This is a neat sequence of photos my Mom got from Barber. This is Classic 125 and I am racing a trick CZ125 with my Berkshire.
(http://i1177.photobucket.com/albums/x348/kartwheel68/149851_1581247245459_1064019390_31409818_6582755_n.jpg)
(http://i1177.photobucket.com/albums/x348/kartwheel68/148369_1581247365462_1064019390_31409819_7761771_n.jpg)
(http://i1177.photobucket.com/albums/x348/kartwheel68/76914_1581247445464_1064019390_31409820_2104515_n.jpg)
(http://i1177.photobucket.com/albums/x348/kartwheel68/73487_1581247685470_1064019390_31409821_2947799_n.jpg)
(http://i1177.photobucket.com/albums/x348/kartwheel68/154394_1581247805473_1064019390_31409822_2452928_n.jpg)
(http://i1177.photobucket.com/albums/x348/kartwheel68/73587_1581247965477_1064019390_31409823_5241616_n-1.jpg)
He had been blocking me a little bit, so I decided it was time to get by. I went outside in the left hander right before the pics start to get to the inside of the right hander you see. We bumped a little in the corner, but I didnt drift wide, he tried to chop down on me and make me shut off, but as you can see that didnt work. :D
Brian
More of the story?
(http://i957.photobucket.com/albums/ae59/CheneySachs/Barber%202010/76440_1581250925551_1064019390_31409847_3561512_n.jpg)
(http://i957.photobucket.com/albums/ae59/CheneySachs/Barber%202010/74537_1581251205558_1064019390_31409848_8131061_n.jpg)
(http://i957.photobucket.com/albums/ae59/CheneySachs/Barber%202010/76064_1581251325561_1064019390_31409849_34984_n.jpg)
(http://i957.photobucket.com/albums/ae59/CheneySachs/Barber%202010/73026_1581251485565_1064019390_31409850_6215615_n.jpg)
(http://i957.photobucket.com/albums/ae59/CheneySachs/Barber%202010/150071_1581251565567_1064019390_31409851_2242553_n.jpg)
1972 Cheney Sachs
1972 Suzuki GT380
1972/73 Cheney Sachs Project
1973 Triumph TR5MX
1973 Penton Jackpiner Project
1974 Penton Berkshire
1974 Honda MT125
Yes Dale, that is the conclusion. I made that pass on the second to last lap, and your sequence is the last corner last lap. In the little straight before that lefthander at the finish I could hear him, and when I shut off for that corner I heard him in the gas WAAAAAY longer than me. When I heard that I knew he would never make that left, so I did not turn in. It was a smart move because he would have T-boned me if I had turned in like normal. It was a kamikaze move on his part, but I guess he was a little upset with me, which I dont know why, I didnt go wide and push him out, he cut down on me. Now, I did not back off or give him any room which caused us to bang bars, but its not my responsibility to back off and give him room if I have the inside.:D
Brian
You know the old MX saying, "There is one rule in motocross, and everybody forgot it.":D
Once the gate drops or the band snaps it's MX, it's war, it's a ground possesion game. No blood no foul. Bars were meant to be banged. That is war in the trenches hand to hand. I'm ready, put me in coach.
Larry P
Brian, it looks like you had a little advantage in the horsepwer to weight ratio???
But when it comes to bumping, sometimes the greater the weight wins, I should know, but I am now down 37 pounds.
Hoping for greater speed and less bumping.
Looks like he was trying pull off a Communist "Block" ;)
Pete Petrick
175 Jackpiner
Slow but Good
Banging bars, locking horns, I have the sudden urg to go hunting for some reason. Without a doubt a "somebody's going to crash" move on his part (in this case him). Done in full view of Dave Lamberth with the checkered flag in hand....
1972 Cheney Sachs
1972 Suzuki GT380
1972/73 Cheney Sachs Project
1973 Triumph TR5MX
1973 Penton Jackpiner Project
1974 Penton Berkshire
1974 Honda MT125
Nice job and great pictures. Thanks Brian for all the hard work you do to make Penton bikes stand out and thanks for Ernie for never giving up on the Sachs power. Makes me feel like I am back in 1974.
