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Discussion Starter #82
Did you lighten any of the gears as you did on the SC project?
I only did the cam gear. I don't think they are ever balanced correct. So I lightened this one and balance it as well. All the other gears I left stock. Good enough for this bike.

This is the stock cam gear



And this is the lightened and balanced cam gear, but this is jumping ahead too far

 

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Discussion Starter #83
I think I have lost some pictures, or just forgot to take them.

Here are some pictures of the pistons.

Since this engine will use the 1000cc 71.5mm stroke crank and 130mm rods, it is necessary to also use the pistons from the DS1000 as the pin height is higher than the 900ss pistons so the deck height will be all good.

So what I did was buy some standard bore Pistal high compression forged pistons. These are 94mm bore which is +2mm over the 92mm 900ss bore. I like this better than 95mm pistons as the cylinders will be thicker where is seals against the head. The 71.5mm stroke and 94mm pistons make 998cc.

The DS1000 heads have a 10cc larger combustion chamber volume than the 900ss heads. The Pistal pistons have a huge dome on them that would result in way too much compression for the street. I am designing this engine to run on 91 octain California crap gas. I needed to cut the pistons down to reduce the compression.

I measured the volume of the 900 head and the dome of the DS1000 piston and decided to acheive an 11.5:1 compression ratio I would have to remove 10cc of volume from the dome of the piston. If I did not cut down the pistons the compression ratio would have been 14.4:1, yikes

I made up some size specific piston cramps for the lathe. Pistons actually have a slight taper to them, so you cant just hold them in a lathe chuck. The clamps I made grab in the oil control ring groove, then lower down the piston on a thin clamping area that eliminated the taper and problem of holding the pistons in the vise.

These are the piston clamps I made



Since I know the weight of aluminum is around 2.7grams per cc I weighed the piston and removed 27grams of aluminum from the domes to take off 10cc of voume. I verified the actual volume again with a burette just to be sure it was correct and it was right on.

The Pistal pistons are available 2 ways. One kind is full compression with the underside of the dome milled out. I could not use these or there would be holes in my pistons. Mark at the Ducshop was able to order me a set of the solid dome ones made for cutting down, (thanks Mark)

One other benefit of this mod I am doing with the crank is that since the extra capacity of the stroker crank would also up the compression ratio. This means the dome on the piston is much smaller than it would need to be if it was a 900 crank. A smaller dome is lighter and gives better burn and a faster flame travel. The valve pockets are also bigger and deeper, so the over-sized valves I will use in the head and the higher lift ST2 cams wont be a problem with piston to valve clearance issues.

Here is one standard un-cut Pistal Piston and one after I took off the extra material. The machined piston will yield 11.57 compression ration or 8.51 Dynamic compression ratio with the ST2 cams at factory spec. which is good for pump gas. Advancing the cams to 106 centerline would result in 8.98:1 dynamic compression ratio which might be pushing my luck. I will have to see what cam timing this engine likes in the end.



Side view showing how small the dome can be because of the extra stroke



After both pistons were cut to size, I went in an smoothed all the sharp edges especially on the valve relief pockets. On these motors the valve opens pretty far into these pockets, so rounding the edges of the reliefs helps with flow. At least this is my theory.

I then sent them out to Swain technology for ceramic Gold coating of the domes. The skirts were already moly coated from Pistal

Ignore the pieces of solder on the domes for now, that was for measuring squish and I will talk more about that later.



Here are some links for ya

Pistal Racing: Home Page

Marietta GA, Ducati service, performance, racing, parts & accessories

Race Coatings | Swain Tech Coatings | Industrial Coatings | High Performance Racing Coatings
 

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Discussion Starter #84
The Heads went out to JPrecision in Canada jprecision | RACING HEADS

They replace the guides and seats new DLC coated oversized valves

He also welds up the intake and exhaust ports then CNC machines the ports to an entirely new shape vs the original heads. Much higher flow and velocity.

I am a big believer in a good "squish" area for fast burn and high compression without pinging. The goal when setting squish is 1mm. More than this can cause detonation in higher compression engines.

I dont know why, but the squish area of the piston is tapered 3 degrees and the taper of the matching squish area on the head is 7 degrees.

This means you can only get the squish to 1mm at the very perimeter of the head and as you go towards the center the number will be bigger than 1mm and in my opinion lead to detonation.

So what I had them do was also weld up the combustion chambers and re-machine the quench area to 3 degrees to match the piston. This way the entire quench area is 1mm. This should provide a much faster burn with less detonation on pump gas.

This is the piston squish area at 3 degrees



The area in the red circles is where he welded it up and re-machined the squish area to 3 degrees to match the piston



The finished combustion chamber with a twin plug conversion by Nichols





In this picture you see the exhaust port where the bottom has been welded up for a "D" shaped port with a much larger radius on the bottom of the port. The round header in combination with the "step" created by the welded port acts as a step to prevent reversion and keep the exhaust velocity high for better scavenging in the mid range



The intake ports are also welded with a special shape to the port floor. The port is also widened considerably and straightened.

He also matched the short intakes to the new port size and leaves a rough finish for better boundary flow.

He does very nice work

This is the intake port - you can look down the carbs and see into the combustion chamber now.

