196 degrees on the exhaust is quite a lot, you are getting into road-racing territory with regards to the exhaust, I'm not 100% sure its the right thing for an enduro bike, having said that I guess the power valve helps calm it down. I used to run a Lectron but they seem to allow dirt into the engine, I think its down to the way that there is a vertical split in the carb, look out for dust on the back of the slide, if you see it then dirt is going into your motor, it will take out the mains, big end and the bore! I now run a STIC setup but that's a different story. I also skim heads, I run around 40 thou squish clearance, I have opened up the bowl so I'm running around 12.8:1 CR, not as high as in the video but then again I run pump fuel. (based in the UK, its moderately crap fuel!) Only on the later heads does it open up extra waterways when you skim the heads, I leave them open, from memory the earlier head already has them fully open anyway.
The mod to the powervalve keeps basically the same curve, just adds 1000rpm on top at the same torque.. if you have the powervalve set right. which for me on the dyno was red with 3 turns in with this setup
Well, one of the ways for maxing combustion engine power is make the power high in narrow useable range, that is how forcing the charge of in combustion chamber air compression pressure typicaly works with simple charging devices and typical two stroke bike has 2 of so called charging systems in engine one is intake air pre compression chamber the second might be exhaust gasses resonant cam timing synced pressure wave directing chambers , some factors that increase the energetical output sum (heat) of the combustion process decrease availability range of such power to output, it has to do with laminar/turbulent aerodynamic flow's characteristics dependences of each and with turbulent flow its reallt getting abstract to accurately predict repercussions
@@galanonim563 I understand how you can maximize engine power at the expense of other things such as the width of the powerband, the thing is you have to take into consideration what the engine is going to be used for, this is why I mentioned the fact that 196 degrees on the exhaust is getting into road race territory. In my past I road raced (TZ350) and I now own an enduro bike (KTM 300 EXC), I can tell you for sure that the TZ engine or its power characteristics would not make for a good enduro engine!
How much compression are you running? I have a 2006 KTM 300 shifter kart , we doubled the base gaskets to raise all the porting and completely changed the squish to achieve a road racing power band. When it was stock it had too much torque spinning the wheels out of the turns, it also pushed real bad making it hard to drive, the other thing and one of the hardest things to figure out was the shifting, the motor would not shift under a load just like the other 250 KTM motor I had, I tried shift interrupts they didn't work because of vibration. The heart of the problem was the detent spring not having enough preload, the de tent was not grabbing the shift drum unless you lifted all the way.I'm curious about the lectron, I'm running a taper bored 39 1/2 pwk, it runs great but could always use more over rev. Karts are different than Moto or enduro your on the gas for long periods. I was thinking about a Vortex ignition but knowbody has any data for karts which means risking the motors life. I also played around with reeds the motor came stock with the RAD valve, I had boyesen make some custom stiffer reeds but initally I had the V Force and my motor builder told me not to run them I did anyways and the motor inhaled them in 2 hours, reciently I just had V Force make me some custom reeds much stiffer and waiting to test them when it cools down. Do you have any ideas? Where would you set the power valve I am using the red spring, The kart rips always looking for some more mid and over-rev. Thanks!
Very informative and good video! I think the same ideas work on a 250 cc to? Also, if you want more peak power, should you do the timing fix the other direction?
should work yep. never tried timing the other way #2 setting retards it a bit and takes some power out of the whole curve when we tried it, so i wouldnt go any farther that way
Do we rise the exhaust port top ege for 2.5mm and then we grind the valve to fit the new port height, or..........do we just grind the ehaust valve for 2.5mm and leave the exhaust top edge as it is?
@@user5428 the name of the game here is getting more travel out of the ex flap. And then raise the main port of the cylinder to match the new height that you can get the powervalve up to. Take the powervalve assembly apart and see where the top surface of the main flap contacts the cylinder to prevent it from traveling farther up. You can remove material from this area to get more travel. Two ways of doing it. either grind the bump stop on the cylinder smooth, or grind a rectangular recess into the top of the powervalve flap that will accept the bump stop into it.
I'm sorry, but does he say to just grind the pad on the power valve so it opens to the maximum and then grind the exhaust port to match the higher position of the powervalve, or does he say to grind 2-2.5mm of the top edge of the port and then grind the pad of the power valve so it matches the higher port edge?
@@1901-d6x How do you decide when you are at the correct jetting? Because i tried going from 165 all the way to 185, and there is no 4 stroking at the full throttle. The only noticable difference is in fuel consumtion. But i get the highest top speed with a 172.
196 degrees on the exhaust is quite a lot, you are getting into road-racing territory with regards to the exhaust, I'm not 100% sure its the right thing for an enduro bike, having said that I guess the power valve helps calm it down. I used to run a Lectron but they seem to allow dirt into the engine, I think its down to the way that there is a vertical split in the carb, look out for dust on the back of the slide, if you see it then dirt is going into your motor, it will take out the mains, big end and the bore! I now run a STIC setup but that's a different story. I also skim heads, I run around 40 thou squish clearance, I have opened up the bowl so I'm running around 12.8:1 CR, not as high as in the video but then again I run pump fuel. (based in the UK, its moderately crap fuel!) Only on the later heads does it open up extra waterways when you skim the heads, I leave them open, from memory the earlier head already has them fully open anyway.
