HIGH GEARING FOR BERKSHIRE BRAIN PICKER

[Larry Perkins]

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

[Daniel P. McEntee]

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

[firstturn]

More explanation? For racing or trailriding?

Ron Carbaugh

[Mike Rosso]

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

[Larry Perkins]

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

[firstturn]

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

[firstturn]

Larry is this under SCTA?  I didn't see the class?


Ron Carbaugh

[Larry Perkins]

Ron, no AMA Bonneville Record Speedweek.  You can find rules, classes, and records in the AMA Bonneville Supplemental Rulebook.

Larry P

[Paul Danik]

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

[Daniel P. McEntee]

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

[Larry Perkins]

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

[Paul Danik]

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

[Larry Perkins]

Thank you Paul!

Larry P

[Carl Hill]

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.

[Larry Perkins]

Thanks Carl.  Great ideas!  Appreciate any and all hints and advice!

Larry P