Ron Carbaugh
More from Luana and Brian's FB page. First moto 100cc class :D
(http://i957.photobucket.com/albums/ae59/CheneySachs/Barber%202010/75375_1581234125131_1064019390_31409762_2277598_n.jpg)
(http://i957.photobucket.com/albums/ae59/CheneySachs/Barber%202010/73597_1581234245134_1064019390_31409763_7760524_n.jpg)
(http://i957.photobucket.com/albums/ae59/CheneySachs/Barber%202010/73481_1581234365137_1064019390_31409764_4315963_n.jpg)
1972 Cheney Sachs
1972 Suzuki GT380
1972/73 Cheney Sachs Project
1973 Triumph TR5MX
1973 Penton Jackpiner Project
1974 Penton Berkshire
1974 Honda MT125
Larry, I agree, its war when the gate/band drops but not everyone sees it that way. I pride myself on being a "clean" rider, and it is a rare day indeed when you see me touch another rider while making a pass, but at the same time I'm NOT going to back off either.
Lloyd, I weigh a good 40-50lbs less than the CZ rider, and my 100 is very fast for a 100 so the power/weight was definitely in my favor.
Dale, on any other bike I get terrible starts, but for some reason on my 100 I always get good starts. I have it geared so I can start in 2nd which lets me avoid the 1-2 shift, so thats a big help.
Brian
Let's just review that you are racing a 100 against a 125 CZ right? So you have given him back the weight advantage. Great job Brian.
Ron Carbaugh
The CZ rider is Bruce Rounsaville. He has some of the best CZ in the country.
Thank you for sharing the great photos of the CZ and Penton. I enjoy viewing the not-so-common motorcycles on the off-road. I think the variety of motorcycles on the starting line is what makes it more of a race. Sort of a manufacturer vs manufacturer race as well as a man vs man. joe
Brian, someone once told me everything being equal, it takes 1hp to counteract every 7-8 pounds in weight a rider puts on. I know we have some engineers out there, is there any truth to this? How much horsepower does it take to counteract added riding weight?
BTW, great pictures.
Lloyd.
This is an interesting analytical question. Technically, one horsepower is equal to 550 foot pounds per second, or the power required to raise 550 pounds one foot in one second. If you run the numbers, 19 HP would raise a 400 pound bike/rider combination at a rate of 26 ft/sec. If the weight were increased by 10 lbs, it would take 19.38 HP (less than one additional HP).
Also, the force,or torque, required to accelerate the bike/rider mass is proportional to the weight and acceleration (hole shot). A 10 lb weight increase would take about 2.5% more horsepower or about 19.48 HP for the same acceleration as the 19 HP example.
Obviously this is all theoretical and there are real world forces that must also be considered. Also, we all know that it is easier to drop the weight than to coax extra horsepower out of a two stroke-cheaper too.
One of the more obvious questions here is how was the 19 HP determined. There are all kinds of HP numbers quoted for different engines with no indication as to how the numbers were generated. Were they calculated, guessed at by the seat-of-the-pants method, tested on a dyno at the engine output (Ron's question), or tested at the rear wheel. All will give different answers.
Nelson Lingle
73 Jackpiner
74 Jackpiner
71 DKW 125
Nelson,
I am glad you worked for our side on the Space Program.
Ron Carbaugh
Nelson, if I understand correctly, if I rode a larger displacement bike that lets say put out 40hp, then to compensate for a 10 pound heavier rider you would need 2.5% of 40hp, or 1 horsepower more to be equal, give-or-take. So for 20 pound 2hp, 30 pounds you would need 3hp, etc? I know there are many variables, traction, coefficient of drag, wind velocity, drafting, etc, but for us lay people, a close ballpack figure is about 1/2hp for every 10 pounds on a 20hp motor, and 1hp for every 10 pounds on a 40hp motor. Did I do the math correctly, or am I just barking up the wrong tree?
Lloyd,
Your scenario would be correct if you assume that the mass (weight) of the 40 HP bike/rider is the same as the 19 HP combination, and the acceleration would be more than twice as great.
