[Jim White]

I too have access to an automotive spin balancer and have wondered the same thing.

[Jim White]

I’m only a 4 cycle guy once a year when I get asked to drive in the Syd White 4 hour enduro.

What I’ve seen and experienced for 3 years now is ignore the rev limiter. Gear for the fastest lap time regardless. This event is held on a sprint track in Monterey and everyone is on the rev limiter half way down the one long straight. This is both with the LO206 and the World Formulas. On this tight track it produces the best times since you are much quicker through the tight stuff.

[Jim White]

Nice column David.

I like your idea of getting the fathers involved in road racing. I’ve always felt that road racing needs to go after more of the middle aged karter. That guy who is tired of getting bashed and crashed and getting whipped by the hot shoe kid at the sprint track. You need to get him on the big track before he just says screw it and sells his stuff. Most of the time these guys have more expendable income to finance a road race program whereas the younger guys don’t. More often than not if you can get this demographic to and on track they are usually hooked. As much by the racing as by the camaraderie of the paddock. It’s a different world from sprinting.

[Jim White]

Find a 34mm Dellorto. Get a 175 inlet needle and a Dellorto fuel pump. As for jet size I don’t know.

[Jim White]

Registration closes Wednesday at midnight. Get your entries in now!

[Jim White]

Throttle response will be greatly improved with a smaller carb.

[Jim White]

You can get down to around 89-90 db with a 14 or 16 inch silencer. They are out there because guys have shown up at Laguna with them.

[Jim White]

If you are still looking at building a B stock with Horstmans’ I’m pretty confident the brass will work fine for the tracks around here.

On my Yamaha sprinter I needed the tungsten to get up the hill at Fernley back in the day. The Reedjet powered sit up pulled the hill just fine with brass.

[Jim White]

I’ve been using the string method for years. It’s cheap and accurate when done properly. I’m amazed that more people don’t do it that way.

[Jim White]

I stand corrected. The race is on the new West track as stated. The configuration however is yet to be decided. I’m sure opinions from the practice day will help to make the decision.

[Jim White]

What you have is cross weight. You can probably get pretty close by simply lowering the right front spindle one washer. That will probably add 3 to 5 lbs to the right front and left rear. If that’s not enough then raise the left front spindle one washer. Your chassis probably has a little bit of twist in it which is somewhat normal for a used chassis. Many times the twist can be easily taken out but will usually return if you run predominantly at the same track.

[Jim White]

This next race is on the “new” West track in its original configuration. We are not racing on the newly installed bypass. This next race is not on the original Thunderhill 3 mile East track.

I have organized an open practice day on the west track Tuesday Sept 29th from 9-4. We will be running the original west configuration in the morning and testing the new bypass section in the afternoon.

PM me for more info if interested.

[Jim White]

Chris if your kid can get around ORP he can get around anywhere. The new West track has ample run off. Not much to hit. It’s kind of a small ORP in some ways. It has 3 pretty tight (for a road course) corners at the end of the lap. The cool part of them is there is a rising bending fast corner between the first two.

The bypass I’m sure was created to try to make the car racers happy. It eliminates the 3 tight corners. and ties in to make the front straight longer. It will make the avg speed faster but take away some of the technicalities of the original course.

Either way it’s a great kart track. I’m looking at putting together a practice day on it at the end of the month. Unfortunately it will be a weekday but the turnout last time was pretty good.

[Jim White]

I wasn’t sayin to run leaner at all. I just said it looked pretty close in my opinion. I just wondered why a sprint engine needs to run richer. And as I said I’m not arguing. I’m just trying to get more educated and exploring why that is.
My view would be that optimum power is optimum power. Regardless of what kind of track you are on. The only difference I see is going quickly through the power band many times a lap on a sprint track vs long extended heat building pulls when road racing.

[Jim White]

As I haven’t sprint raced in years I’m curious why you say that Walt. And I’m not bashing or arguing here :-) Just wondering the reasoning behind that thought. Is it because you go through the rpm range so much quicker and the load is different?

