m-vg motorcycle questions

[cammer113]

I am new here so any help is very appreciated.
If I am in the modified vintage motorcycle class can I run a late model 1958 ignition system?
Am I only allowed to extend the wheelbase by 10%???
Can I add two cylinder head bolts? Or can I only run with the ones from the factory?? Six would be much better than the four from the factory.

[Nortonist 592]

Not having my rule book to hand I can take an educated (relatvely speaking) guess.   Yes on the ignition.  If the rule book say 10% then thats your limit.  And yes on the head bolts.  On the wheelbase issue I would refer to the current rule book which won't be available until around March.  I don't think the wheelbase limits were changed for this year.  If anyone out there has a 2006 rule book maybe they can let you know what it says.











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[cammer113]

I read online in the Australian rulebook that it was 10%

Is that thing pretty accurate? Because for a newbie like me, that book and offhand quotes from friends are all I have right now. One reason I like this forum so much. Maybe I should get some new friends. Cannot wait to recieve my rulebook!!! But yes, I have already started construction!!!


quote author=Nortonist 592 link=topic=2062.msg23089#msg23089 date=1169853257]
Not having my rule book to hand I can take an educated (relatvely speaking) guess.   Yes on the ignition.  If the rule book say 10% then thats your limit.  And yes on the head bolts.  On the wheelbase issue I would refer to the current rule book which won't be available until around March.  I don't think the wheelbase limits were changed for this year.  If anyone out there has a 2006 rule book maybe they can let you know what it says.











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[Nortonist 592]

I sent my 2006 rule book to LJB.  Maybe if you PM him he can quote the wheelbase rule.  2005 rule stated that a max wheelbase of 60" for under 250cc.  But I believe that rule has been changed.  Just how long a wheelbase are you planning?

[cammer113]

My factory wheelbase is 51.5"  With 10% I would max out at 56.6" In an effort to lower the bike, which is a rigid rear end. I figured I would max out on the wheelbase rule in the front end. It is a 125cc. So if the rule is 60" That would give me quite a bit more.

With the rule for modified being 50% original tubing in front of the swingarm. And where does that apply to a factory rigid frame?  What can I do to lower the rear of the bike? Smaller wheels and raking the front end?

Factory ground clearance is 8"

I sent my 2006 rule book to LJB.  Maybe if you PM him he can quote the wheelbase rule.  2005 rule stated that a max wheelbase of 60" for under 250cc.  But I believe that rule has been changed.  Just how long a wheelbase are you planning?

[Hans Blom]

Depending on how much you want to cut up your frame, other than cutting the triangulated rigid section and repositioning, you could make some pretty simple weld on(or bolt on if designed right) brackets that attach to your current axle plates in the rear that would raise the axle locatio 4 inches or so...depending on your fron end final height of course. The plates could be made with a 'keyway' to slide into the original axle adjustment slots to locate the plate and make it ridgid. Your plate could have two attachment bolts that would be at either end of the original axle slot to further prevent movement.  I wouldn't try roadracing with this setup, but in thsi aplication and speed you can probably get by if designed correctly. If you are using a different rear wheel(reccomended) the inside distance between your rear axle plates would not matter too much anyway. I would start by getting some dimensions of a few front forks that you might use/modify. with frame set up on your table and approximate length of forks you can see where you frame ends up. The bonus of lowering the rear is that the angle of your rake will increase giving you more high speed stability and less twichy....not usually a concern with Hummers but...

[tomsmith]

According to the 2006 rule book:

Engines must utilize OEM crankcase, OEM cylinders on flatheads and two strokes and OEM heads on OHV engines.  Above components made after 1955 and exact reproductions may be considered legal in Vintage classes if they offer no competitive advantage.  Pre-installation by the contest board is required.  It is the entrants responsibility to provide documentation and samples. 

I don't see anywhere that the crankcase and cylinders can be modified.  For example, it looks like you can't clean up the transfer ports, because the cylinder would then no longer be OEM.  I have a Puckett cylinder on my Hummer.  It has aluminum fins heat-shrunk over the top half of an OEM cylinder.  I also have the transfer ports opened up and a new inlet pipe welded on (I want to change to a Mikuni round slide instead of the current Servi-Car Linkert),  The Puckett cylinder was made in maybe 1955 but I don't remember.  How legal is this?  How can I find documentation on the Puckett cylinder?  OBrien is dead, Puckett HD is long gone and there was never any sales documentation as far as I know.  I also have a swing-arm frame modification I bought around 1955..

