RK TEK Head Review- KTM 250 EXC

[@OxxidCZ]

This is so underrated channel! Very good, keep it up man! I love your content:)

[@TokyoOffroad]

Thanks for the positive feedback. I have lots of new video ideas in the pipeline...

[@OxxidCZ]

@@TokyoOffroad I think an interesting video could be modifying MX bike to suit enduro riding... Something like SXF 350 and softening the suspension, adjusting the gearing, lowering compression ratio, smoothing the power output, adding fans, etc... MX bikes are a lot cheaper in europe and many people would buy them for casual enduro riding.

[@bradspm9at]

This is the first time i've heard your bike lug low down. The low down pull is perfect for this type of riding.

[@sonoma314]

I had RK Tek cut their patten in the stock head of my 300xc, it made a significant difference in power, no lie that you can climb in a higher gear, back to back comparison on the same hills. Also burns cleaner, so I know the combustion is better.

[@JF32304]

It's not the pattern, it's merely more material in the combustion chamber hence... More compression.

[@handyman6366]

Thank you so much for all of your video !! From france !

[@rajkirannatarajan9276]

When ordering a head for KTM’’s on their site you have to specify which octane gas you plan to use. I’m guessing higher octane rated heads have smaller clearances to the piston at top dead center because higher octane gas won’t detonate at higher compressions.

[@TokyoOffroad]

Yes, as a general rule the higher the engine compression the higher the octane fuel required to prevent detonation. The RK Tek heads for sale on the Tokyo Offroad webshop can be used from sea level to 10,000ft with pump gas. I personally use premium pump gas which is 100 RON (equivalent to about 93, or 94 RON+MON/2).

[@billybob1773]

RK TEK heads/inserts look to have very rough surface finish on the combustion chamber, a lot of tool chatter with an obviously fine cutter, makes me wonder how much carbon they collect comparatively. Your videos are are excellent and interesting

[@TokyoOffroad]

Thanks for the positive feedback regarding the videos. I checked with RK Tek and the surface finish is not tool chatter, but deliberately machined that way and is patented. There is no carbon build up.

[@billybob1773]

@@TokyoOffroad Interesting, thanks for the reply

[@ngrnomad3514]

@Tokyo Offroad - Can you do a video or quick write-up explaining the difference between the XC-W TPI and the EXC TPI as they pertain to Japan only. I really get confused when watching the US channels and they explain it as they seem to have different applications for the bikes. Here in Japan, I noticed that both the XC-W and the EXC are available for sale. The XC-W seems to be a few hundred dollars cheaper when compared to the EXC (brand new). Are both bikes road legal?

[@TokyoOffroad]

In Japan only the 250 EXC TPI is road legal. The 250 XCW TPI is mechanically exactly the same, but has a different wiring loom, switch gear and no turn signals or mirrors. Considering the price difference is only 49,000yen I think the EXC is better, especially when you consider used resale value.

[@moonzy11]

Just ordered this for my 2021 250XC...My apologies...I didnt realize you sold it!!!.....I feel obligated to buy some other stuff from you to make amends !!! ;)

[@TokyoOffroad]

No worries. I'm sure you'll love the RK Tek head. If you have any questions about other products please don't hesitate to contact me: www.tokyooffroad.com/contact/

[@moonzy11]

@@TokyoOffroad Thank you!

[@pervono]

So to make a 250cc like a 300cc you need a new head RK TEK and a Stick for the carbie, would it not be better off just buying the 300cc as the cost are now getting very close? Why all the mods to the 250cc?

[@TokyoOffroad]

Yes, if I'd wanted a 300 I would have bought one, or put a 300 kit on my 250. But my goal has never been to make my 250 in to a 300. I love the free revving and response of the 250. The mods I have made take nothing away from those characteristics, but add more power, even better response and broader power band. It's a lot of fun to ride.

[@charlesgutscher1923]

Adding some mods to a 250 is a good mix. You get good torque like a 300, but keep the revvy playful nature of the 250.

[@IcemanSam650]

BrokenSkull 2025 Rotating mass is a thing, plus the 250 has the best of both worlds. Light, nimble, more than enough power.

[@pervono]

Thanks for your time on this as I now understand. It might be something I look at when I get my next bike as I have a 300cc two stroke now.

[@kobybenyakar4714]

Any chance for a video on brake caliper repair?

[@youtubeaccount9058]

Hi Tokyo I appreciate your videos. May I ask what would be the advantage to buying the head from you vs. RK directly?

[@TokyoOffroad]

Thanks for your interest. You could save on shipping if purchasing with other items offered on the Tokyo Offroad Webshop

[@mt1885]

Hi Tokyo Offroad - where you buy the squish band tool at?

