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 Post subject: Re: Aussie TT2 track bike build
PostPosted: Fri Mar 22, 2013 8:27 pm 
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pat slinn wrote:
Unfortunatly I do not have any photographs of that mod. In the early 1980's people did not seem to carry cameras with them everywhere.


yes, the kids just can't perceive a world where you didn't have a smart phone in your pocket.

so it's a hole thru the rod to shoot oil straight up along the rod to the small end pretty much? sort of between the grooves they have std?


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 Post subject: Re: Aussie TT2 track bike build
PostPosted: Fri Mar 22, 2013 10:24 pm 
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Discussions with Anthony Carillo years ago when I was building my 900 led to him EDMing an oil hole up the center of my rods to provide pressurized oil to the small ends. I've never had a problem since '93 when they first went in. It was kinda weird drilling a hole in a brand new bearing but I got used to it. The hot 750s back then were really hard on piston pins and usually had pistons cycled out every few race weekends.


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 Post subject: Re: Aussie TT2 track bike build
PostPosted: Sat Mar 23, 2013 6:41 am 
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Location: Melbourne, Australia
pat slinn wrote:
Unfortunatly I do not have any photographs of that mod. In the early 1980's people did not seem to carry cameras with them everywhere.


Hi Pat,
thanks for your input and info. I'm think you mean this modification (below) back in the good ol days! I think, Brad kindly thinks you are a hip young man! hehe. And, why didn't you have a box brownie? You engineers' are always sketching on toilet paper!
Conrods- see the holes either side of the small end plus the one through the top centre?;
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Anyway, I've been a little busy whilst I'm waiting on engine parts...
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As you can see, I'm excited and jumping the gun...
Keeping you posted.
Cheers,
Steve

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"...Honey, it's only a project bike...."


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 Post subject: Re: Aussie TT2 track bike build
PostPosted: Sat Mar 23, 2013 6:46 am 
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Location: Melbourne, Australia
There is one more...
the fork braces.
I wanted to have the aluminium look rather than painted black. I've seen some factory photos with the fork braces painted red... No, didn't want this.
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Cheers,
Steve

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"...Honey, it's only a project bike...."


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 Post subject: Re: Aussie TT2 track bike build
PostPosted: Sat Mar 23, 2013 8:15 am 
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I still have my box brownie, it was my mom's must dig it out !.

The hole I refere to was drilled just below the "D" of where Ducati is stamped on the con rod and straight through into the radiused part of the big end. I did think of drilling the length of the con rod, but I did not have a drill that long ! The mod worked very well. I can remember that some of the BSA A50/65 racing engines had holes drilled from the big end straight up the con rod to the small end, and that was in the 1960's.

Some of my "design" drawings were done on either the palm or the back of my hand, this worked quite well,...untill I washed my hands. !.


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 Post subject: Re: Aussie TT2 track bike build
PostPosted: Sat Mar 23, 2013 5:36 pm 
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pat slinn wrote:
I still have my box brownie, it was my mom's must dig it out !.

The hole I refere to was drilled just below the "D" of where Ducati is stamped on the con rod and straight through into the radiused part of the big end. I did think of drilling the length of the con rod, but I did not have a drill that long ! The mod worked very well. I can remember that some of the BSA A50/65 racing engines had holes drilled from the big end straight up the con rod to the small end, and that was in the 1960's.

Some of my "design" drawings were done on either the palm or the back of my hand, this worked quite well,...untill I washed my hands. !.


HA! I thought so. I did some contract draughting work for a small engineering workshop and I had to transfer toilet paper drawings into CAD! I think he also used to sketch on his hands too! Love it Pat, classic engineering!

Thanks again for your information. And thanks for looking at my piston skirts. The burn marks and grooves on the gudgeon pins are really really tiny I can't feel them. I just feels polished all over. Because this is a budget build, I'll just reuse them. It's advantageous to have friendly advice & support on this forum. I'm learning quite a many things!

Cheers,
Steve

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"...Honey, it's only a project bike...."


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 Post subject: Re: Aussie TT2 track bike build
PostPosted: Sat Mar 23, 2013 7:45 pm 
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We had the same issues with the 888 corsa's in 1991. I did the same through drilling mod to the rods. Even the factory bikes of the day were blowing up before the flag. They seemed to suffer from small end failure due to the liners sitting deep into the crankcases and masking the oil fling up to the small end. The answer being to feed it up the rod and pressurise the small end.
The H section rods were only 3mm wide in the centre of the web, so drilling a 2mm diameter hole, some 120mm deep without it breaking out of the sides was quite a challenge. A good set-up and a lot of patience was the answer.
If you do this rod drilling mod then it is much better to fit a new small end bush without the original oil holes. (or remove and re-fit the old bush say 20 deg out of position to blank off the holes. These holes are clearly there to let the oil IN not out. Just turn a small groove into the bore at the oil feed hole to allow the oil to go around the pin and it will find it's own way out of each side.

We made the factory team aware of the significant improvement so they sent over a batch of rods for drilling. Not only did it improve the attrition rate at WSB, this mod eventually found its way onto the production line with the 888/916SP series. They had the Pankl rod web machined thicker to allow a larger, easier to drill, feed hole.


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 Post subject: Re: Aussie TT2 track bike build
PostPosted: Sun Mar 24, 2013 8:13 am 
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pat slinn wrote:
I still have my box brownie, it was my mom's must dig it out !.

The hole I refere to was drilled just below the "D" of where Ducati is stamped on the con rod and straight through into the radiused part of the big end. I did think of drilling the length of the con rod, but I did not have a drill that long ! The mod worked very well. I can remember that some of the BSA A50/65 racing engines had holes drilled from the big end straight up the con rod to the small end, and that was in the 1960's.

Some of my "design" drawings were done on either the palm or the back of my hand, this worked quite well,...untill I washed my hands. !.


so you were firing oil up at the piston pin / piston underside and letting it work its way around?

you can still get the drilled big end shells for the 888/916 sp rods too i think.


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 Post subject: Re: Aussie TT2 track bike build
PostPosted: Sun Mar 24, 2013 5:25 pm 
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Posts: 107
Exactly that. The oil being thrown around and up the underside of the piston is helping to cool it, but doesn't always contribute enough to lubricating the small end sufficiently. There is already a lot of heat up there due to the big fire going on above it.

The official Ducati bulletin at the time suggested allowing 0.003" or 0.08mm clearance on the gudgeon pin to help stop them overheating - siezing - throwing the rod - wrecking the engine, and your whole weekend. A half solution, but not really a fix.
Clearly this larger clearance could only mean changing the pin and small end bush far more often than usual as it is essentially already worn out when fitted ! !

One other thing to consider. I machined an 8mm long x 2mm wide slot in the top shell rather than a feed hole. This allows a more positive flow. The oil feed hole from the crank has a greater time passage across the slot in the top shell and then feeds up the rod. No more small end/rod issues.

It is VERY VERY rare a conrod breaks due to the rod itself. The rod is almost always just the most apparent victim of the real cause. Take a careful look for the reasons behind the obvious consequence.


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 Post subject: Re: Aussie TT2 track bike build
PostPosted: Mon Mar 25, 2013 11:02 am 
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Posts: 138
My rods have a groove machined into the rod covering approx. 30deg. on each side of the center hole and the bearing gets the small hole 20 or so deg. advanced of TDC. Same as idea as Sports,different execution.


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