I have an RK head on my 300. I think there's a large part of buying an RK head that you have not mentioned at all. You call and talk to Kelsey and custom order your RK head for your needs for your bike.. Different RK head setups are different. Some are for race gas and some not.. Some are for different elevation...some are changing port timing.. Some are more high compression than others. You talk with Kelsey about what your use will be for you and your bike and the terrain you riding in. It's different too if you are racing mx etc. In this vid you mention absolutely nothing about ordering the different setups for an RK.. at least I didn't see it. That's a huge part of getting an RK. My head setup isn't the same as just another RK head.Each is different. I've got to say that I'm super happy with my RK setup head.
Hawaiidirtrider Great point about them being customizable. This is far as I understand it from Kelsey, is simply opening up the bowl volume to lower compression at lower altitudes.
DirtGearTv Thanks for posting up though.. It’s good info. Just adding that when getting the RK talking to Kelsey will help tailor a better choice of head for the buyers needs. To me it’s essential to get his input. It’s good for people to see the order form on his website too. My 300 has more power and torque but it’s not overly aggressive in midrange like you describe. I also didn’t want that so told a Kelsey what I wanted and he gave me more what I wanted which was just more everywhere and still being smooth and linear. There’s no hard mid hit like you are describing on your bike on my 300 but just more power every where. There’s still other mods like playing with power valves too if need be if I wanted it more aggressive.
I just ordered off the site. Didnt have any options when I ordered for my 11' KTM 300. Im sure I could have customized but it was a plug and play as I understand. Worked well on my bike. Next go around im trying the S3 head with the low compression insert.
You can take the squish band down to approx .020 on a 300cc machine. Less squish equals more turbulence, more compression, less area for detonation to start. Rule of thumb, squish should be as close as possible without interference at max rpm
Very good and informative video. I have a Husky TE 250 2015 and it has now a 0.5 mm milled TC 250 head (similar to SX head in KTM`s) with squish band 1.2 mm. It has also TC 250 CDI box and one step colder spark plug like TC 250 has (now 8 vs. 7 NGK heat range) and I changed water/glycolene mix for just distilled water with Red Line Water Wetter to improve cooling. It is not suitable for winter use anymore because no glycolene and no antifreeze. I use normal pump gas 98 RON. With these mods and correct jetting no detonation problems. I have drilled four 1” holes to the left hand side panel so it gets more air as these Huskys are more ”asthmatic” than the KTM`s because of more restricted air boxes. I have changed the carb from Keihin PWK 36S to Keihin PWK 38S with better jetting. NECJ needle from RM 250, 175 Main jet, 42 pilot jet etc. There is also V-Force 4 reed cage in it. I`m still waiting for Bill`s Pipes exhaust so I can test with this TC 250 head it first. I have a RK Tek head I will install next when I have first tested that Bill`s Pipes exhaust with TC 250 milled head. I hope RK Tek head and Bill`s Pipes exhaust will give me even more linear torque and power. I still use yellow power valve spring but will test the red spring later. When I take my cylinder off next time I will install Wiseco Racers Elite 1-ring piston to it. I will do a few small things to cylinder also but not change the port timing. Only small mods like in Jeff Slavens good ”porting” video. So far my mods to this TE 250 have been very good. It definitely improves the power/torque when doing all of this: drilling those four 1” holes to side panel to improve airflow, change larger carb with correct jetting 36 => 38, V-Force 4 reeds, TC 250 head milled 0.5 mm and TC 250 CDI etc. It feels already like a whole different bike but I hope Bill’s Pipes full exhaust system, RK Tek head and Wiseco Racers Elite 1-ring piston and my small cylinder mods + red exhaust spring will give even bigger change. I want it to have more power/torque at the whole rpm range not just top end. How much more fuel do you think it needs with RK Tek head vs. milled TC/SX head? I have now 175 main jet and have 178 and 180 to try. NECJ needle clip is now in 3rd position = middle. I have also NECD needle that should be half a clip richer. So NEDJ in 3rd clip postion is like NECJ in 3.5 position. With RK Tek head it should benefit from more fuel.
