Modified Mbp Shims And Collets

Hi there,

I recently put MBP collets on the 900 D2 of my Supersport (1989). Being a 2V motor, I replaced the 8 half rings by 8 MBP collets (no need for modified opening shims on a D2, as they stand far enough from the closers) and whatever shims needed to adjust the valve lash as required. I don’t really see any valid reason (aside from budget) to only partially replace them as leaving even one stock half ring in the engine would negate the main aim of this upgrade which is to increase mileage between valve adjustments.



Here’s what Mike from Mike Brickwood Performance (MBP) has to say about these:

« It is important to note that when installing the MBP retainers, the closer clearance measured with the stock half rings may change if just the retainers replaced them. Typically, the clearances get a little smaller, around .002 to .004 inches for the 2V and .004 inches for the 4V. But I have seen this vary for the 2V. The reason is the retainers fill up the volume of the groove in the valve stem more so than the stock half rings. Also the fit in the closer shim is tighter. With normal tolerances on all the parts, the resulting clearances will vary a bit. So dont be frustrated if you calculate the new shim size you need and then put it in and when the clearance is checked, you find you have to put another closer shim of a different size in. That is why it is important to always check the clearances after assembling a new shim. When installing the retainers in a 4V bike, it can take some time, cause typically you replace all of the closer shims. Another tip, after the installing the retainers it is important to "seat" them by giving the closer rocker a good wack with a wooden dowell or other soft material. The impact will set the closer shim and force it upward to seat on the retainer. By doing this you will actually see the closer shim move up a few thousanths of an inch. If not done, the closer clearance will loosen up over time.


Shops will charge more to put them in compared to just doing a regular valve adjustment, because all the shims are usually changed out. But when done properly the results are definitely worth it, especially on a bike ridden hard. »

 

Hi G, is this covered in enough detail in the desmo times you so kindly group bought for me to have a go at? I'm reasonably competent but not done valve shimming before

Ivor

 

I think LT Snyder calls the valve train chapter the « heart » of his books (both D2/3 and D4). So yes, plenty of details about how to do this the right way, with many pictures, tips and FAQs answered. There are a few mistakes to avoid, he mentions all of them, but overall, the longest and most difficult part is to prepare the bike to access the valves in the best possible conditions, some bikes being more difficult than others. Supersports, for instance (including IE, if I am not mistaken) require to remove the rear shock to access the vertical exhaust valve cover…

- Don’t drop a valve in a cylinder when turning the motor with the closer off…
- Don’t drop a half ring in one of the oil ports located in the vertical head. Block these ports before starting.
- Don’t forget to free the ports when done, before closing the valve covers.
- Be super careful not to rip and destroy your valve stem seal when pressing on the closer rocker.
- Order shims adapted to your engine (7mm, 8mm)
- Always measure your shims with appropriate tools (micrometer) and method, don’t rely in the markings.
- etc.

In my own (recent) experience, prefer to do this with someone who knows how to do this if it’s your first time. It’ll be a world less stressful, if stressful at all.

 

Thank you, I'll start readying myself...

 

It's best not to think of a time limit for how long it will take because you may try & rush to get it done in that time and make mistakes. Besides it always take 4 times longer than you imagined.

When doing the Darmah I made up a stand, 4 threaded bars in the same orientation as the head bolts through a piece of marine ply with nuts/washers on which I could slide the head over and do the necessary in the comfort of the dining room table. Admittedly I was doing a pretty full resto so it made more sense and it might not be something you want to do as part of maintenance. It does make things a hell of a lot easier mind.

And always use the most accurate closing shim measurement tool you can because different tool's constructions give different measurements e.g. there might be a gap 0.2 with an existing shim that you have measured to be 6.45, so you order a shim of 6.65. But if the guy you order it from has a more accurate measuring tool he might have measured your old shim as 6.40 so a 6.65 shim (as measured by him) would be too big. I bought one of these (notice how fine the ledge is) https://laceyducati.com/ducati-part...05_200_83/8mm-shim-measuring-tool-p-1163.html

Once you understand the concept of what you are doing, so plenty of revision is recommended, it is a quite simple operation but must have lots of patience & lots of time with no need to get 'it done now' .

Oh did I mention lots of patience... lots...

But when you fire him up to the quite rustle of nicely adjusted valves you just know it'll be worth it.

 

I've got MBP retainers in both my 916 and M900, only the 916 needs the modified opener shims as the M900 shims are bigger and the retainers fit however, I also bought shim kits for both to save me waiting for/relying on anyone.

Since fitting them I rarely need to change any shims which shows most of the re-shimming required is because of the half-rings wearing.

They are far superior to the 'bent-wires' that Ducati fit and I would definitely fit them to any Ducati I owned.