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Discussion Starter · #1 ·
Here is the second go around.
Not too much externally from round one.
Its a 558 now with stock cam.
Runs good 56 hp and 41 tq peak. Tons of power soon, not too much late (thanks to the cam). We have 8/07 and a custom ubercam coming as we speak.
The case is apart and the crankis getting stroked and our new billett cylinders with 100mm+ are being developed. Thats right, billett cylinders with nicasil linings and over 100 mm bores. We are testing tall and standard height cylinders. We are cooking up a 650cc set up. Of course we have to see how long it takes us to break it then we can sell it.
We had Barker help us with the initial testing of drag pipes. We modified some 660R pipes to fit and so far so good. We will be doing more testing soon, including in frame duner pipes, in frame drag pipes and out of frame drag pipes. We will have a complete exhaust line available soon.
We have some pretty cool new stuff coming out soon.

Anyhow we took it 300' racing at a local Idaho race. It was about .2 off the fastest all motor yfz's there, but we gave up about 100 pounds at least to that bike. We still have not even tried a different gear or tire pressure.
It turned 85" 16 extremes no problem.
Its going to be a fast machine once we get it all figured out.
 

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56 / 41 with a stock cam, gads....... let that bad boy breathe and it's gonna rip n tear......

billet cylinders; there be a queue of dirt bikers bangin on your door cause the tall KTM SMR jugs and the european stuff is $$$$$$
 

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kiwi-craig e-mailed me a heads up on your post about large cylinders. you are trying to make billet cylinders? over 100mm? some kind of ktm crank? 78mm stroker? are the cylinders the same as ktms? factory 100mm is $1,200 retail. aftermarket up to 103.5 are $1,500 or so. available now. limiting factor is the crank as it spreads when lots of hp put through it. the new ktms are stroke restricted in the case design to keep you from stroking the engine. I can post ktms picture book for the dealers last year showing an engineering computer drawing showing the forces spreading the crank which eats the roller bearings. the new motors are ball bearing to help this problem but the load capacity is 1/2 of the roller and the ball bearings are much more damaged by dirty oil versus the roller. which is why the new motors are limited so far to 510cc's. my lc4 620 has giant roller bearings and rod bearing versus the rfs motors. this is old news to the supermoto folks. how do you make it live? don't rev it. what? you heard what I said. those who do not learn histories lessons are doomed to repeat them. I have 3 613's and two 565sx's and 1 510 and two 483's and 1 453 and 1 400. 8/07 cams and dragging the heavier atvs is cool but remember it must come apart from 20 to 80 hours depending on how lucky you are. ktm does not sell rfs stroker cranks anymore because of the failure rate is you rev it and add compression. mine are set up to be tractors low rpm cams. keep the compression down and weld the crank pin on the clutch side so it does not twist. the factory 72mm crank is fairly low build quality as the rod is soft and the interference fit between the crank pin and web half is fairly loose. the stroker had a harder rod so use it if you are making your own stroker and tighten the press fit on the pin like the factory did on the stroker. good oil(motul 15-50 300v) is mandatory. billet? not the problem. crank is. billet crank would help where the pin is on the clutch side web one piece as factory ktm race cranks are made this way$$$$$. throw away when you need a rod kit. bob
 

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Discussion Starter · #4 ·
kiwi-craig e-mailed me a heads up on your post about large cylinders. you are trying to make billet cylinders? over 100mm? some kind of ktm crank? 78mm stroker? are the cylinders the same as ktms? factory 100mm is =000005306,200 retail. aftermarket up to 103.5 are =000005306,500 or so. available now. limiting factor is the crank as it spreads when lots of hp put through it. the new ktms are stroke restricted in the case design to keep you from stroking the engine. I can post ktms picture book for the dealers last year showing an engineering computer drawing showing the forces spreading the crank which eats the roller bearings. the new motors are ball bearing to help this problem but the load capacity is 1/2 of the roller and the ball bearings are much more damaged by dirty oil versus the roller. which is why the new motors are limited so far to 510cc's. my lc4 620 has giant roller bearings and rod bearing versus the rfs motors. this is old news to the supermoto folks. how do you make it live? don't rev it. what? you heard what I said. those who do not learn histories lessons are doomed to repeat them. I have 3 613's and two 565sx's and 1 510 and two 483's and 1 453 and 1 400. 8/07 cams and dragging the heavier atvs is cool but remember it must come apart from 20 to 80 hours depending on how lucky you are. ktm does not sell rfs stroker cranks anymore because of the failure rate is you rev it and add compression. mine are set up to be tractors low rpm cams. keep the compression down and weld the crank pin on the clutch side so it does not twist. the factory 72mm crank is fairly low build quality as the rod is soft and the interference fit between the crank pin and web half is fairly loose. the stroker had a harder rod so use it if you are making your own stroker and tighten the press fit on the pin like the factory did on the stroker. good oil(motul 15-50 300v) is mandatory. billet? not the problem. crank is. billet crank would help where the pin is on the clutch side web one piece as factory ktm race cranks are made this way$$$$$. throw away when you need a rod kit. bob
Thanks for the info.
We are working on a solution to the crank issue.
We will be using a different rod and pin its all going to be new.
Hopefully it can work.
 

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Kam

The case will be very thin around the cylinder for the large bore cylinders. I have a billet cylinder made up right now but I dont think the market will alow me to make money selling them. Its just a very specialized market. Also the cranks do have some problems spreading but you can make them live with a little bit of setup work.
 

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Kam

The case will be very thin around the cylinder for the large bore cylinders. I have a billet cylinder made up right now but I dont think the market will alow me to make money selling them. Its just a very specialized market. Also the cranks do have some problems spreading but you can make them live with a little bit of setup work.

need to see a case from a quad but if it similar to my rfs cases I can post picture of the case modifications necessary for strengthening the 108.5mm hole in the necessary for a thick walled cylinder with a large enough and long enough skirt to fully support the piston at the bottom of the stroke and thick enough not to deflect under heavy loads. the euro 103 cast cylinder/piston setup is around $2,000. how much would your billet piece be? second photo is a 107.50mm hole that was originally 103.50mm and the welding in the camchain tunnel from strength and to stop the base gasket from weeping. last photo show the support at the bottom of the stroke by the cylinder bob
 

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need to see a case from a quad but if it similar to my rfs cases I can post picture of the case modifications necessary for strengthening the 108.5mm hole in the necessary for a thick walled cylinder with a large enough and long enough skirt to fully support the piston at the bottom of the stroke and thick enough not to deflect under heavy loads. the euro 103 cast cylinder/piston setup is around ,000. how much would your billet piece be? second photo is a 107.50mm hole that was originally 103.50mm and the welding in the camchain tunnel from strength and to stop the base gasket from weeping. last photo show the support at the bottom of the stroke by the cylinder bob
bob when we had my motor apart i must say that there were significant case differences. we had a set of bike rfs cases there to compare them too, but unfortunately no camera to take pics... not only were they a lot deeper, but the webbing was much beefier than the bike cases; the oil passages were also larger and different. i will see if i can get josh woessner from lonestar ktm to chime about the specific differences as it was done up at his shop.
 
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