[Alan Sheidler]

AFAIK, it has never been attempted or deemed necessary in SCCA solo competition for any regular class.  Having a single maker and size set as a spec tire has advantages in some racing series, based on advertising, regulatory needs, availability, etc.  Even in more tightly controlled Solo classes such as CM and FM, there has never been a specified tire, to my knowlege.  I do not know of anyone who competes in either of those classes who might be in favor of a spec tire.

Please don’t confuse the issue for an open class by comparing with FJ.  The rationale for MG Red as a specified tire has much more to do with safety and cornering capability than anything else, besides helping to limit costs for parents.  Remember also, that FJ is not a “normal” class, but a restricted one without a National Championship.

This request for a change in the rule is about opening up the possibility of actually using the already-legal 6″ rim, by adjusting the legislated size number to encompass those which are actually available.  Currently, the listed 7.1 number effectively legislates that 5″ diameter rims must be used.  Changing that to 8.0 means that the always-legal 6″ rims can also be used.

*****************************

Let me ask this of those who compete in, or who are interested in KM for SCCA Solo competition: Would it be a more appropriate request to delete tire size references altogether, and instead regulate only the rims?  For ALL other SCCA Solo classes, it is the RIM size which has specifications and limitations, not the tire.

From my research of a large number of wheel manufacturers, both specialty/aftermarket and OE suppliers, there is a fairly narrow range of Metric wheel sizes which are used on racing karts.  I investigated VanK, Douglas, Burris, DWT/MagTech, Oryx, in addition to Tony Kart (OTK), CRG, Birel, and others.  Wheel widths at the bead seats for fronts vary from 120 to 140 MM for fronts, and 180 to 214 MM for rears.  Most kart racers/autocrossers assume them to be 5″ for the fronts, and 7.75″ to 8″ for rears.  For rear rain treaded tires, 6 or 6.5″ rims are commonly used.  But the inch sizes appear to be a simplification, with metrics being more precise.

If the rim is regulated, and not the tire, it would certainly serve to control the tires which can be effectively mounted, but it would give competitors a wider choice in which tire to run.  Note that the numbers molded into a tire do not mean that it will be identical in actual measurements to one marked the same from another manufacturer.  For rims, conformity to a standard is easier.

[Alan Sheidler]

Thanks!

[Alan Sheidler]

I should have been a bit more specific: The Metric part refers to the bolt pattern for attachment to the hubs.  In the States, there is still a huge portion of the sport, fairly collected in the circle-track segment, which uses inch fractions measurements.  The wheels for each (Euro = Metric, American = Inch) are sport segment specific, although crossover is always possible.

 

So, what I want to know is:  Where can I go most easily (website with online ordering?) to obtain 6″ Metric bolt-pattern kart racing wheels?

 

Thanks for the reply Ian.

[Alan Sheidler]

[quote quote=17303]So what we’re doing is trading a major shakeup in wheels,tires, testing, stability and possibly package availability, for maybe a couple of theoretical entrants? I’m just not seeing the advantage to solo karting.[/quote]

Major shakeup?  Perhaps you do not understand about the 6″ wheels.
At the inception of the KM (F125) class, and for some years after, there were several options for tires in both 5″ and 6″ rim sizes.  A popular and successful tire was the Firestone YFA, a 6″ rim diameter slick.  Seen on karts at major national events were tires from Maxxis, Bridgestone, Dunlop, Hoosier.  Even later, when the YFA tire carcass was apparently altered for specialized use in oval racing, there were options.  Many of the early competitors still have the 6″ wheels.  They are easily available.  Yep, they are legal, and have been since the beginning.  But without the tire allowance, they can’t really be used.
For the years at Heartland Park, the Vega tire was highly competitive.  As in… Winner.

Since then, what has become essentially the “spec” tire for autocross is the MG YZ or “Green” racing slick.  “One size fits all” is not really true, I don’t believe.  There are differences in chassis, and in driving styles, for which the MG is not the best tire, and 5″ is not the best rim diameter.

So, how much of a change are we talking about here?  My primary interest is in the Hoosier R45 “Superkart” rear tire, part # 22800.  The front tire numbers meet the limitations posted in the current rules .
Based on the Hoosier Factory specifications, the 6″ R45 tire is 0.25 inches wider at the tread, and 0.5 inches larger in circumference than the 7.1/11.0 – 5″ tire.  Those numbers compare closely when matched to the currently popular MG tire.

My measurement of the rear MG tire (mounted, inflated) indicate an approximate tread width of 6.4 inches when measured from the edges of the contact patch, 7 inches when using the shoulders of the tread.  Diameter measures 11 inches, with a circumference of 34.25 inches.  Note that the measured tire has 13 runs of approximately one minute each on abrasive concrete.

