| Author | Message | ||
     Deanh8 |
Both done on 91 California gas. Notice power drops off sooner with xb9 pistons Stock with micron open air and tune - 92hp:  Added Milled XB9 pistons with 52mm throttle body - 108hp:  | ||
| Bike_pilot |
Very nice results. I've seen that others also have power drop off early with XB9 pistons. Any idea why this is? Typically more compression doesn't alter how long a four stroke will pull - I've ridden a 14:1 TL1000S that was proof enough of that  A very nice torque increase as well. Looking forward to a ride report on it - how it does around town, at idle, throttle response, that sort of thing | ||
| Greg_e |
Could the drop be from an airflow issue? Just wondering if you may have hit the limit of aircleaner or other part of intake. | ||
| Terrys1980 |
Did you swap the pistons or connecting rods too? | ||
| Deanh8 |
just pistons. | ||
| Portero72 |
Very curious about this mod, and the added torque. Anyone know if it will work with more of a 'stock' tune? Race ecm, high flow filter being the only modifications. | ||
| Deanh8 |
No. Ran like shit with my previous tune. | ||
| Gunut75 |
I like it. i'm going to remember this one for when I rebuild my 12. That'll be a few years though. Fun to ride eh? | ||
| Syonyk |
What are you doing with the ignition timing and fueling to handle the added compression? I'd definitely suspect intake flow issues for an early power dropoff. | ||
| Wutend007 |
Any chance of posting or pm the fueling and timing maps to compare with? I dropped in a set this fall and made a couple changes but the idle is still off. | ||
| Bike_pilot |
His maps with a 52mm TB will be WAY off for a stock TB - huge amount more airflow for a given throttle opening, especially at smaller % throttle openings. | ||
| Wutend007 |
Your right BP. It would be toooo much air for stock. Just looking for a comparason to start with but mainly the timing. | ||
| Ourdee |
I wonder if it is running out of fuel supply? | ||
| Deanh8 |
I had bigger injectors but figured they wouldn't be needed. I don't know how to post maps. Head work and cams are next | ||
| Boltrider |
Ping-free with those pistons? I've wondered how those pistons in a 12 would do on CA 91 octane. What compression do you get after putting 9 pistons in a 12, assuming everything else is the same? 11:1? | ||
| Boltrider |
I see you milled the pistons. Did you mill the crown? | ||
| Ericz |
It looks more like the dyno operator just didn't take the motor to redline on the most recent run. The power dropoff at the end is not from continuous 100% throttle. The factory injectors running factory pressure are good for 115-120hp at the max. You can easily replace the FPR with a higher pressure unit to increase the HP capability of the stock fuel system. | ||
| Slaughter |
I have to agree with Ericz - that looks like a roll-off in both cases. A good dyno operator will avoid hitting the rev limit unless told to take it all the way up since it's really hard on these motors bottom ends. | ||
| Deanh8 |
Keep in mind this was a SUPER budget build. Just using parts I had laying around. These pistons where supposed to go into my tube frame bike but I wanted some more power out of this bike. Now I gotta track down another set of pistons to finish my tube frame. fresh off the machine before being cleaned up.  after:  | ||
| Deanh8 |
Got about 1000 more miles on her so far. More of a review... Very heat sensitive. Doesn't like to putt around in traffic, or sit at a light for a long time and then immediately get ridden hard. Kind of an ovbious thing, the bike stock had this issue but more predominant now. I live in a very congested part of town, so when im at a light for 5 min after beating on here It requires some clutch slip until you get some air rolling over those barrels or it will ping. Cant just let it heat soak and dump the clutch with the throttle open. Runs really rough when its cold. Regardless if it is 40 or 80 out. Really likes to be warmed up before it gets ridden. Never had this issue before. Power sub 2500 rpm is a little soft, probably due to the timing they had to pull with the crap 91 octane gas we have out here in California. After 3k it pulls like an animal and feels great all the way to redline. and keeps pulling in the next gear pretty hard. Overall I am very happy with it. Just not a "friendly" as before, but once you know your bike its not an issue. | ||
| Deanh8 |
http://www.youtube.com/watch?v=ToHTC0do9UU | ||
| Gunut75 |
 Nice ending too. | ||
| Wutend007 |
I agree mine is a little cold blooded in the AM. Maby Ericz could chime in on the posting from Ecmspy.  | ||
| Syonyk |
Is there a way to pull timing back based on cylinder head temps to help reduce the pinging? Sustained detonation isn't great for engines... | ||
| Xoptimizedrsx |
yes you can pull timing back based on temps but you will have to start using Tunerpro rt to do this. I sent Eric the full profiles on the ecms with offsets and multipliers and ect. he may be busy studying and learning it by heart... | ||
| Ian03xl |
Seems you would benefit from a different set of cams a later intake valve close timing would allow some of that timing to be brought back and show a nice gain over the entire rpm range. Maybe even be easier to ride in heavy traffic. Looks good so far nice job. | ||
| Bike_pilot |
^ I would think that too. Its a different motor, but for example, a good friend's TL1000S was running aggressive cams combined with 14:1 pistons. It ran awesome on crappy CA pump gas with no pinging. Didn't do anything weird hot or cold, very rideable in traffic. Does an honest 135-140 at the rear wheel (depending on altitude) with more power everywhere in the curve than stock. I don't understand why XB12s with XB9 pistons peter out on the top end, but I've seen this reported other places as well so I'm not sure its down to dyno op error. Trackdaymag got the same result from XB9 pistons in their XB12. The article was "red white and buell," IIRC. Can't find it on their site now, anyone got a copy laying around? | ||
| Deanh8 |
I was looking for their write up also, cant find it ANYWHERE | ||
| Wutend007 |
i saw the same article but its offline now. here is a couple from another fourm thats simular. I agree thats its the dyno operator that cuts it, thats a hell of a drop and I have been at 6800 RPM (too excited,my bad)and it didn't cut like that. maby it was the RPM limiter cutting in? http://mods.buellxb.com/index.php/Engine/xb12-moto r-with-xb9-piston-fyi.html http://www.buellxb.com/Buell-XB-Forum/Do-It-Yourse lf-Buell-Mods/XB9-Piston---XB12-Motor-write-up-tho ughts-long-and-not-100-complete-yet | ||
| Bike_pilot |
Even if its the dyno op in this case, why would power drop off up top in most of the dyno charts for XB9 pistoned XB12s? Like this one? http://www.badweatherbikers.com/buell/messages/327 77/527608.jpg |
