Big Bore vs High Comp - Ducati.ms

galaxy · Nov 7th, 2011, 11:03 pm

This may have been discussed, but a quick search didn't turn up too much...

What are the major differences (maybe go pro vs con style) between getting a big bore kit vs just dropping in high compression pistons?? What's the best way to go considering things like cost, ease of installation, ease on the motor/other parts, sound, drivability, tuneability, other parts or upgrades required to support, whatever else you can think of...

Mainly talking generalities here, not necessarily one particular motor; but yes, talking 2V motor.

ZDM · Nov 7th, 2011, 11:49 pm

I had purchased a 1038cc "Big Bore" kit thru BCM Ducati last year for my 2003 999. The kit was a "drop in" meaning that no crank balancing would be needed. I spoke to Leslie Grossman at BCM regarding your very question. He felt I would be very disappointed if I went with just installing a set of HC pistons. I guess basically you have to R and R the cylinders anyway so why not spend the extra money to get the bigger cylinders. My kit came with over-bored nikasiled cylinders along with Pistal HC pistons. Which are a thing of absolute beauty by the way! I had FBF do the install along with installing a set of 999 "S" cams, DP light weight cam belt pulleys, new valve guides, valve work and some porting as they saw fit. I wanted a "mid range" motor for the street and boy did FBF deliver. The 1038cc kit came with some gaskets although I spent approx. $200 extra for base gaskets, O-rings, cam cover washers, etc. So my entire top end is new. Both BCM and FBF felt my 999 engine didn't need any bottom end work such as crank lightening, blue printing or rebuilding. The testastretta crank is pretty stout and unless I was racing my 999 they didn't feel the x-tra expense was warranted for a street bike. So given this info I decided not to go for any bottom end work at that time. .
IMO if your going to pull the cylinders why not spend the extra $$ and get over bore cylinders installed? If you do decide to go with the over bore kit make sure you discuss what parts the dealer intends to replace or reuse.( FBF leaves nothing to chance and replaced everything with new parts which is fine by me!)....anyway make sure what he has in stock and what he needs to order. This way you'll have all the gaskets, O-rings, etc. needed to do the job with out delay. My project was delayed a week because FBF had to order a few parts. Took about 10 working days to do the installation and mapping.
My 2003 base 999 ended up with 149hp and 86ft.lb. torque w/ a Termignoni "slip on". I've since installed a Termi 54mm "full" exhaust kit which made a huge improvement in performance.
I've had the kit now since late July of 2010. Put approximately 3500 miles on it, so far no issues at all. I'm very impressed with the power, it has a huge mid range with loads of power from idle to redline...it just doesn't flatten out. I'm ecstatic to say the least and I'm so glad I decided to improve my 999's performance rather than buy a new BMW S1000 which I had a chance to demo. Oh......and the sound is wicked.. which no BMW can compare by the way.... it's really unbelievable !!! Especially when your at full throttle but even at idle it just has that deep burble sound....to be honest when your on the throttle and you hear the exhaust booming so loudly it makes it worth every penny you spent...pretty cool.
Cost....mines a 4v testastretta and I had new S cams ($1300 extra) installed along with DP light weight cam belt pulleys...IIRC the labor and incidental parts including $200 worth of gaskets and O-rings, the washers that go on under the cam cover nuts are $8 ea x 12=$96, 1-closing rocker, valve guides, etc..... so you can see how quickly things add up. So $3100 parts & labor, $1300 new S cams, $240 DP cam belt pulleys, $1000 for 102mm cylinders and Pistal HC pistons, $425 magnesium vert/horz. cyl. covers. THe S cams were essential for making this kit work so well.
Your costs would be much, much less..of course this included mapping etc.
Hope this helps you a bit!

herrgray · Nov 8th, 2011, 12:52 am

Hi,
You can't compare the 999 to a 2v motor... The 999 has pretty high compression out of the box and going higher would literally force you to run race gas. In your case going big bore was the correct direction. The older 2v motors have 9-1 compression... That is pretty weak, I have a set of hicomp pistons in my 750. At 11-1 it should provide a big bump through out the complete rev range. You can go up to 12 or 13 to one but I don't want to run race gas. Nikasil cylinders can be honed. You need to get the correct hone to do it though. All pistons should be checked for proper clearance. Even drop in pistons.

Gray

galaxy · Nov 8th, 2011, 7:15 am

Gray, I assume yours runs good at 11:1 on pump gas? Premium?

Joe-B · Nov 8th, 2011, 7:25 am

Dunno about big bore, but my track 900 SS has 11:1 FBF (Wiseco) pistons (fine on 87 octane gas), 41 FCRs and SilMoto full system and it runs super well. If I was going to try to get more power, I'd go for head work.

greenmonster · Nov 8th, 2011, 8:50 am

>>What are the major differences (maybe go pro vs con style) between getting a big bore kit vs just dropping in high compression pistons??<<

Major: Cost. Bigbore not worth it IMHO.
Minor: Bb gives a little more torque at lower RPM.

I`d go w free breathing, hicomps and a custom map. Most bang f buck IMO.

LeoLegend · Nov 8th, 2011, 9:05 am

if you go big bore and no hi comp, you just wasted your money. check out

BikeBoy.org - 900SS CARB WITH 944 KIT

BikeBoy.org - 900SS with FCR and High Comps

1fast750ss · Nov 8th, 2011, 10:51 am

Hey Jon,

My .02, since I've had both. My personal opinion is that the BBkit will be the best option. They both do very well and your HP increase is more a result of the compression than the capacity, in this case.

Here's where the difference comes in. Even though both will have a similar compression, the extra capacity allows you to tune the bike's peak HP in the sweet spot of its' volumetric efficiency. Since they are two valve and can only rev so much, use the bike to its' advantage and move the peak TQ down a bit while increasing your TQ with the extra capacity.

This gives you more drive out of corners and subsequently more speed down the straight. Since your stroke is the same, the handling will not feel affected due to the capacity increase.

BTW, if you want a bike attached to your BBkit, I am tooling with the idea of selling mine.

herrgray · Nov 8th, 2011, 11:50 am

Hi,

galaxy: I will run premium gas in my bike but at 11to1 you should be able to run normal gas.

Like 1fast750 says you could do both, I am not a fan of big bore kits. Though in combination with higher compression they will produce more power. More power = more heat, thinner walls + aircooled motor = hotter motor = more power fade... But to be realistic you probably wont run it hard enough to have problems with power fade...

Soooooooooooooooo get a high compression big bore kit.
If need a 92 GSXR 1100 oil cooler, then you have gone too big....

Gray

wdietz186 · Nov 8th, 2011, 7:11 pm

As the others have said,raising the compression will give you more noticable power.The big bore side of it is kind of secondary. Increasing the bore raises the compression too but not by a great amount. For power on the absolute cheap hi-comp pistons will do it.Usually engines being upgraded are kinda tired to begin with so wanting a fresh bore to go with new pistons makes the big bore the best value and the extra displacement has the potential for more power than just a compression increase. Of course the " While I'm in there" conundrum arises in having the heads off with the valves and ports staring you in the face/wallet.