My measurement of the Hoosier R45 tire # 22800 (mounted, inflated) indicate 6.75 inches to the edges of the contact patch, 7.25 inches if carried around the shoulder of the tread.  Diameter measures 11 inches, with a circumference of  34.75 inches.  Note that the measured tire has 12 runs of approximately one minute each on somewhat abrasive concrete.

Based on a hands-on comparison of two tires, the Hoosier shows an increase of approximately 5.5% in the direct contact patch width over the MG.  Additionally, the circumference of the Hoosier measures approximately 1.5% larger than the MG.

Visually, the tires are very close, with the most obvious difference being the shape of the sidewalls.  Mounted on the same width rims, the MG has a rounded sidewall, whereas the Hoosier’s has a more square or flat profile.  Part of that appearance has to be due to the difference in rim diameter, 5″ vs 6″.

Legalization of the tire size will allow an option in the KM class where few, if any, exist on a practical basis today.  There are certainly no guarantees that the proposed tire size would be competitive.  As with all changes to any competition vehicle, additional tuning and adjustments would be required before the full level of competitiveness could be evaluated.

One more IMPORTANT thing:  Hoosier is a strong supporter of SCCA Solo, and has been for many years.  Hoosier offers contingency for successful use at National events.  Try and get anything out of MG.

[Alan Sheidler]

Periodically some 45MM stuff finds its; way across the eBay offerings list.  If I were looking for that stuff I’d set up a “Followed Search” so that a notification hit my email every time a lister posted one.  Some years ago there was an entire new 45MM setup offered, including the axle, bearings, and a brake hub.  Have no recollection whether it was sold or not.  I went hunting and think I found the dealer: http://www.ebay.com/usr/itsonlymoney

Might be worth a shot to drop a note if any of that stuff is still around, but breath-holding is not advised.

[Alan Sheidler]

Glad to see you are figuring out what makes the kart work for what you are doing with it.

And….  The guy who passed you appeared to blow up/stick the motor on the straight.  I was noticing how he appeared to have more power than you did, until it went bang.  Sometimes safer jetting wins the race.

On another subject, Congratulations on your Nationals win, Carter.  Can you say that running the kart improved your performance as a driver in the SSM car?

[Alan Sheidler]

[quote quote=15128]Any updates on the course decided, Alan?[/quote]

Eh, not yet.  I was out earning the money to do one of the above, and have not gotten back to the guy who would supply the parts.  Waiting for my paycheck, and a good conversation with a small engine expert on the best path to follow.

[Alan Sheidler]

Varies by year.  This year, I think nearer 75 MPH, faster than usual.

[Alan Sheidler]

Bump.

Although I have found “one” of these, I’m still looking for a pair.

But I’ll take one if anyone has just one!

Thanks to all who replied via PM or email.  I may end up at some point just wrapping whatever color is available and calling it a day……  :-)

[Alan Sheidler]

Bill the first link I could find was this, for the attachment to the MagLight:

http://www.zieh-fix.com/shop/contents/en-us/d76_Optik-Vorsaetze_fuer_MagLite.html

First one at the top of the page.  I picked up one of those at a local store several years ago.  Advantage is that it is very thin and allows more room to look through the spark plug hole.  They are here in the States, you may have to look around.  Best to try and view the piston in relative darkness, make a “tent” over your head and the engine if you are outside in daylight.

What you are looking to see is not only the color, but the shape and size of the combustion pattern on the piston.

Black all over = rich

Small brown center/black outside = still rich, but better.

Brown circular pattern reaching to within 1/4 to 1/8 inch of the piston’s edge = pretty much prime territory.

Brown all the way out, any lighter/whiter or “pecked” looking spots = Don’t Go There!

+1 for Chris’s advice.

+1 for Christaan’s comments too.

If any of the running issues are happening at part-throttle, it is time to research needles for your carb.

[Alan Sheidler]

Thanks for the advice guys, I’m going to start by measuring everything, to see what parts are out of spec, and what needs to be done about it.

For sure I’ll need a piston/rings and a rod.  Beyond that… maybe not much.

I’ll keep you posted, but this is a back-burner project now, as it is unlikely for me to get that kart to the track before October.  Too many things going on!

[Alan Sheidler]

Not in any of the K classes that I can see…..

Have not searched the rest of the 1K plus spots for a Garfield name, but Brian is not the quiet type usually.  If he were to be there, we’d probably know.  I almost expected to see Julian run Lisa’s KM kart this year; I think the BoD agreed that kids like him are ok to run one.

