[Alan Sheidler]

Looks heavy.  Might be OK if the driver is particularly small?

Before you buy, I’d suggest checking with the local tracks where you intend to have your grandson compete, and see what classes and rules they have for the little guys.  Might be easier to pick up a good used setup from a family whose driver has outgrown it.  As always, how a machine was treated and maintained is of prime importance.

[Alan Sheidler]

Nice photo, Michael.

 

Looks like double wishbone independent suspensions, front and rear.  That kart must be heavy, and a complicated one to setup too.

[Alan Sheidler]

Does your kart have a built-in provision for the cable?  Some do, with a threaded fitting on the balance bar.  The front end would then have a home on the pedal, perhaps with a standard U-end, plus post and clip:  http://www.kartwarehouseusa.com/FORK-M6-COMPLETE-WITH-LOCKING-p/k337.htm  or http://www.kartwarehouseusa.com/LONG-FORK-M6-COMPLETE-WITH-LOCKING-p/k338.htm

I’d expect the threads to be included in the length, but you should inquire at the source.  Don’t forget to include the non-threaded portion of the ends for the length of the cable you need.

[Alan Sheidler]

Awesome!

So, for us curious-minded types… Did you pull the old pump apart, to see where the fault was?  I’m still betting on a split in the main membrane, which would allow fuel to be drawn directly into the pulse line, therefore bypassing the carburetor entirely.

And FYI, don’t toss the old pump.  It is so very rare that anything could be wrong with the castings, maybe a fitting….  And the kits are easy to install.  Will do you good to rebuild it, then put caps on the fittings to keep junk out, and keep it as a spare.  I am aware that I probably carry too many “just in case” items in my trailer.  But if I was forced to whittle down the selection, a spare pump would be one of the very last to get cut.

There was that one time when we were on the grid, ten minutes to go, and the motor would NOT start!  And we had just warmed it up/checked it out an hour earlier.  One side of our double-pump (AKA Pump-around) system had failed.  We got the spare and put it on, and made the scheduled start with a minute left to warm up.  Yea, the spare pump stays where I can get it on short notice!

[Alan Sheidler]

A 2-Litre jug is plenty of capacity to feed a carb.  Taking off a tank and using that for gravity feed is so much work… On both of my karts you pretty much have to pull the floor pan to get the tank out.

But some things have been found out.  Get a kit or two, and rebuild the fuel pump.  I don’t recall reading whether you have the round or the smaller rectangular pump.  Whichever, just be sure that all of the gaskets are properly aligned, and tighten the screws gradually in a crossing pattern.  The flapper valves in the round pumps can be finicky…  It occurs to me that if the main membrane between the fuel side and vacuum side of the pump is faulty, then that pulse line could have been scavenging fuel and air.  Not good, and it could cause the runaway condition you described.

As far as the pulse or vacuum line, that is a critical connection.  It is OK to use fuel line for it, but I prefer a fiberglass reinforced line, as it is very resistant to distortion due to the negative pressure.

Sounds like you have already checked out the carburetor well enough.  Just be sure that the float needle is not able to stick in the inlet and block fuel flow.

Keep at it, you’ll get there.

[Alan Sheidler]

I’m trying to understand how an engine could get to the “screaming” mode in any case unless the throttle slide was being raised, at least a significant amount.  In order for an engine to wind up, it needs both fuel and air.

Of course the things you have already done are a good start.  But an air leak alone won’t cause this effect.  As far as the bubbles in the line, that can happen, but a rebuild of the pump may be in order.  Your system uses just one pump, is that right?

[Alan Sheidler]

So, this is not “The Meadowlands”, where a couple of Pro events have been held before?  Perhaps it is another site, and I just did not look closely enough.   The pavement at the location I am thinking of was quite good.  Excellent even, with plenty of grip and minimal tire wear.

[Alan Sheidler]

+1.

Ventilated rotors behave essentially like radial fans.  Air pumps, like Steen says.  If the internal vanes are straight, obviously it does not matter which way they spin.  But if the vanes are angled, the ends near the center should lead the outside ends in the direction of rotation.

 

Something that has always bugged me is seeing aluminum wheels on cars, which have spokes shaped like they might be able to move some air.  But they are almost always identical no matter which corner they are on.  To me that makes it look like they are backwards on one side of the car.

[Alan Sheidler]

Well OK, Tim….

But you really should not use starting fluid in a 2-stroke motor.  You have to remember that the intake charge goes through the crank-case.  Anything other than fuel and the appropriate oil going in there can have a detrimental effect on bearings.  The stuff can be corrosive, and it is volatile, of course.  Unlikely, but still possible that it could ignite under the piston, instead of on top of it.

[Alan Sheidler]

The real issue is that the setup you describe was designed for an ICC clutch.  Funky even then, IMO.

 

 

And I show the only proper way to do a Honda clutch.  See the discussion on the “Classic EKN site:  http://eknclassic.com/viewtopic.php?t=113994&highlight=

[Alan Sheidler]

That thread has apparently been deleted.  I could not find it either when I tried last week.

