m-vg motorcycle questions

[cammer113]

Ok so my new questions are as follows.

Only interior modifications from 1956 allowed. Can I use a nikasil cylinder liner? Titanium rods? ceramic bearings? Graphite coatings? Can I modify the ports and convert it to a reed valve setup? Mine was stock with a magneto but I wanted to use a later model magneto, is that ok? Can I get rid of my tomato can carb and use a late model Mikuni?

Can I make a custom cylinder head for my 2 stroke or do I have to use the factory head?

Can I use the front end, forks and wheel from a 1975 honda? Or does that need to be vintage components?

Is the wheel base extension limited to 10% more than factory or is that dependent on the displacement of the motor?

thanks

Kevin

[Nortonist 592]

Looking at a 2005 rule book and I don't think the vintage class has changed too much.  The engine description says you must use OEM crankcases and cylinders.  On four strokes you must use OEM head but it doesn't say you have to use OEM heads on a two stroke.  As far as innards go it doesn't say you can't port it or put in reed valves or change the carb.  On the frame front one of the rules says that original forks are optional and the (2005) rule on wheelbase says for motorcycles under 250cc the wheelbase limit is 60".  What the new rulebook says is anyones guess.  I guess we'll find out in a month or so.

[JackD]

The guess, wait, simplicity, and suitable participation by the entrants is a valid complaint that deserves more attention.
 

[Dean Los Angeles]

Don't confuse frame rules with engine rules. Production, Modified Production and Special Construction are the frame classes. There are no vintage rules here. You stated Modified Production, Vintage Gas.

The engine should represent 1950's technology, so I'm sure that mikuni carbs won't work, extra cylinder head bolts won't work, The stock head would have to do. If you want to make a custom head, move to Class G and have at it. Although the rules don't say OEM heads for a two stroke, I doubt if a water-cooled head would cut it. If you want to stick with VG, then you have to put up with restrictions. I doubt if a reed valve modification would be allowed on a piston port. All of this is very visible on the outside. On the inside I doubt if you have any restrictions.

DKA printed the rules sections, then went on to site production (7.J.1) rules for the vintage modified class. There is no cross. Vintage is more like Class G, unlimited, with the vintage restrictions. It definitely is an open class. I would ask for official written clarification before I put out money for a titanium rod.   

[Nortonist 592]

Are you running modified or production?  If it doesn't say its illegal does that make it legal?  Or vice versa.  A titanium rod would be legal in production (out of sight).  We need words of wisdom here.  But are there any wise ones?

[JackD]

You have to ask yourself when is the last time anybody in SCTA checked the alloy of a rod or crankshaft ?
 How about the quality of a bearing or the finish material on a cylinder ?
What about the fit of the valve or the profile of the cam ?
The rules could be made to read simpler and that would lead to less speculation, interpretation, and subsequent abuse.
More rules, poorly expressed are their own reward.

[DKA]

Jack is right. No one is checking the metallurgy of the engines.  When I referred to Production engine rules I was trying to illustrate that even in Production we can modify the inside to our heart's content.  In Modified engine classes it seems that we should be able to modify the exterior too, as long as it is something that would or could be accomplished in 1955.  I think for clarification you could  contact the motorcycle committee chairman, Russ O'Daly at techchairmc@scta-bni.org.  He should be able to help.  I was running Production Vintage and so I made sure everything was as original looking as possible and made a notebook with pictures to prove everything, but then was never questioned about anything at tech (except my lanyard kill switch).  They only checked bore and stroke after a record run.
This year I'm hoping to be nearly as fast as Nortonist.
David

[Seldom Seen Slim]

The complete 2007 rulebook is available online and in your bathroom (so to speak).  That is, all changes from '06 have been posted on the SCTA website for a month or two, and the rest of the rules (from the '06 book) still stand.

[Nortonist 592]

Hi Dave,  Once you get the bits in the attic of your BSA sorted you'll fly.  Good luck.  P.S. The Beeser looks very well on the SCTA site!!

[DKA]

Jon, are you going to have rulebooks in all the porta johns this year?  And how did you know I kept mine in the bathroom?

[cammer113]

My frame and engine are both dated 1955. Utilizing the factory cases and cylinder, no matter what you can do to the insides, are limitations that are fun to try to overcome. I push myself out of the technology envelope of 1956 when I put oil in the gearbox. Didn't think it would be illegal to use graphite coatings and other space age technology on the engine internals.

It is a two stroke, can I make my own cylinder head?

The carburetor is a big issue? Can I use a late model or does it need to be pre 1957 also?
I thought you could use any exhaust of carb you wanted.
Does the exhaust need to be forestry approved with a spark arrestor?

Thanks
Kevin

Jon, are you going to have rulebooks in all the porta johns this year?  And how did you know I kept mine in the bathroom?

[Seldom Seen Slim]

David, for a few years now I've been telling the story that racers should always get three copies of the rulebook:  One for the coffeetable, one for the workshop, and one for the back of the toilet.  I don't see any reason to change my story.

However -- SCTA did run out of rulebooks in '06, and perhaps the three books per racer requirement is what exhausted the supply.  Maybe I'll soft-pedal my suggestion.

As for books in the potties -- yeah, right.  Good idea -- but I'd first ask for donations from all of you to pay for the books, then see who'll donate the high-security system to keep the books from walking away, and then go on to see about getting each page plastic-laminated so the car guys don't use the bike pages for some purpose other than reference.  You know them car racers -- some of them think s*** about us bike riders, and this'd be their chance to really show us a thing or two. . .

[Speed Limit 1000]

SSS. I sure do not miss the Michigan winters, but I do miss the lakes and the trees, the summers were great. What happened to your photo? All it shows now is a red X.

[Seldom Seen Slim]

I wish I knew how I couldn't replace the photo.  I took out the old one -- me and Charles Ferge, the "real" Seldom Seen Slim, and tried to replace it with a more to-the-topic shot of me.  I haven't figured out how to get the new one in there.  If'n you know how -- tell me, tell me true.

As for lakes and trees -- we've got 'em, and the winters help keep the riff-raff under control and outa sight.

[Nortonist 592]

To come out of the potty and get back to the subject.  I can't see anywhere in the rules that says he can't make his own head or use a different carb or use reed valves.  Or for that matter using any "space age technology".