Stock appearing kt100

With the many differnt definitions of eyebrow .
Arching the top of the port or cutting the port at an angle to get the increased port height/ time duration ?
There is also eybrowing the piston .
Raising the overall port height would that be considered eyebrowing ?
 
With the many differnt definitions of eyebrow .
Arching the top of the port or cutting the port at an angle to get the increased port height/ time duration ?
There is also eybrowing the piston .
Raising the overall port height would that be considered eyebrowing ?
I consider eyebrowing arching and/or widening the exhaust port around toward and above the rear transfer ports. I have never cut on the piston above the ring. I like to keep my squish uniform. The only piston eyebrowing I know to do is to cut on a 4-cycle piston to give the intake & exhaust valves room to open for high lift camshafts.

Brian #89
 
Al,

Have you actually tested this on a KT100?

PM
Personally, on the KT100, no.
There are people who I know that do. Mark Zartarien is known to have built illegal counter waited KT100's. Kyle Atkins is known to have built piston port engines with counterweights added. Jeff Nelson was disqualified after winning the 200 cc class at the IKF Induro Nationals with Atkins built engines. I personally did the break-in on those engines. While one was very strong, I noticed a tuning problem on the other. Turns out the lead was coming out of the hole it filled. Atkins used lead while Zar used tungsten. I've seen TKM stock piston port cranks with what looked like inserts in the crankshaft.
A driver I was mentoring was beat at the San Diego clubs yearly championship by a Zar built KT100. That was before I'd heard about his engine being disqualified at the Nationals in Oregon.
 
Al,

Are you aware that a Hi-Rev engine was DQ'd many years ago at the RR nationals for having the crankpin filled with weight? I suppose it's possible that the crank could have been weighted not only opposite the pin, but *at* the pin as well, simply to increase crank inertia.

Have you checked balance factor on any of the engines that were apparently weighted?

I guess my comment would be... simply stating "add counterweight to the crank" is a bit of a crap shoot if the balance factor is not known to begin with.

PM
 
Good day Pete hope all's going well for ya I was standing next to Loui Figone at tech in Portland when he showed me the tungsten on the inside of the crank opposite the crank pin and also was heavier than stock that's how they found out by scaling new and his, there were other visible signs also. Makes them run good as the RPM increases.
 
I guess my comment would be... simply stating "add counterweight to the crank" is a bit of a crap shoot if the balance factor is not known to begin with.

PM
You're absolutely right, as always, still, people have been adding weight to the crankshaft without knowing what they were doing for many years. Myself included. Gil Horstman made the counterweights that I used in my McCullough, they seem to work out, maybe he did the math. Maybe Mark did the math before adding weight to his Yamaha crankshafts? Maybe Kyle Atkins too. In any case, it seems to have been beneficial.
 
Ok, if you were stroking a KT, do prefer to use a long KT rod or a shorter European rod? I know from building race car engines in the past, a longer rod is preferred to change the area/timing of the fuel charge going into the combustion chamber.

I know what I would do just want to hear others thoughts/opinions.

Ok, GO!

Brian #89

(Why do I keep coming back here? I'm supposed to be working on my yz250 build)
 
Refresh the ol memory :)
With the recent question about kt rods .
I would say European as i assume its stronger plus no spacer plate so looks totally stock .
 
Since you all are talking about open kt100's, 25 years ago we ran one summer at Slippery Rock against the open kt100 engine Dave Turner built for Cort's kart.

It was sold to I think the name then was Brad who had it on his red UAS type side board kart but if i'm remembering Brad correctly he never ran it much if any with the UAS. The kart was red side boards and all and it was kept up very well.

We ran second in points that year to it with our gas and oil stock( built by Donald Rati per the notes he bought on building yammi's from Dave) yammi and could make up time on him in the corners but he'd run away from us on the straights.

Per Dave 25+ years ago it had internal reed valves from a motor cycle engine he found would work. He told me the engine he got them from a few times but I don't remember its name.

What else was done to it that he may have told me I don't know.
Sure would be fun to have that old engine.
 
I was told this was a turner but who knows
 

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I've got a couple of these but, no reed valves. It does have a special WB3A on it. I liked the carb so well, I had it copied so now I have 2.

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Brian #89
 
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