[@TokyoOffroad]

I bought the shape tracing tool about 25 years ago at an arts and crafts store

[@mt1885]

@@TokyoOffroad Thank you Tokyo Offroad! : )

[@NirHason]

That's really nice that you can get your hand that easy on parts like that! A side question, how frequently do you change the gear transmission oil (according to KTM 40 hours which I think it's too much)?

[@TokyoOffroad]

Nir Hason - I typically change my transmission oil every 20H or sooner. It’s quick, cheap and easy to do and without doubt better to do regularly.

[@NirHason]

@@TokyoOffroad Tnx for that. Your tool sure makes life easier for this task but it's a bit pricey IMO :)

[@TokyoOffroad]

@@NirHason - Yes, I understand that the Tokyo Offroad Oil Drain Tools (and other tools) are not cheap, but I personally hand make the tools out of solid 6061 aluminum on a manual lathe. It takes quite a while for me to make one tool. I use top quality parts including NBR o-rings, silicone hose and UV resistant zip ties to ensure long life. It would be difficult for me to make the tools for any less than I currently do.

[@NirHason]

@@TokyoOffroad I understand that :) And the tools' quality is visible in the videos. BTW do you know why there is no way to send you KZbin IM? :)

[@TokyoOffroad]

@@NirHason - I think KZbin discontinued the private messaging service back in the summer. If you'd like to chat with me please contact me using a private message on the Tokyo Offroad Facebook page. facebook.com/tokyooffroad/

[@noriyukikawata5636]

Can you please tell me carburetor setting directions with high comp head? I would like to know the difference between the standard carb setting and the high comp setting. Because I'm in trouble with S3 head jetting direction. Engine idle instability, and breathing when throttle closing (open -> close) (feel lag in down rotation)

[@TokyoOffroad]

河田教之 - What bike (model and year) and what carb do you have?

[@noriyukikawata5636]

@@TokyoOffroad 2017 Beta X-trainer 300 with std carb (Keihin PWK) + Slavens S3 AA Head + Boano Race Pipe X-Trainer just installed jet kit with Boano Race Pipe ( Slow 38, Main 160 Needle N2ZW )

[@pervono]

Thanks for clearing that up, I now understand. Keep up the good work.

[@250race]

Did you squash your motor out? If you did I would like to know what it is on both domes?

[@TokyoOffroad]

No, x-dimension is stock setting.

[@JohnVanHolt]

Does increasing the compression significantly reduce the longevity of the top end before a rebuild?

[@TokyoOffroad]

That has not been my experience. My first top end overhaul I did at 145H and the piston, rings and cylinder looked in good shape (140 of those hours was with the SX head).

[@AuMechanic]

@john van holt The main parts under more load from higher compression is the piston and crank bearings, more power = more load on them (meaning check them for wear every top end rebuild). In engines with cast pistons it's a good idea to move to a forged piston if you are going to raise it a lot from stock and a head with more pronounced squish band (like the new head in the video) to shorten the distance the flame travels that reduces potential for detonation. With increases in CR the power increases throughout the RPM range that may mean you don't have to rev it as much to get usable power which can offset the wear a bit considering that an increase in RPM exponentially increases wear in particular to rings and piston.

[@iainhutchinson345]

I fitted the RK head you sent me, wow! What spark plug are you using?

[@TokyoOffroad]

I use the stock specified BR7ES

[@TokyoOffroad]

Pleased that you like the RK TEK head and thanks for your business.

[@iainhutchinson345]

@@TokyoOffroad Just been out for a spin, I really need to put the GET traction control on, and set it to 11. I am having the Bike Dynoed early June. It feels like a lot more power than my Modified 2020 FX 350.

[@hpenduro000]

What upgrade would you performe first on a 2018 xcw 250 carb model, rk tech head or fmf gnarly pipe??

[@TokyoOffroad]

Out of head, or pipe mods I think the most gain will com from the head, so my recommendation is to fit an RK Tek head first. I really like the FMF on my 17 KTM 250 EXC too and of course the Keihin 38mm PWK Air Striker + STIC performs great (broad linear and responsive power).

[@hpenduro000]

@@TokyoOffroad Thanks for your response👍 Your youtube channel is one of the best out there in the dirt bike world👌

[@V8AC]

Do experience and spark knock with this head? I tried the S3 from Jeff Slavens and not even race gas and two steps colder plug would help. He basically told me to buy a street bike. Last dime he gets from me

[@TokyoOffroad]

No, bike runs great with this head. I use Premium pump gasoline which here in Japan is 100 RON. Riding elevation is from sea level to 2000m.

[@V8AC]

Tokyo Offroad thanks for the reply. I’m using 93 octane (r+m)/2. I tried VP Racing 105. I’m still perplexed at what the problem was. Anyway I’m going to call RK Tek and try theirs

[@kirkthepimp1]

V8AC ya man Jeff is a ass hole I’ll never buy from him again either rk tek is a way better head anyway!