Janne P Good Job with the current mods! I also tried the suzuki needles and they worked fine but I did end up going back to the ktm needles myself as I founds ktm to run slightly more consistent for me. The red spring on a 250 makes a huge difference, your gonna love the top end with it, i’m sure the exhaust will help too. It’s really difficult to say where the jetting should goto next since you’ve swapped carbs and have other mods but I like to start with mains, idles and then figure out my needle for the best transitions. I haven’t run the RKTek on a 250 but i’m sure it’s gonna rip. I probably would not have gone to a 300 if I had all the mods your doing. 300 is great for low end though 👍
Thanks! It will be interesting to see how next mods will improve performance. I hope the red power valve spring is not too wild for other than wide open throttle motocross riding. But I can also adjust the power valve screw for my taste if it gets too hard to ride it. I measured today my RK Tek heads squish band just from the combustion chamber edge and it is around 0.90-0.95 mm. I have piston level at TDC. There is marking ”13.5” in the combustion chamber insert. I will ride also at sea level.
Red spring alone isn't unwieldy, it just pulls harder up top. If I could start from scratch Id have the 250 with RkTek head and red spring with your mods. RKTek on the 300 is just a bit much for me personally but on a 250 it should be amazing!
I was riding today for the very first time my 250 with the RK-Tek head. It has very good torque and power at low rpm and mid range. I am just doing a small break in for that 1 ring Wiseco piston so no high rpm use yet. I have still my original FMF factory pipe. I have changed red auxillary power valve spring and also softer main power valve spring with coil diameter of 1.8 mm. Power valve adjuster set flush with the cover. When I had my cylinder off I polished exhaust side and aligned the exhaust flange. I set Z dimension for std 48.0 mm but I had to raise my cylinder to get X dimension to zero 0.0 mm with that Wiseco Racers Elite piston. I have now 0.5 mm and 0.4 mm base gaskets so total of 0.9 mm. With Vortex piston piston was 0.2 mm below cylinder top at TDC with 0.7 mm base gasket. This Wiseco has higher compression height. But now with the raised cylinder I have an advantage as transfer ports open fully at BDC and main exhaust port opens almost fully at BDC. So I have more duration but also very tight piston to head clearance (1.00 mm actually when measured accurately). I have now 178 main jet, 45 pilot jet, NEDJ 3rd clip, AS open 2 turns. I changed my mixture ratio from 50:1 to 32:1 to have better lubrication and piston ring seal.
Janne P Nice! Sounds like your tuning quite the runner. This is exactly what I wish I had done to my 250 rather than the 300 conversion. The 300 is fine but something about how lite a modded 250 2T is pretty magical. For what it’s worth, keep in mind you can’t follow ktm recommended jetting specs at 32:1, not that you need to but jetting is a bit tougher since you’ll need to run richer with the extra oil is taking the place of fuel 👍
Great review and as a owner of a TX300 with this head I think it's spot on! I'm a slow technical trail rider and found that I really had to add some fuel to feel the difference with the RK Tek head. I can now ride 1-2 gears higher but have to be careful not to grab too big a handfull of throttle in the really technical sections. The only downsides for me were 1: Fuel consumption, I'm hitting reserve at 30 miles with my Keihin 36mm n8rg needle in the 3rd 42p 175m at 1000'. 2. Spooge, I'm getting tons of spooge and plugged up silencer packing in 20hrs (Maxima 50:1)
@@DirtGearTv I'm running this head on my '19 TX300. Love it! Richened my Mikuni a little with it & bike is a rocket! Using the red spring & my experience with it is it's very controllable, more twist, more go. Pulls 3rd gear hills in 4th easily & 1st rarely used unless obviously starts or very slow going--stock gearing. Btw, for the Mikuni users, my jet block gasket looked just fine but I put a .020" one from JD & boy did it improve throttle response. Stock one must've been leaking by. Last few rides mpg has been lower to mid 30s, a little lower than my previous 300s but I guess one pays for the increased power sometimes, (maybe twisting more)?
