gathering mat'ls / prep for head swap (900 era)

Started by junior varsity, February 22, 2011, 01:11:49 PM

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junior varsity

Well, the 1999 M900 fixxer-upper (perhaps M900fu for short) is getting to the point where there's only a few odds and ends left to tie up.

One is belts and valves. It came with the W-stamped heads. From the project parts shelves/pile-o-parts, I have the V-heads from the 02 900 ie (SS). I see several benefits in doing the heads swap: the bigger valves and the better IE cams. Additionally, since these heads are just sitting on the bench, I figure I will be able to do the valve shim adjustments (as necessary) much more easily, install the lightweight pulleys, and get ready to swap them onto the bike.

Here's my short list of supplies I'll need in preparation:
Valve Cover Gaskets
Shims
Cam End Gaskets (Cam ends were off of V-series heads)
Pulley nuts
Intake manifold Gaskets
Exhaust Manifold Gaskets
Belts
O-Rings that seal oil passages from cylinder to head
(The dowels that 'locate' the cylinders should not need replacing, do they?)
Putting CA-Cycleworks coils with new plugs and wires on as it goes back together as well

Plan:
Do the valves, seal up the v-heads, nurse a beer.
Remove intake manifolds, exhaust manifolds, belt covers and belts from Engine with W-series heads
Remove W-series heads
Replace oil-passage sealing O-rings and install v-series heads, torque nuts, drink beer.
Replace Intake manifolds with new gaskets
Replace Exhaust manifolds with new gaskets
Install Belts and Set Timing, Quadruple check work, nurse beer
Reinstall carbs, airbox, coils, plugs & wires

Remaining to do, I think, would be fiddle with carb jetting I suppose. Celebrate with beer cocktail of sorts, or maybe starting the bike for the first time.

Please throw out some ideas, correct omissions, do a spec of criticism and make suggestions!

junior varsity

Don't say the JE drop-in 92mm high comp 900 pistons, because I am going to do that much later on this beast. Step #1 is getting it to run.

Cloner

I'd be prepared to degree the cams.  Stuart and I did one of these swaps last fall and the cams in the new "V" heads were so far out of time from those in the old "W" heads that the darned thing would barely run!  It would idle, but wouldn't build revs.  Frikkin' junk-azz Monsters!   ;D
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'67 Aermacchi/HD Sprint SS (race bike)
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junior varsity

Haha. Definitely going to degree cams as I will be putting on new lightweight adjustable vee two pulleys as well.

I am considering putting the MBP collets in that I have. It was for the motor that's getting the 'race cams' and short manifold split singles, but the bonus in reliability would be pretty cool - the grocery getter could be the bike with the motor that requires less maintenance... Decisions decisions.

I've got a box of parts that was for the 'project'. Most of it I don't think will be getting used for this bike, which I intend to be a grocery getter setup (has 98-99 era round headlight fairing, keeping it with standard riser-mount handlebars). The Jako Motorsport short intake manifolds are still on the shelf until I get split singles for the other Monster or I acquire an SS. The VeeTwo race cams for the 900 and the VeeTwo "high-torque" cams are still on the shelf as well.


Besides degreeing the cams, what else might come up?

With standard cylinder studs equipped, good idea/bad idea to investigate thinner base gaskets to raise compression slightly?

I may get the local "stu" to help with this (Stuart Rust, former AMS guru, current guru's step-pappy [jordan])

greenmonster

#4
Check/lap valves on new heads.
Ditch base gasket after checking squish & valve clearance. Gives +0.4-0.5 comp if gasket is 0.40 mm.
Nurse beer after important measuring....
M900 -97 
MTS 1100s  -07

junior varsity

Quote from: greenmonster on February 22, 2011, 04:29:18 PM
Check/lap valves on new heads.
Ditch base gasket after checking squish & valve clearance. Gives +0.4-0.5 comp if gasket is 0.40 mm.

No base gasket altogether?

no external oil lines so no alt cover holes to plug.

Quote from: greenmonster on February 22, 2011, 04:29:18 PM
Nurse beer after important measuring....

Roger that.

ducpainter

Quote from: a m on February 22, 2011, 04:42:45 PM
No base gasket altogether?

no external oil lines so no alt cover holes to plug.

Roger that.
The cylinder will seal just fine to the case without the gasket.

The 'squish' and valve clearance part are the important variables. ;)
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junior varsity

good to know.

i've read the tech article from Chris K on DucatiTech about setting squish. Think I'm going to let one with more experience do that - seems like its straightforward but someone who has done it before should would make a good in-person teacher.

greenmonster

No gasket on any of my 2 900`s.
Good squish & no problemos, but do measure to b sure.
M900 -97 
MTS 1100s  -07

battlecry

Take a couple of old bolts and nuts and drop them on the parts pan.  That way when you put it all back together the extra bolts on the pan will not need to go on the bike.   [thumbsup]

junior varsity


Düb Lüv

Quote from: ducpainter on February 22, 2011, 05:04:53 PM
The cylinder will seal just fine to the case without the gasket.

