[Classic_Duc]

Posted in 'Sportclassic' forum, but as some of us share the same block I'll try here as well......

Hope someone can shed some light on this for me..... Work done by qualified mechanic and 2v owner, assisted by the Noddy that owns the bike.

Heads are on the block, in the bike.

Starting with V Exhaust then V Inlet changed split rings and rechecked clearance.
No issues doing the Vert head at all. Continued with H Inlet and H Exhaust.

Horiz Inlet: After removing opening shim closing shim appeared bound to valve stem, pushing closing rocker also took valve and shim with it so unable to remove split rings. Held valve stem and used a socket over the stem with plastic screwdriver handle to very gently tap [and I do mean gently] closing shim to free it up. Changed split rings, measured clearances, replaced opening shim, rocker and clip. Moved on to H Exhaust.

Horiz Exhaust closing shim also bound to valve stem, released in same manner as H Inlet closing shim, changed split rings, measured clearance.
Replaced opening shim. Found we were unable to slide opening rocker back over opening shim, If opening shim is removed rocker can slide freely back over the valve stem.

Checked if there is clearance between rocker and opening shim when fitted. There is at least 10 thou between the rocker and shim so something [cam?] is stopping the rocker from coming back over the shim.

Appears as if inlet valve is bound or locked or on the cam in the wrong position, unable to rotate cam thru 360*. Does rotate forward about 90deg then stops, will not rotate backward. Checked if piston at TDC is prohibiting valve movement as belt is off, rotated crank forward and back 90* from TDC but still not able to cycle through 360*.

Checked for foreign items, confirmed nothing fallen into head locking cam or rockers.

Removed inlet rocker keeper clip, unable to move inlet rocker off opening shim for further investigation. Rocker not under load.

Nothing was overly difficult, nothing forced, nothing to indicate an issue with the Horiz inlet side at all.

Has anyone been here before? I have read that split rings may not be seated correctly- possibility for the inlet but unable to check.

 

[ducvet]

I don't have time to give a proper reply right now but try re-installing the original closing shims. It sounds like the closer shim is too big or the 1/2 rings are not seated, I assume they are oem 1/2 rings?

With the closer installed , no opener and the piston down can you rotate 360?

 

[Classic_Duc]

Thanks ducvet, no, without the opener it rotates forward approx 90 then stops, no backward at all.
We are back into it tonight, thinking the keepers on the closer aren't fully seated. after loads of searching I did find 1 refrence on the web to the fact that if the rocker will not come back over the opening shim then closing isn't seated or too tight.
More tomorrow.

 

[Classic_Duc]

Sooo, the last pair of split rings we fitted didn't seat properly, and once right it was all sorted.
Will certainly remember that for the next one.

 

[duc96cr]

Are you saying they appeared to have seated and there was no indication they weren't seated at all, yet changing them cured the issue ? Did you figure out why they didn't seat ?

 

[Classic_Duc]

Yes, exactly. they looked to be sitting on the shaft OK but when compared to the others they were slightly more visible in the shim. We'd had several goes at putting them in but gravity and fat fingers were making life harder than it needed to be.
Should have used a little grease to 'stick them in' and a mirror.....rather than battling away.

Ah... the things you learn!

I was a bit surprised that there seems to be only 1 refrence on the web to the fact that, if the opening rocker *will not* return then the closing shim is too tight. For us it also pretty much locked the cam, so we were

 

[wdietz186]

The collets do wear, and one side will give you the correct clearance but won't seat if they are upside down[one or both] also sometimes the concave in the shim has a slight lip at the top edge that won't allow the collets to seat properly. I've tried a different shim or taken a Dremel to the inner top edge of the shim. A frustrating P.I.A and hard on the fingertips.

 

[ducvet]

This is not uncommon and something that most of us that work on these bikes needs to be aware of, never trust a shim and 1/2 rings are seated without close examination. I always rive the opening rocker a few taps to seat them after installing as a slight change can give a false reading.

1/2 rings DO have a top and bottom after use and though they should fit either side up if you put one in the reverse of how it came out the clearance you just set will usually loosen .001-.002" after you put miles on the bike. The same with installing new 1/2 rings after the 1/2 rings wear to the shim and valve they will be looser. This is the reason we do NOT change 1/2 rings if possible , the looser the closer clearance the more wear - the more wear the looser the closer clearance= downward spiral.

The hard part is reading the 1/2 rings and getting both back in right side up and then setting closer to zero play and zero drag. Get it right and you have a closer that does NOT wear out 1/2 rings and once the heads are broken in (usually 15000-20000 miles) we run valve adjusts out to 10,000-12000miles between services with small changes to the valves at services. Any time I find a broken 1/2 ring I need to use new so I know that that valve will be loose the next time I see it and it will be at greater risk of damaging it than any I did not change.

