| Author | Message | ||
     Blake |
To clarify for the confused (like me)  ... When Aaron says our Buell twin cylinder engines fire at 405o and 315o intervals, he is saying that the rear cylinder fires 405o (360o+45o=405o) of crankshaft rotation after the front cylinder fires, and that the front cylinder in turn fires 315o (360o-45o=315o) of crankshaft rotation after the rear cylinder fires, thus at 405o and 315o intervals. In other words... If we designate an instance of ignition spark on the front cylinder's compression stroke as occurring at 0o, then the rear cylinder ignition spark will occur after 405o of crankshaft rotation and the next ignition spark for the front cylinder will happen at... 720o of further crankshaft rotation (720o= two complete revolutions). What Russ (Ara) is asking is... do some dirt trackers set their cams so that the rear cylinder fires just 45o of crankshaft rotation after the front, almost as if the bike were a thumper (single) even though it has two (twin) cylinders, thus a twin-single or "twingle." I think the answer was that for a single carburetor configuration that would not be a good thing since the intake strokes of each cylinder would then overlap thus putting a much bigger demand on the volume of air the carburetor must flow at one time. With a separate carburetor for each cylinder like the XR750's run, it would be okay. I'd like to hear what a twingle Buell would sound like. That would have to be very unique. Excellent question Russ. As to the torque load on the drivetrain, It might be okay since the meat of the power stroke is not much more than 45o in duration. Is that right Aaron, Pammy? | ||
| Jprovo |
Jose, Yeah, they fired 360 degrees apart. The twingle is a funky thing! The cool thing was that the guy with the XS650 had a FXR700 that he converted to a twin. The pistons rise and fall as a pair, 1&4 and 2&3 rise and fall together and it has two dual-spark coils. He cut the cams in half and then rotated the cams for 3&4 180 deg to align with 1&2. It was a nifty sporting twin, could have used some refinement, but it was fun to ride. James | ||
| Jim_m |
"The cool thing was that the guy with the XS650 had a FXR700 that he converted to a twin. The pistons rise and fall as a pair, 1&4 and 2&3 rise and fall together and it has two dual-spark coils. He cut the cams in half and then rotated the cams for 3&4 180 deg to align with 1&2. It was a nifty sporting twin, could have used some refinement, but it was fun to ride. " I've heard of that...the big concern was the additional stress the crank would be getting having 2X the torque at 1/2 the intervals per rotation (IIRC). | ||
| Jvv |
http://www.dgweb.com/~haderach/flyer.pdf INFO ON THE BRAG/AMERICA SPORT BIKE NIGHT LAGUNA DINNER..........hope to see some of you guys there........ride safe............Jack} | ||
| Ken01mp |
well, the general discussion board is the only place i can get into on this thing, all the other places are too big. (kuwaiti computers suck) some of you remember me, some of you dont, i used to post somewhat often until late january. those that did know me knew i was a marine reservist, well, i got mobilized to kuwait, then iraq, now kuwait again. my military police company provided route recon, convoy security, and traffic control points all the way to bagdhad. sometimes we were behind the front lines, sometimes were were frightneningly far ahead of them. we lived out of humvees for two months, then controlled civillian and military traffic while providing security on a bridge in bagdhad. some of you might have heard of us, i guess they talked about us a great deal on the news. we did and saw a lot of crazy shit up there, and it was one helluva ride, but now we've been tasked with customs work for the last few months while everyone else goes home. sucks balls. anyway, just thought ild drop in and let everyone know the badweb was well represented in the war. i sure miss my bike though, and it looks like ill be home just in time for wisconsin winter. anyone live anywhere warm i can come and visit so i can ride when i get back? ill buy all the beer and tell all the war stories. i live at camp matilda kuwait, in the middle of nowhere desert, where the thermometer reaches 135 daily and never drops below 100. nothing but heat, sand and wind. we got to make a libo (short for liberty) run the the port, kuwuait naval base, where im writing this email from. anyway, i hope all of you are having a great summer, riding safe, and drinking lots of beer. at least thats what i would do if i could have fun, ride, or drink beer. all of you better have a cold one for me on the fourth, as i will be inspecting military containers for contraband in 135 degree weather, dreaming of a bar-b-q, cold beer, my girl, and my bike. ride safe and have a great summer | ||
| Jst |
My 69 Triumph 500 fired both plugs at the same time. Of course one cylinder was on the compression stroke and one was on the exhaust when they did it.  JT | ||
| Blackcatracing |
Reecipe" Crimping tools are about $250, if you purchase one with connectors and pins going for $5.00 for a two (pin/plug) combination. How many sets do you need. I'll loan you my criming tool. | ||
| Se7enth_sign |
Has anyone here ever had the engine surface where the oil filter mates to crack? | ||
| Reepicheep |
Blackcat... $250? Ouch! At least the cost of the actual connectors is reasonable ($5). Can you get a source of PCBoard mount Deutsch connectors that match the speedo sensor connectors? That would be awsome, and I would not need the crimp tool (nor need to bother with the hassle of pigtail wires at all). Bill | ||
| Mbsween |
