| Author | Message | ||
     Ezblast |
Thank You! | ||
| Berkshire |
Thanks - I thought I was going crazy! I interpreted "offset the cylinder" as moving the cylinder forward or backward on the deck surface, which would be very strange. But I figured Mr. Buell to be a reliable sort, and since EZ said he'd been stumped for awhile... I considered that maybe H-D v-twins could have been designed with the cylinders offset from the "correct" location, to provide extra room at the base - like if you took a 60-degree twin and angled the deck surfaces toward each other by 7.5 deg. each, to tilt the cylinders toward each other. With such an arrangement, the pistons wouldn't see the full stroke. So why not just make it a 60-deg. twin to begin with? I dunno - to fit in an old bicycle frame? aesthetics? Who knows! So many years later, they decide to build a single - the Blast! ...and the engineers raise a question: "Do we make the lone P3 cylinder tilted 7.5 deg. like the twins, or should we straighten it up?" As in all big companies, the answer from management is obvious, "Just change as little as possible - quit trying to milk overtime out of project Thor! Just use XB cases, bolt on a rear blockoff plate, and call it a day. Then design some fancy overpriced CHROME blockoff plates that we can sell to the Blastard stepchildren that buy these things!" But production informs management that the reduction in machining would make it cheaper to produce special cases for the P3, and marketing tells them that the P3 target demographic is "a bunch of cheap Blastards" who won't spend money on fancy overpriced chrome doodads anyway." Thus, the one-hole P3 cases are born! Then some crazy Blastard engineers over at the Buell division got their hands on a pair of raw Thor castings, and build a motor with the cylinder in the "correct" location, so the piston got the full stroke - 650cc's, baby! Years later, their ringleader gets all liquored up after dinner and leaks the story to EZ. What?! It could happen!  The only problem with all that is this: To make a 500 into a 650 by simply correcting a bad OEM cylinder offset (assuming the 492/500 displacement "brag factor" applies, and assuming we are moving the stock cylinder & piston), the stroke would have to be increased from 3.125" to 4.0625". In this case, we are assuming that the stroke at the big end of the rod was ALREADY 4.0625", and that the piston pin was only seeing 3.125" because of the cylinder base location originally being offset from it's correct position. Mathematically, this is equivalent to keeping the base location the same and leaning the cylinder over. Regardless, the piston was only seeing 3.125" of the 4.0626" stroke. No big deal, right? I'd figured the cylinders could have been leaned 7.5 deg. from the "correct" centerline, so that would take off some stroke, right? If a piston sees the full 4.0625" of an actual 4.0625" stroke, we can say that it has a "motion ratio" of 1.00 (4.0625"/4.0625"=1.00), and when the cylinder is pointed exactly at the crank centerline, we can say it has "lean angle" of zero degrees (0.00). So which angular function gives a motion ratio value of 1.00 for an input lean angle of 0.00 deg.? After a little trial & error, we find that it's the cosine: cos 0.0=1.00 ...so to find the motion ratio for 7.50 degrees: cos 7.50=0.99 ...so at a lean angle of 7.50 degrees, we get a motion ratio of 0.99 - wow! Plugging this back into the "actual" stroke gives: 0.99x4.0625"=4.03" ...so a 7.5 degree lean angle wouldn't even have come CLOSE to de-stroking that 650 down to a 500! Okay, so how much would the deck surfaces have been angled originally? A 650 stroked down to a 500 would have a motion ratio of 0.769 (3.125"/4.0625"=0.769), so we need to find an angular function that will output the lean angle when we input the motion ratio. Testing with the previous values confirms that the inverse cosine is our huckleberry: cos^(-1) 0.99=7.50 degrees ...so for a motion ratio of 0.769, we get: cos^(-1) 0.769=39.7 degrees. edit: Continued below. (Message edited by berkshire on June 30, 2006) | ||
| Buellistic |
Just to throw this into the MIX ... The reason the BLAST is not a GOOD "DIRT TRACKER" is it has a short stroke ... IF IT HAD THE XB12 STROKE IT WOULD BE A GOER ON THE DIRT TRACKS !!! | ||