As far as getting past the registration question, the answer appears to be ”   both   “.

I sent an email to the admin about that stupid system, suggesting that the registration section be listed as “gimmickrally.com” instead of roadraceautocross.  Never got a reply  Come to think of it, I’m not sure that I am yet registered for the site, I did not get a confirmation, and I have not been back to try logging on.

From what I can gather, some changes in procedures and tech, and allowable devices may be in the pipeline.  We will all be paying attention.

[Alan Sheidler]

FROM: SCCA National Office

TO: All Solo Participants

SUBJECT: Kart Safety

SCCA wishes to remind all kart owners and drivers to ensure that their vehicle’s control parts, including, but not limited to, those relating to throttle and brake pedal assembly function (including extensions) and safeguards such as throttle return springs, etc., are in good working order without the potential to perform unintended functions.

 

So, that was meant for ALL karts, not just the FJ’s.

 

Years without (avoidable) mechanical failures leading to a problem at an event means that complacency sets in.  And tech inspection becomes less complete, and less effective overall.

When I was a regular tech guy at regional events, one of the things I did was a “stomp test” on the brake pedal.    I never burst a line, but a guy who I had trained did…  Better in tech than on course, or  on the street somewhere!

[Alan Sheidler]

Robbie asks:

Question:
– Can the brakes on a JA kart overpower the engine? I plan to test this on our JB World Formula kart, but I haven’t had the chance yet.
– Is this the beginning of the end of the junior program?

 

They certainly should be able to.  My first year in a shifter, the throttle stuck wide open in 3rd gear, and I went off of a track (not at an AX) into the grass.  The front brakes would then have a negligible effect on slowing the rotation of the rear axle.  The rear brake was enough to stop the engine.

I hope not.  This is not a small part of the SCCA anymore.  Taking it away would be in all likelihood a second and unnecessary blow to the Eaddy family.

That is not to say that like all misfortunes, there is not something to be learned.   I’d expect some new and specific requirements will likely for J drivers, their parents, and for Youth Stewards.

Edit: As of yet I have not gotten any indication regarding the investigation of the cause of this tragedy.  From what I have been led to understand, there will likely be both primary and contributing causes.  It is fairly certain that a stuck throttle was not an issue in this circumstance.  I for one hope that someone who knows karts and has a keen eye for problems had a chance to look at it, before anyone altered it in any way.

In any case, don’t believe what scuttlebutt may indicate.  We should all wait for official answers to all of the questions.

[Alan Sheidler]

If it were up to me, I’d be out there practicing for the month of August….

And of course, I really need it.

[Alan Sheidler]

Mod?  That’s rich!  Currently I run a dirt bike motor, with the only exception being the RCE pipe, and deletion of the kick-start mechanism.  The 36 PJ is what came with it,  a 1996 motor I found brand new in 2000.  Included was the ignition, which has not been altered even for timing from how Honda set it now 18 years ago.  More stock than “Stock Moto”.

Easy to expect that the carbs run by the fastest guys are either Keihin PWK or PWM, possibly a Mikuni, but I have not spotted one in a while.  Sizes 38 or 39.  There may be a 40 or even a 41 on a PI motor or two, but I have no way of knowing that.

[Alan Sheidler]

First off, even running the same size, the change from PWM to PWK  (or the other way) will pose challenges, and should also change your power band a bit.  Both are used in the class, and I am right now running a 36 PJ, just to throw more numbers and letters into the mix.

So, will making the change give you something that you do not currently have?  That pretty much depends on your motor, more than anything else.  The general rule of thumb is that the larger the venturi size, the more the horsepower.  The drawback is, the power band narrows and is higher in the rpm range.  Too big of a venturi can cause issues with fuel atomization at any but the highest rpm, so drivability can suffer.

More air = more fuel required, so jetting you are used to will no longer be applicable.

My attitude: Unless you are maximizing the handling portions of an autocross and zinging the corners very accurately already, a little more power in a narrower band will not improve your lap times, and may hurt.  The driving is still king.

[Alan Sheidler]

So, how did it go with the baster?  Do you have functioning brakes?

Looking at your photos, the first thing I’d say is to clean them up.  Rust on the pad retaining bolts and return springs is not good, it may inhibit the release action.

The old EKN had a thread about getting Brakes to work well.  Find that here:

http://eknclassic.com/viewtopic.php?t=111402&highlight=

Let us know how your system is working….

[Alan Sheidler]

Of note is that whether you use RTV type silicone or not, some type of material which acts as a lube during installation of the pipe should be part of the assembly.  I have used a silicon lubricant in a tube, bought from NAPA, when not using the high-temp RTV.  Important is that the ring grooves should be thoroughly cleaned every time the o-rings are replaced.  And, the inside of the pipe which slips over the flange should be very smooth.  I use “Scotchbrite” there.

