HC Pistons - Perf Cams - Valve related Q's

[junior varsity]

Why hello all. I am yet again itching to tinker, or at least learn prior to any tinkering, about:

Upgrading Cams --> Longer Inlet Valves --> High Compression Pistons --> Required Machining --> Ignition.

I've got a carb '99 M900. It has spaghetti headers and dp pipes, open airbox, dyna coils, Vee Two adj. belt pulleys, lightweight flywheel and clutch, and stock Mikuni Carbs (these will be upgraded, so don't bust my balls on that).

I've got a deal on the V2-03-210 'Torque Grind' cams from Vee Two for 900SS/M Duc's. I see they've got longer inlet valves (V2-13-201) which are required for the V2-210's. I have read on TOB that one could lengthen the factory valves, to accomplish the same goal. Here's the homework I did before hand: http://www.ducatimonster.org/forums/tech/152410-preload-new-main-bearings-v2-camshaft-talk.html

I will 'summarize' the parts that I have used below:

ACE:
Say Brad, read your report on Moto-one of the 900 carb with Vee Two cams. (http://www.moto-one.com.au/performance/900carbv2cam.html)
I am rebuilding a monster engine that has a BIG crack in the cases, with the cases from a SS that was from a race engine that had a rather nasty meeting of piston and valve.
The race engine has i think Vee Two 210 high torque cams on it, with FBF high comps and V2 adjustable pulleys.
Have you seen any other bikes with those cams in it? In your moto-one report did the bike have standard pistons? Have you heard any adverse comments on the V2 product?

BRAD:
The 210 cams will hurt the top end. Also, they'll exaggerate cylinder pressure at lower rpm making it likely more prone to pinging with high comp pistons. The motor in the report got a DP 944 kit (they're about 12:1 or something very high) later on and pinged like a mother.
We had to run premium and octane booster. Went well though. This was done before i knew a whole lot and we couldn't get info like I know now - like retarding the timing at the pickups, etc. we didn't see it for years and when it reappeared someone had jet-kitted it and I don't know what else. Didn't ping anymore anyway.

ACE:
Was looking at some JE high comp 11:1's, but looking at the original specs (blue line) with just the standard pistons looks quite nice.
I'm putting in some 41mmFCR's, would this make any difference to top end drop off?

NORM:
I built a motor with the 210 cams & 12:1 pistons (all from Vee Two) about 6 years ago. Instead of retarding the timing at the pickups, I just went with the Pedrozini(sp) ignition boxes & it ran well on pump gas without any detonation. I sold it some time ago & recently reacquired it through some trades & it still runs like a mother. The usable RPM range seems to be about 1000 higher than a stock cam.

ACE:
Did you need to do any modifications to the piston crown, and install the longer inlet valves?

NORM:
No, the pistons cleared just fine. I used titanium valves of the same size as stock (although if/when I do it again, I will go up 1mm on the intake). The only problem was that because of the cam lobe size, I had to get special, oversize shims (also available from Vee Two) to avoid sinking the valves into the heads. The carbs are 41mm FCRs on stock (long) manifolds that were port matched but nothing else. I used a light clutch & flywheel.

ACE:
Does this make sense, with the more lift of the 210's, putting in the longer valves would require the work to the piston. On the Moto-one site, Brad mentions that the valve cutouts in the pistons need to widened and deepened. With you putting in the oversize shims, it negated this.
I've got 41mm FCR to go on, so might be a good way to go

NORM:
Sinking valves into the heads seems to me to defeat the whole idea of a bigger cam. While I've never done it, I would think that carving out a little valve relief on the heads for the intake would seem like a good idea.

SPEEDDOG:
You need the longer valves or special shims with the 210's because the base circle of the cams is smaller (the closer rocker has the valve pulled closed further).
You need to re-do the valve cutouts because the 210's have much more valve lift than the stock cams.
As an alternative to using longer valves or special shims, you could sink the valves in the head.
V2 should be able to tell you how much you need to sink them such that you can use the stock valves and shims.
Be aware that this will not necessarily let you get away without re-doing the valve cutouts, but it may.
Again, V2 should be able to give you some guidance on this.
If you sink the valves, it will increase the combustion chamber volume.
That's not all bad, as those 210's build cylinder pressure due to the short duration.
I've not sunk the valves on a Duc, so get some feedback from someone who has, as some cylinder heads are very sensitive to this procedure.

ACE:
As a matter of interest, has anyone used the DP performance cams (# 964034AAA, or the old 06090).
They have the same cam profile as the V2 210's.
If you haven't seen it, check out Brad's rundown of these cams, it's what sparked my interest.
http://www.moto-one.com.au/performance/900carbv2cam.html

BRAD:
The reason you need to machine the std pistons is due to the 210 cams greater lift at TDC overlap (inlet opening) as it opens earlier and faster than a std cam. As a general rule, aftermarket high compression pistons have bigger cutouts, so don't require machining.
If you were running std pistons you could retard the cams to get away from the piston to valve clearance issue, although you might then have exhaust valve clearance issues depending how far you go. You'd need to go about 8 degrees based on my notes.
You can get the valves extended. A good head shop should be able to weld an extra mm or so on them. I wouldn't sink them.
Norm has experience with this specific combo (including the fcr) whereas i don't, so his info is more relevant.

