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good question, i found this on the net, not sure if it's true, i'm sure someone here will be able to confirm, or if we can use these new shims but might be an easier alternative:

The MBP collets are extremely hard to install and remove, which makes any adjustments very difficult. They just about have to be driven into place. Ducati addressed the problem these collets solved, sometime around 1998, I think. The collets are round and the space in the shim that they used to fit into was flat on the bottom, causing the collets to wear and loosen over time. All newer closer shim from Ducati are round in that area now and wear has been minimized. The truth about Ducati valves is that after about 12k they rarely change much.



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About a year ago I received a batch of 7 mm MBP retainers from Guy Martin and I noticed that some fit a bit tight. We both didnt think it would be a problem but started to get calls from customers who were having problems installing some of them. We looked into the problem further and decided that some of the retainers were just over the high side of the specification. We found what caused the problem. We pulled the entire lot.

The current lot of retainers fit much better. They do not require excessive force to install and they can be removed easier also.

The statement about the closing shims changing in 1998 by adding a radius is simply not true. I owned a 97 916 and the closer shims had a radius. The 748 R bikes also have the radius on the closer shims used in them. These bikes were notorius for breaking the half rings during a race and even dropping valves and blowing up their motors. It was this problem that caused Guy Martin to come up with a better mouse trap to avoid engine failures. Hence the MBP retainer was born.

I have spent many and hour designing my shims to work with the OEM ducati half rings and the MBP retainers. Here is my opinion on this subject.

First of all the stock OEM half ring system is in use in thousands of Ducatis all over the world including the new 1198 superbikes. It works adequate. The round cross section ring fits into the groove in the valve stem and also inside the counterbore in the closer shim. The half ring is contained down inside the closer shim as the opener shim sits right on top of it. If the half ring should break the pieces are usually contained in the closer shim and no catasrophy results. The tighter the fit the better half ring performs. Unfortunately the OEM half ring is not precision made. It is simply wire stock round a round a mandrel and snipped in half. You can see it is literally snipped in half as the ends are not square. I also have measured the half rings and they are not uniform in cross section, meaning the thickness from one ring to another can be different. Also the half rings are not very hard and definitely deform over time.

In comparison the MBP retainer is precision made of A2 tool steel and heat treated (hardened) to a much higher hardness than the stock half ring. Also it fills the up much more volume and has more surface area of contact to hold the closer shim onto the valve stem. More surface area means less micromotion and less wear. See the diagrams of the two designs I have included.

From personal experience from bikes I have owned and from customers I can say that the MBP retainers will increase valve adjustment intervals over the standard half rings. You will see the advantage of the MBP retainers the harder you run the bike. I have owned 4 Ducatis, two track bikes and two street bikes. The street bikes (ST4, 46,000 miles, Monster 2V, 43,000 miles) have the stock OEM retainers. I started doing the valve adjustment every 6,000 miles but increased to 10,000 miles as in the last 20,000 miles I noticed the clearances not changing as much as when the bikes had lower miles. I never had a failure and the experience was a good one with the stock half rings. On one of my track bikes (916) I installed the MBP retainers at 6,000 miles and put on 3,500 track only miles in a 4 year time period. I checked the clearances at 10,000 miles and only one shim had changed by .001 in. I know the stock half rings would not have performed as well if used in this bike.

In conclusion, the stock half rings work adequately in street bikes. In track and race bikes they get hammered pretty good and can break. Even Ducati saw their limitations and came up with a completely different collet system in their "R" bikes (999R, 1098R, 749R).
If you want a better system to either increase your valve adjustment intervals or keep your piece of mind when racing your Ducati then the MBP retainers are a good alternative. If you simply ride your bike around the street and do not mind the recommended valve check intervals, then keeping the stock system is a good choice.

Mike
 

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MBP collates are extremely hard to install and remove?

Where do people come up with this shit?

Umm, had them on 2 motors, best thing ever made to keep your bike from having clearance issues. Don't forget, poor clearances are the #1 reason for rocker failure in desmoquattro's.

Buy the complete kit from EMS, but make sure you leave sometime in between needing the bike and receiving the kit. It does take sometime to install and get all the proper shims. Most kits come with what you need, but I've run into several issues with customers bikes where all the shims were almost identical! Very strange occurrence, just leave some extra time, thats all.

Mike; thanks for that write up, good stuff! ;)



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[QUOTE=tye1138;652996

Umm, had them on 2 motors, best thing ever made to keep your bike from having clearance issues. Don't forget, poor clearances are the #1 reason for rocker failure in desmoquattro's.

