Opinions and any experience sought. What is the absolute highest gearing a Berkshire can pull? Not being practical but pulling from a dead start what can it pull gear wise? Thanks for any help. Thinking of taking one to Bonneville next year.
Larry P
I would think Rick Bennett would have some insight into that given the epic journey he just went on with his. Finding a reliable and efficient gearing for road riding is a step in the right direction, I think.
Type at you later,
Dan McEntee
More explanation? For racing or trailriding?
Ron Carbaugh
Larry that may be something that you will need to actually test or experiment with IMO because the final or top two gears may throw all of the paper calculations right out the window. We had a KTM 6-speed wide ratio transmission once that the top two gears were "over driven" and with some high final gearing top gear was almost useless with a head wind and required frequent down shifting. It was not that much of a problem to get it going from a dead stop as the WR trans had the usual "walking" low first gear. Also I think at Bonneville you are allowed some assistance in getting the bike or vehicle going from a dead stop or maybe I'm mistaken, but it seems there are pushers and push or tow vehicles to help at the start?? There are ways to calculate top speed using max engine RPM, primary ratio, top gear(s) ratio and then final drive and wheel/tire size but it still comes down to the engine's ability (and rider/bike weight and aero resistance) to pull at the conditions. I still have a program (I think) from a friend KTM engineer that can calculate top speed using all of the info listed above and if I find it we'll need to get all of the above primary drive ratio, gear ratios, etc., and see but I'm still guessing finding a small local airport (Wakeman, OH airport comes to mind) and seeing if they would let you do a few test runs will be the final answer.....I'll even show up to push you off to get started :)
Mike
Brother Ron, talking about Bonneville.
Dan, will definitely pick Rick's brain!
Mike, thanks for all the suggestions. That program could prove to be a very helpful timesaver. I know that I will need to test, just don't to wear a motor out to get close. Would love any and all help especially brain power in trying to get a Penton in the record books. The class I will compete in is PPC, production frame, production motor, and classic which is 1981 and older. You have to start that class without assistance. You can not change much other than tires, bars, and gearing. If you can help with any thinking this out it would be welcome. I can work on the ratios you were talking about. My cell is 217-414-2295 and email is bajamonkeys
Larry P
Thanks Larry. Great post Mike. What is the current record, and since I haven't messed with Bonneville in a longtime, how are the records broken down by cc? One calculation I think would be needed is torque chart.
Ron Carbaugh
Larry is this under SCTA? I didn't see the class?
Ron Carbaugh
Ron, no AMA Bonneville Record Speedweek. You can find rules, classes, and records in the AMA Bonneville Supplemental Rulebook.
Larry P
Larry,
Not sure if you have mentioned it yet, what type of speed now holds the record for the class you will be in ? What is the distance for a run up before you get clocked? 14 x 54 is what I used in enduros back in the day and wide open on a highway it would be in the high 80s mph.
I asked the Penton road racer in another forum if he remembered what his gearing was and he said he ran as small a rear sprocket as he could till the hub got in the way and I think he mentioned a 15 on the front.
Yes, my gearing and his were both on 125s not 100s, but it is a starting point. Not sure if Rick Bennett would be willing to balance a crank for you, but it is nice to not have the engine working against itself.
Just my 2 cents...and possibly not worth even that :)
Best of luck,
Paul
If you do the Facebook thing, see if you can contact Rock Yamane on the VINDURO Facebook page. before Yahoo dropped the special interest groups, he kept us filled in on a friend of his that he was helping that set an 80cc record at Bonneville. I do not remember what brand of engine and motorcycle, but that is getting into the realm of the gearing that you would be looking for, I think. Can you fudge on the gear box ratios a bit by altering the primary gear ratios? I can't offer any other technical help, but going out to Bonnevile for the speed week is on my bucket list. I don't know much about them but love the look of the speed record cars. My cousin worked for Mickey Thompson back in the late 60's/early 70's and his speed record cars were awesome looking. It was a treat to see some of them old cars in "World's Fastest Indian."
Type at you Later,
Dan McEntee
Paul,
Thanks for the info! Your 2 cents has always been worth 1000s to me. Need to hit 55+ for a mile on the 100 class I want to runand I think I will do a 125 also as it will only take about 75 to hit in that class. Both seem doable. Biggest trick is like all two stroke hold it open a long time getting it to last. On the 100 I will need to keep stock exhaust. Any tricks to getting the best power from that? We always cut the shroud to get better power but it looks like in the 100 class I would run that will not be allowed. There is no sound restriction. Ideas? Thanks for any and all help!
Larry P
Larry,
I sort of expected a need for a higher top speed, but I have been around long enough to know that it is foolish to underestimate the difficulty of reaching what may look like an attainable goal at first glance.
Several thoughts,
I used to spend countless hours working on minor details, such as rolling resistance as it robs you of precious power of which those small displacement machines have none to spare. Make sure the machine rolls as free as possible with no tire rub, special attention to choice of chain, good wheel bearings and proper brake adjustment.
I am sure there are certain "tires of choice" that work well on the sand for a purpose such as yours.
As for a mile held wide open, have an expert machinist do your bore job and piston setup. With a top quality bore job and with a top quality piston a proper fit can be obtained, and maintained, even under difficult conditions.
Obviously proper jetting. I am partial to the Bing with a choke on the handlebar as you can use it to give a little extra enriching if you feel the need.
