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Author Topic: Ducati Valve Adjustment Interval Questions  (Read 33375 times)
legalninja
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« on: January 10, 2010, 01:13:28 PM »

I know all the new models have 7500 mile valve adjustment intervals, but does anyone see that spec increasing to 12k miles or even as high as Yamaha's 26,000 miles intervals?  The precision of desmodromic valve actuation is often cited as the reason for the frequency of the valve adjustments, but is simple metal fatigue the primary reason behind the frequency of the valve adjustment, ie, the cam followers are cast rather than forged and not hard enough to remain within spec beyond an estimated number of engine revolutions? 

My Speed Triple 1050 had 12,000 mile valve adjustment intervals and I also recall Sport Rider doing a race build on a Daytona 675 in which they discovered that despite the high performance of that engine a lot of the internals were made from heavy castings rather than lighter stronger forgings (as the Japanese have in their sportbikes) due to relatively high engineering and manufacturing costs for such a small manufacturer.  The small size of Ducati made me wonder if that high development/manufacturing cost was a factor in the valve adjustment intervals. 

I'm obviously bored and daydreaming about Ducati minutiae.
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aaronb
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« Reply #1 on: January 10, 2010, 01:22:30 PM »

i believe the half rings are are the main culprit... which you can buy aftermarket versions of which claim higher service intervals.  i do not recal the company though, brain fart

edit, it's mbp

http://www.mbpducati.com/2v/colletoverview.htm
« Last Edit: January 10, 2010, 01:25:42 PM by aaronb » Logged

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« Reply #2 on: January 10, 2010, 02:03:01 PM »

The mechanical nature of the closing necessitates the shorter intervals. Without complete closure, the engine would obviously run like crap. The other manufacturers using simple springs to close do not need to worry about the tolerances in the same way. Its not simply the metal fatiguing, either. On many 2V ducati's, the majority of adjustment happens early in the life of bike ownership, with subsequent service interval clearance checks showing things are all in-spec. This may be attributed to things "breaking in" and adjusting to heat cycles, etc, among other things.

And yes, MBP is supposed to increase the length between valve adjustments, but not between valve inspections. You'll still need to peak in there and make sure things are doing their job, etc.
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« Reply #3 on: January 10, 2010, 02:03:50 PM »

From my understanding only....im no pro..

but generally speaking opners get tighter and closers get looser. The closeres get looser because the collets wear out from repeatedly being pushed against the closer.

so as aaronb posted if you get better collets, your interval extends since their collets are shapped differently and are made of tougher material.
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« Reply #4 on: January 10, 2010, 03:23:05 PM »

The higher the mileage on a Ducati, the longer you CAN go between even looking at the valve specs.

I have a friend w/an ST2 currently at 133K miles on it.  He NEVER looks at the valves until he's done 20K miles and he can't honestly remember the last time he needed to put a SINGLE shim in it.

The change Ducati made recently from a 6K interval to 7500 miles is purely for marketing.  They changed NO parts between the one year it was 6000 and the next when it was 7500.

MBP collets are OK I suppose, but after a while the stock split rings become so work hardened that it's a moot point.

I don't see Ducati's getting to 12K between valve services from the factory in the near future.  It's just the nature of the desmo system that requires more fiddling with it to keep it running well.
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« Reply #5 on: January 12, 2010, 03:04:26 PM »

Yea, Everything Duck-stew said.

The term work hardened is key.  After 6000 and for sure 12,000 mi. the valve clearance is relatively stable.  You still check it, but depending on how it was left at the last check, clearance is likely to be withing spec.

My current bike (34,000 mi.) has been checked adjusted as necessary, but really hasn't changed much since 6000 mi.  The shop has been kind enough to give me the numbers and I keep em.

Like said when Ducati increased the maint. intervals, it was just a stroke of the pen, as it were.

LA

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« Reply #6 on: January 12, 2010, 07:41:27 PM »

Had a customer with a '99 M750 and I set his valves up at 24K.  Set them textbook to 0.004" on all the openers and 0.001" on all the closers (took a bit more time but was worth it IMO).  He brought the bike back to me at 33K for it's next valve service (a little late but he was busy w/stuff).  All the openers measured 0.005" and all the closers were at 0.002".  I left it all alone.  No need to mess with that...
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« Reply #7 on: February 04, 2010, 02:51:51 AM »

Mine has 34k kms,never had the valves adjusted.good or bad? bike runs well so far.
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« Reply #8 on: February 04, 2010, 01:36:50 PM »

Ducati lists on their website that the new Multistrada 1200 has extended the intervals to 15K.  They say that the reason is the new valve timing.  http://www.ducati.com/od/ducatinorthamerica/news/detail.jhtml;jsessionid=XM520GWEWEREMCRNCB3CFFQKFUIHSIV2?newsId=31642
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« Reply #9 on: February 04, 2010, 03:33:59 PM »

From the above link:
http://www.ducati.com/od/ducatinorthamerica/news/detail.jhtml;jsessionid=XM520GWEWEREMCRNCB3CFFQKFUIHSIV2?newsId=31642

With the arrival of the new Multistrada 1200, Ducati will reach a significant milestone in the company's engineering history by extending the periods between major services on the new model to an owner-friendly 15,000 miles.