EXACTLY what I experienced, except I didnt even have the SX head just a cut OEM XC head to correct the squish, I didnt touch the bowl. It had stump pulling torque down low. Went to a RK Tek and lost bottom, but mid and top improved. I will be selling the RKtek head and putting the original modified head back on.
Well done video and very informative. I have a 2016 ktm 250 xcw and want more low end. I primarily ride mild enduros (family) and harescrambles, but would like to dabble into some hard enduro type events. I would like more responsiveness in that 1/4 throttle pull, right off the bottom. Not worried about top end, but would hate to lose any mid range. I have an SX head that came with the bike (not currently on it) and would like to try it out. Wonder if I should see how it does with no mods first? Please let me know what you think and might recommend. Thanks again
Hey buddy Im looking to mod my head till I do rebuild this winter at which ill do the RK head / gasket… what did you do to the bowl did you take off just some of the roundness so it more like the RK? ( tapered ) What did you use to Remove the material from the bowl. thx
Bro I can tell your a rider. Love your approach. I can't believe that cost 350 bucks my buddy has one on his xcw. I smoke him all the time in str8s. I have an xc. Love my bike I put a smart carb on it and scalvini exhaust wow bike gives trills.
Dale Whitehurst Thanks! On these bikes I like to shoot for a squish between 1.1-1.3mm as long as you are not exceeding 210psi or you’ll begin to have deto issues. If it’s the 1.9mm my SX was stock i’d test your head pressure with no less than 1.5-1.6mm at first to make sure you don’t go too far. I had to cut more bowl volume on my SX to reach the 1.2mm i’m running, you may or may not have this same issue with the XC head
@@DirtGearTv .... Thanks for the reply , I like the 300 but not sure if it will right for it after what you said about it's crazy power. I like power but need it to suit the riding.
GhostHammerX It’s hard to describe but it sounded better with the RK-tek. It just sounded more “stout” with a metallic snap to it, if that makes any sense. Kind of the difference between a mild vs wild cam on a V8
So I came hear on a search for RK tek review, but I have a 2020 YZ250x. Great bike, great chassis and suspension, but like any 250 lacks power down low. I tried a Gnarly and it took more from the top than it gave to the bottom, so I am thinking an RK Tek head to provide that low end boost. What are your thoughts about this on a 250?
95jersey Absolutly on a 250! Honestly, if it’s low end you want a modified SX head with 210psi will provide that, the RK will get you close to that without having to mod it yourself and also provide better mid and top
S3 is good in that they include different drop ins based on your altitude riding. Rk Tek you simply tell them your style and altitude and they provide a suggested drop in for your riding and location
Do it, just make sure to measure your squish during the process. I would also recommend making sure your pressure stays under 210psi. I’ve found that to be the high end before detonation will occur
Trevor G You can lap these with auto wet sandpaper. I used a coarse, mid and fine approx 420, 600, 1500 or so. I used a figure 8 pattern and and granite counter top. Glass is appropriate too if you don’t have granite.