[Alan Sheidler]

One think that you have found out is that although at first glance many kart chassis brands look alike, in reality, once you take measurements, they are quite different.

[Alan Sheidler]

Another option might be to reconsider what is being used as an engine mount.  Many of them are fixed laterally, with the only adjustment being fore and aft along the frame rails.

The one we began with and still use is flat, and allows side-to side adjustment as well.  That came in handy when getting the proper  clearance.  The frame we have was designed as primarily for outer right drive (such as the 2-cycles, KT-100, etc) where the rear sprocket is inside the RR wheel.  Mouting the WF was not all that tough, though.

The Gold chassis does not have the 3rd bearing hanger.  I thought only the frames built for higher power engines used those?  That must be some beefy frame you have there.  Are you sure it is for a kid?  ;-)

[Alan Sheidler]

Trying to get a mental picture of your method to find steering center.  That does not seem to take into account the adjustability of the tie rods.  Might you have a photo or two?  In my mind, centered steering begins at the steering shaft and inner tie-rod ends, and goes out to the spindles via the connection, not the other way around.

The kingpin bolt is just that, and should be straight.  All of the European (metric) karts used to employ 8mm.  Now most have gone to 10mm.  Your kart should have what are called “camber pills” attached above and below to the “C” shaped part of the frame where the spindle attaches via the kingpin bolt.  Those items are what have the offset holes, and they can be rotated to adjust camber and caster.  Note that adjusting the pills will also change the toe setting, so toe comes last.

Here was the first diagram of some camber pills I found:

http://italianmotorsusa.myshopify.com/products/pair-of-8mm-adjustable-castor-camber-pills

There are many styles, and each manufacturer has their own way of approaching the engineering task.  Recent TonyKarts have what looks like a flying saucer, with 20 perimeter holes to set the adjustments.

I am aware that some karts were delivered with non-adjustable kingpin placement.  The kingpin merely rides in holes in the spindle-mount “C”.  If I had one of those, I’d go straight out and modify the frame to accept camber pills.  The only alternative is bending the frame where the spindle attaches to cure a camber issue.

BTW, all of what is being discussed is dependent on the frame itself being straight and square.  It does not have to be perfect, that is what adjustments are for!  I just got back a frame from being straightened at PKT in Wixom, MI.  Looks great, Kim did an awesome job.  Can’t wait to get it together and drive it!

Oh, and…  In at the top is Negative camber.

[Alan Sheidler]

Currently at 26 open + 4 for the L class gives KM the largest entry in the Modified category.  Great Stuff.

Anyone else?  For most normal paying entrants, registration closes at midnight tonight, when the fee nearly doubles.  There are always a few who pay the extra tariff, but I would not.  High enough as it is!

I see the name of an old class Champion on the list….  Will wonders never cease?  Tom Harrington, welcome back from wherever you have been.  Now if Dave Hironaka suddenly signed up, I’d likely have to pick my jaw up more than once.  Dan Cyr is off running in BM.  That should be worth watching.  I don’t see Mr. Andrews….. in or not, Larry?  Quite a number of the “Old Guard” from the Forbes days would be fun to get back in some year.  No sense listing the names.

The countdown begins.

Kart in parts.  Uh-oh…..

[Alan Sheidler]

Yes both numbers seem high to me.  We generally shoot for a close to zero toe as possible, and that is with someone sitting in the seat, tires properly inflated, etc.  If you are measuring total toe, depending on where the steering center is, most of that might be on the side which is wearing poorly.

Same for camber, and that typically increases with load.  Add a driver, and the number probably will go up.  Karts don’t need front tires tipped in at the top like are seen on the current Indy cars.

A good place to start, if you can get even half a day to test, is to go to zero for toe and camber, and the middle setting for caster.  From there you can check results of track width changes (easy to do, relatively) and caster adjustments.  Understeer/slow response = add caster, Oversteer/twitchy = reduce caster.

As it is, the numbers you list for camber and toe probably are to blame for the wear you see on the inner section of the tire tread.

Here is a thought:  Instead of pulling the kingpin bolts, just loosen and spin them with a wrench or socket.  If a spindle waves around as the bolt is turned, that bolt is bent.  Replace it before making adjustments!

[Alan Sheidler]

Regarding the Master Cylinders…

If they are like mine, the pistons should be good, and the springs too, unless a lot of moisture got inside.  Of primary concern is that the bores are smooth and round where the seals fit.  Up in the front, even where the pistons slide, is less critical.  Water got in, and the kart I am working on sat for a long time, causing some corrosion in the front, ahead of the pistons.  Not a functional problem!

