Jeremy's Dyno Test

[Dan Hodges]

Jeremy I forgot to ask in the previous post what your ignition timing curve was for your test. Does your motor have the stock bore pistons and have the heads been cut or ported? 90 H.P. is a very good number for one of these things. I tried to E-Mail this message but for some reason I got it back so I will post it.

[Jeremy_Sells]

Dan,

The engine is totally stock internally. I had a minor starter pinion gear failure at 18,000 miles and had the engine apart to clean out all of the pinion teeth from the gearbox. At that time, I honed the cylinders and de-carboned the combustion chambers and put everything back together with new gaskets. The bike turned 43,000 miles this year and is stronger than ever! As far as timing settings, I have left everything stock so far and it seems to be great.

Take care,

[xExcessive 1120]

Jeremy's Dyno Test

Now here is an issue that I have been trying to nail down for years. And that is the well known performance difference between the '78E and everything else. I can find some logic for a slight degradation in performance from '80 on and the quarter mile times posted by the big magazine testers seem to bear this out. Some of it is EPA mandated emission standards that forced all the manufacturers into overly lean carburetor settings and modified timing curves, but I cannot find anything to explain any substantial power output differences between the E and the F/SF. Carburetor jetting is almost identical and timing can be set the same. I have wondered if there isn't a difference at the advance unit resulting in an explanation for the outstanding low end grunt the E is known for. Does anyone know if the cams are degreed differently? Has anyone ever tried a head with the big valves from, say an SG on the bottom end of an E or F with their long duration cams? Seems I have lots of questions, but I think I came to the right place! Christopher. "The Gimp"

[pgg]

eXe, The E hasn't got much low end grunt the power comes on further up the range. My 80SG/78E has a big valve head and I've used 78 cams in it a couple of times. Most noticable in a top gear roll on, bang open the throttle at 4000 in 5th, and the 80' cams leap the bike forward like the 78' cams are standing still. You'd be 10 bike lengths ahead within a few seconds. The weights and springs in the mechanical advance unit are not identical on all models either.

[Dan Hodges]

High Gear roll ons

Pgg- I have never raced anyone using only high gear. I use them all and hope I have enough. The second design does more grunt down low in my 81, but the first design makes more oats from 5G. up. Neither one would be considered very radical. I have the early ones in my 81 now and it runs pretty strong.( Strong compared to other bikes of Disco era)

[pgg]

Camgrind to .400 - .500 lift and some extra duration but you'll need to modify the valvetrain. Talking radical, full on drag bikes have .600 or more lift. I ran some 165 main jets with no air filter once - the carbs wouldn't respond till 3000 then suddenly switched on and kicked like a mule. Trouble was, because of the the high compression wiseco kit, shutting off the gas at 3000 in 1st or 2nd damn near sent me flying over the handlebars. Real fun riding in town traffic. Not!

[xExcessive 1120]

Hammer It!

Hello there PGG and Dan. I have to admit to falling in the "use the gears" camp. Isn't it amazing how much the tranny in the XS is biased toward WOT shifts? I mean more times than I can count, if I get lazy with the 2-3 shift, it pops back out of gear into a "false" neutral, but if I Hammer It I have never missed that shift. The thing seems designed to be run hard. Not abused, but my Stolen F was broken in new by me and was run 7K before the first valve adjustment and then it only took two of the smallest shims over the whole valve train to get it near perfect and at 40K still needed no further changes. And I ran that bike to Red-Line every day at least once and at the 40k compression test (hold that throttle wide open while cranking of course) she read 150, 155,155,150. Not too Chablis! Christopher.