I started with 1500 and it was taking a bit... Switched to the coarse and it came down quick so be careful. Make sure you take measurements as you go. Also, to get my squish down to where I was happy I had to dish the bowl out so I didn't get my pressure too high as to cause detonation. If you're going to go with a cut SX head, get a compression gauge. I believe 210psi was about the upper limit of what I found I could run this bike at without detonation. If you're not comfortable opening up the bowl, I would sacrifice a little bit of the corrected squish before I would exceed 210psi.
seems crazy to put a high comp head on, then dial the power back by going to green spring. Ive been riding KTM 250 2 strokes for about 5 years now and the green spring is no fun, feels like a banana in the pipe. I've been doing a lot of research on the RK tek head and planning to buy one though as I'm generally in mid range on my 250 while riding single track
Right, first you can’t compare a 250 to the 300, totally different power bands. The 250 really begs for the RK-Tek head, the 300 doesn’t need it. You are thinking that the power curve is affected the same way with adding RK-Tek as the red spring, but it’s not. Both of those mods affect different parts of the power band. Green spring +RK head is going to produce a linear power band that is so smooth it rivals a 450F. It’s all about what part of the power band is being manipulated. You will absolutely LOVE the RK on that 250! 👍
I have an RK head on my 300. I think there's a large part of buying an RK head that you have not mentioned at all. You call and talk to Kelsey and custom order your RK head for your needs for your bike.. Different RK head setups are different. Some are for race gas and some not.. Some are for different elevation...some are changing port timing.. Some are more high compression than others. You talk with Kelsey about what your use will be for you and your bike and the terrain you riding in. It's different too if you are racing mx etc. In this vid you mention absolutely nothing about ordering the different setups for an RK.. at least I didn't see it. That's a huge part of getting an RK. My head setup isn't the same as just another RK head.Each is different. I've got to say that I'm super happy with my RK setup head.
Hawaiidirtrider Great point about them being customizable. This is far as I understand it from Kelsey, is simply opening up the bowl volume to lower compression at lower altitudes.
DirtGearTv Thanks for posting up though.. It’s good info. Just adding that when getting the RK talking to Kelsey will help tailor a better choice of head for the buyers needs. To me it’s essential to get his input. It’s good for people to see the order form on his website too. My 300 has more power and torque but it’s not overly aggressive in midrange like you describe. I also didn’t want that so told a Kelsey what I wanted and he gave me more what I wanted which was just more everywhere and still being smooth and linear. There’s no hard mid hit like you are describing on your bike on my 300 but just more power every where. There’s still other mods like playing with power valves too if need be if I wanted it more aggressive.
I just ordered off the site. Didnt have any options when I ordered for my 11' KTM 300. Im sure I could have customized but it was a plug and play as I understand. Worked well on my bike. Next go around im trying the S3 head with the low compression insert.
You can take the squish band down to approx .020 on a 300cc machine. Less squish equals more turbulence, more compression, less area for detonation to start.
Rule of thumb, squish should be as close as possible without interference at max rpm
VERY technical and thorough review!! Extremely informative! Thanks!
Very good and informative video. I have a Husky TE 250 2015 and it has now a 0.5 mm milled TC 250 head (similar to SX head in KTM`s) with squish band 1.2 mm. It has also TC 250 CDI box and one step colder spark plug like TC 250 has (now 8 vs. 7 NGK heat range) and I changed water/glycolene mix for just distilled water with Red Line Water Wetter to improve cooling. It is not suitable for winter use anymore because no glycolene and no antifreeze. I use normal pump gas 98 RON. With these mods and correct jetting no detonation problems.
I have drilled four 1” holes to the left hand side panel so it gets more air as these Huskys are more ”asthmatic” than the KTM`s because of more restricted air boxes. I have changed the carb from Keihin PWK 36S to Keihin PWK 38S with better jetting. NECJ needle from RM 250, 175 Main jet, 42 pilot jet etc. There is also V-Force 4 reed cage in it.
I`m still waiting for Bill`s Pipes exhaust so I can test with this TC 250 head it first. I have a RK Tek head I will install next when I have first tested that Bill`s Pipes exhaust with TC 250 milled head. I hope RK Tek head and Bill`s Pipes exhaust will give me even more linear torque and power. I still use yellow power valve spring but will test the red spring later. When I take my cylinder off next time I will install Wiseco Racers Elite 1-ring piston to it. I will do a few small things to cylinder also but not change the port timing. Only small mods like in Jeff Slavens good ”porting” video.