Again, if like mine, all you’re likely to need in the way of parts is a pair of rubber cups.  Guess what?  They are a standard automotive replacement part, originally used in drum-style brake cylinders.  The masters should be 7/8″.  While I do appreciate all that kart shops do to support the sport, I have an issue with pricing on stuff like this.  Even at a local NAPA, I can get them for $2 each.  Picked up two sets of ten (10) on eBay for $21.98, with free shipping.   That is $1.10 each.  Nice that they also fit the front (cast) calipers on my old kart too.

[Alan Sheidler]

Interesting wear pattern.  I’m wondering if something got loose in there, and that is just where it got trapped?  I am really surprised that the rod can spin that much.  Was the ball in place in the pressure plate?  Is the clutch end of that rod somehow damaged too?

Many moons ago, when I put a clutch in a 60’s car and got a good look at the parts:  I decided forevermore to spend as little time as possible with the clutch pedal pressed.  Have carried that over to motorcycles, and karting too.  I never sit more than a couple of seconds with the clutch cable in tension, preferring neutral in the gearbox as a better alternative.

[Alan Sheidler]

Not sure either about the specifics regarding the port, etc.  I have never heard of anyone cutting a hole in one to match the original factory unit.

What I was told, however, was that Wiseco requires a different cylinder clearance and finish than the stock Honda piston.  That was from Eric Gorr many years ago.  If you have any doubts about fit or performance, pay a couple of extra $ and buy the OE part.  Peace of mind.

[Alan Sheidler]

Folks,

The mysterious “Josh” is my pal “TonyKartMan” Josh West from the DC area.  We think we have hooked him up with a ride.

Note that for a big event like The Nationals, I’d be leery of putting some newb into a seat just to make numbers and add participants in the class.  However, when someone you are familiar with, especially one with plenty of shifter kart experience, is looking for a seat, I hope you will do as I always have, and share your machine if possible.

As Jason Vehige puts it, there is nothing like “The Crack Pipe” for getting potential drivers hooked on KM in autocross.  While that initial experience is great at a laid-back local event, for Nationals I’d want someone with more seat time.  There are exceptions.  Enter one experienced autocrosser, Michael Casino.  He impressed the hell outta me at the Toledo Pro, only his second event in KM.  Duck, this is water.  Make a splash.  Have fun.  Eh, hmmm…. Seems like you have some natural affinity for this…..  ;-)

[Alan Sheidler]

Is the clone restricted for RPM?  (either by limiter, valve float, or BANG! if run too tight)  What RPM were you seeing?

The WF is limited @ 7100.  Some tracks are so tight inside that staying off the limiter on straights leaves you with a chattering clutch and/or no power in the small radius corners.  BeaverRun/PittRace is like that for me.  On the advice of a local guru, I geared for limiter hit near the S/F line on the front straight, and it was much better inside, lap times lower.  Our clutch has the orange springs, because for some of its use we needed the hole shot.  If it were to be only used at a track, I might put in some lower rpm springs so that it would stay engaged.

The gear I had on for that track was 15/60, same ratio as you were using on the clone.  If you have never been to Pitt: It has a 500′ main straight.  But, I was running the last corner, and the esses preceeding it, flat out, and that adds another 650′, with some scrub to slow down acceleration.  So, at around 950′ WOT until the limiter hit.

If the clone tops out at 6K rpm, the same top speed in the WF would mean running an 80 gear.  Of course you want to go faster, with more power… maybe a good place to start is 68-72?

Disclaimer:  I have never raced W2W in the WF, only track days with friends.  Still, in 3 separate sessions and with two drivers taking turns, our WF has 300+ laps at Pitt.  A couple of hundred laps at Pelee in Ontario too.

[Alan Sheidler]

Just a few days to go, and we are at 22 Open class drivers, and 4 Ladies.  The general goal is to stay above 30 total, so we are still a few short of the optimum minimum.

Has anyone been able to arrange a co-drive for my old buddy Larry Andrews?  XL seat and Extended porch will get you a very good co-driver.

Speaking of co-drivers, I might need one myself.  The usual super-guy, JT McClintock, is not running the Nationals this year.  I don’t mind running by myself, but there is one reason that I could use a tire-warmer/fast guy in the seat.  I am 180/5’9, fit great in the ML Tillett.

[Alan Sheidler]

Kevin,

Do you have to run the clutch with the drive sprocket “outboard” in order to clear the chassis properly?  From what I have seen since we got our WF many years ago, the general consensus is that running it “inboard” places considerably less strain on the crank and drive-side bearing.

[Alan Sheidler]

Do some sanctioning org’s prohibit carbs that have an integral fuel pump?

[Author]

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