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Corona
Joined: 26 Jun 2008 Posts: 118 Location: Norfolk
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Posted: Tue Oct 08, 2013 8:23 am Post subject: ST2 cams into a DB4ie ? |
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Well it's that time to take slim off the road and put some new cam belts on , thing is I have an ST2 motor in bits with a nice set of cams just gagging to be fitted . Now the quandary is do I fit them in the pursuit of more power and what would that entail for the fuel injection? I also have a power commander to jigger about with the fuelling.
Anyone on here tried similar mods, injected or carbed ? I would be eternally grateful for any info. |
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brian
Joined: 22 Aug 2011 Posts: 3769 Location: Australia
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Posted: Tue Oct 08, 2013 12:54 pm Post subject: |
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How do they compare to the 900ss cams? More lift? More duration? Are they identical other than the lift/ duration? _________________ '99 DB4 #104, '96 SB6 #1165, '94 DB2 J #652, '99 DB4 #088, '08 VTX1800, '93 ZXR750R M1, '95 ZXR750, '95 ZXR750 Race Bike, '94 CBR400rr NC29 Race Bike, '94 CB250, '49 BSA C10 250, '61 BSA A10 650, '89 ZXR750, '91 Ducati 851 |
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spidermaan
Joined: 04 Jul 2012 Posts: 92 Location: nord-east Italy
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vort28
Joined: 22 Mar 2010 Posts: 2194 Location: Northwest , UK
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Posted: Wed Oct 09, 2013 7:41 am Post subject: |
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ST2 cams are similar to the VEE TWO high torque cams and for a carb bike are the ones to go for now vee two are no longer. However, the ie engine cams are also a good alternative for the carb engine but just not as much lift or as much duration as the st2. Can't remember the figures off the top of my head, but there are a few USA sites that list the stuff. Think st2 cams in a 900 high comp carb engine are good for about 90bhp at the rear.
Out of interest what is the ST2 engine for ??? Because I've also heard the st2 944 barrels fit, and the only difference in the cooling is the fluid ducati put into the jacket, ie you can use water or oil as same basic casting, other that you would need to give a good flush.
Always thought of doing this myself but would need to buy an st2 motor to see if possible. But as you have one spare !!! |
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polyesterpig
Joined: 30 Jan 2011 Posts: 76 Location: California USA
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Posted: Fri Oct 11, 2013 3:40 pm Post subject: |
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The injected 900 cams are good. It is the stock intake and exhaust ports that can be modified with great results. I have the same bike that I am putting back together. I had a bad valve guide and decided to replace them all. Since I had it apart, I had the heads ported and the throttlebody butterfly shaft machined down. New butterflies were machined with knife edges for more flow. I also added a Giannelli exhaust. That's it for now. When I dyno it, I will post the results. I didn't want to put larger pistons in since it decreases the cylinder head sealing surfaces. _________________ 2002 Cannondale E440
2003 Cannondale Super Mono 440
(3) 2003 Cannondale E440R
2010 Ducati Hypermotard evo SP
2000 Bimota DB4ie BiPosto |
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Corona
Joined: 26 Jun 2008 Posts: 118 Location: Norfolk
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Posted: Sat Oct 12, 2013 10:39 pm Post subject: |
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I believe the ST2 has a bit more lift and duration, but not much compared to the 900ss injection cams, as I am putting out 84 rwhp already a few more would be good especially near the top of the rev range (90bhp would be orgasmic). The bottom ends are identical apart from the lhs cover which has the water pump casing on it, easily swapped out for a standard casing, the water jacket runs through the heads and the barrels together and don't look up to taking oil pressures, swapping the motors completely is also a thought but putting a radiator in would involve a spot of dark magic.
Just wondered if changing the cams alone would be enough for a bit more power and a quick fettle with the power commander to sort any fuelling issues. |
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deebee4
Joined: 08 Jan 2011 Posts: 266 Location: Netherlands
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Posted: Sun Oct 20, 2013 8:01 pm Post subject: |
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91,2 RWHP @ 7.300 rpm and 96 Nm @ 5.600 rpm on my db4 tracky. But to achieve that it needed 944cc Pistal Racing, some cylinder head work, 41mm FCR's with K&N filters, Carillos, crankshaft rebalanced and lightened, open exhaust en some minor stuff. Engine gets out of breath above 7.500 rpm and power decreases. It will easily run 10.000 rpm but no power. It just doesn't get enough mixture in the combustion chambers. Needs a turbo compressor .....
Still holding on to the long inlet tracts, I know short manifolds with separate FCR's will give just a little more, but at a great financial cost.
But I'm satisfied like it is now, power to weight ratio 1HP:1,7kg so that's OK. It's a blast to ride at the track and cornering speed is just as good as - or better than - 160 HP multis. Out of the turns it keeps up with the big guys for the the first 50 meters (I can get on the throttle sooner....) but then their outright speed is too much for the aircooled 2-valver.......
But my laptimes ar dropping, so that's nice. Obviously they will drop quicker when I've got 70 HP more, but because my db4, with a good rider at the bars, can be up to 10 seconds faster on a 4.5 km track, it's up to me to improve.......
On the dyno I discovered that a carburetter regulates the mixture in a fairly crude manner, compared to the modern injected bikes nowadays. Rejetting, lifting and dropping needles is all a matter of compromise....... _________________ Track riding on a Bimota: FUN! |
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