I have a 944 kit installed on my 96 900ss and have some issues. I purchased the kit second hand and it appeared to be in near new condition. I have to run the timing all the way retarded to prevent detonation. I have seen some discussions on this site that indicate this should not be needed. The dome on the piston did seem rather large when I installed them. Here's the questions : Did I get something I should not have ? Can I get new pistons, i.e. Pistal, and just drop them in ? Where can I source them ?
The driveability has suffered.
Any help is appreciated.
Have you re-jetted the carbs for the added compression and displacement?
Really it's hard to tell just what your problem is. I've heard that you can also purchase retarded ignition modules that will retard the ignition even more that the stock units will. The pistons will work it's just that you need to work out the fuel and ignition requirements.
My old 87 horse 944 SSie would rattle a bit when I'd roll on the throttle at 60mph on the freeway in top gear while riding on a 106-degree day. A simple downshift took care of the problem every time.
Art, did you have your computer remapped or go PCIII? My 91hp 944SSie with ported heads and 11.5:1 pistons has no problems with knock at all thanks to a BCM custom FIM map.
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1999 944SS i.e., justly tweaked
2000 M900 i.e.
No amount of carb tweaking will get rid of pinging.
I'd be looking at whether or not you've got 11:1 pistons or something more radical. Should not ping dramatically at stock timing with 11:1s although a 2 degree retard is advised. How are you retarding the timing yourself? Rotating the backplate? If so, I'd return to stock alignment and see if that is better or worse. Somehow the rotation thing didn't work out for me and I ended up going with the DP ignition modules.
Yes, mine 944 was mapped by the previous owner at BCM. Bruce built the motor. I assume it was perfect out of the gate. It was just the difference in alt. and temperature that upset the motor. When I took it to Laguna a couple of years back it ran perfect with no pinging at sea level and cooler temperatures. It going through a radical rebuild as I speak. You know you can buy Marvic Mag wheels cheaper for my 1999 SSie, than a set of ten spoke Forged Aluminum wheels. Think I’ll go with the Mags. Oh Lofgren is getting to tune this one also.
944s
If he added the kit and did no rejetting to the carbs that motor will ping like a mother from a lean mixture. He just added 44cc of additional flow to the motor. It will even hole a piston if left like it is and ran it hard, ok it won't hole a piston, just melt the upper ringland for the top ring. That's the reason why I asked if had done the re-jetting. Like always, it’s hard to make a call with only one tenth of the information needed.
I know the info was limited. I am first of all trying to figure out what I have for a piston. I was hoping for some ideas on where to look for comparison and identification. I rotated the pickups in their carrier to maximum retard. Pinging goes away but driveability suffers. Tons more power at revs, but crappy and jerky at low speed / part throttle.
I believe most 944 11.5:1 kits need to have the timing retarded by 2 degrees. I'd start with that and then rejet the carbs. You'll then have to use 91 or 93 octane fuel to not get pining.
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Ride safe,
Edward
Ducati '72 750GT (#751379)
Ducati '98 900SS/FE (#231)
IBA #18798 http://www.geocities.com/edwyun/index.html (including the FE Registry)
the ducati performance kits with the ram pistons are usually about 12.5:1 and will cause lots of problems on our fuel. the carb bikes, with the single stage ignition advance, have 32 degrees advance from 2,000 or so rpm onward. the injected bikes get that about 5,000rpm and have mid 20 low down. with 11:1 or so they're fine. my st2 was about 11 and it didn't ping, altho it was maybe a bit coarse around 4,000 or so. the pistals come as 10.5 and 11.5 i think as do the ferraci (je) ones maybe. i've run je 11.5 in injected 900.
the carb bikes are a real problem because you can only retard the pickups giving idle and just off idle issues or you can buy an expensive silent ketnick setup. it is possible to run a 1.6m ecu off a crank trigger (mv do it) meaning you could do it with a 1.5m also as they're the same software pretty much and duane can fix that. so you could with fim software run a 1.5m using a rpm only map. it'd be wasted spark but the std carb ignition system is anyway. you could add a manifold vacuum sensor to get a tps like signal that with the right manipulation would give you a 3d map. i'd like to try that on the 750m if i ever get all the other stuff done first, like having the engine assembled and fitted.
the dp ones are easy to id. they have big round domes and the skirts have lots of lines running around them. they're made by RAM.
If he added the kit and did no rejetting to the carbs that motor will ping like a mother from a lean mixture. He just added 44cc of additional flow to the motor. It will even hole a piston if left like it is and ran it hard
No such calamaties will occur in particular if you have FCR 41s which have more than adequate flow. Going to the 944 with 11:1s, my mains stayed at 155, slows acutually decreased to 55 from 60 and the only additional fueling I adding was a slightly richer taper on the needle to help around 4000 RPM. Probably had that stock anyway. I re-iterate, the only reason your 944 kit will exhibit pinging tendencies is the increased compression and not carburation, at least within a range close to stock settings for carbs & timing.
My 93 has gone from 904, to 944, to 966 all with 41mmFCR's installed. In that time the main jet has not been changed. The needle was raised sometime ago 1 notch and that continues to be the setting the bike likes for nice roll on.
About being lean and an additional 44 CC's. I'm not a tech and did not stay at a holiday inn. Still though, why would a carb care that you made the cylinder diaplacement larger?
Open the airbox, flow the head, scavange the exhaust with a spiffy header, and I can see moving more air then the main jet can spritz fuel into, but just beefing up the jugs?
Any explanation would serve to enhance my limited knowledge.
Yes, I have had to run premium gas with the 944 in the summer. I've been trying 89 with the 966 when conditions allow.
My 97 fcr 944 pings on roll,but I know my guides, seals need some work,Your ping could be like my ping from the oil thats getting into the chamber,its like reducing the octang level of the gas.Its a thought.....rings or guides source of oil. Craig
944 piston choices ???
Linear Mode