The mod to the powervalve keeps basically the same curve, just adds 1000rpm on top at the same torque.. if you have the powervalve set right. which for me on the dyno was red with 3 turns in with this setup
Well, one of the ways for maxing combustion engine power is make the power high in narrow useable range, that is how forcing the charge of in combustion chamber air compression pressure typicaly works with simple charging devices and typical two stroke bike has 2 of so called charging systems in engine one is intake air pre compression chamber the second might be exhaust gasses resonant cam timing synced pressure wave directing chambers , some factors that increase the energetical output sum (heat) of the combustion process decrease availability range of such power to output, it has to do with laminar/turbulent aerodynamic flow's characteristics dependences of each and with turbulent flow its reallt getting abstract to accurately predict repercussions
@@galanonim563 I understand how you can maximize engine power at the expense of other things such as the width of the powerband, the thing is you have to take into consideration what the engine is going to be used for, this is why I mentioned the fact that 196 degrees on the exhaust is getting into road race territory. In my past I road raced (TZ350) and I now own an enduro bike (KTM 300 EXC), I can tell you for sure that the TZ engine or its power characteristics would not make for a good enduro engine!
@@sidecarbod1441 in enduro the most important part is the driver ;)
How much compression are you running? I have a 2006 KTM 300 shifter kart , we doubled the base gaskets to raise all the porting and completely changed the squish to achieve a road racing power band.
When it was stock it had too much torque spinning the wheels out of the turns, it also pushed real bad making it hard to drive, the other thing and one of the hardest things to figure out was the shifting, the motor would not shift under a load just like the other 250 KTM motor I had, I tried shift interrupts they didn't work because of vibration. The heart of the problem was the detent spring not having enough preload, the de tent was not grabbing the shift drum unless you lifted all the way.I'm curious about the lectron, I'm running a taper bored 39 1/2 pwk, it runs great but could always use more over rev. Karts are different than Moto or enduro your on the gas for long periods. I was thinking about a Vortex ignition but knowbody has any data for karts which means risking the motors life. I also played around with reeds the motor came stock with the RAD valve, I had boyesen make some custom stiffer reeds but initally I had the V Force and my motor builder told me not to run them I did anyways and the motor inhaled them in 2 hours, reciently I just had V Force make me some custom reeds much stiffer and waiting to test them when it cools down.
Do you have any ideas? Where would you set the power valve I am using the red spring, The kart rips always looking for some more mid and over-rev. Thanks!
Very informative and good video! I think the same ideas work on a 250 cc to? Also, if you want more peak power, should you do the timing fix the other direction?
should work yep. never tried timing the other way #2 setting retards it a bit and takes some power out of the whole curve when we tried it, so i wouldnt go any farther that way
So few reactions, although it is so interesting.
Do we rise the exhaust port top ege for 2.5mm and then we grind the valve to fit the new port height, or..........do we just grind the ehaust valve for 2.5mm and leave the exhaust top edge as it is?
@@user5428 the name of the game here is getting more travel out of the ex flap. And then raise the main port of the cylinder to match the new height that you can get the powervalve up to.
Take the powervalve assembly apart and see where the top surface of the main flap contacts the cylinder to prevent it from traveling farther up. You can remove material from this area to get more travel. Two ways of doing it. either grind the bump stop on the cylinder smooth, or grind a rectangular recess into the top of the powervalve flap that will accept the bump stop into it.
@1901-d6x thank you for your reply
I'm sorry, but does he say to just grind the pad on the power valve so it opens to the maximum and then grind the exhaust port to match the higher position of the powervalve, or does he say to grind 2-2.5mm of the top edge of the port and then grind the pad of the power valve so it matches the higher port edge?
I would grind the recess in the powervalve flapper first to get more range, then match your cylinder to it
👍👍@@1901-d6x
Just noticed in your shorts that you use an engine Dyno. What HP would that be at the rear wheel? (If you had one😁)
@@vech400 not sure of the losses sorry
What is the power increase with the power valve mod
You hold peak torque another 1000rpm or so. So do your math based on that
@@1901-d6x holy shit u can get lot of horsepower out of these 300
for low effort power can i only grind the side power valve sprocket things?
sry not sure exactly what you mean
@@1901-d6x i am looking to make extra top end power without making it run on racing gasoline. any tips?
Who in alberta would you reccomend i send my cylinder to too get ported
Split Second Ralph or Tom (Mot's)
How much would you expect to go up in jetting from this?
@@vhjvbhjb5280 a lot. I think I had a 4-3 or a 3-3 in my lectron with a stock motor and went up to a 7-3 for this setup
@@1901-d6x How do you decide when you are at the correct jetting? Because i tried going from 165 all the way to 185, and there is no 4 stroking at the full throttle. The only noticable difference is in fuel consumtion. But i get the highest top speed with a 172.
@@vhjvbhjb5280 read your plug
B9es or B9eg
Is the better plug to run
@@250race plugs are plugs man. They all make the same power as far as I’ve seen. The iridium’s maybe last a bit longer.
@1901-d6x
No there not bud.
Just like spark is spark?
Do u lose torque or gain torque in this setup
gain tq all the way through.
What year is this cylinder?
17-19