster, appear identical to the stock ones. And they are hardened.)
In my minds eye - something might be shifting position as the CAM rolls over its peak... ??
Dunc: Porsche style tappet adjuster? Not sure what that is. This is a new CAM and I ordered the new Rocker arms from Mikes. The only difference between what I had and what is in it now - is the "adjuster". It was a square extruded (male) shape and now it is an allen (5mm?, female) shape.
Jim: Yes - with tensioner removed.
Rasputin: Interesting. It was making the nosie with the tensioner there and valve covers in place. I removed the valve covers and the tensioner to see I could still here it, and I believe it became louder. But, that could also be due the the removal of the covers... But, maybe it is actually louder. I'll test that tonight.
Jpdevol: The valves themselves, including the springs and being assembled in to the top head - was not touched nor disassembled. I did not hear any noise like this when the engine was all together.
Total miles on the engine are maybe 50 miles - PRIOR to me starting the 277 crank conversion. The engine ran well with the exception of: Vibration (normal amount, but detrimental when mounted as a stressed member), clutch slippage, Oil leaks and starter motor not disengaging as quickly as it should.
So I did not see any need to touch the valves. As to the source - I can only say that they appear to be stock. Valves are stock size, etc. The lifters appear to be stock as well. The old CAM appears to be stock. Brand new CAM is a megacycle, 277, mild flavor (250-20).
I wonder - could there be an issue with the old valves/retainer and the new CAM / Lifters? (The Lifters, other than the aforementioned adjuster, appear identical to the stock ones. And they are hardened.)
In my minds eye - something might be shifting position as the CAM rolls over its peak... ??
rehar
rehar
Put the cam chain tensioner back in, I guess the volume of the clicking didn't really change. Placed copious amounts of oil on the valve adjusters. Put finger on the tip f the adjusters as a rotated the engine. It feels like the click is immediately after the cam peak. Like it's jumping down the slope of the cam.
That's why I questioned chain tension on the last page. Only 2 things (that I can think of) could cause a click... the chain, as load on the lobes goes from pulling to pushing
... or bad cam bearings letting the cam shift from the load change. Not sure what else would even know if the lobes just passed peak.
What kind of cam sprocket do you have? Stock style or adjustable 2 piece style? If it is adjustable, with the screws not tight, then the cam could "jump or click" when it passes max lift.
rehar
rehar
Good thought. It is a single piece though, not separate, not adjustable.
Is there a way to double check the Cam Position VS the Crank position, without removing the top Head/CAM Cover?
Is there a way to double check the Cam Position VS the Crank position, without removing the top Head/CAM Cover?
Normally, you could compare the advance dowel hole position on the right end of cam (RH TDC = 12:00) . This being Megacycle (uncut 277?), IDK if that has been changed.
rehar
rehar
JP, (Can I call you JP? 
) Thanks, I'll poke around and see what I can find.
) Thanks, I'll poke around and see what I can find.
rehar
rehar
OK, there is a hole on one end of the Megacycle cam that can be used for visual reference.
(The marking is on the opposite side of the engine though...)
36 tooth sprocket - means alignment is either correct (assuming it was assembled correctly from the factory), or could be off by 10° increments.
Not 100% sure, but alignment looks about right.
Next, I backed off the adjusters most of the way out, then spin the engine. No sound, no clicking. The cam does still move the valves a bit, but not fully open.
(The marking is on the opposite side of the engine though...)
36 tooth sprocket - means alignment is either correct (assuming it was assembled correctly from the factory), or could be off by 10° increments.
Not 100% sure, but alignment looks about right.
Next, I backed off the adjusters most of the way out, then spin the engine. No sound, no clicking. The cam does still move the valves a bit, but not fully open.
If those cam pics are with RH piston @ TDC (compression or exhaust no matter), you appear to be in time (subject to Mega instructions). The noise not being present with original cam and not present with adjusters backed off, tends to indicate a possible issue with the extra ~.050" lift of the 250-20 cam.
Megacycle indicates that cam should be ok with stock springs and guides, but a possibility exists that the previous builder used a different spring or shimmed the stock springs to where the springs are approaching "coil bind" with this cam. I'd pull the rocker cover and measure spring installed height and full open height and compare to spec. I'm a geek and would just be curious to measure all that stuff anyway: springs, guides, etc..
As the head has run as assembled, my previous concern about the keepers (esp on a '73era motor) is likely all wet and the camera just makes it look like 3 of the 4 pairs aren't sitting straight vs the stem (again I'd have a look anyway).
Megacycle indicates that cam should be ok with stock springs and guides, but a possibility exists that the previous builder used a different spring or shimmed the stock springs to where the springs are approaching "coil bind" with this cam. I'd pull the rocker cover and measure spring installed height and full open height and compare to spec. I'm a geek and would just be curious to measure all that stuff anyway: springs, guides, etc..
As the head has run as assembled, my previous concern about the keepers (esp on a '73era motor) is likely all wet and the camera just makes it look like 3 of the 4 pairs aren't sitting straight vs the stem (again I'd have a look anyway).
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rehar
rehar
Thanks JP, looks like I know what I'm going to be doing this weekend.
Questions (which really boil down to: When is it necessary to install a "new" head gasket?).
1) Loosening and removing the rocker cover, relieves pressure on the Head gasket, would this not cause it to leak? Does it need to be replaced? or - other option? (I feel like I'm over thinking this...)
2) If the (top) head were removed - has anyone re-used a Head gasket?
3) Same thing for the Base gasket? At what time does that need to be replaced, or sealant reapplied?
Questions (which really boil down to: When is it necessary to install a "new" head gasket?).
1) Loosening and removing the rocker cover, relieves pressure on the Head gasket, would this not cause it to leak? Does it need to be replaced? or - other option? (I feel like I'm over thinking this...)
2) If the (top) head were removed - has anyone re-used a Head gasket?
3) Same thing for the Base gasket? At what time does that need to be replaced, or sealant reapplied?
I've found that head gaskets that haven't seen any heat cycles (ran) yet are generally safe to reuse. Same on the base.
Edit: having said that, you'll have to weigh reusing it against the possibility of tearing the motor down yet again if the gasket doesn't seal properly.
Just speaking for myself, I'd reuse it. But that's a roll of the dice you'll have to weigh for yourself.
If the top-end gasket were installed dry - no worries. Of course, the rocker cover will need re-sealed. I've made spacers to take-up space of rocker cover (3/4" PVC) so I can roll the motor over with head snugged-down to prevent issues.
I've been in Honda land too long; on the XS you'll have to measure the spring height when valve fully open with the rocker cover in-place
(caliper depth gauge) then disassemble if desired to check the rest
(caliper depth gauge) then disassemble if desired to check the rest