The 'squish' and valve clearance part are the important variables. ;)

Mental bookmark. a poormans drop in.  Gracias
Building, building, building

junior varsity

Just chewing the cud for a second:

I don't understand the nomenclature of "drop-in" with reference to piston kits (that come with pistons, rings, pins, and clips). Is it because they have all the items you'd need to install? I was under the impression that one would need to balance the crank for the aftermarket pistons, (and really the bike would benefit from a balanced crank even with the stock pistons).

This was brought about by a suggestion from an old duc friend in Nashville who said "while its apart, you ought to raise the compression" - I had remembered reading about thin base gaskets from the CA-Cycleworks 100hp 2V article/ads, and now see that it is possible to run without the base gasket altogether (though I do wonder about the higher-lift IE cams on the M900, and the even higher lift ST2 cams or VeeTwo high torque, street, and race cams - the 210 through 212 grinds).

Talked to him again, and he said he was thinking about high compression pistons. Sure enough, I see that both JE and FBF have these high compression pistons in 92mm (I believe the FBF kits are made by WiseCo from reading around on the net). I'm sure there are more manufacturers out there, or at least one could contract a manufacturer to make some, but the ready-made kits are more my cup of tea.

I guess he was getting at - since the heads are off, why not take the cylinders off (got to if you mess with base gasket) and put in some high compression pistons while you are tinkering around. Here's where I thought that this wasn't so straight forward - does "drop-in" kit mean that its drop-in - with a piston mass close enough to the stock pistons so that the crank doesn't "have" to be balanced (even though it would be nice to do it anyhow - regardless of piston change)?

Splitting the cases is far beyond the scope of this project, so if that's the case, I want nothing to do with it (either at this time for this bike, or at all with regards to a fixxer-upper).

junior varsity

and then when searching, I find this in regards to the different weight of the 92mm JE pistons (guy was going to modify the pistons):
http://www.ducati.ms/forums/57-supersport/72543-fbf-je-pistons-2.html

Quote
In other words, you're stuck with the additional weight. This will not affect the balance of the motor, so long as both are the same. The counterwights on the crank balance the crank; they do not balance the piston/rod/wrist pin assemblies. The weights of those two assemblies offset each other on a 90 degree (or a 180 degree) crankshaft.

Countered by this response:

Quoteand i do not agree to the fact the counterweights on the crankshaft do balance the crank on a 90° L-twin, they are there to balance the whole crankshaft assembly including pistons, pins and conrods.

including this statement:
QuoteJE Pistons are said to have the same weight as the stock ducati pistons, so matching their weight will be your first priority here.

(with regards to the OP's questions as to piston to piston weight matching)

Countered by 3rd party:
QuotePistons are reciprocating mass, and thus do not enter into the balance question, nor do the wrist pins and the small end of the rod. The big-end does, however, and the rod itself as both reciprocating and rotating mass, so it also has an effect on the balance, albeit variable.

and that was confirmed by first party in above:
Quote...that's another way to put it. There is simply not enough mass, and it is too close to center, for the counterweights on the crank to "balance" the piston/pin/rod assembly. Yes, the big end of the rod adds two components to the equation, but the added weight of one big end is still offset by the added weight of the other in both of these components.

Sorry [2nd party], but we balance crankshafts all the time. They are balanced bare, all by themselves. Actually, there are two different kinds of cranks - "internally" or "externally" balanced. In the former, just the bare crank gets balanced to itself. In the latter, the flywheel is attached when balancing, and must forever remain matched with that crank.

We run some racing cranks with no counterweights at all. Kind of the extreme example of the lightened flywheel approach, it's an effort to reduce reciprocating mass. Surprisingly, vibration does not increase noticeably at all. A flat crank (boxer twins, VW fours, Porsche sixes) or a 90 degree crank (like ours) is surprisingly well balanced even with no counterweights. Stock Beetle motors have never had them.

Now look at our 45 degree Harley cranks. You simply cannot hang enough counterweight on the crank to offset the weight of those piston/pin/rod assemblies separated by only 45 degrees. They must balance each other - the crank simply cannot. Neither can the crank ever balance a single - look what BMW did with theirs, with the false piston to counterbalance the real one.

The dynamics of this are complicated. There are dozens of engineering papers explaining the nuts and bolts details of cylinder angle vs. balance. In a nutshell, we can achieve a "zero" primary balance at 90 and 180 degrees. This is with a single cylinder as a baseline "100%" shaker. A 45 degree twin becomes about an 80-some-odd percent shaker, 60 degrees takes a massive drop to well below 50%, and the "sweet spot" is hit at 90 degrees and again at 180 degrees. The piston/pin/rod assemblies are entirely responsible for the mass contributing to this vibration; remove them, and all of these cranks should be at "zero" balance.

Travman

#14
Quote from: a m on February 24, 2011, 01:05:07 PM
does "drop-in" kit mean that its drop-in - with a piston mass close enough to the stock pistons so that the crank doesn't "have" to be balanced (even though it would be nice to do it anyhow - regardless of piston change)?
Yes, that is what it means.  You still should weigh the new pistons to make sure they weigh what they are supposed to, but you do not need to have the crank balanced.  Who are you ordering the pistons from?  

I'm pretty sure the Pistal 1123 pistons I used might have actually been lighter than stock.  I think the main thing is that they weighed the same.