[patrick hubbell]

A KT100 needs a bit more octane or you run the risk of detonation. Not too much more, say something like 100or 103 is ideal.  But don’t use pump gas on a race day, pump gas has too many other chemicals in it’s formulation that will get you disqualified.

Some tracks and local kart shops sell race gas, check with your club first, they can tell you exactly what they use and where you might be able to pick a gallon or two.

[patrick hubbell]

Kuwayne, welcome to the world of karting.

Both clutches have their good points and bad.  I do not have much experience with the Steel Nitro. I do have a lot of experience with the L&T though.  The L&T is an engineering marvel, simple and it works but does require maintenance. the L&T is best at .028 air gap and is checked with a feeler gauge. The main difference is the Steel Nitro’s  method of engaging the clutch is to push the discs together.  It is better, more consistent to pull the discs together. When the L&T first hit the market it was  a 1/2 second faster than any other clutch. If you choose to run the L&T, replace the lever arm pins aka ‘dog bones’ every 3 to 4 race days, use only L&T clutch oil. The adjustment of the stall speed is opposite that of a Steel Nitro. Check with L&T for this procedure.  In the day, we use to refer to the Steel Nitro, as the ‘Steel Grenade’ because they would blow up all the time. If any part inside of a steel nitro failed it would destroy the clutch, whereas the L&T would keep on going.  I had lever straps break, dog bones break and a disc delaminate. Never affected any of the other components.   Maybe  I just got lucky.

[patrick hubbell]

Lawrence, lots of good questions.  pop-off should be more like 9 to 10. I would look for an experienced kart shop and have the inspect the carb to be sure it’s legal. 16K, never seen a KT turn that many revs.  At least not for long.  CHT is almost useless by it self. To many variables. Get EGT if you can. I have to go, will continue later.

[patrick hubbell]

As far as engine builders, go with someone local to you. This may get you track side help. Woltjer Racing Engines carried me to many wins including my first Duffy.

 

Engines: Older is better when it comes to Yamaha’s.  They used better casting techniques. The cases were stronger and flexed less than the new ones.

[patrick hubbell]

Sure it can.  Check with the track/club rules first.

[patrick hubbell]

I had an Arrowax6 that would lift the inside front exiting certain corners.  Nothing wrong with it.   Best handling kart I ever drove.

[patrick hubbell]

I would go with the pipe. A good RLV A2, you will have more fun when the clutch locks at 10,000 rpm. The non-sense that a pipe will cause increased engine wear is not true at least in my experience.

The can mufflers have a couple of problems. First there is a baffle plate inside the can. Notorious for cracking. A cracked inner plate is a DQ. Two, They don’t help to scavenge the exhaust gasses. Because they don’t help to evacuate the gasses they have a tendency to load up with fuel making it difficult to start the next time your on the grid.

The expansion chamber(pipe) helps scavenge the exhaust gasses. Yes there is more maintenance. You will need a good clutch too. I prefer the L&T 3 disc 4 spring or 6 spring.

 

[patrick hubbell]

There are quite a few kart shops in NorCal.

Cambrian Kart is a good one, Lots of inventory. Located in Campbell. (408)377-kart

R&C Kart Shop, located in Gilroy.(408)842-3060

Fastech Racing. Located in Marina(Monterey area) Probably the beat prices and customer support of all the kart shops.  (831)375-5529

Bob Snow, located in Milpitas. (engine builder)408-5770597

NorCal kart sport, located in Portola Valley. Arrow kart dealer.650-851-0454

Ron White. CRG dealer located in San Jose.  (408)844-8998

[patrick hubbell]

Thanks Gif, A copy just wouldn’t be the same.  That would like making a copy of a Duffy.  This is one of the few items left on my bucket list.  After 9 years, it’s probably a door knob or something.

Thanks.

[patrick hubbell]

Have you replaced the lever strap pins yet? Also referred to as “dog bones”.

My opinion is the L&T is the best clutch. They do require more maintenance than a Horstman . Also, require more internal set up.  Always use the factory oil.  This nonsense with using ATF is wrong.

[patrick hubbell]

You shouldn’t need Teflon tape to seal any part of the carburetor.  It is normal for the needle to pop once and then leak down.  You have a Mychron and are able to download data, excellent. All you need is EGT and you are set.

Why EGT over CHT.  EGT responds instantly to changes in temperature. CHT responds much slower to changes in outside temperature, casting type, pipe etc. When tuning with EGT, you always want the temp to be increasing to some unknown maximum and it should increase quickly as soon as you open the throttle. Start with the “L” speed needle set at 1-1/2 turns and the “H” needle at 1/4 turn.

Note: the low speed circuit feeds gas to the engine up to 12,000 rpm then the high speed circuit opens and both high and low are feeding the engine.

Once the engine is up to temperature, open the “L” needle to 1-3/4. As you get close to the end of the longest straight, the engine may be to rich and loose power. This is called “four cycling” and sounds like “blaaaaaa” open up the H needle an 1/8 turn more, if the engine is still 4 cycling then lean the “H” needle 1/8 turns at a time until the engine runs crisp all the way down the straight. If the engine is lazy off the corners , richen the “L” an 1/8 turn.  If the engine is stil lazy then you might have to adjust the pipe’s length, the gear ratio or the stall speed of the clutch.

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