Nelson Lingle
73 Jackpiner
74 Jackpiner
71 DKW 125
But I am curious how fast the blood loss is of a frog on a train travelling to Chicago at 42.7 mph with Red Cross blood donations at an all-time low.:D
Holy Cow! Just ride it. If it goes too slow hold it open more. If it is still too slow get out the dremel. If it is still too slow do the push the plate away exercise.
Most races are lost from not cranking the throttle enough than pounds even on a 100. If you are WFO all the time or on the brakes hard when not and still losing then the academics of power to weight ratio plays out. Until then GAS IT there are no magic fixes.
Larry P
I don't care what anyone says, that is just about the saddest excuse for a motocross track I've ever seen. [xx(][:0][B)][8D]:D
Dont get me started on the horrible Barber "motocross" track. Its not a track, its a dirt parking lot. The first two years we were over on the other side of the facility in a grass parking lot which actually was not that bad, the first year we moved to the current location (08) they promised "next year we will have the 'worlds best vintage track'". Its an absolute joke, and it proves Barber only cares about the road racing to put us on this ridiculous track. Every year I swear to Ernie that I wont come back again, but for some reason I always end up going.
Brian
The track does look really flat but it might just work well for the small bikes,, like my buddy would say, thats a 125 track...It would be more about the rider than the bike. good job brian. I am not one for banging bars either but you never know what can happen. A few years ago I was racing on a track that had these ponds around the outside of the track, they were there to allow water to run off the track, It worked good too but coming out of the second corner we were all bunch up and I headed for a hole in the crowd the thing is another rider thought the same thing and we ended up banging bars,, We are good friends now and to this day he kids me about being the only rider who ever put him into the pond... all in good humor....too this day though he will also tell you that he would rather race with me than anyone else and we often pit and race together... good times and that is what this is all about.
Thom Green,Still crazy after all these years!
76' 250 MC5 (orginal owner)74'
250 hare scrambler (project bike)
Equal riders on equal bikes --- big boy looses every time[V].
Big boys on small bikes that pull hole shots and win wire-to-wire are either riding a hand grenade, cheating or really exceptional riders ... sometimes all of the above:D
The 100cc classes were pretty puny this year. I hope the 100cc (120cc 4stk) class gets reinvigorated -- I'm anxious to see more of those hot California Hondas[:p]. And, of course, we need more Rats. Do the Hodaka's only show up for the ISDT-RR?;) Where have all the Berkshire races gone?
Brian Kirby will tell you all (and his results prove it), his SoCal Berkshire is the best 100cc machine on the AHRMA circuit -VMX,CC, ISDT. It's fast, it handles, it's reliable, it s.i.ts (h f). Well, a gear is skipped every now and then. Nothing's perfect. It helps that he is a flyweight of only 140 and not jumbo 200 lb.[8D]
Ernie P.
Chattanooga, TN
Best 100 on the circuit? Hope to drag race it on starts at AHRMA MX next season then with the one in my garage and my fat self.[8D]
Larry P
So you have a rocketship 100? Better add boosters if you want to hang with SoCal Berkshire.
Ernie P.
Chattanooga, TN
My bike is surely not the fastest nor the most peak HP of any Sachs 100, but the thing that makes it so fast in CC and over a lap of MX is it has a very wide and usable spread of power from low-mid and up. It does not wail on the top like I expected, but its actually pretty user friendly and flexible.
Brian
I've seen Larrys "weapon of class Destruction"! It practically rolled its' self up onto the trailer...and it didn't even have an engine at the time! Mike
Michael R. Winter
I enjoy rebuilding and appreciating Pentons!
1974 250 HS Pentons-1980 KTM 175-400'S
75 Can Am 175 TNT & 77 250 Black Widow
1976-78 RM & 77-79 PE Suzuki's
74 CR250M 07 CR125R & CR150R
The 100 Sachs engine has different engine characteristics due to it's design. As a stock engine, it has a 54mm stroke, and a 48mm bore. Engines with small bores and a longer stroke have a different power band than those with a different combination. Many two strokes tend to have a bore and a stroke which are very close ie. 54mm bore x 54mm stroke. I think this is called "square". This type of engine tends to rev a bit quicker than those with longer strokes. I once rode a Suzuki RM which had a larger bore than it's stroke. It was the quickest revving bike I had ever ridden. Joe