[@BradHale]

So same compression as SX head but pulls harder and can run a gear higher?

[@TokyoOffroad]

Yes. It's not just compression, but also the head shape which affects performance. As shown in the video the SX and RK Tek head shapes are completely different designs.

[@Wathappn2u]

Just wondering on jetting. What would I need to change if anything

[@TokyoOffroad]

That would depend on how your bike is running currently and personal preference. I like my bikes to run slightly rich as they typically lug much better and run cooler.

[@Wathappn2u]

@@TokyoOffroad I don't wanna lean it out by putting the head on it and hurt it.

[@TokyoOffroad]

@@Wathappn2u - Yes, I understand. The bottom end you should be able to fine tune just using the airscrew. With the RK Tek head on start with the airscrew 1/4 turn in from where you currently have it set. And change the main jet for one size larger. Then test it and see how it feels.

[@akrider174]

Would this be an upgrade to my 19 250sx with a stock high comp head?

[@TokyoOffroad]

Yes, the combustion chamber shape is completely different from the SX head, as I showed in the video. The RK Tek head is an optimized design. Cooling of the head is also improved.

[@akrider174]

Tokyo Offroad ok thanks for the info, will the low end be improved as well at all? And you are a dealer for rk now?

[@TokyoOffroad]

@@akrider174- Yes, the RK Tek heads lug really well too and pull right the way though to the top. Yes, I stock RK Tek heads on the Tokyo Offroad Webshop and am happy to ship worldwide: www.tokyooffroad.com/product-category/rk-tek/

[@mt1885]

Hi Tokyo Offraod what Oil do you run in your KTM?

[@TokyoOffroad]

I use Motorex Crosspower 2T two stroke oil.

[@mt1885]

@@TokyoOffroad Thanks!

[@jjoeabhn2526]

Are planning to do a botom end overhaul anytime soo

[@TokyoOffroad]

I’m planning to do a bottom end overhaul one, or two years from now. Typically these bikes will do 500H before requiring a bottom end overhaul. Right now my bike has done 290H

[@jjoeabhn2526]

@@TokyoOffroad thats guite good for a 2 stroke but you take amaizing care of yours we just rebuild them hear when they start makeing noises

[@YilgarnRallye]

so how many hours do you reckon one of these 2T could last for with regular refreshes ?

[@TokyoOffroad]

Typically people who use their 2T KTM/Huskys for off-road trail riding seem to do top end overhauls every 100~200H depending on their riding. Bottom end overhauls are a lot less frequent and it would be surprising to need to do one before 500H. The cylinder will need replating at some stage, but Nikasil is very hard and low wear so will probably last 500H, or longer, depending on how you startup, ride, oil you use and maintain the air filter. Best to measure the bore and decide. Keep up with the maintenance and the bike will last a very long time with minimal issues. These bikes are built tough and last a long time.

[@YilgarnRallye]

cool, thanks that's a lot more hours than most would expect from a 4T KTM

[@stone4858]

Just saw a video of a 250 tpi on a dyno test fitted with an after market header, it just added less then 2HP and only 2NM of torque. Honestly can't see the big fuzz about these headers, glade I did'nt spend the money 🤨

[@TokyoOffroad]

Please can you confirm whether you’re talking about a header (pipe), or head. What product was tested?

[@stone4858]

@@TokyoOffroad It a VHM Head, you can find the video here on you tube, just type ktm exc 250 tpi dyno test

[@TokyoOffroad]

Kyle Stone - Thanks, I’ll have a look. Dynos are valuable tools for measuring performance, but won’t tell you how the bike feels and responds when being ridden. Most dyno testing is done at full throttle which is not typical during normal riding. Also for most people out trail riding the peak power isn’t that important. More important is how the bike responds when you open the throttle, how well it lugs at low rpm and how it runs at partial throttle openings. I’d recommend talking to others who have tried various heads for some riding feel impressions. Yes, impressions are subjective, but if a large number of people all feel the same way you can be fairly sure something is good and that you too will probably like it.

[@TokyoOffroad]

The video I found is 9months old and a 2018 TPI was tested. Would be interesting to see the test repeated on a 2019 with the current map. Anyway, the power increase is from bottom to top and you’d definitely feel the difference when riding. Whether it’s worth it for you really depends on if you are satisfied and like the performance of the bike with the stock head.

[@stone4858]

@@TokyoOffroad The map of the 2018 and 2019 are the same, because all 2018 maps were up dated after they found they were running lean. I would really love to see a Dyno test with the RK Tech head to see if it will give more power then other heads and by how much to power will go up from stock head