I've followed the rocker issues fairly closely for the last five years and I don't recall as absolute fact poor clearances has been the #1 reason for rocker flaking. It has been suspected in some circles as a contributory factor, but no one will comitt based on factual data this is the case. I will go so far to say based on the research I have done it is wise to keep up on your clearances and maintenance schedules, otherwise things can go wrong just as I would also recommend warming up your engine for 90 seconds in order to get the oil into the far reaches of the motor, in particular the verticle cylinder rockers. If Ducati has a tech advisory warning poor clearances can lead to rocker failure, I would love to see it.

You can have a 96 and 95 916s side by side and keep up on the scheduled clearances and you can predict the rockers will flake on the 96 model (mid year on) and not on the 95. Same with the 97 and 98 916s. It had nothing to do with clearances, it had everything to do with the sublet plating process Ducati employed after TPG bought them in 96.
 

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Mike did say it was true at one point in his above post.
I guess it depends on what bike, what year, what valve's and of course, how your particular set of collates were manufactured. I never had an issue with a gen 1 kit or a recent install that I did for a client. Sure, the variables are high, but still the OP's comment "pain to get off", I just never saw that... Though I also have good tools. ;)

I've followed the rocker issues fairly closely for the last five years and I don't recall as absolute fact poor clearances has been the #1 reason for rocker flaking. It has been suspected in some circles as a contributory factor, but no one will comitt based on factual data this is the case.
Well, I mean if you've got bad rockers, the wrong oil can cause them to flake from not creating enough lubrication between the lobe and rocker.

What happens is; the 1/2 rings actually fail over time. They're made out of a softer material and can crack, or just become un-round. As this happens, the clearances wonder, sometimes the closing shim migrates up the valve. Other times, the cracked bits get stuck in the closer shim and make the tolerances even tighter. I've seen both happen and all my 1/2 rings had failed on my 2nd 748 (so had the rockers) but my first one with more mileage, the rings were great and rockers were 100% perfect.

Another reason why rockers fail is directly related to motor RPM's. As the desmoquattro motor increases RPM's into the 10,500 range, the cam's start to bend. This bending causes the clearances to not only get tighter, but also the lobes won't hit the rocker straight-on. You'll see an unusual wear pattern in the rocker and that's proof the cam is bending. Obviously street riders don't suffer this problem, but track guys do and its a pretty huge issue. This is one reason why bikes like the 12,000 RPM revving 748RS has different clearances then all the other bikes and why the Testastretta version (749RS) has a 13,500 redline. The Testastretta has a larger cam bearing assembly, which prevents the cam from ever bending. Take that Desmoquattro! ;)



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Having helped fit MBP collets to a 748R a 748RS and having looked at them on a 999s engine i can say that it depends on the enginge your installing on and how much stuff you pull to do the install.


//amullo
 

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http://www.ducati.ms/forums/showthre...&highlight=mbp

I posted the above when we were in the middle of the tightness issue before we really had a chance to study the problem thoroughly and determine how much of a problem it really was. We hadnt sold that many sets of the retainers and noted that with a bit of assembly force we could get the retainers in. All though it seemed to work pretty well, it was a PITA to get some of them to seat all the way. What made it difficult was that not all the retainers were the same, some worse than others. When you consider there are tolerances in making the valve stems and shims, you can appreciate the problem. Also tight fitting is good cause it really locks everything together, but if too tight and they dont seat all the way, then not good!

The retainers offered now fit much easier and do not require alot of force to seat them in. Some more than others of course, but worst case can still be assembled easily.

Mike
 

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Mikes shims are very consistent in the outside dia. of the collet seating area but the O.E. shims often vary enough to cause a tight fight over even the stock collets.On engines that have seen lots of high revs and/or infrequent adjustments the collets can hammer the upper part of the collet groove and raise an edge large enough to make the closer shim almost impossible to remove.The only solution is to sand the ridge down with the closer shim held down out of the way.Or get primitive and use a punch to hammer it through.But using striking tools usually results in hammering the valve into the guide and scarring up the bore.And the rocker issue is due to a poor plating process more than clearance or oil quality.
 

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Discussion Starter #15
Thanks much for all the replies. My consensus is that I will stick with the stockers for now since this is a street bike. Since this is a used bike and I am not familiar with what it will do with clearances over time I will also check adjustments more regularly. Currently waiting for all 16 rockers to come back from megacycle after which I will start the install process.

Any tips on "easily" getting the closer rockers in with the springs?

Just received my new ohlins rear shock and new ohlins from forks. This so far has been a fun (although expensive) restore.
 
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