I hear that the Zink Ranch '04 ISDT-RR had two track terrain tests that had the bikes pinned in top gear. In case they have something like that this year, does anyone know what the top speed of a 6A/6B is with the standard gearing? Anybody know off hand how much gearing a 100 can pull on flat ground? Any of you real ISDT Vets (Dane in particular) have any advice on how to set a Berkshire for high speed riding?
For another brand bike I have a factory manual that actually lists with a matrix the speed in each gear with a given set of c/s and rear sprockets, is there anything out there like that for the Sachs?
The couple of times I've ridden my 100 hard I think I barely ever got into 5th gear on a motocross track and for sure not 6th with 12/57 gearing. I've got a 13T and a 12T c/s sprocket, I've got the 12T on there now for MX so I can start in 2nd gear, but it sounds like I'll want at least the 13T for Zink Ranch. Will a 100 pull 14/57?
Brian
'73 Berkshire Team d-Con
//www.d-conproducts.com America's #1 Rodent Control Brand
Brian:
I have found this link to be of interest for calculating speed by various gear ratios.
http://www.tonup-nc.com/tonupracing/images/racers/Lightning/Gearratiocalculato.xls
I don't use it myself as I limit my speed to 2000 rpm and 20 mph to stay within my riding ability.
Bill
Brian,
I will try to give you some help with your gearing question for your 100, but most of my experience is with 125cc machines. The gearing that I will discuss is totally wrong for MX. There are a lot of factors involved, not just gearing so please bear with me.
The trick to running fast on a small bore is to carry as much momentum with you as possible at all times, reason being you don't really have the power to slow down and speed up at will. Your momentum will carry you up and over, or through nasty stuff, but you need to be carrying speed/momentum.
The 125cc machines came with 14 - 60 gearing, in tight woods and in rough going it is quite hard to get a real head of steam up in the lower gears with that gearing. I run 14 - 57 and sometimes 14 - 54, with that gearing you have a wider range of ground speed in any one of your gears, within the usable power band of the engine. This allows you to hit a lot of nasty stuff in the lower 3 gears with a lot of momentum, and with a decent amount of RPM range to carry you through the tough stuff without having to constantly shift and possibly brake the tire loose.
The part about braking the tire loose is very important, and that leads to another area, having your bike jetted correctly. If you run the gearing that I have suggested and your carb isn't jetted properly it will not work. You need to have what I refer to as crisp jetting in the low to mid range so that you can allow the engine to pull cleanly through some nasty stuff, without loading up. If you are letting the engine pull, it is important to not just hold the throttle wide open, try to hold the slide only open as far as needed for the RPM that the engine is turning, unless you are in a situation where the engine can gain RPM, but don't flog the engine if possible.
It is a real blast to run the kind of gearing that I have mentioned, you really get to work the engine and feel it pull. It is fun to carry a lot of speed in the lower gears over or through some really nasty stuff and pass guys who have lots of power on bigger bikes, but they always rely on the power and sometimes they can't get the power to the ground. Running that little 100 with some good woods gearing and hitting the tough stuff with plenty of speed is an E ticket ride, that is why small bore riders smile more often:D
Will a 100 pull 14/57 gearing, if it was me I would try it, but you might also want to try the 13/57 and compare. I can imagine a few times where you might have to clutch it, if you get totally stopped in a bad spot or get hung up on a bad hill, but most times it ought to give you a good ride. Sometimes if I get messed up on a bad hill,instead of fighting the hill, I will just return to the bottom, select a good line and get a head of steam up and ride it up and over, gotta save your energy.
If Dane chimes in and says different I would go with his thoughts as he has a lot of experience on the 100. You will need to really turn that Sachs engine to use that gearing and get the most from it, just take your time when you shift, hit the nasty stuff with some RPMs, not lugging the bike. Hope this helps, sorry it isn't a short answer but there are a lot of factors involved.
Paul
Paul, I am certainly no expert at such things but I was wondering if size and weight of rider would effect the gearing....
Thom Green,Still crazy after all these years!
76' 250 MC5 (orginal owner)74'
250 hare scrambler (project bike)
72'sixday (project bike)
Thank you Paul, it helps a lot getting guidance from someone who has real experience. I've always been a small bore rider, so I know exactly what you mean about carrying momentum. I have always said that if you can ride a small bore bike fast, you can ride anything fast. They force you to be efficient in everything you do from line choice, to shifting, to knowing when to cut your losses and go back to the bottom of the hill for a fresh try.
