High comp pistons in a M900 ?

the lodger · 24-11-2019, 11:08 AM

I have the possibility of fitting high comp pistons and rings in my M900. Apparently the cost is less than the cost of OEM Ducati rings only so a bit of a no brainer. However I would like to be reassured that if I go down this route then the bike will still be nice to ride

I am no racer, so extra power for its own sake is not a high priority, just a nice to have. So has anyone fitted high comp pistons and what was the effect? Many thanks

Darkness · 24-11-2019, 11:16 AM

Make sure your starter motor and its cable and earths are in perfect condition!

Darren69 · 24-11-2019, 11:38 AM

If the cost makes it a no brainer go for it. Upping the compression should give you a bit more mid range torque not increasing overall power as much. Have you been considered a bigger bore kit 944 if you are going to the expense of hi comp with the 904 you might as well put more cc in there and the 900ss stuff is bolt on.

Saint aka ML · 24-11-2019, 11:39 AM

The starting motor comment is valid for early carbed m900 when they went IE they also changed gearing on starter motor.
However nice clean earth is good idea either way.

There is no real side effects to off the shelf HC pistons.
Whom ever fits them should adjust timing (retard it), adjust fuelling a bit and off you go. If you can fit adjustable belt pulleys and get them to dial in cams. All is cheap and slippery slop to modding hehe.

It will run bit hotter so at 30c stuck in traffic you will feel it. Nothing to worry about.
You will have more low and mid torque, if you do fuelling on dyno you could get 2-3 bhp.
Main benefit is torque and with correct timing throttle response.

Saint aka ML · 24-11-2019, 11:56 AM

Quote:

Originally Posted by Darren69

If the cost makes it a no brainer go for it. Upping the compression should give you a bit more mid range torque not increasing overall power as much. Have you been considered a bigger bore kit 944 if you are going to the expense of hi comp with the 904 you might as well put more cc in there and the 900ss stuff is bolt on.

900ss was also 900cc so if you going 944 you will need to bore cylinders. Not hard job so ok on cost but then you need to do proper fuelling and better pipes if not present.

Yorkie · 24-11-2019, 02:18 PM

I have dropped in JE Hi-Comp pistons to both my 900SS powered Monster and its replacement ST2 944 engine with no issues.

Open cans, or even a spaghetti style system, and a performance air filter all dialled in on a dyno would be best.

Yorkie

Dukedesmo · 27-11-2019, 09:36 AM

High comp definitely an improvement with, IMO no downsides.

A word of warning though, be careful that supplied rings are compatible with Nikasil bores (chrome rings eat away the coating).

I have JE high comp (944cc) pistons in mine and have had a battle with bore wear, I think I've won said battle now but only after a couple of replates & new rings...

24-11-2019, 11:08 AM	#1
the lodger Registered User Join Date: Oct 2019 Location: Chorley Bike: M900 Posts: 160	High comp pistons in a M900 ? I have the possibility of fitting high comp pistons and rings in my M900. Apparently the cost is less than the cost of OEM Ducati rings only so a bit of a no brainer. However I would like to be reassured that if I go down this route then the bike will still be nice to ride I am no racer, so extra power for its own sake is not a high priority, just a nice to have. So has anyone fitted high comp pistons and what was the effect? Many thanks __________________ Contents may settle !

24-11-2019, 11:16 AM	#2
Darkness . Join Date: May 2007 Location: Stockbridge Bike: M900 Posts: 1,984	Make sure your starter motor and its cable and earths are in perfect condition! __________________ Original and Best since 1993

24-11-2019, 11:39 AM	#4
Saint aka ML Junior ah to be young Join Date: Nov 2007 Location: London Bike: Multiple Monsters Posts: 2,058	The starting motor comment is valid for early carbed m900 when they went IE they also changed gearing on starter motor. However nice clean earth is good idea either way. There is no real side effects to off the shelf HC pistons. Whom ever fits them should adjust timing (retard it), adjust fuelling a bit and off you go. If you can fit adjustable belt pulleys and get them to dial in cams. All is cheap and slippery slop to modding hehe. It will run bit hotter so at 30c stuck in traffic you will feel it. Nothing to worry about. You will have more low and mid torque, if you do fuelling on dyno you could get 2-3 bhp. Main benefit is torque and with correct timing throttle response. __________________ "I am Lucazade"

24-11-2019, 02:18 PM	#6
Yorkie Anglo-Saxon Warrior Join Date: Aug 2002 Location: North Yorkshire Bike: M900 Posts: 2,485	I have dropped in JE Hi-Comp pistons to both my 900SS powered Monster and its replacement ST2 944 engine with no issues. Open cans, or even a spaghetti style system, and a performance air filter all dialled in on a dyno would be best. Yorkie __________________ NO ICE, GUN IT!

27-11-2019, 09:36 AM	#7
Dukedesmo Registered User Join Date: Sep 2010 Location: Leics Bike: M900 Posts: 2,894	High comp definitely an improvement with, IMO no downsides. A word of warning though, be careful that supplied rings are compatible with Nikasil bores (chrome rings eat away the coating). I have JE high comp (944cc) pistons in mine and have had a battle with bore wear, I think I've won said battle now but only after a couple of replates & new rings... __________________ M900, 916, LeMans II.

24-11-2019, 11:38 AM	#3
Darren69 Transmaniacon MOC Join Date: Sep 2013 Location: Sutton In Ashfield Bike: Multiple Monsters Posts: 6,091	If the cost makes it a no brainer go for it. Upping the compression should give you a bit more mid range torque not increasing overall power as much. Have you been considered a bigger bore kit 944 if you are going to the expense of hi comp with the 904 you might as well put more cc in there and the 900ss stuff is bolt on.