I would be careful not to gear it for 98 miles per hour if all you need is 65 or 70, but maybe having it pulling, accelerating, steady thru the timed section is better than topping out early and having it pegged for a long distance. Something to think about for sure, actually lots to think about :)
Paul
PS A local gentleman who is about 7 miles away built his own land speed record chasing car a few years back. The video in the link below is from a test run a few years ago, it takes about a minute for him to get going form the start of the video, but it is worth the wait. Unfortunately, during an attempt to break the record at the last Speed Week he had a presumed tire failure at over 400 MPH and destroyed the car and he is lucky to have survived. He is recovering and I do hope to stop in and shake his hand for giving it his all and fighting his way back when it is safe to do so. I know it isn't a cycle, but the run is pretty neat. Turn up your volume and go to full screen if possible.
https://www.facebook.com/CarbiniteLSR/videos/677376255697305/?v=677376255697305&external_log_id=402b082c-3686-4cea-9b15-bb96ee624c66&q=Carbinite%20LSR%20video
Thank you Paul!
Larry P
I used to race some mini moto and I recall a guy telling me ceramic wheel bearings offered less rolling resistance. Just a thought. Also I read an interview with Rob Muzzy where he talked about setting up road race engines a bit "loose" for less friction and running lighter oil so the gears would spin more free.
Thanks Carl. Great ideas! Appreciate any and all hints and advice!
Larry P
Larry
My 100 will easily reach the speeds you are looking at and more. My gearing is 15/57 but I would gear higher for your project. I had to carry camping gear and climb mountains. I would start at 15/54 and see what happens. Lower the bike to cut wind resistance. Use an 18" front wheel. It will really help. In a tuck, I was able to go much faster. Check out what speed bicyclists wear for suits and helmets. The motor will have no problem running at full revs for a mile. Mine did it for way longer. Port and balance carefully. Cooling the motor will add power. Are you allowed to spray water on it during the run? Use rear set foot pegs and controls. Are you allowed to use a faring?
Rick
How about an inter cooler? Pack ice around it. That would really help.
Rick
Rick,
On the 100 class I will run in the 21 has to be maintained and rear sets are not allowed. I could use the 32s and run them up to lower but rear shock length can not be changed. In the 125 class I will run I can change more so will follow your advice. I appreciate all your advice and help. Did you build and balance your own wheels and crank? Any other low friction good rolling tips?
Larry P
Find the lightest pilot possible and have them lose five pounds.
Note: Do not use small children, they will take off with your bike.
Pete Petrick
175 Jackpiner
Slow but Good
I am told that weight helps to a certain extent because of the surface. Experienced people say on a good day that the surface is like wet pavement as far as traction and that weight is a benefit to a certain degree.
Larry P
Larry
I do all my own work except cylinder boring. Wind resistance will be your biggest problem. Are you able to run wheel covers over the spokes? How about streamlining the fork and frame tubing? Is this allowed? Round tubing has lots of drag. Could you add trailing edges to any parts?
Rick
On the 100 Production frame Production engine so no streamlining. You can change tires, bars, and gearing and that is about it. I have a good amount of body position experience from bicycle time trials and with practice that should help. Will find out about leading edge but I suspect not.
Larry P
Larry Do you have access to a wheel Dyno ? The more testing you can do before you go the better off your record attempt will be. The Salt is known as the big white destroyer of Motors.[}:)]
Larry
If you want help, count me in.
Rick
Would welcome your expertise Rick! Would it be best to text, email,or call?
Larry P
Make sure to just wear a Speedo and do your best Superman impresion like Rollie Free in his 1948 record breaking run.
Timothy Walls
Larry,
I came across a few NOS 50 tooth Hi-Point rear sprockets today while looking for something else. I didn't hold one up to a hub to be perfectly sure, but it looks like an easy bolt on. If you have an interest I would be glad to donate one to the cause :D
Paul
Paul, that would be very welcomed. I am building a 100 and a 125. If you can spare 2 that would be sweet. Any help is appreciated. Thank you!
Larry P
Larry,
Two it is, no problem. I sent you an email....
Paul
I may be way off base...but I seem to recall reading some articles that smaller 2 stroke (and 4 stroke for that matter...) bikes did NOT pull the higher gearing anticipated at Bonneville due to the altitude as well as the rolling resistance of the salt. Perhaps try to make contact with some of those small bore racers to see what their experiences were like? Best wishes on a great Penton race project!!! Keep us posted!
Richard Colahan
1969 V1225
Upper Black Eddy PA
Richard, I am told by people who have been there that on a good day the surface is like wet pavement. The jetting will be a big consideration as I remember riding my 250 in Colorado and even with changed jetting it ran like a 125 as far as power went. Thanks for the input.
Larry P
Track elevation is 4212. I was over 6500 on my last ride. Some wheel slippage will have to be figured in to the gearing. Final adjustments will have to be done on the spot. Take every sprocket you can find.
nd allthe
And all the jets for the Bing Carb. A device that tells corrected altitude is a must as it changes often. Dont take any tow car or trailer to the Salt that you plan on keeping! Advice I got a long time ago who raced there for yrs. It proved to be really good advice![:p]
Gearing...jetting...good E-0 VP (or similar...) race gas...Larry, just curious, what tires will you run?
Richard Colahan
1969 V1225
Upper Black Eddy PA
You have to get gas from the promoter and your tank is sealed for a record to be valid. I am thinking Heindau tires as they seem to be the most used.
Larry P