[Scott Boito]

There are still American oval kart chassis makers but I don’t know if they make/use the same sort of stops you need. Try Buller karts. Margay is still American, but I don’t know if they use English or metric goodies. I think everyone else is now European or Asian using metric stuff.

[Scott Boito]

When I ran my TM moto for part of a season, it was quieter than my Honda CR125.  Using some junky silencer off the TM pipe.  Repack your silencer with some fresh packing and it should be good.  We had a 96 db limit and I never approached that – but did get in the 93-94 range with the Honda.

[Scott Boito]

Sorry, everything is packed up for Blytheville so I can’t get to it.

Did you test it under load (as in sitting in the kart and throttling up)?  On the stand it can act a bit unpredictably until the clutch is broken in.

[Scott Boito]

I’ll check our spare one tonight, but I think that’s correct for the inboard mount. Some folks actually run the shoes the opposite way on purpose, so that shouldn’t be an issue anyway, once the clutch is broaken in (with a load, preferably on a track with some time to heat cycle it).

[Scott Boito]

Pic not working.

Stalling the WF will really take a lot of effort.

[Scott Boito]

Mount the battery to the seat, not the chassis is all I’ve heard.  Vibrations on the chassis kill batteries.  Should be able to find something on LiPo batteries in the Briggs forum I think.  They are not cheap.  I recommend removing starter and battery anyway…

For the clutch, what Joe said.  Also are you sure you have the axle sprocket lined up correctly?  I don’t ever remember Kieran’s chain jumping around.

[Scott Boito]

Gear oil discussion above: Royal Purple Synchromax for me.  Robbie is using Mobil1 10W40 High Mileage.  I tried the Pennzoil Synchromesh and it was not very good.  Amsoil makes a good Synchromesh, too.  Just about any thin oil will work.  Not gear oil.

[Scott Boito]

She (and you) should be able to slip the clutch at least a little.  It sounds like it’s engaging like a TM ICC motor does.

I’ll assume that there’s nothing physically interfering with it next to the seat or a bend in the cable housing itself entering the case.  If it’s not the cable or something interfering with it physically, it might be time to dig inside the case to see what the actuator assembly looks like.  If everything is in order, the pull of the cable should be almost buttery smooth.

[Scott Boito]

I don’t know that anyone is using aftermarket/race springs in their Hondas.  Stock springs are great and durable.

Definitely check the smoothness of the clutch cable as Robbie said.  I also found that changing to the Royal Purple gear oil improved my shifting smoothness and quickness a bunch.  At Blytheville on the practice course last year I and everyone watching thought my motor wasn’t shifting.  Turned out that the new oil made it so much faster than it had been with the SynchroMesh I had before.  Only Royal Purple for me now.

[Scott Boito]

That’s a great video and I’m thankful (for future dads switching) that you included the mistakes, too.  Based on my experience, installing the clutch “backward” from the intended mounting got me twice, too.  Even after I was aware of what I should have been doing, I still did it wrong twice.

The good news is that once it’s all together and mounted correctly, you shouldn’t have to worry about much else related to the motor.  It should run for years with only minor tweaks to the valves.

[Scott Boito]

Thanks, Frank and EKN!  All taken care of now.

[Scott Boito]

I’ll second what Craig said.  Comer 50 or 51 on a baby kart or a cadet-sized kart, depending on the size of your kid(s).  The Comer is indestructible and the worst thing you’ll really ever need to worry about is a grain of sand in the carb jet.  Well changing the clutch is worse, but you can get help for that.  The kart chassis rattles itself to pieces, so safety wire and nylock nuts are definitely your friend.  The axle gear is a spec size (89), so they can’t go much more than about 25 mph.

[Scott Boito]

Last chance to submit letters on these topics. We’ve received little feedback…

[Scott Boito]

7100 is max.  We run a 17T with 65-73T axle sprockets.  So around a 4:1 ratio, plus or minus 0.3 ish.

And from what we’ve experienced and what I’ve read, you ideally want to gear for hitting the rev-limiter ~2/3 down the straight(s) before braking.  So hitting the rev limiter is the best way to set your gearing.  Kieran hates when it happens, but it helps keep the gearing OK for digging out of the tight corners elsewhere.

[Scott Boito]

I’ve found that running the sprocket inboard is the easy way to get the axle sprocket to line up with the key slot in the axle.  I couldn’t get ours to line up otherwise.  There are ways around it, but the easiest is to flip the clutch.

Instructions for flipping are provided int he paperwork with the clutch since it’s commonly done.  Basically separate the clutch assembly from the drum, reverse the screw things, then put it back together.  You need to add the additional washer against the crank at the case to make it work.  Overall pretty simple to make the change if your crank’s key slot isn’t too tight.  Videos are available on swapping for inboard running, I think.