| Mmelvis |
EZ: So are you saying Brian at revolution performance can do this ? | ||
| Berkshire |
 Now you see why I thought I was going crazy - a motor like that would NEVER fit in an old bicycle frame!  | ||
| Berkshire |
What kind of cylinders would be used? Buell & XL would have the regular head/cylinder bolt pattern. Would twin cam or evo big twin work? edit: ...or 1600 sporty? Revolution DOES have a 3-7/8" big twin cylinder listed - that's getting close! Kit #116-011 is shown for $1K, but that's for 2 of everything. (Message edited by berkshire on June 30, 2006) | ||
| Gearheaderiko |
Without doing all that math, its just as simple as spacing out the cylinder mounting bolts to accept a bigger cylinder and since 1550 overbore kits are available from the factory, thats 'off the shelf'. And no I havent done the actual math to figure out which Big Twin cylinder they used!. This is all really 'old school' anyway. Change the V to 60 degrees? Now thats blasphemy! | ||
| Berkshire |
tell me about it!  | ||
| Ezblast |
Mmelvis - yes - in fact the thought of it has got him - Brian - chomping at the bit to do it - I figure - your going to bore the cases anyway - whats the big deal welding up and drilling out for bolt holes for bigger jugs as well - if your in for a penny might as well go for the pound - lol - and 809cc would be a hell of a pound! GT - JBOTDS! EZ  | ||
| Berkshire |
Buell XBRR features: * 1339cc (81.7 cid) Thunderstorm Powertrain: o 4.080 inch (103.6 mm) bore and 3.125 inch (79.4mm) stroke o 12.5:1 compression ratio o Dual 62 mm down-draft fuel-injection throttle bodies o 150+ peak engine horsepower at 8000 rpm (per SAE J607) o 100 ft. lbs. peak engine torque at 6500 rpm (per SAE J607) I wonder when parts will be available? | ||
| Buellistic |
XBRR Cylinder and Head = 669.5 cc !!! | ||
| Ezblast |
And add the XB12R stroke?;0) GT - JBOTDS! EZ (Message edited by ezblast on July 01, 2006) | ||
| Buellistic |
Ezblast: Long stroke for DIRT TRACK "ONLY" ... Short stroke works better for ROAD RACING !!! In BLASTing LaFayete | ||
| Ezblast |
Think about this - max rpms for a racing XB12 is 7100rpms - if you stroked the Blast up to that stroke - that would apply - which would be fine for both dirt and track - since the max for the short stroke would be 7500 - the extra stroke would be worth the 400 rpm loss in terms of power and help deliver that down low grunt Buells are famous for. Remember - Torque is the source of all that is good! GT - JBOTDS! EZ | ||
| Buellistic |
Ezblast: IMHO 3.8125 in. Stroke(XL & XB 1200)max. 7K RPM and 3.125 in. Stroke BLAST/XB9/XBRR max. 8500 RPM ... In RACING LaFayette | ||
| Ezblast |
Racing XB12s are set at 7100 to 7500, the xb9s at 7500 to 8000 - depending on the setup - thats the facts. GT - JBOTDS! EZ | ||
| Buellistic |
Ezblast: XBRR max. rpm 8500 ... IF YOU ENGINE DOES NOT MAKE ANY HORSE POWER AFTER 6000 RPM TO SPEAK OF(or where ever your HP peaks), THEN YOU WILL JUST BE wasting your ENGINE TO REV MORE !!! In BLASTing LaFayette (Message edited by buellistic on July 02, 2006) (Message edited by buellistic on July 02, 2006) | ||
| Cobalt60 |
YOU WILL JUST BE WAISTING YOU ENGINE TO REV MORE Is waisting a technical term for really smart engine guys or did ya mean wasting? Sometimes yelling in broken English is hard to decipher. What holds these engines back rpm wise? Is it piston speed, valvetrain, bottom end or just yes. (Message edited by cobalt60 on July 02, 2006) | ||
| Berkshire |
Aside from the factors listed above, cylinder head flow capability can also hold an engine back, rpm wise. If two different sized engines use the same heads, then the smaller one will be able to rev higher. Buellistic, the whole reason to build an engine that CAN rev to 8500 is that it WILL make more power after 6000. Yes, it wouldn't make any sense to rev an OEM-spec blast engine to 8500, but nobody would build an engine with an 8500 rpm valvetrain and bottom end if they were going to keep the 9:1 compression ratio, stock cams, and an unported stock head. The reason the XBRR motor makes almost twice the horsepower per cubic inch as a P3 motor is because it revs higher, and because the compression ratio and valve timing is targeted toward making