So far my mods to this TE 250 have been very good. It definitely improves the power/torque when doing all of this: drilling those four 1” holes to side panel to improve airflow, change larger carb with correct jetting 36 => 38, V-Force 4 reeds, TC 250 head milled 0.5 mm and TC 250 CDI etc. It feels already like a whole different bike but I hope Bill’s Pipes full exhaust system, RK Tek head and Wiseco Racers Elite 1-ring piston and my small cylinder mods + red exhaust spring will give even bigger change. I want it to have more power/torque at the whole rpm range not just top end.
How much more fuel do you think it needs with RK Tek head vs. milled TC/SX head? I have now 175 main jet and have 178 and 180 to try. NECJ needle clip is now in 3rd position = middle. I have also NECD needle that should be half a clip richer. So NEDJ in 3rd clip postion is like NECJ in 3.5 position. With RK Tek head it should benefit from more fuel.
Janne P Good Job with the current mods! I also tried the suzuki needles and they worked fine but I did end up going back to the ktm needles myself as I founds ktm to run slightly more consistent for me. The red spring on a 250 makes a huge difference, your gonna love the top end with it, i’m sure the exhaust will help too. It’s really difficult to say where the jetting should goto next since you’ve swapped carbs and have other mods but I like to start with mains, idles and then figure out my needle for the best transitions. I haven’t run the RKTek on a 250 but i’m sure it’s gonna rip. I probably would not have gone to a 300 if I had all the mods your doing. 300 is great for low end though 👍
Thanks! It will be interesting to see how next mods will improve performance. I hope the red power valve spring is not too wild for other than wide open throttle motocross riding. But I can also adjust the power valve screw for my taste if it gets too hard to ride it. I measured today my RK Tek heads squish band just from the combustion chamber edge and it is around 0.90-0.95 mm. I have piston level at TDC. There is marking ”13.5” in the combustion chamber insert. I will ride also at sea level.
Red spring alone isn't unwieldy, it just pulls harder up top. If I could start from scratch Id have the 250 with RkTek head and red spring with your mods. RKTek on the 300 is just a bit much for me personally but on a 250 it should be amazing!
I was riding today for the very first time my 250 with the RK-Tek head. It has very good torque and power at low rpm and mid range. I am just doing a small break in for that 1 ring Wiseco piston so no high rpm use yet. I have still my original FMF factory pipe. I have changed red auxillary power valve spring and also softer main power valve spring with coil diameter of 1.8 mm. Power valve adjuster set flush with the cover. When I had my cylinder off I polished exhaust side and aligned the exhaust flange. I set Z dimension for std 48.0 mm but I had to raise my cylinder to get X dimension to zero 0.0 mm with that Wiseco Racers Elite piston. I have now 0.5 mm and 0.4 mm base gaskets so total of 0.9 mm. With Vortex piston piston was 0.2 mm below cylinder top at TDC with 0.7 mm base gasket. This Wiseco has higher compression height. But now with the raised cylinder I have an advantage as transfer ports open fully at BDC and main exhaust port opens almost fully at BDC. So I have more duration but also very tight piston to head clearance (1.00 mm actually when measured accurately). I have now 178 main jet, 45 pilot jet, NEDJ 3rd clip, AS open 2 turns. I changed my mixture ratio from 50:1 to 32:1 to have better lubrication and piston ring seal.