[Scott Boito]

I got a trip with the family to Universal Studios Orlando for a few days.  I bought another kart last month but can’t pick it up for awhile yet since it’s 7 hours away and my truck is down for some more service.  Just working on my son’s kart (new floor pan) yesterday and biding my time until March when we can start back up.

[Scott Boito]

Sorry, I missed your question about the ages.  We clarified that sometime in the last 18 months in a FasTrack.  Essentially, 12 year olds can run either JB or JA.  So if your 11 turning 12 yr old wants to stay in JB all year, that’s OK.  Kieran will be starting the year in JB and making the switch to JA probably for Toledo.

Be prepared to weight-balance the kart for the WF.  It will be completely different from the KT100 since it weighs more than 2x that motor.  Slide that motor as far inboard as you can to help.  Even doing that for Kieran he was pretty bad with the side to side weights.  Depending on the height of your kids, you may also have to move the motor pretty far forward to get it to turn (~42-43% weight in the front with kid on-board). Once we figured out to do that he had no problem turning, but the chain is so long now that we need to add a sprocket guard to keep it on the axle sprocket.

We ended up getting him pretty well balanced overall, but still with a right rear bias due to the weight of the motor and his relative lightness.  Much better midway through the year, so I advise you to get that right from the start and everyone will be happier.

[Scott Boito]

Alan, according to the Hoosier site, the R45 and R50 have approx the same durometer.  I wonder how much of a difference, if any, there is between the two tires.  Of course the sidewall flex could make a difference between the 5″ and 6″ wheels/tires, so there is still some data to be gleaned there.

If I had more than two asphalt events planned in 2014 I would buy a set of R50s to play with.  9 planned National events on concrete, so MG is where I’ll be p(l)aying.

[Scott Boito]

FYI, we have received only a few letters on the tire proposal so we need more input either way before we can decide anything.

And if the rim instead of tire width sounds interesting, we need someone to write that up and submit.

Thanks.

[Scott Boito]

Unofficially I think I like that idea better than playing with the tire size.

[Scott Boito]

Don’t forget a new chain breaker for the 219 chain.  And I have a set of 35 axle sprockets for you.  PM me.

You don’t need another drive sprocket, except maybe for really fast national courses.  I’m getting one just for the track and hopefully some of the fast courses at Wilmington and Lincoln.  That’s especially true if you run a 35 chain since you can get smaller axle sprockets with the 35 teeth than 219 (it’s a major challenge with the 219 that you can’t get smaller than 64T).

[Scott Boito]

219 chain is lighter but narrower.  I don’t have a good feel for why you’d run one over the other, but since we already had all 219 stuff, we stuck with that.  To switch after you’re already set with one or the other is expensive, so choose what you want first.

[Scott Boito]

Hey Robbie,

We made this switch earlier this year after running the KT100 for 2 1/2 seasons.  After a few months of growing pains we finally got it figured out and it’s a dream to run now.

Initial costs are higher than the KT100, but there are minimal hassles associated (no starter battery to charge, no charger to lug around, no tuning of the carb).  The weight of the motor is our biggest problem to overcome since it’s more than 2x the weight of the KT100.  Corner balancing is still impossible side to side due to Kieran’s size.  I had to move it pretty far forward to get the correct front/rear split, but the chain is super long as a result.  It will get better as he gets taller and heavier, but it is a real limitation.

He’s on an older Top Kart SL28 chassis with a moveable seat stay and using a two piece mount easily allowed us to mount the motor without interference from the seat/seat stay.

My advice: work that clutch early in the process.  The clutch was our only source of consternation those first few months.  It wasn’t until he ran it at a track that it properly broke in and started functioning as it should.  After that it has been a dream motor.

As for gearing ratios, I gear it between 17/73 and 17/65 for JB (#219 chain).  Next season he moves up to JA and I’m getting a 19T clutch sprocket so he can get up to higher speeds with the same axle sprockets.  The 17/65 was perfect for Blytheville Summer Nats this year.  17/67 would have been the perfect choice for Wilmington.

If you’re interested in running #35 chain, PM me as I acquired several fast #35 axle sprockets that we’re not going to use.

[Scott Boito]

Any updates on the course decided, Alan?

[Scott Boito]

Way to completely miss the point, Tom!  The simple facts:

You rebuilt a motor

You shipped the motor

You insured the motor for only $1000

The motor was lost by the shipping company – which is why you insure the item for the value of the item…

I’ve never seen a TM K9B for sale for less than $2000

You’ve managed to expose yourself on here – Pete didn’t do it.  Congrats!

[Author]

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