[Jim White]

I’d have competent builder look that guy over. 16 hours is a lot on a yammie. It may not need a total rebuild but as said above if it goes boom its going to cost way more to fix. Preventative maintenance is the key to both power and longevity.

[Jim White]

I roadraced Yamahas for 20 years. The last few using the carb trigger to lean the hi needle down the straightaway. I ran 110 with 8oz of oil like you did. Not sure how it compares to sprint racing but many times I ran over 450 head temp. Looking back at some data I see one race where I ran 14 consecutive 3 mile laps between 470 and 500 and with egt in the high 1200’s with no damage. I also only used CHT as a reference and actually tuned using EGT. I could always tell when it was running it’s best. Not so much from the gauge but at top RPM the fins just gave off a distinctive ring that told me it was happy.
That being said, in my opinion your flex color is pretty close to ideal. In the top picture of the header on the engine you can see what’s known as the wet line. Some people tune off the length of it. Once again it’s another reference to look at and learn from. I would be happy when mine looked like yours does. You also said you were turning some of your best lap times. That also leads me to believe you were in a pretty good state of tune. Now when you are running that close to the edge you have to be careful. Depending on weather those settings may be too lean some days and even still too rich on others. This all also relates only to the fuel you ran that day. Go back to pump gas or whatever and it all changes.
As you sound to be new to this I would probably be safe and follow others advice and richen it just a tad as you learn, but now you do know the feel and sound of having a pretty good tune. As you learn more you will eventually get a little greedy and stick one. My engine builder told me along the way that I would (and did) eventually stick one. But he also said that’s not a bad thing. At some point you have to find the limit so you know how far you can go.
I would be highly surprised if you damaged anything although running near the edge also lessens piston and bearing life as you are making more power. I would probably at least pop the head and check out the bore and piston crown (the color of which is another tuning aid). I would always do that after every race regardless.
Now that just my opinion…you’re mileage may vary :-)

[Jim White]

The “same” carb on both? Or the same “type” carb? No 2 walbros are the same in the way they tune. There are some better than others. When you find the “one” you will know it.
You need to learn to tune on the fly. All the fast guys do it. Personally I would lean the low down for the start and then open it up as you get up to speed.
An older fart than I used to say “tuning is tough” he was correct. It’s one of the more important things that separate the guys in front from the guys in back.

[Jim White]

It sounds like it’s loaded up.  The clogged screen would hurt most at high rpms not just lugging around.

Leaning the low would help but like said above you have to remember to open it back up. It’s all about tuning and knowing how to keep the engine cleaned out.

[Jim White]

It’s been a while but last time I got some it was from Comet. Came in a sheet.

[Jim White]

Make sure you check your REAR tire circumference. Any stagger in the rear will create a pull down the straight. At some tracks its advantageous to run a little stagger but for the most part you want both rear tires as close to the same as possible. I’m thinking that’s the problem. Especially if it was sitting with one tire flat and one still holding air.

[Jim White]

Did the new builder rebuild the carb too? You say you are running his settings but how do those compare to what you used to run? A slight change in pop off can effect the needle settings. I’ve only run a walbro on a Yamaha but it was never a set it and forget if you wanted to be fast. I’d be looking there. Slightly rich will kill RPM’s every time.

[Jim White]

Never could make contact. I found what I needed at Averill Racing stuff in Michigan. Costs a little more than Pierre but way less than from KFP direct. The guy at Averill doesn’t have part numbers and such but since I knew mine it was no problem. He said he’s work with others as needed to get what you need. He may need a tracing of the pad in order to get the right thing for you. He was pleasant to deal with.

[Jim White]

The pit area at the West track isn’t nearly as big as Willow Springs. We’ll all be together.

[Jim White]

Greg I sent you an email.

Yes, you can just show up. Registration will be from 8-9. Checks will be made payable to me. We will go green a little after 9. Lunch 12-1 and then green again till 4.

 

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