ACE:
To summarize, base modifications as is:
•   41mm FCR's,
•   DP conti replicas, standard headers,
•   V2 adjustable belt pulleys
And my options are:
1.   Leave head as standard - easy, quick, slightly better with FCR's. Anyone want some V2 cams?
2.   Insert V2 210's, leave standard pistons, enlarge cutouts in piston, longer valves- little bit harder, slightly better
3.   Insert V2 210's, JE 11.1:1 92mm drop-ins, possibly enlarge cutouts in piston, longer valves, Pederzini ignition boxes- $$$, the full monty
I would just go with the longer valves, the idea of getting the oversize shims every time i need to do valve adjusts isn't appealing.[/font]

My questions are:

The longer inlet valves are necessary because the valve 'closes further' with the V2-210 cams, because the lobe is smaller on the closed side than stock, correct?

Machining the piston crowns is necessary in order to get clearance when the intake valves are open at TDC? Is machining also necessary for the exhaust valve clearance - meaning both sides of the piston crown need to come in some for the V2-210 cam's profile?

If a person uses high compression pistons, such as JE 11:1, Pistal 10.8:1, or FBF 11.1:1, then the crown already may be machined appropriately for the needed clearance - however, there's no guarantee and the pistons may still require some machining?

Is machining necessary for the heads themselves?

The product bulletin from Vee Two states:

When fitting these camshafts it may be necessary to machine 1.25mm out of
the depth of the inlet cutaway and 1.00mm out of the radius on both pistons. The underside
of the closing rocker should also be checked for clearance on the valve stem seal. If
necessary, grind enough off the rocker to allow sufficient stem seal clearance.

Is the 'inlet cutaway' the pocket in which the valve "seats" into when the valve is closed? I'm confused regarding the terminology.

As far as ignition goes, if I simply use a higher octane gas, such as 91/93 instead of the 87 my bike enjoys currently, will I be good to go? Or should timing be retarded / fancy electronic ignition needed? I see CA-Cyclework offers a programmable ignition: The Ignitech Sparker TCIP4 Ignition

[junior varsity]

The people mentioned above are:

Ace70
SpeedDog
Brad Black
Norm

[Speeddog]

-----snip------------------

My questions are:

The longer inlet valves are necessary because the valve 'closes further' with the V2-210 cams, because the lobe is smaller on the closed side than stock, correct?
Yes, that's the only way they can get the lift.

Machining the piston crowns is necessary in order to get clearance when the intake valves are open at TDC? Is machining also necessary for the exhaust valve clearance - meaning both sides of the piston crown need to come in some for the V2-210 cam's profile?
See below

If a person uses high compression pistons, such as JE 11:1, Pistal 10.8:1, or FBF 11.1:1, then the crown already may be machined appropriately for the needed clearance - however, there's no guarantee and the pistons may still require some machining?
It's safe to assume that the pockets will need some work.
You do need to check, IMO, no matter what pistons you use.

Is machining necessary for the heads themselves?
Dunno.

The product bulletin from Vee Two states:
Is the 'inlet cutaway' the pocket in which the valve "seats" into when the valve is closed? I'm confused regarding the terminology.
No, they mean the part of the piston that's cut away for valve clearance.

As far as ignition goes, if I simply use a higher octane gas, such as 91/93 instead of the 87 my bike enjoys currently, will I be good to go? Or should timing be retarded / fancy electronic ignition needed? I see CA-Cyclework offers a programmable ignition: The Ignitech Sparker TCIP4 Ignition

Brad seems to have gotten some really good results with that ignition setup, from what I remember of his reports.

[Norm]

Some people manually retard the stock ignition 2 degrees throughout the curve, but I've always used the 1.1 modules. The new adjustable units that Chris sells, "should" provide lot's of better options. We've been testing them for awhile and are planning a 13:1 project soon.

[junior varsity]

Awesome. Thanks for the info. Just to clarify:

The maching is 1.25 'deep' into piston cutaway for valve clearance, and the 1.0mm 'radius' cut is also in the piston, yes?

That's the part that confused me on the product bulletin. I suppose things will make a lot more sense to whoever I can find thats competent to do this kind of thing. But I am trying to learn as much as I can before I jump into such a project.

[brad black]

is yours a big valve or a small valve motor?

[Norm]

When assembled, just lay a thin strip of modeling clay accross the piston/valve area and run it thru by hand. That will tell you your "cold' clearence. I forget what is min., maybe Brad can remember? Also do this to measure squish.

[junior varsity]

is yours a big valve or a small valve motor?

Big valve - "V" series heads.

[brad black]

going by my numbers the je should have enough clearance to run the 210 cams at around 108 inlet centreline.  spec is 105, which would have it down to around 1.00mm piston to valve clearance.  110 has it around 1.80mm.  i aim for 1.5 min, although you can certainly go closer.  they close the inlet at 55 degrees abdc, so retarding them 5 might not hurt anyway.  they do have very short exhaust duration, so you probably wouldn't want to go too far tho.

i measure lift at various points - 10 to 15 degrees atdc inlet opening is the closest point - then remove the belts and redo the piston settings, but wind the cam around and measure at what lift the valve is stopped by the piston.  that gives you the maximum lift available.  the difference between the two is the piston to valve clearance.  personally i'd dummy assemble it and check it - then you'll know.