Janne P Nice! Sounds like your tuning quite the runner. This is exactly what I wish I had done to my 250 rather than the 300 conversion. The 300 is fine but something about how lite a modded 250 2T is pretty magical. For what it’s worth, keep in mind you can’t follow ktm recommended jetting specs at 32:1, not that you need to but jetting is a bit tougher since you’ll need to run richer with the extra oil is taking the place of fuel 👍
Great review and as a owner of a TX300 with this head I think it's spot on! I'm a slow technical trail rider and found that I really had to add some fuel to feel the difference with the RK Tek head. I can now ride 1-2 gears higher but have to be careful not to grab too big a handfull of throttle in the really technical sections. The only downsides for me were 1: Fuel consumption, I'm hitting reserve at 30 miles with my Keihin 36mm n8rg needle in the 3rd 42p 175m at 1000'. 2. Spooge, I'm getting tons of spooge and plugged up silencer packing in 20hrs (Maxima 50:1)
PrimalEnduro Thanks for the feedback those are excellent points!
@@DirtGearTv I'm running this head on my '19 TX300. Love it! Richened my Mikuni a little with it & bike is a rocket! Using the red spring & my experience with it is it's very controllable, more twist, more go. Pulls 3rd gear hills in 4th easily & 1st rarely used unless obviously starts or very slow going--stock gearing. Btw, for the Mikuni users, my jet block gasket looked just fine but I put a .020" one from JD & boy did it improve throttle response. Stock one must've been leaking by. Last few rides mpg has been lower to mid 30s, a little lower than my previous 300s but I guess one pays for the increased power sometimes, (maybe twisting more)?
Have you tried Motul 710 and air screw adjustments to help with spooge?
EXACTLY what I experienced, except I didnt even have the SX head just a cut OEM XC head to correct the squish, I didnt touch the bowl. It had stump pulling torque down low. Went to a RK Tek and lost bottom, but mid and top improved. I will be selling the RKtek head and putting the original modified head back on.
Well done video and very informative. I have a 2016 ktm 250 xcw and want more low end. I primarily ride mild enduros (family) and harescrambles, but would like to dabble into some hard enduro type events. I would like more responsiveness in that 1/4 throttle pull, right off the bottom. Not worried about top end, but would hate to lose any mid range. I have an SX head that came with the bike (not currently on it) and would like to try it out. Wonder if I should see how it does with no mods first? Please let me know what you think and might recommend. Thanks again
Nicely done... I'll prob get one and try it out. Picking up my new XC when it arrives this week.
NECJ and NEDJ are the needles not NECD. It was just my typo and mistakenly wrong written...
Hey man thanks for this video it was very well done.
What number is stamped on your insert?
Hey buddy Im looking to mod my head till I do rebuild this winter at which ill do the RK head / gasket… what did you do to the bowl did you take off just some of the roundness so it more like the RK? ( tapered ) What did you use to
Remove the material from the bowl. thx
I like to know what the SX and RJ weights?
Bro I can tell your a rider. Love your approach. I can't believe that cost 350 bucks my buddy has one on his xcw. I smoke him all the time in str8s. I have an xc. Love my bike I put a smart carb on it and scalvini exhaust wow bike gives trills.
Really good vid! I learn SO much from this channel! What type of wet sandpaper did you use on the head?
nutnboujee I start with a 320grit to take off most of the material and finished it with a 600grit till it’s niceeeeee and smooootttthh
Great video !
Ive got a 2017 ktm 300xc & was thinking of modding the standard head squish , what squish mesurement would you recommend ? Thanks
Dale Whitehurst Thanks! On these bikes I like to shoot for a squish between 1.1-1.3mm as long as you are not exceeding 210psi or you’ll begin to have deto issues. If it’s the 1.9mm my SX was stock i’d test your head pressure with no less than 1.5-1.6mm at first to make sure you don’t go too far. I had to cut more bowl volume on my SX to reach the 1.2mm i’m running, you may or may not have this same issue with the XC head
Great honest vid, Q - KTm have a torque spec for the head bolts (35 Nm), doesn't this automatically give you the correct squish factor? Cheers
It gives ktm's oem squish, but not necessarily the optimal squish
Will a RK TEK head work on a 2020 KTM 300 TPI ? Not carb
Ringo Gingo Yes absolutely, have a buddy who had a 250tpi and loves his RK-Tek
@@DirtGearTv .... Thanks for the reply , I like the 300 but not sure if it will right for it after what you said about it's crazy power. I like power but need it to suit the riding.