Ken, glad to hear you're okay . Man I used to cuss you MPs, well the army ones anyways, when I was in at Benning/Hood  Well I guess I'm not trying to ride back onto base without a helmet anymore. I'll be sure to hoist some pints and pull a wheelie or two (when I get the bike back from the shop!) for you Keep safe and know that we appreciate your efforts back at home And hell I'll ride in the snow with you and buy you a beer Matt | ||
| Aaron |
Ken: thanks for checking in and thanks for the job you guys and gals are doing over there! | ||
| Cjmblast |
Ken01mp, I'll have a cold one for you and think about you and EVERYONE over there on July 4th !! Stay Safe CJM  | ||
| Ara |
Ken01mp: I am a 27-year career civilian of the U.S. Army working at Redstone Arsenal in one of the anti-tank missle programs. It's rideable all year long here in Huntsville, Alabama and I never mothball my S3. I'd be delighted to have you decompress at my place. Bring your bike and I'll show you some twisty local roads. Ping me off line at russ.asson@msl.army.mil Thank you for your service in such nasty places! Russ | ||
| Duck |
Ken, The boys and I here at Ft Monroe, VA will be hoisting one for you. Thanks. | ||
| Blake |
Ken, Totally cool of you to check in. Hell yes, we heard of your exploits over there! Way to go marine!! The riding around Kilgore, Texas isn't spectacular, but I can get you onto a little track nearby for a couple days of tire shredding fun. Let me know if you are interested. Stay safe over there.  7thsign, I think I recall seeing one instance posted here somewhere where a bike had the heim joint pull out and crack the case at its connection point, but I've not ever seen the or heard of the case cracking at the oil filter flange. You might want to have an experienced metalurgist inspect the failure to see if there was an inherent defect in the casting that might have caused it to crack. Can you post a photo of the crack? We'd be interested in seeing it. Maybe overtightening of the oil filter might cause a crack between the flange and the post. | ||
| Jim_sb |
Great job, Ken!
Your money is no good if I'm in the room. If you get out SoCal way let us know on Storm Fronts (SoCal page). We'll go for a ride, eh? | ||
| Snail |
Salt Questions. Got my rule book and am a little confused. the class I am interested in is the 1000 cc PP class. 1. Stock everything, I understand, but is NOS allowed? 2. Gearing for salt. If I disarm the speed restrictor the bike should easily exceed the 178 mph current record, (at least on pavement). So, with an excess of speed should I consider dropping a front tooth to make up for the friction loss of the salt? 3. How hard is it to ride a bike on the salt at speed? Am I being dumb to consider this? Paul | ||
| Firemanjim |
Paul,no NOS in production class.And depending on how much HP you have you may want to gear for MORE top speed.Just bring an assortment.Easier than riding on those frikkin gravel roads.Its kinda like a high speed hard pack dirt road.Besides you are not gonna turn.Remember,P/class needs stock exhaust,anything goes inside engine. Dumb??No,just crazy like the rest of us,come on down. | ||
| Choptop |
Anyone have an 99 FI bike owners manual around? What is checked/changed at the 15k mile service? | ||
| Blake |
Paul, Never done it, never been there, I could be totally wrong, but I don't think so... ![:]](http://www.badweatherbikers.com/buell/clipart/proud.gif) As I understand it, the power required to go fast on the salt isn't significantly different than for asphalt at sea level. The main thing is that at the speed you hope to achieve, you will most likely need to contend with fairly significant wheel spin in trying to determine your optimum final drive ratio. I also think you may be making a huge assumption in estimating the top speed of the big gix. Horsepower required increases with the CUBE of speed. So if a gix 600 with 100rwhp can do 150 mph and the aerodynamics of the big gix are identical to that of the lil gix (if anything they are probably less slippery), it would take (180/160)3*100HP=173 RWHP to get to 180 mph. If a stock lil gix can make 160 mph, you'd need at least 143 rwhp to make 180 mph. You might kin do eeet compadre. I'll be there rootin' fer ya. Suggest you take a look at a dyno chart for your bike (one of the moto rags or MO publish them), and identify engine speed at peak HP, tally the corresponding speed in top gear and subtract 5% for wheel spin. If you are real lucky, you'll be able to get there. If it ends up being a bunch over 180 mph, you might want to gear down some. That make sense? Blake (hears Aaron chuckling in the background) | ||
| Blake |
Chop, I don't have a manual for a fuellie, but I don't recall ever hearing about any special maintenance being required on the DDFI or related systems. The 15K maintenance is the same as that required for the 5K interval if that helps any. | ||
| Jim_sb |
Hi Blake, I don't know the elevation of the Bonneville Salt Flats but the airport at nearby Wendover, Utah is at 4235 MSL. A normally aspirated engine won't make the same power at 4235 MSL that it will at sea level (less O2). So I'm guessing you're going to need more power to achieve a target speed at Bonneville than you would to achieve the same speed at sea level. Admittedly the air is thinner and as a result you'll experience less drag than at sea level but the HP loss due to less O2 will outweigh the drag savings. | ||
| Jim_sb |
Said differently, assume your bike has 150 rwhp at sea level and that's how much you think you need at sea level. Assume the same bike, at 4235 msl can make only say 90% of it's sea level HP. Then you'd be 15hp shy of the amount needed. That's my guess and I'm sticking to it until someone educates me otherwise. Which may happen... | ||
