More power in my M900 -98

[almgren.t]

Last year I went that route with my '99 M900.

- head swap (from W to V1/V2)
- piston swap to high comp ones
- carb swap to FCR 41:s
- air box ditch for air pods
- better coils
- Ignitech ignition

Bike is, well, another bike. Still struggling a bit to get the jetting of the FCRs right, but overall this has been a fun couple if mods.

[Graymonster]

Last year I went that route with my '99 M900.

- head swap (from W to V1/V2)
- piston swap to high comp ones
- carb swap to FCR 41:s
- air box ditch for air pods
- better coils
- Ignitech ignition

Bike is, well, another bike. Still struggling a bit to get the jetting of the FCRs right, but overall this has been a fun couple if mods.

Sounds fun  Do you recon the jetting struggles comes from high comp pistons?

[koko64]

The jetting struggles are often from the FCR carbs being very precise instruments. The Off idle-1/8 to 1/4-1/3 throttle range has a number of overlapping circuits that influence it. The high level of adjustability is what gives the carbs the capacity to deliver strong performance everywhere in the rev range with little compromise. It also gives plenty of scope for error (kind of like fully adjustable suspension). So there are more layers to tune, but at least they are reasonably linear. Therefore an understanding of the carbs is important in tuning them.

Some people are lucky and put them on as delivered with great results. IME, the biggest hassle for tuning was when I did quite extensive airbox modifications.

[Graymonster]

Found out the heads I planned to buy, was no good.. I found these ones

http://www.ebay.com/itm/91-98-Ducati-900SS-SP-FE-CR-m900-PAIR-DUAL-SPARK-V2-CYLINDER-HEADS-BIG-VALVE-96/121408048050?_trksid=p2047675.c100011.m1850&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D23491%26meid%3D8964221631613288437%26pid%3D100011%26prg%3D10073%26rk%3D3%26rkt%3D10%26sd%3D121384435048

on E-bay.
They are dual spark plug. Is this original or converted like this? Is it good or bad with dual spark plug? On the vertical head, it looks like the big valve is burnt... Do you agree?

Wiktor

[ducpainter]

It's a conversion.

The valve doesn't look burnt to me...just sooty.

They'd be good for a modded engine. Unnecessary for stock.

[Graymonster]

Thx ducpainter

Unnecessary, as in you only need dual plugs in a tuned engine?
Is it a good idea to make an spark plug dummy, and use them as normal heads?

Wiktor

[ducpainter]

The theory, as I understand it, is with a high domed piston the flame doesn't travel all the way to the other side of the combustion chamber so there is unburned fuel, and a 'waste' of power. Add a plug to the other side and problem solved.

Ducati used the concept on the 1000DS. I don't know if it was done for performance based or emissions based reasons.

[koko64]

 I wouldnt go out of my way to do it as a mod, but if the heads came that way,and suited my needs,  why not? Hopefully if they went to that trouble they ported the heads and did a good valve job.  Did they did do anything else to the heads?

[brad black]

as a generalisation, a dual plug conversion on a crappy combustion chamber will give better fuel economy, maybe some more power and be smoother.  it also needs less ignition advance.

[koko64]

The theory, as I understand it, is with a high domed piston the flame doesn't travel all the way to the other side of the combustion chamber so there is unburned fuel, and a 'waste' of power. Add a plug to the other side and problem solved.

Ducati used the concept on the 1000DS. I don't know if it was done for performance based or emissions based reasons.

Wonder if idle is cleaner and throttle response  crisper?

[Rudemouthsky]

as a generalisation, a dual plug conversion on a crappy combustion chamber will give better fuel economy, maybe some more power and be smoother.  it also needs less ignition advance.

Would seem like a dual plug head with high compression pistons and no timing adjustments would almost be counter intuitive/destructive then?

[brad black]

it'll ping like a mofo.  but only because you changed it and didn't do it properly, like everything else.

[koko64]

as a generalisation, a dual plug conversion on a crappy combustion chamber will give better fuel economy, maybe some more power and be smoother.  it also needs less ignition advance.

I believe it in regards to ignition mapping.
Hemi head Sportsters liked it, but blew up if you didnt retard the ignition.

[koko64]

it'll ping like a mofo.  but only because you changed it and didn't do it properly, like everything else.

BN's got the services of a reputable engine builder. He should be right.

[brad black]

sorry, general comment on the not done right causing a problem bit.  not aimed at buck.