User opinions on 102mm big bore

[Ben710]

Can you guys please share your experiences with the 102mm big bore engines please?

I´d like to know how it did perform against the 98mm stock bore and how well it holds up.

Thank you!

[08hyper]

Originally Posted by Ben710

Can you guys please share your experiences with the 102mm big bore engines please?

I´d like to know how it did perform against the 98mm stock bore and how well it holds up.

Thank you!

Ben, with a 102mm piston you will have to buy new cylinders (like NCR's) & then take the whole motor apart so the cases can be bored out to accept the new cylinders, then you will have to get the crank assembly rebalanced to the 102mm pistons.
With the stock stoke & 102mm pistons you will get (1166cc) with the NCR stroker crank you will get closer to a full 1200cc. Only a handfull of people have done this because of the work & cost involved.

There are many of us that are using a 100mm piston (1123cc) the stock cylinder can be bored to this & the stock head gasket modified will work as well.

The 100mm bore (1123cc) vs (1078cc stock) will make more HP & especially more TQ than the stock bore, & remember this is a high compression piston.
The downside is because of the thin liners, the bores may not stay round as long as the stock 98mm bores, so the top-end wil not last as long.

IMHO this mod is for the power hungry crowd ONLY, (like me) most street/track riders will be better off with a HC 98mm piston.

Would I do this mod again? HELL YEAH!! I might even get the 102mm NCR cylinders down the road. I'm just a little sick that way.......... Aloha Alex

[Ben710]

Hello Alex, thanks for your opinion. I do not really believe in the big gain a 100mm bore offers over a 98mm bore. The difference in displacement is just too little. I got told 10% more displacement gets you 7% more power. That would be 1078 to 1123cc, which is 45cc. How much is that, 3 hp? Hm. Not a lot of bang for the buck. Of course I understand your argument regarding the hc pistons.

There was a 102mm kit on ebay, don´t know anything about the quality but I´d guess you definitely have to mill the crankcase for the bigger 102mm piston. Also I´d be worried about the thin walls, tuners told me they become oval quite quickly.

I heard disgo duc has a 102mm kit with everything NCR, but he´s not digging out the dyno sheets (probably glued together by now if you know what I mean... hehe ).

Check out these links:
CILINDRI CON CANNE IN ACCIAIO Ø102mm PER DUCATI 1000DS 1100 MONSTER HYPERMOTARD | eBay
kit cilindri e pistoni completi da 102mm per motori ducati 2 valvole

[poakone]

Originally Posted by 08hyper

Would I do this mod again? HELL YEAH!! I might even get the 102mm NCR cylinders down the road. I'm just a little sick that way.......... Aloha Alex

Yes, Yes you are but your experiences have helped alot of us save money and hassel. So "come on get down with the sickness"-Disturbed! keep it up and continue to let the rest of know what we are getting into if we attemp to be as disturbed as you are!!!

[poakone]

Originally Posted by Ben710

Hello Alex, thanks for your opinion. I do not really believe in the big gain a 100mm bore offers over a 98mm bore. The difference in displacement is just too little. I got told 10% more displacement gets you 7% more power. That would be 1078 to 1123cc, which is 45cc. How much is that, 3 hp? Hm. Not a lot of bang for the buck. Of course I understand your argument regarding the hc pistons.

I heard disgo duc has a 102mm kit with everything NCR, but he´s not digging out the dyno sheets (probably glued together by now if you know what I mean... hehe ).

I've been doing some rough figuring on numbers and from what I can figure you can gain between 2 and 6 horse by having the throttle bodies rifle bored to increase airspeed and fuel atomization. These are just calculated guesses based on the gains I saw when I had this done the throttle bodie in my Vw rabbit gtu car. There is no way of telling for sure though till some one does it and dyno's the bike. Alex in obsession with power have you looked into this? You can obtain throttle bodies cheap off of ebay and it's only a couple hundred bucks to have an experienced throttlebody shop do the work. Just an Idea I've bouncing around in my head...


This was and still is my sickness,(although this Ducati needle I put in arm seems to infecting me pretty good now) A vw rabbit Gtu car 1.8L motor with diesel crank, 1.6L custom rods and pistons = 2.2L stroker motor balanced and blueprinted. Ported polished big valve heads, cams, digisquirt efi controller on and on and on............ 170hp at wheels all motor 1600# will smack the crap out of a 2010 factory Corvette stoplight to stoplight. And yeah the dyno sheets from it are all glued together, So atleast I know what you meen....

[TOP_DUC]

Originally Posted by Ben710

..... I do not really believe in the big gain a 100mm bore offers over a 98mm bore. .......

Ben,
The "gain" associated with slightly larger bore isn't reflected in a peak hp number on a dyno. If you want a killer dyno number, just throw some nitrous into it and hang on.

The gains from the larger bore is mainly in the torque (low-mid range grunt). The peak number gains need larger ports/valves to get more air into and out of the engine. The bore increase simply makes bigger sucking and blowing efforts through the same old holes, so max flow doesn't increase much.....

IMO, if you can't go "all-the-way" with full porting, big-bore cylinders, balancing, and a dyno tune then just stay with stock engine and play with bolt-ons. Basically, GO BIG or STAY HOME when it comes to internal mods.

[CAlexio]

Originally Posted by Ben710

Can you guys please share your experiences with the 102mm big bore engines please?

I´d like to know how it did perform against the 98mm stock bore and how well it holds up.

Thank you!

Alex, tell the guy how many engines you done blowed up

Originally Posted by TOP_DUC

Ben,


IMO, if you can't go "all-the-way" with full porting, big-bore cylinders, balancing, and a dyno tune then just stay with stock engine and play with bolt-ons. Basically, GO BIG or STAY HOME when it comes to internal mods.

Interesting point... Had never thought of that

[08hyper]

Originally Posted by CAlexio

Alex, tell the guy how many engines you done blowed up

Heyyyy.......I only "blew" up one engine, & maybe "dented" one, so there!! Aloha Alex

[Ben710]

poakone, can you explain what you mean by rifle boring? Is that fine honing?

Originally Posted by TOP_DUC

Ben,
The "gain" associated with slightly larger bore isn't reflected in a peak hp number on a dyno. If you want a killer dyno number, just throw some nitrous into it and hang on.

The gains from the larger bore is mainly in the torque (low-mid range grunt). The peak number gains need larger ports/valves to get more air into and out of the engine. The bore increase simply makes bigger sucking and blowing efforts through the same old holes, so max flow doesn't increase much.....

IMO, if you can't go "all-the-way" with full porting, big-bore cylinders, balancing, and a dyno tune then just stay with stock engine and play with bolt-ons. Basically, GO BIG or STAY HOME when it comes to internal mods.

Yes, I am fully with you on this one. If one was to do a 102mm big bore, you´d probably have to do all the other obvious modifications beforehand. First being headwork and cams of course. I don´t think the internals of the 1100DS engine allow for much lightening, except for the crankshaft and piston/rods. The gears are already bored, so that would not make much sense. You could stuff in some aluminum gearbox drum, but how much is that going to bring to the table...? I´d love to see someone posting a before and after 102 bore dyno chart from their bike. But I guess it´s a tough call because usually people get the 4mm bore increase while having the head ported and flowed, cams, pistons, etc. at the same time. Too many variables that are changed at once to measure what does what.

Originally Posted by 08hyper

maybe "dented" one, so there!! Aloha Alex