I think I will order a 14T c/s sprocket and try it before Tulsa, the bike pulls 13/57 just fine in off road conditions. The only reason I have 12/57 on there right now is for MX I want to be able to start in 2nd without having to punish the clutch too much. A high top speed could be a big advantage in the 100 class at Zink if its got open tests like I hear it had in '04.
Bill,
That is a really neat program, it could be handy for all kinds of things.
Brian
'73 Berkshire Team d-Con
//www.d-conproducts.com America's #1 Rodent Control Brand
Thom, I only weigh 140lbs soaking wet so I'm just about the ideal size for a 100/125.
Brian
'73 Berkshire Team d-Con
//www.d-conproducts.com America's #1 Rodent Control Brand
Paul,
I had very good luck with the 13 / 56 gearing and a 350x18 rear tire on my 100. I am not in your or Danes class of rider but that setup worked well with a stock 6/A 100 for me. The only place it gave me trouble was at the first big ride i ever entered. That was in 72. It was the 2 Day qualifier in Va and NC?. Any way I leaned the bike out for altitude and had a heck of a time with the Mountains . 5 plugs fouled in the first 30 miles
and i was done [:I].
That was before John P did the article on jetting and I learned that a lean mix can make you think your rich and drive you nuts in the wrong direction.
I hope Dane chimes in on this. His experience with the 100 would be worth its weight in Gold.
John D.
I have not ridden a Sachs off road since 1974, so I have no idea of what sort of gearing that I was using. However, I can comment on the actual use of the gearing.
I would set the gearing, so I never had to use 1st gear other than starting from not moving. I would do the clutch slip, if I needed to keep the bike going while in 2nd gear.
Since I didn't do that much motocross racing, I didn't get used to doing of the gate (rubber band?) in second gear. However if you are trying to do that, then you maybe you need to have a higher gear ratio.
The last thing I can comment on, would be in regards to the chain use. I would normally use the largest sprockets, because it will help keep the chain in better shape than using small sprockets.
That's all I can comment on so I hope it helps the subject.
Dane
Dane ,
Thank you.
Brian. you may want to put a chain slider on the swing arm also. We made one up a while back out of 1/4 inch Teflon sheet.
(http://farm3.static.flickr.com/2230/1805532367_3059036a24.jpg)
It will help the chain and swing arm out with a 13T front.
14/60 will give you almost a 13 / 57 gearing per Danes advise on bigger is better.
John D.
Thanks to everyone that added some wisdom, this has been a lot of help. With 13/57 the bike rode like Dane described, I could use 2nd for anything except getting going from a complete stop. I'll still get a 14T and swap it on at lunch on day one if I feel 13/57 is too short. Then I can also swap on a 12 for the grass track, it only takes 5min to swap a c/s sprocket.
Brian
'73 Berkshire Team d-Con
//www.d-conproducts.com America's #1 Rodent Control Brand
Brian, How fast (top end) do you want to go? [:p] Let's do some quess-timating. Suppose a good-running 125 with standard 54/14 final gearing will do an honest 80MPH. Here's what you will get with different sprocket ratios.
54/14 = 80 (baseline)
57/14 = 76
54/13 = 74
60/14 = 72
57/13 = 70
54/12 = 69
60/13 = 67
57/12 = 65
60/12 = 62
Now, let's acknowledge that the SoCal Berkie runs very strong:D. But, will it be able to pull this tall gearing (57/14)? What do you gain (or loose) on the terrain test? Let's say that the test is open and you get to run top gear, flat out, for 1 mile. With everything else being the same, you will be 8 seconds quicker (76 vs 65). But, this is only true if you can sustain maximum RPM. Any difficulty such as a slight incline, sand, tall grass, change of direction ... all put additional load on the engine which reduces any advantage and may actually be a disadvantage:(.
Ernie P.
Chattanooga, TN
I want to go as fast as it will go. I guess the real question should be, does anybody know what the top speed is on a Super Rodent?:D
I do know what riding on a soft sandy dirt road the SoCal Berkshire easily topped out 13/57, so I think 14/57 should be do-able. My concern is I might make some of the gaps from gear to gear too wide even if it will pull 6th.
