Introduce Yourself

[Speed Limit 1000]

Mike, Stainless and I both restored antique aircraft for the Department of Defense. Mostly B52s

[wobblywalrus]

It was 1973 in Oakland, California, and I was an apprentice machinist.  Our job shop made some B-52 parts the DoD could not get.  They gave me the plan for the one operation I did.  It was drilling a hole, as best as I can remember.  They would not give us the drawing showing the complete part or tell us what it was.  One machinist made a good guess that is was the frame for a bombsight. 

[Panzer944]

Hello all,

I've just joined the forum and I am looking to compete in the M-VG-350 or MPS-VG-350 bike classes with a trusty (sorry that should have read rusty) BSA 350cc Rigid Framed B31 ... (if I can find a high compression piston!). 

I am based in Buckingham, England (UK) and have raced 'bikes, cars and gearbox karts in my youth (first 50 years of my life) and now I am intrigued about extracting power for straight line speed ... so, I have a dream to take to the salt (and the sand over here in Wales at Pendine Sands) in something that I can assemble from vintage BSA stuff lying around in the garage from previous projects. 

I have a question about the 2019 rule book if I may ... it says I am allowed up to +0.50" overbore in the VG class - but then states ?... only if the OEM bore diameter is within 0.050inch (1.27mm) of maximum class displacement and will be discounted when the bore size is measured.?   

Standard bore and stroke for this bike is 71mm x 88mm respectively with a standard capacity of 348cc.  My schoolboy hard sums tells me that a 0.020" overbore will put me at 353cc - as this exceeds the 350cc limit, I am guessing it means that I will have to compete in the 500cc class?

I can get high comp ZB32 Gold Star pistons at +.020" and +0.040" but not at STD bore ... this has resulted in much gnashing of teeth etc. 

So, if anyone can help in interpreting the rules with regard to overbore or in procuring a STD bore High Compression piston ... then I'll be mighty happy! 

Thanks all, Rob

[Stainless1]

That rule means that your 77mm bore can be increased by .050 because it puts you over the class limit.
If your motor was a 300cc and .050 made it 349cc then that is also legal.. but if you bored it another .010 and made it 310cc you be be in 500.
The rule means you can clean up the stock bore by .050 in vintage even if you go over the limit... but only if that .050 puts you over....  if the .050 does not put you over it is also legal to bore whatever you want, but your limit is 350cc.  So you can't bore to 350cc and then go .050 over. 
Hopefully I explained that so both of us understand it   

[Panzer944]

Thanks Stainless1 ...

I think I have it - your phrase of "... you can clean up the stock bore by 0.050" in vintage even if you go over the limit" seems to hit the nail on the head.

So, for the avoidance of doubt in my tiny head, my bike's capacity at standard bore is 348cc - therefore, according to the regs, I am 'allowed' an overbore of up to 0.050" even if it puts my capacity above 350cc as a consequence - but, for example, if I had gone for a 0.060" overbore and it put me over 350cc then I would have to compete in the 500cc class?

I think I can start spending money now! 

[Stainless1]

Be sure you can provide documentation of your vintage bike's bore and stroke.  And remember it is up to .050.... does not have to be at the limit.... you don't want to be measured over the limit.

[Panzer944]

Thanks Stainless1,

I will probably be happy at +.020" or +0.040" at worst. So, even though +.020" makes the actual/real capacity 353cc ... it will still be eligible (as I understand).

As you suggest, I suppose there is method in the madness of not going past 0.040" so as not to get overly close to the limit and thereby risk exclusion?

Thanks again 

[Stainless1]

Probably easier to get .5mm and 1mm over pistons than 1.2 over.... 
Good luck with your project
See ya on the salt 

[comet]

Welcome to the pool Panzer, jump in and enjoy the fun.
What event are you thinking of running at?
I see you are not a million miles from me, I am down in Kent.

[wobblywalrus]

Panzer, welcome to the forum.  Statistically, the weather is usually good for the BMST bike event and the USFRA event that immediately follows it, based on my experience.  Entering the BMST with a backup plan of a last minute entry to the USFRA event if the BMST is wet, would be what I would do if traveling from the UK.

[Panzer944]

Thanks Comet - I'm looking to be ready in March/April for a possible shakedown at a nearby airfield (Turweston - halfway between home and Brackley, Northants); hopefully, then going to the sand in Wales (Speed Week, Pendine Sands) which should be around middle of May 2020.  I went to the Pendine Sands event this year (May 18/19) and it confirmed within me the desire to compete - there was a whole bunch of serious racers (Zef Eisenberg et al) and complete nutcases (100mph shed) ... but all had the same passion and zest for life!  Pendine are running another event in September (14/15) and I may try to get to that ... even though it's a 3 to 4hour drive for me (longer still for you!) it's worth it, just in terms of asking questions and preparing oneself and bike.

[Panzer944]

Thanks Wobbly Walrus - that's the sort of 'int' that I need to make sure I get the most out any visit State-side; I remember seeing a documentary about Bonneville Speed Week about 5 years ago and the most compelling phrase I recall from it was the lady (Bonneville's historian?) speaking to camera right at the end of the documentary saying, "This is where grown men [and women] come to seek relevance in their lives!" ... a fantastic quote as I sat there wondering what to do with my now spare Villiers 2-stroke race engines from my Karting days (210cc - apprx 35-40bhp - not bad for engines made in the late 1950s and I have plans for them too!) and the B31 Rigid that I am developing for the M-VG-350 or MPS-VG-350 classes.

Thanks all for the warm welcome and the help - much appreciated.

[wbnash]

I changed my email address and could not log on so re-registered.

I live in Tucson and am a longtime LSR fan.  I am part of the Steinegger & Eshenbaugh posse.

[manta22]

Hi Walter. I have not seen you at lunch lately.

Regards, Neil  Tucson, AZ

[danwal215]

My name is Dan Waldrop, I am a member of the Autopower/Bean Bandit team out of San Diego and a member of the San Diego Roadster Club.