I will also add that the most common 1/2 ring (collet actually) to not seat on installation is a NEW Brickwood (MBP) collet. I have seen numerous cases where the installer thought they were seated and installed a too small shim, when the motor ran it seated but now the clearances were loose. This is NOT the fault of the collet but installer error so as always check your work, once used they usually do not have the issue.

 

[ducatimike]

This is not uncommon and something that most of us that work on these bikes needs to be aware of, never trust a shim and 1/2 rings are seated without close examination. I always rive the opening rocker a few taps to seat them after installing as a slight change can give a false reading.

1/2 rings DO have a top and bottom after use and though they should fit either side up if you put one in the reverse of how it came out the clearance you just set will usually loosen .001-.002" after you put miles on the bike. The same with installing new 1/2 rings after the 1/2 rings wear to the shim and valve they will be looser. This is the reason we do NOT change 1/2 rings if possible , the looser the closer clearance the more wear - the more wear the looser the closer clearance= downward spiral.

The hard part is reading the 1/2 rings and getting both back in right side up and then setting closer to zero play and zero drag. Get it right and you have a closer that does NOT wear out 1/2 rings and once the heads are broken in (usually 15000-20000 miles) we run valve adjusts out to 10,000-12000miles between services with small changes to the valves at services. Any time I find a broken 1/2 ring I need to use new so I know that that valve will be loose the next time I see it and it will be at greater risk of damaging it than any I did not change.

I will also add that the most common 1/2 ring (collet actually) to not seat on installation is a NEW Brickwood (MBP) collet. I have seen numerous cases where the installer thought they were seated and installed a too small shim, when the motor ran it seated but now the clearances were loose. This is NOT the fault of the collet but installer error so as always check your work, once used they usually do not have the issue.

I wanted to comment on the last paragraph concerning the fit of the MBP collets.
A few years ago, I (EMS) licensed the MBP technology from Guy Martin of MBP (mbpducati.ca). I had been selling the MBP collets for quite a few years and noticed there to be some fitment issues, meaning that sometimes the MBP collets (both 7 mm and 8 mm) fit tight and sometimes were difficult to seat properly. I discussed the problem with Guy Martin and told him that with my engineering background, I could solve the issues. For me to do that we also agreed on a licensing contract.

I had been studying the problem for a couple of years and decided the design needed a complete tolerance study completed using a CAD system (this was never done before). Also an investigation into the heat treating process was also needed. To make a long story short, I discovered a couple of problems:

Concerning the 8 mm MBP's, The design analysis showed that a at MMC (maximum material condition on all mating parts), there was a slight interference. This was easily fixed by changing the tolerance of the OD of the machined part.

Concerning the 7 mm MBP design, it was seen that the cross section changed drastically in shape going from the bottom to the top of the part. This non-uniform cross section was causing warpage during the heat treat process. The warpage was not always the same from part to part. Sometimes the parts would fit and sometimes tight, and other times they would not seat at all properly. To fix this, I changed the actual design (shape) of the part and made it much more uniform in cross section (similar to the 8mm MBP design). I also worked with a metallurgist at a heat treat company to minimize warpage.
Both designs now fit nicely. The variation from part to part is now down to a minimum. My scrap rate is very low. The result is a product that is easier to install than the half rings and also easier to seat.

Mike

 

[jollyroger75243]

Sooo, the last pair of split rings we fitted didn't seat properly, and once right it was all sorted.
Will certainly remember that for the next one.

Glad you sorted it. You are not alone. I've not run across this problem on the OEM style 8mm collet, but have on on the OEM style 7mm.

 

[ducvet]

Mike
Great to hear you have worked to improve the MBP collets, given that the shims and valves both have production (and wear) variances I am sure it is not the easiest thing to cover them all. Anyone who installed the MBP collets in the past will surely rejoice that what was once a pain on first installation will now be better. It was not just owners who got it wrong in the past as I had a bike straight from a dealer with them set wrong.

Again this was installer error but making it harder for someone to make that error is a very good thing, keep up the good work!

 

[ducatimike]

Glad you sorted it. You are not alone. I've not run across this problem on the OEM style 8mm collet, but have on on the OEM style 7mm.

Over the years of owning and maintaining both 8 mm and 7 mm valve stems, I have had the same experience where the 7 mm half rings get hung up more often than the 8 mm half rings.
Mike

 

[ducatimike]

Mike
Great to hear you have worked to improve the MBP collets, given that the shims and valves both have production (and wear) variances I am sure it is not the easiest thing to cover them all. Anyone who installed the MBP collets in the past will surely rejoice that what was once a pain on first installation will now be better. It was not just owners who got it wrong in the past as I had a bike straight from a dealer with them set wrong.

Again this was installer error but making it harder for someone to make that error is a very good thing, keep up the good work!

Thanks for the compliment. I have also talked with many MBP users since I changed the design, and have been encouraged by their comments.
Mike