[JackD]

Too many unenforceable rules leaves the door open for too many undisciplined friends.

[tomsmith]

Me? Undisclipined? How did you find out about me?  I used to do computer contracts as part of my job as a data center manager, so I know about weasel words and escape clauses.  By the way, my cases are polished (underneath a lot of grunge), so it looks like they are no longer OEM (not counting the stuffer plate with the grooves machined inside the cases to hold it).  My hubs, brakes, foot pegs, front forks and front half of the frame are stock OEM, but I can't think of any thing else that's OEM.  I'm getting a custom spool front hub, so it won't be OEM either.  The connecting rod has an extra big end roller bearing or so which was done by Rich Budelier HD after I broke the crank pin at Catalina in 56. The clutch is Barnett, it has a later, stronger, first gear and an aftermarket magneto (installed in 1955). I finally found rims and tires in Holland.  They are 2.00x18 and 2.25x18 50cc road racing (no speed rating so I think they are legal) Bridgestones but I don't know if I can afford them.  Next is taking my motor apart and measuring the bearings for the ceramic replacements.  While it is apart, I'll get the piston and maybe tranny parts plated with magic drag and heat reduction stuff.  Otherwise my Hummer is stock, except for the alloy seat and bicycle handlebars and maybe some more stuff.  I just hope the comma and parenthesis police lay off me.

[Speed Limit 1000]

Slim is out of town for the weekend, so you are safe till next week.

[JackD]

RELAX
Your time frame seems to indicate you may be rushing things a bit.

[tomsmith]

Jack is right, my hummer is very likely to NOT make it this year.  It will take me a month or two just to clean off the 40 years of accumulated and baked on sludge.  And I have to try to remember how it comes apart and goes back together.  I am negotiating for a stock (OEM!! Really!!) bare frame so I can just move my motor and forks over and leave the rest alone.  This will save an immense amount of work.  I still have the original tires installed that I put on it in 1951.  They need air.

[JackD]

The air today is a bit thicker and will also require a bit of jetting to account for the solids.
Fresh tires seem to be in the wind and should beat the rest of the schedule.
Gilmore has an oil and dirt kit for suitable restoration that is important to the authentic look you are working for.
Most of the wrinkles on the rider can be covered with suitable period clothing that includes the red printed bandanna across the face.
It will be the look in the eyes that is most telling and might still scare the kids.
Remember to lift the bandanna a bit before you spit and a chaw would add to the visual impact and the flavor.
Teeth are not important because many early riders didnt have any in the front anyway.
All of this was shared with me on the knee of Earl Flanders.

[Seldom Seen Slim]

We WERE out of town, but now we're back.  Tom, you get a bronze star -- punctuation was pretty good, and you had the courtesy to acknowledge that you were trying.

Two points, plus an attaboy.  Maybe a drink if you stop by the pit, too.

[DKA]

Hey guys, I'll add my 2 cent opinion here.  I've been reading the rule book for a few years now and this is my view of the rules.  ( I have not checked with the motorcycle rule review committee to see if I am correct on this)

7.J.5 Class F: Unlimited in design...

7.J.6 Class G: Same as Class F...

7.J.10 Class VG and VF: Same as class G or F, except that the class is limited to motorcycle engines produced prior to 1956. For reasons of historical authenticity, vintage engines modifications are restricted to older technology levels, so far as is practical.  Accordingly, in classes VF, VG, VBF, and VBG, newer technologies, such as EFI or electronic reactive ignition systems, are not in keeping with the spirit of the Vintage Classes and are not allowed.  Computers are allowed for data collection purposes only.
Engines must utilize O.E.M. crankcase, O.E.M. cylinders on flatheads and two strokes and O.E.M. heads on O.V.H. engines.  Above components made after 1955 and exact reproductions may be considered legal in Vintage classes if they offer no competitive advantage...

My take on this is that, in Modified classes, as long as you start with OEM components, or exact reproductions of them, you can modify them anyway you want as long as you stick to older technologies.  7.J.1 states that Production engines and bikes only have to have "stock external appearance".  The interior can be anything that could be done in 1955.  Modified classes can run bigger carbs and different ignitions, as long as they were available in 1955.  The real spirit of land speed racing is taking OEM vehicles and modifying them to go a lot faster than the factory set them up to run. 

Remember to be careful to keep the bore within class limits and that if you are using tubes in your tires you have to run a higher speed rating than your bike will go.(7.B.

See you on the salt.
David