power at those revs, and it has cylinder heads that can deliver the required flow. Why do jap bikes make more than 5x the power of a blast with a motor that's just 2x the displacement? Because they rev even higher than the XBRR. Having said all that, I still agree with EZ - FOR THE STREET, I would rather have more displacement than higher revs. ...or maybe a little of both! The long & short of it is that you can either build for max peak power, or for reliability, economy, and a wide powerband... or compromise somewhere in between with a little (not a lot) of each - you can't have your cake and eat it too. ---------------- This discussion should really be held in the "I/C Engine theory" thread, since it applies to all I/C engines, and this thread is supposed to just be about embiggening the P3 motor.* * "embiggening" is a technical term for increasing the size of something. It's a perfectly cromulent word. (Message edited by berkshire on July 02, 2006) | ||
| Buellistic |
Cobalt60: THANK YOU for the 'PROOF READ" !!! WHAT HOLDS A ENGINE BACK RPM WISE: Valve size, port size(FLOWING), compression(compression aresa shape, valve springs(weight of valves/valve train), carb./throttle body throat size, long stroke, bottom end "AND" TOO FAT A RIDER !!! IF YOU WANT A COPY OF "KENTUCKY BUELL Riders", e-mail me so "i" can get your e-mail address and you will get a copy ... CHECK Storm Fronts, KENTUCKY BUELL Riders ... In BUELLing LaFayette Ljenne73c@verizon.net (Message edited by buellistic on July 02, 2006) | ||
| Buellistic |
Berkshire: When "i" get back to HOUSTON to visit relatives "i" will be bringing my HIGHLY PRODUCT IMPROVED 2000 BLAST ... E-mail me so "i" can get your e-mail address and "i" will PING you of my ETA and LENGTH of stay ... You can then show me some of the GOOD ROADS in your area ... In BLASTing LaFayette (Message edited by buellistic on July 02, 2006) | ||
| Jmynes |
Is embiggening a technical term for really smart engine guys or did ya mean more cubes? | ||
| Buellistic |
If you do not have CUBIC INCHES(easy HORSE POWER) then you have to REV IT to get HORSE POWER !!! | ||
| Cobalt60 |
All in good fun, Buellistic. The bigger, better, higher revving blast is an interesting discussion. At some point you lose the uniqueness of the blast. I think I'll just ride the torquey little wheels off mine. | ||
| Buellistic |
Cobalt60: It is not my intent to make my 2000 BLAST "BIGGER", BUT to "PRODUCT IMPROVE" the basic product to the limit ... Remember this: THE DEVIL IS IN THE DETAILS !!! When "i" get it to HOUSTON where you can see it, you will understand ... In BLASTing LaFayette | ||
| Berkshire |
Jmynes - no, it's more of a layman's term. Read the small print at the end of my post, and/or google it. Buellistic - you got mail. | ||
| Cobalt60 |
For those that prefer to be less erudite: Main Entry: cromulent Part of Speech: adjective Definition: fine, acceptable Usage: slang Many of the things that people want to do with their blasts are already available from other manufacturers (chain drive, more displacement, higher revs, more reliability). Hell the old Yamaha SR500 would toast even a highly modified Blast. Modifications are never about economics, but sometimes you need to go hmmmm. Then again life is about the journey not the end result. | ||
| Buellistic |
erudite: to instruct, learned ... rudis: raw, rude(ignorant) ... erudition: extensive knowledge acquired chiefly from books(ie: an ENGINEER where by a "mechanic" tells same how to make it work !!!) | ||
| Gearheaderiko |
Cobalt: while its true that most of the stuff is already available for people to do to their Blasts what they want to do, much of it is not listed as being made for or fitting a Blast. A lot of research goes into finding some of this stuff. | ||
| Ezblast |
To further this discussion - I just talked with Brian Nallin of Revolution Performance - http://www.revperf.com/default.aspx - to get my facts straight - he said the biggest they could safely go to would be 4 1/8" bringing you to 685cc, with a 4" being a true 650cc and that the real trick to making that power count would be lightening the flywheel to XBRR type spec;0) - yes - he said it would still work for the street - I love talking to the experts! GT - JBOTDS! EZ |