The point is that the o-rings should be tightly compressed between the flange and the pipe.  The pipe should not just slip on easily, there has to be a snug fit, otherwise it will leak quickly, whether RTV is used or not.  The danger comes in not putting the pipe on squarely during installation.  An o-ring which slips partially out of a groove will be cut through, and fail to perform the function for which it was installed in the first place.

[Alan Sheidler]

Spindle.  From the age of your kart, spindles are probably (like mine) 17mm.  They can bend.

Unlikely that the chassis itself is bent, unless it has hit something.  Not likely, but still possible.

Also, the kingpin bolts do bend often.  Make sure they are also straight.

[Alan Sheidler]

Yep, I got a reply to an email: eBay’s “gogokarts” is the guy.

[Alan Sheidler]

Thanks for the quick reply.

With the weather we are having this year, getting everyone under one roof at Hara is a great idea, BTW!

[Alan Sheidler]

For some of us, the fees for parking and admission do make a difference in the decision to attend or not, or how many family members go.  But I do not find that information on the linked page, or on the flyer.

How much per vehicle, and how much per person, please?

[Alan Sheidler]

So, will there be a class emerge which allows FI?  I’m not up on the latest rules in the EU, but AFAIK, the classes are divided in part by carburetion.  Here in the US, I’m not aware of any sanctioning organization which allows FI.

[Alan Sheidler]

I inquired about that in the Superkart forum, got this:

https://id3528.securedata.net/test.burrisracing.com/merchantmanager/index.php?cPath=0_30_39_41

 

[Alan Sheidler]

At least you are expressing an opinion, and that is good.

I hope I can explain a couple of things.

With only the exception of the non-national championship FJ classes, there has never been a spec tire for ANY class that I am aware of.  For SCCA solo, doing that would be a major step/paradigm change from a Solo tradition and fact: In nearly every class, there are a variety of vehicles which compete fairly and closely against each other, while having tire manufacturer and size options as part of the mix.  It is up to the developer/tuner/driver to choose what works for him or her, based on many factors.  Among those is the fact that different vehicles perform better with product having slightly different tire carcass construction and tread rubber compound/chemistry.

To someone fresh to the KM class, all the karts “look alike”.  To someone with experience in the class, nothing could be further from the truth.  For some chassis, a soft 50MM axle will be best, along with maximum available caster and a soft sidewall tire.  For others, it is a hard 40MM, six seat struts, minimum caster, and a stiff sidewall tire.  What works for one will not necessarily work for another.

Wheels and tires are so much a part of that in autocross.  As far as there already being a defacto spec tire in the class: Of course you are right.  People tend to play “follow the leader”, particularly if there are few other options to choose from.  For some of those drivers, only the advent of a blatantly faster “miracle” tire would get them to change, because people become complacent and set in their ways.  For the guy at the front, there is zero incentive to shuffle the deck and re-deal.  For everyone else, there really should be.  It is all about the options, and what will make each kart work the best it can, at the direction of the person squeezed into the Tillett.

The point is that what is “the fastest” can differ between chassis and driving style, if there are real options to be explored.  Right now, there do not appear to be any in tires.  I have mentioned earlier that the 5 and 6 inch rims have always both been legal in F125/KM.  That is a fact, and it was not brought in from thin air.  When karts were first proposed for Solo, the rules set came from basically a combination of IKF, WKA, and SKUSA.  At that time, it was possible to run the 6″ rims with them.  The change to only 5″ for sprint W2W came through several influences that benefitted national series.  Tech inspectors did not need to deal with variety there, and sponsorship influx was a big factor.  Part of that had to be from the European chassis manufacturers influence: Their products are designed with specific rubber in mind for sprint racing in specific classes.  Other uses are adaptations, and Autocross is pretty much as far as you can get from the factory, unless you throw in Ice Racing.

Do a little research, and if you dig deep enough you’ll see that in the earlier days of F125, competitive drivers used Firestone YFA’s in 6″ (Including Paul Russell, ask him, or look up the results from 2003) and Maxxis (also 6″), MG, Bridgestone YEX, YFA and YFB in 5″, plus Burris, Vega, Dunlop, and… I forget the others, but there were some.  Don’t be fooled into thinking that the competiton was ruled by one tire or driver, or that the class was still so embryonic that tires did not matter.  It was really difficult to get an edge, and there were a lot of options for hunting one down.

Am I asking for change?  Not really.  I’m asking to be able to use the 6″ rims which I’ve owned for a decade, by legalizing the tire  size currently in production that fits.  And, that have an outside chance to work, as I develop a new-to-me chassis which just hit the ground in September.  I’m asking for options.  Like used to be available.  The fact that a company which has a stake in, and a history of support for SCCA Solo makes a potentially workable tire is icing on the cake.

If KM were to be truly a spec class, then why not sealed Rotax Max, + Tonykart Krypton + Mojo D2 tires?  Oh, this isn’t W2W?  Well then, how about keeping open ALL of the options?

[Author]

Posts