| Author | Message | ||
     Agusta74 |
First up I have posted here because we are the people here dealing with these engines and I didn't think the engine section of the forum was general enough to cover the overall picture... Here are some thoughts I have put together over the past week or so after reading the Performance Handbook for Sportsters and reading as much on the subject as I could find on the net (a lot of which was plainly wrong!) I am posting it to see if I am missing the point of something. Here goes.... I would normally be a person who would say "the factory did all the testing and have the company behind them so they will get things right from the start" BUT I have come to realize that HD/Buell were constrained in the design of the 1990 XL1200/Buell RS1200 engine by the following restrictions. Cost. (both immediate and ongoing) Meeting noise regulations. Meeting exhaust emissions regulations. Designed to run on the lowest octane of gas available. They had to use the right intake, jetting exhaust, cams, compression and ignition systems to get their product to market. Intake to suppress noise. Jetting lean to reduce emissions. Exhaust to suppress noise. Cam with no overlap to suppress noise and help with emissions. Compression ratio low enough to run on any gas from any pump. Ignition, dual fire to help burn any un-spent gas to help emissions and cost. My question is this.... Without those constraints, BUT still wanting to build a bike with "real world" (not race track), on road performance low down and in the midrange with something on top but that's not the focus... then what parts would they have chosen given a free hand and 91 and 96 octane gas to run on? I don't want a radical rocket ship I just want to make the very best of what I have. Screaming Eagle Air cleaner with K&N filter. Re jet carb to suit overall set up. More open exhaust. (Supertrapp in my case) Andrews type V2 camshaft? Single fire ignition with higher than 5200 rev limit. Avoid the wasted spark that can't be any help to smooth running, but might help emissions and it was cheap. Higher than 9.0:1 compression. 9.5 might be enough with the high cranking pressure generated by the V2 cams? The V2/N2 cam seems from what I read to be a win win for both bottom and a little top end. Does anyone have dyno charts comparing standard to V2/N2? They not only have more lift and duration and some overlap but the cam lobe timing is also moved. Anyway that's what on my mind. Now I better stop stalling and get back to a work! Regards Gavin New Zealand 1990 RS1200 | ||
| Agusta74 |
http://www.calsci.com/motorcycleinfo/HP2.html That site make a lot of sense to me... Regards Gavin |