 

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After both pistons were cut to size, I went in an smoothed all the sharp edges especially on the valve relief pockets. On these motors the valve opens pretty far into these pockets, so rounding the edges of the reliefs helps with flow. At least this is my theory.
Actually, removing the sharp edges from the pistions removes potential hot spots on the piston face.

I think, that using ceramic coatings on the piston face may be actually counter productive. The coatings were develope in dry sump water cooled NASCARs. Our air-cooled bikes have an oil jet that sprays oil on the bottom of the piston. This oil cools the piston and lubricates the small end of the rod. The oil then falls into the wet sump where it cools. This is why I did not have my pistons coated, just food for though :D

Really nice build, I am enjoying watching you put it togeather. :)

Gray
 

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Discussion Starter #88
I see what your saying about the ceramic coating keeping the oil from doing its job on the piston crown. I also look at it as a way to keep the heat in the head to make more power. It is also said it evens out any hot spots on the piston. Ya never know what is correct until you try it. My goal is 100hp on pump gas with no detonation and cool temps for all day street use.
I did not do the heads for the reason you say, as I was thinking about the air not the oil doing the cooling. hmmm, makes me wonder?
 

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Discussion Starter #89
No 900ss 100hp build would be complete without a set of ST2 cams. I bought mine from a member on this forum, Thanks.

Since I cant leave anything alone, I decided to drill the cams to help balance them and save some weight.





Since they are hardened you will need special straight flute carbide drill bits to do this. I already have a bunch so why not.

Bigger lift and faster revs need some MBP collet style half rings for the closer retainers.



Some valve guide seals from AV&V AV&V Advanced Valves and Valvetrain - Ducati Valve Seals The OEM ones seem so crappy compared to these



Nichols did the work to twin plug the heads. It now uses a tiny little plug to make it possible to fit



A picture of the twin plug location and the adjustable cam pulley from RedFox Ducati



 

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No 900ss 100hp build would be complete without a set of ST2 cams. I bought mine from a member on this forum, Thanks.

Since I cant leave anything alone, I decided to drill the cams to help balance them and save some weight.

Since they are hardened you will need special straight flute carbide drill bits to do this. I already have a bunch so why not.

Bigger lift and faster revs need some MBP collet style half rings for the closer retainers.

Some valve guide seals from AV&V AV&V Advanced Valves and Valvetrain - Ducati Valve Seals The OEM ones seem so crappy compared to these

Nichols did the work to twin plug the heads. It now uses a tiny little plug to make it possible to fit

A picture of the twin plug location and the adjustable cam pulley from RedFox Ducati
Beautiful work 848. Is it too rude to ask what you budget is for this rebuild?
 

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Beautiful work as always. With all of the material you've removed from the engine internals, you've probably gained another liter of oil capacity - lol.

I'm curious about your opinion of how light is too light? How much reciprocating mass can be removed before the motor becomes difficult to use day-to-day? What compromises are you willing to make when lightening the internals?

Thanks again for all of the pics! Your heads look fantastic.
 

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Discussion Starter #93
Very very nice build, I love the attention to detail.

What did you paint the heads with?
The heads were striped of the old paint before welding. They were nice and clean from being blasted, but still a little dicoloration. So I took some VHT high temp silver and lightly dusted them to even out the color. Not thick and heavy, just a light coat
 

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Discussion Starter #94
Beautiful work 848. Is it too rude to ask what you budget is for this rebuild?
No budget on this, just take my time and do it right. I would be afraid to add it all up. No way is it worth it, and I bet I could not get half of what I have in it if I sold it. These projects need to be a labor of love to justify it.
 

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Discussion Starter #96
Beautiful work as always. With all of the material you've removed from the engine internals, you've probably gained another liter of oil capacity - lol.

I'm curious about your opinion of how light is too light? How much reciprocating mass can be removed before the motor becomes difficult to use day-to-day? What compromises are you willing to make when lightening the internals?

Thanks again for all of the pics! Your heads look fantastic.
Well, no more oil as it is in the sump, but I can imagine there is a big volume of metal removed from the crank. This crank is a little bit lighter than the crank on a 749r, and basically the same rods. Ducati sold this bike as a street bike? I have also used a Nichols alloy flywheel. I can say the bike revs great, no problem easing off the clutch, and it idles at 1000 RPM with no trouble. I never understood what people meant about the engine weight and how it was not streetable. Maybe I know how to use a clutch, or maybe because all of my bikes have light internals and I don't notice it much. The only thing that is strange is when you are sitting on it when it is idling. Everything inside is so light that you hear the noise of the exhaust but don't feel the pulsing of the engine below you. Its as if you were sitting on a much smaller cc bike making a bunch of noise.

So, no I personally don't think you can make them too light. Just me thought. I could always quickly add weight back on with a steel flywheel. So I like the crank as light as possible, and then use a flywheel to suit. Much easier than leaving the crank heavy to find out you should have made it light and its too late to change it.
 

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Discussion Starter #98
Since I have bought Split 41mm FCR carbs I will need short intakes to make them work.

I did not want to deal with finding the Malarossi intakes and them still not angling the carb in the correct position. So I did some searching and came up with these. Drehbare Ansaugstutzen

A short intake made with a rotational flange so it can be twisted to modify the angle of the carb, Brilliant.

I e-mailed them and a set was on the way. Nice parts, good quality.

here they are bolted to the heads.

 
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