Did you notice any more engine vibration when you added the SX head?
sethcal88 I didn’t notice any more vibration, but there is a change in the exhaust note
Do you sell your RK Tec Head?Send me a mail
@@DirtGearTv how did the exhaust note change? Can you give me an example?
SHADOW WALKER TM I sold it
GhostHammerX It’s hard to describe but it sounded better with the RK-tek. It just sounded more “stout” with a metallic snap to it, if that makes any sense. Kind of the difference between a mild vs wild cam on a V8
So I came hear on a search for RK tek review, but I have a 2020 YZ250x. Great bike, great chassis and suspension, but like any 250 lacks power down low. I tried a Gnarly and it took more from the top than it gave to the bottom, so I am thinking an RK Tek head to provide that low end boost. What are your thoughts about this on a 250?
95jersey Absolutly on a 250! Honestly, if it’s low end you want a modified SX head with 210psi will provide that, the RK will get you close to that without having to mod it yourself and also provide better mid and top
@@DirtGearTv Since it is a YZ I cant put an SX head on it, but I will probably go with the RK
95jersey Right, I missed that part 😜 Curious what a yz250 head has for psi (untouched) have you tested yours?
@@DirtGearTv around 180-185
My friends yz250 is way too powerful off idle.. What am I missing here?
What about the S3 head from slavens racing?
S3 is good in that they include different drop ins based on your altitude riding. Rk Tek you simply tell them your style and altitude and they provide a suggested drop in for your riding and location
S3 was nothing but problems for me. All pining and detonation and putting up with Slavens “holier than thou” attitude
Im thinking about shaving my TE 250 head🤔
Do it, just make sure to measure your squish during the process. I would also recommend making sure your pressure stays under 210psi. I’ve found that to be the high end before detonation will occur
@@DirtGearTv i just want a little bit grund back i lost stepping down to a 250. i'd go to 1,25mm squish should be fine isnt it?
RunnerFX abc 1.2mm is best
@@DirtGearTv 2017 models included? I'm not sure if i should get a sx head or shave my stock one in case i dont like the power delivery
What method did you use to shave the SX head?
Trevor G You can lap these with auto wet sandpaper. I used a coarse, mid and fine approx 420, 600, 1500 or so. I used a figure 8 pattern and and granite counter top. Glass is appropriate too if you don’t have granite.
@@DirtGearTv I appreciate the response, I will try it! How long did it take you? I have to take off .93mm to get to 1.2mm squish.
I started with 1500 and it was taking a bit... Switched to the coarse and it came down quick so be careful. Make sure you take measurements as you go. Also, to get my squish down to where I was happy I had to dish the bowl out so I didn't get my pressure too high as to cause detonation. If you're going to go with a cut SX head, get a compression gauge. I believe 210psi was about the upper limit of what I found I could run this bike at without detonation. If you're not comfortable opening up the bowl, I would sacrifice a little bit of the corrected squish before I would exceed 210psi.
seems crazy to put a high comp head on, then dial the power back by going to green spring. Ive been riding KTM 250 2 strokes for about 5 years now and the green spring is no fun, feels like a banana in the pipe. I've been doing a lot of research on the RK tek head and planning to buy one though as I'm generally in mid range on my 250 while riding single track
Right, first you can’t compare a 250 to the 300, totally different power bands. The 250 really begs for the RK-Tek head, the 300 doesn’t need it. You are thinking that the power curve is affected the same way with adding RK-Tek as the red spring, but it’s not. Both of those mods affect different parts of the power band. Green spring +RK head is going to produce a linear power band that is so smooth it rivals a 450F. It’s all about what part of the power band is being manipulated. You will absolutely LOVE the RK on that 250! 👍