| Mikej |
People hear of the Bonneville Salt Flats and some think of Death Valley and then assume both are below or near sea level. Little do many realize that the lowest point in the Salt Flats is higher than the highest point in Wisconsin, elevation wise. Them high deserts have much more going on than just the heat, and that heat too adds a whole 'nuther factor to factor in. Iced intake anyone????? | ||
| Aaron |
My guess is that Blake is assuming the actual horsepower lost at 4214' is offset by the reduced air pressure. No comment I will say, though, getting the gearing right is critical for max speed. Unfortunately, getting the gearing right has to be done somewhat empirically because wheelspin is a huge variable that can change dramatically from one event to the next and even change somewhat from day to day. So do the calculations and gear your bike based on a wheelspin assumption, but bring a variety of sprockets in both directions from that number and dial it in for the exact conditions you encounter. | ||
| Blake |
Jim, Admittedly the air is thinner and as a result you'll experience less drag than at sea level but the HP loss due to less O2 will outweigh the drag savings. If that is true, then how is it that even propeller driven airplanes travel most efficiently at higher altitudes?  The reduced drag and lack of O2 are offsetting. If air density is reduced xx%, so is drag, and so is HP. The extra wheel spin kicking up salt does rob some additional power. Winston Cup races at Pike's Peak, right? You can also compare records at Maxton versus Bonneville. Ask the Sportster list LSR guys. In some ways achieving higher speeds at Bonneville less challenging... it takes less actual HP to go the same speed versus at sea level, so the engine is less stressed. In case you can't live without the math... If you know drag (fD) in LBs and speed (V) in MPH you can easily calculate the power (P)required as... P=(fD*V)*(5280/3600/550) HP Within the range we are discussin, drag varies consistently with air density as does available engine power. | ||
| Jim_sb |
Okay, this is gonna be fun: If that is true, then how is it that even propeller driven airplanes travel most efficiently at higher altitudes? Efficiently or faster? For a given cruise power setting my Bonanza will fly the fastest at the highest altitude at which it can maintain the desired power output level. Go any higher, even 1000 feet, and the TAS (true air speed) drops because the engine can no longer maintain power. But the A36 can maintain 75% power quite a ways up, I'm guessing around 7500 MSL (I'm not exactly sure, I'll need to look it up). But if I want to maintain 100% power for a high speed run(hopefully for not too long) I had better stay low. Aircraft have both parasitic (airframe) and induced (caused by lift) drag to overcome. They are definitely more efficient at altitude due to reduced drag (meaning more miles per gallon) but at full throttle will it be faster at 4200 msl than at sea level? I don't think so. Now I'm no Engineer (I'm sure you've noticed, ) but I didn't see anything in your calc's per se about temperature or altitude. I know the International "Standard Atmosphere" used in many aviation related calc's is 29.92" of barometric pressure at sea level on a 59 deg. F. day. Those standards are typically used when determining or quoting an engine's power output. It seems to me then that to determine true RWHP at 4200 msl one must adjust accordingly. I have flown out of enough high altitude airports to KNOW that my engine does not put out nearly as much power at 4200 msl as it does at sea level. Your argument suggests that my aircraft should perform similarly at altitude due to reduced drag. But it doesn't. Such a deal! Plus I've ridden my bike more than a mile high often enough (like I will tomorrow ) to know that the same passing power and speed simply isn't available. So how could I achieve the same top speed? I apologize for not having the graphs and math to back this up but I'm going to have a look around and see what I can dig up! Stay tuned. Blake, BTW, everything is meant with good intentions, I am just a skeptic on this one.... | ||
| Blake |
Jim, Nope, I am not saying a motorcycle or airplane will perform the same at altitude versus near sea level. I am only saying that the peak speed will be the same. Assuming you have the time and space to accelerate, peak speed is dependent on only two things... propulsive power and drag. What you are sensing is the loss of power due to the thinner air. Acceleration (the time rate of change of velocity or a measure of how quickly speed changes) must fight mass (a=f/m), so with less power producing less thrust (lower "f" ) , acceleration "a" for a constant mass "m" is reduced. In other words, it takes longer to achieve peak speed with less power, but if drag is reduced equivalently you will still get there. Also consider... with less power imparting less stress on the engine, parasitic losses are also reduced. Fun stuff. edited by blake on June 26, 2003 | ||
| Tripper |
A36? Picture please! | ||
| Blake |
Air density varies with pressure, temperature and... humidity. Air density is THE one parameter that is directly and linearly affecting both drag and the engine power output. You might also consider the effect that humidity plays. It's not often that it is very humid at Bonneville. Does humid air at the same temperature and pressure provide more or less oxygen per cubic foot than dry air? hmmmm Got ya really thinking now I bet. |