Doubling the mileage between valve clearance inspection has been made possible with the introduction of a new valve seat material combined with improved combustion efficiency and temperature management designed into the Multistrada's new Testastretta 11° engine.

So called because of its minimised 11° of 'valve overlap' - the interval of crankshaft rotation during which both the intake and exhaust valves are open at the same time - the new Desmodromic power plant not only transforms the world championship-winning 1198 configuration into a super-smooth 150hp motor for sport touring, but also improves fuel efficiency, emissions and cost of scheduled maintenance.


So they say.  coffee
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« Reply #10 on: February 04, 2010, 03:46:35 PM »

The higher the mileage on a Ducati, the longer you CAN go between even looking at the valve specs.

I agree...

My ST2 has 51k miles on it and since the 18k service I am only checking the valves every 12k, BUT....I am still adjusting the belt tension at 6k. I have noticed that if the belt gets too loose, if the engine is still a little cool adn you chop the throttle, the belt can slap the belt cover and wear a groove in the smooth side of the belt. I have also noticed that aroudn 10k-11k, the belts get loose enough that the engine will start to run a bit rough and backfire a lot easier.....I will not skip the 6k with a Desmoquattro engine, though. Mine have not proven to me that the rockers will not flake, so I play it safe and make sure they can make it to the next 6k service....I did replace the openers with Megacycles, but even with those I need to watch them and let them prove to me that I can go longer than 6k.
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« Reply #11 on: February 04, 2010, 04:09:26 PM »

So, what happens if you don't check the valves and they're out of adjustment other than a loss of power from increased overlap? Is there anything catastrophic that could result?

I always saw the valve check intervals as a good idea, but an experienced mechanic I know told me that he usually doesn't end up having to do an adjustment but every 12K or more, so I could go longer without checking since I didn't really abuse the bike.
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Armor
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« Reply #12 on: February 05, 2010, 07:40:04 AM »

What happens - the valve seat wears and the opener clearance closes up, the closer clearance increases.  You can get to the point were there is no opener clearance.  When this happens, the valve will not fully close and you can  burn the valve and seat.  You must check the valve clearance.
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« Reply #13 on: February 05, 2010, 08:08:58 AM »

The 11° angle is the included angle between valve stem centerlines, not overlap.  Overlap is the period of time during the transition between exhaust and intake strokes when both the exhaust valve and intake valve are open simultaneously.  This can be altered by cam grind.  The included angle is a characteristic of the head and cannot be changed without significant machine work.

As to wear in Ducati valvetrains, there have been some excellent points made here.  Valve seats do wear, tightening the opener and loosening the closer.  However, I know, without reservation, that the collets (or half-rings if you prefer to call them that) that tie the closing shim to the valve are the primary cuplrit in valve clearance deviation.  I think that the most important part of any valve adjustment is to make double, triple, and quadruple sure that you put the half rings back into the engine the same way they came out!

When half rings are new they have no top and no bottom, and it is irrelevant which way they're put into the engine as long as you use two per valve and they're seated correctly.  However, once they've been "run in", there is a distinct top and bottom, and if you put them in upside down you change the clearance of the valve.  The "top" has a small groove worn into it where it has been pressed upward against the shoulder of the groove in the valve.  The "bottom" is generally flat and shiny where it has worn on the closing shim.

I have found this to be the most significant variable in Ducati valve train clearances.  Once the rings are "worn in" the valves clearances don't float much.  As long as you put the rings back in corrctly when adjustment is required, the new adjustment will last for an extended period of time.  If you shatter a half ring (they tend to break when you really beat on the bike....like when you race it) and replace it with a new one you'll have to use a thinner closer to get the new collet to fit...but don't get rid of the original shim, as next time you check it I'll guarantee the valve will be out of adjustment and will require the original thicker closer.

That's my 2 cents worth,

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« Reply #14 on: March 18, 2010, 11:24:15 AM »

Quote
Set them textbook to 0.004" on all the openers and 0.001" on all the closers
Is this the accepted valve clearance for all of the 2V engines?  My Hanes manual has a huge range for them depending on model.
I just checked my valve clearances, and I'm wondering if it has ever had an adjustment...my measurements are waaaay too loose on the closers, but that's a whole 'nother thread.
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