Brian
'73 Berkshire Team d-Con
//www.d-conproducts.com America's #1 Rodent Control Brand
Brian.
I think the 13/57 should be a good compromise . I dont think there will be any special tests that will give you a straight long enough to top out in 6th. In all the ones we have ridden , except for the acceleration and braking the special test's are technical, 4th gear tops maybe 5th in the grass track . The special tests will be big deals. If this years RR is laid out like the others, the speed average between checks is low. Thats to give the riders of the 50's and 60's bikes an opportunity to have fun and compete also.
Remember , its 2 days, all special tests completed and stay with in the hour to finish for a medal. Dont break the bike and dont break your body chuckle chuckle!!!!!
Its a different way of thinking. Not the same as CC or MX.
Dane and Pauls advise is the same. Have 2-5th gear where they work the best and your good to go.
:)
John wish i could be their D.
Don't have any data on Super rodents but the iron barrel 90 cc pre-Rodent top speed was 104 MPH
(http://farm4.static.flickr.com/3023/2659515333_42b362da98_o.jpg)
Wont have any new #'s on the Super Rodent till alter this fall.
One ran on the Salt this year as a first try at a land speed record.
(http://farm4.static.flickr.com/3205/2860692189_b814f1decf_o.jpg)
Rodents don't ever stop trying it seems Brian [8D]
John D.
That bike looks like it would be less than ideal in the woods John. :D
Brian
'73 Berkshire Team d-Con
//www.d-conproducts.com America's #1 Rodent Control Brand
Quotequote:Originally posted by brian kirby
I want to go as fast as it will go. I guess the real question should be, does anybody know what the top speed is on a Super Rodent?:D
Brian
'73 Berkshire Team d-Con
//www.d-conproducts.com America's #1 Rodent Control Brand
Top speed of a Hodaka 100B+ is 50mph with trail gearing. A Super Rat will probably do 55mph because of a bit more RPM.
My Zundapp GS125 (5spd gearbox) tops at 55mph. My Combat Wombat tops out about 55mph. My Hercules K100GS has 13/54 gearing and I think it tops out about 60-65mph. My Kawasaki KE100 / G5 tops out about 55-60mph depending on pipe used. My Honda SL100 tops out about 60mph. Now Mike Burgess used to have a Penton Berkshire 100 that would top 80mph. He outran Don Rosene down a dirt road and Don was on a 250 Hare Scrambler. I think Doug Wilford had a Six Day 125 that would top 90mph. Or so he says....LOL.
My feelings are that a 100 that will do 50-60mph is plenty. A 125 that does 55-70 is plenty.
IMO,
Dwight
Thanks Dwight, that is good info too. If your Herc K100GS has 13/54 then I feel better that 13/57 will not be that far off. I'll still bring a 12 and 14 with me just in case though.
Brian
'73 Berkshire Team d-Con
//www.d-conproducts.com America's #1 Rodent Control Brand
Brian,
there isn't a lot of drastic elevation changes in Tulsa at Zink Ranch. So taller gearing would certainly be easier to carry here than, say, Missouri in 06.
Quotequote:Originally posted by brian kirby
I hear that the Zink Ranch '04 ISDT-RR had two track terrain tests that had the bikes pinned in top gear. In case they have something like that this year, does anyone know what the top speed of a 6A/6B is with the standard gearing? Anybody know off hand how much gearing a 100 can pull on flat ground? Any of you real ISDT Vets (Dane in particular) have any advice on how to set a Berkshire for high speed riding?
For another brand bike I have a factory manual that actually lists with a matrix the speed in each gear with a given set of c/s and rear sprockets, is there anything out there like that for the Sachs?
The couple of times I've ridden my 100 hard I think I barely ever got into 5th gear on a motocross track and for sure not 6th with 12/57 gearing. I've got a 13T and a 12T c/s sprocket, I've got the 12T on there now for MX so I can start in 2nd gear, but it sounds like I'll want at least the 13T for Zink Ranch. Will a 100 pull 14/57?
Brian
'73 Berkshire Team d-Con
//www.d-conproducts.com America's #1 Rodent Control Brand
Larry Seale
I choose to ride...slower and slower all the time