Ducati tolerances

[uclabiker06]

I was recently informed that Ducatis have loose tolerances relative to the Japanese bikes and thats why Ducatis are as cheap as they are.  Are there any benefits to having tighter tolerance??

[venomousr1993]

When you are talking about tolerances, what exactly are you talking about?  Clutch? Drivetrain? Valvetrain? Bearings and which ones?  Engine?  Not trying to be a smart ass, just trying figure out what we are trying to compare.

[He Man]

As cheap as they are? I dont think ducati's are cheap.

The loose tolerances are there because the engine is air cooled. The tighter the tolerances of the engine, the more efficient it is. but its also more expensive to build and maintain.

[uclabiker06]

Okay, well I probably don't know half as much as you guys do.  All I know is I was talking to a well respected mechanic about the accuracy of a caliper.  He was saying that I should not worry if I am .001 off when using the caliper to measure shims and that he uses the same caliper for more important measurements.  Then he went on to say the tolerances are loose and that is a huge cost saving method that Ducati uses.   I found this to be very interesting.

The loose tolerances are there because the engine is air cooled. The tighter the tolerances of the engine, the more efficient it is. but its also more expensive to build and maintain.

He then went on to say that I should not mix up tighter tolerances with quality.  How do tighter tolerances contribute to efficiency?  And what does the fact that its air cooled have to do with loose tolerances? 

[Speeddog]

Your guy is full of BS regarding Ducatis.

[Capo]

The tolerances that Ducati use are sufficient for the task, just like the Japanese

[He Man]

I NEED TO GET ANOTHER JOB, i spend to much time here.  lol

Tighter tolerances means that there is less room for things to move around. Less things to move around means less wear and tear, and also means you can punish more. if you try to run an engine that has relatively loose tolerances in a race environment, your likely to have to rebuild it sooner than under normal operation becasue things wear out much faster.

Aircooled bikes tend to get hotter than their liquid counter parts, so as metal gets hotter, they expand more. Since there are a variety of metals being used in the engine,you have to accomodate for how much the metal expands when its fully warmed up. Thats why you shouldnt redline your engine at warm up. Everything hasnt heated up equally and expanded properly (that and oil hasnt gotten everywher yet). Thats also why your engine makes more power when its nice and warmed up, its also why your engine wears quicker if you dont let it warm up properly before getting on the throttle.

Theres a thread in the HOW TO section on breaking in your bike. Theres an argument regarding how you should break in your engine. Its debateable, but i am for it rather than against it since i know friends who have done the process  in cars that had great results. Either way, my point is, engines that are ran hard without a proper warm up, break faster. In the case of that specific thread, if you run your engine hard without warming it up during break in, chances are, your pistons rings wont properly break in and youll loose power, burn oil, or get aot of blowby gas etc.

+1 to Capo. Our engines are deigned the way they are and loose tolerances are perfectly fine in this case. those jap 4 cyls run MUCH higher revs (12,000rpms+) so they need the higher tolerances.

Theres a lot more to it im sure, but this is the basics.

[uclabiker06]

I NEED TO GET ANOTHER JOB, i spend to much time here.  Roll Eyes lol

No, I spend to much time here.

Your guy is full of BS regarding Ducatis.

He's not "my guy".  I just ordered some stuff from his website.  Anyways you guys cleared it all up for me (as usual). 

[Duc Fever]

I was recently informed that Ducatis have loose tolerances relative to the Japanese bikes and thats why Ducatis are as cheap as they are.  Are there any benefits to having tighter tolerance??

I have heard Ducati's called a lot of things but never "cheap"   I know my S2R was not cheap thats for sure!

[Norm]

I'm so confused

[A.duc.H.duc.]

I'm so confused

Me too Norm.

[bigiain]

Your guy is full of BS regarding Ducatis.

Possibly, he might instead just have been misunderstood - the pre '99 official Ducati valve clearance tolerances were quite a lot tighter than the 99 and later specs (or maybe it was '98 they changed?), and if he was just talking about the accuracy of measuring tools required to do valve clearance adjustments to the current sloppy factory specs, then he's pretty much right - you wouldn't bother spending extra money to get a tool that measures accurately to under a thou, where you might do if you were doing shim jobs on modern Japanese superbikes or supersports machines... The "cheap" comment might well have been explaining the claimed "50% lower service costs" that Ducati are advertising these days - so far as I can tell that's pretty much all about these new looser tolerances combined with longer service intervals.

'course, even if that's what he said, if that gets passed on as "Ducatis have loose tolerances relative to the Japanese bikes and thats why Ducatis are as cheap as they are", then yeah, its BS...

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[uclabiker06]

So building a bike with tighter tolerances isn't more costly than one with looser tolerances?

[uclabiker06]

EDIT:

When I say "costs" I am not referring to the total cost of one bike versus the other.  I just am asking whether it costs more to have tighter tolerances versus looser ones.

[bigiain]

So building a bike with tighter tolerances isn't more costly than one with looser tolerances?

Not so you'd notice with modern manufacturing methods - it's more about "the right tolerances for the design", as someone mentioned upthread, air (or air/oil) cooled motors _need_ larger tolerances because they don't stay as temperature stable (and hence as dimensionally stable) as water cooled motors - Monster motors (at least 2 valvers) don't miss out on tight tolerances to save money, they wouldn't run right with tight tolerances.

(Having said that, it could be argued that Ducati continue using the air/oil cooled motors to save costs, but that's a kind of round-a-bout way to claim the loose tolerances are a cost saving issue.)

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