Need more power for my crf 250m

[gordon from yasothon]

need some advice in getting more power out of my new bike i going to get a new exhaust. thinking a yoshimura and a power commander but dont know any place that sells them and are they a hassle to install??? and what else can i do to the bike??

any advice would be greatly welcomed..

cheers

gordon

[paz]

Sorry to sound like a biker magazine readers letters section, but the fact is that with "simple mods" you will not get much more power (1 or 2 HP at the most) out of a today's fuel injected engine. But the bike will be more noisy and use more fuel, and you may end up placing thing back as they were. Also from what I know, your bike comes unrestricted already, so there is no easy trick to play first.

Here's why:

- "performance" exhaust on a small displacement, non-tuned 4 strokes engine does very little. The job of the exhausth is to pull out as much spent gases as quick as possible, because the engine is turning fast and/or a lot of fresh mixture need to take its place in the chamber. What happens, is that in a not-tuned engine, there is never a lot of "fresh mixture".

- "custom ECU" also will do little. What it does is try to trick the factory ECO to alter the fuel/air ratio in certian ranges to give more grunt, in that sense it can be effective for some low torque, but not for peak power. The reason is that peak power is reached with a lean mixture, and that is exactly what the factory ECU does, for the sake of emission testing, and fuel usage.

Now, the two things above would instead be very needed once the following is done first:

- Engineered airbox. First and foremost power factor is chamber pressure, that's why turbo kicks ass. On a naturally aspirated engoine one can get slightly above 1 atm with special air intakes, unfortunately these are not really effective at slow speeds like a street bike likely goes more often.

- Top end rebuild. Here things gets interesting, and really expensive. Special parts are hard to get, and labour must be performed to exceptional levels to be effective and not destroy things. Usually one starts from the top end, with a complete head port, head skimming, also the throttle body gets ported according to the specific goals (torque or peak power). Add the usual custom cams (try two or three profiles before getting the right one), and of course a big bore kit is also a must (if available, otherwise just a racing piston with short mantel and two rings only), as well a restroking kit.

Then if you are sick enough and with too much money you will start working the bottom end. Titanium conrods, skimmed and polished crank, skimmed flywheel, hi-speed bearings, then lightening work on clutch and gears.

All that considered, my best advice for more power on a bike that is unrestricted alreadys, is to buy more bike.

Edited September 23, 2013 by paz

[denkiblue555]

As said, if you are looking for more than a few ponies it would be far cheaper to buy more bike.

The D-Tracker/KLX at least have the BB kit options, but I am not aware of any for the CRF yet - maybe 'Athena' will do one?

[paz]

Engine parts for the CBR250R would work

http://www.motorbeam.com/bikes/honda-cbr250r/raceconcepts-enhances-performance-of-the-honda-cbr250r/

But for head/throttle body must be ported too.

Edited September 23, 2013 by paz

[taninthai]

apparently on the 250 l changing the ecu and throttle body to the same as the cbr 250 is suppoosed to be a great improvement, dont know how different the 250 L and m are really engine wise,whats your top speed showing crf 250l will show 140 and cbr 250 i believe shows around 160

[Martin54]

Go and have a look at the 250L forum on ThumperTalk.

[paz]

Go and have a look at the 250L forum on ThumperTalk.

Work list for that bench? Because 32% power and 45% torque increase is a lot for N/A engines.

[piston broke]

Sorry to sound like a biker magazine readers letters section, but the fact is that with "simple mods" you will not get much more power (1 or 2 HP at the most) out of a today's fuel injected engine. But the bike will be more noisy and use more fuel, and you may end up placing thing back as they were. Also from what I know, your bike comes unrestricted already, so there is no easy trick to play first.

Here's why:

- "performance" exhaust on a small displacement, non-tuned 4 strokes engine does very little. The job of the exhausth is to pull out as much spent gases as quick as possible, because the engine is turning fast and/or a lot of fresh mixture need to take its place in the chamber. What happens, is that in a not-tuned engine, there is never a lot of "fresh mixture".

- "custom ECU" also will do little. What it does is try to trick the factory ECO to alter the fuel/air ratio in certian ranges to give more grunt, in that sense it can be effective for some low torque, but not for peak power. The reason is that peak power is reached with a lean mixture, and that is exactly what the factory ECU does, for the sake of emission testing, and fuel usage.

Now, the two things above would instead be very needed once the following is done first:

- Engineered airbox. First and foremost power factor is chamber pressure, that's why turbo kicks ass. On a naturally aspirated engoine one can get slightly above 1 atm with special air intakes, unfortunately these are not really effective at slow speeds like a street bike likely goes more often.

- Top end rebuild. Here things gets interesting, and really expensive. Special parts are hard to get, and labour must be performed to exceptional levels to be effective and not destroy things. Usually one starts from the top end, with a complete head port, head skimming, also the throttle body gets ported according to the specific goals (torque or peak power). Add the usual custom cams (try two or three profiles before getting the right one), and of course a big bore kit is also a must (if available, otherwise just a racing piston with short mantel and two rings only), as well a restroking kit.

Then if you are sick enough and with too much money you will start working the bottom end. Titanium conrods, skimmed and polished crank, skimmed flywheel, hi-speed bearings, then lightening work on clutch and gears.

All that considered, my best advice for more power on a bike that is unrestricted alreadys, is to buy more bike.

well said bloke...

[ll2]

Go and have a look at the 250L forum on ThumperTalk. 

 

 

 

 

This is significant increase with simple mods.

Anyway, even 2 hp you get from a pipe and an ecu translates into 10 percent increase on a crf 250 which i can say it is something.

Sent from my GT-N7100 using Thaivisa Connect Thailand mobile app

[BirdsandBooze]

As Thaninthai said, CBR250R ECU and throttle body is going to give you a performance boost. I think the CBR250R has nearly a 4HP advantage over the CRF250M.

[paz]

Someone posted this on anther thread and I'm just copying.

http://bestdualsportbikes.com/2013-honda-crf-250-l/

Seems quality, reliable work to me.

[gordon from yasothon]

Thank you everyone for your advice and tips I have a pretty good idea of what I need to do now so cheers and thank you......

gordon.............

[Hoopidy He Ho]

You won't get much. Keep it simple with a air filter, fuel controller and pipe. These will probably cost you 20-25% of the cost of the bike and give you around 10% more power.

Probably better to just get more bike. Look at used CBX 500's or even Er-6n's. Depending on just how rough the terrain you want to ride is.

I would probably sell it, and put the mod money into getting a used cbx.

Of course the used market now is certainly not a seller's market.

Edited September 25, 2013 by Hoopidy He Ho

[Neilly]

The D-Tracker/KLX at least have the BB kit options, but I am not aware of any for the CRF yet - maybe 'Athena' will do one?

Bill Blue does a BB kit (305cc) for the CRF-L

https://www.wheelingcyclesupply.com/shop/product/bandb-305-big-bore-kitcrf250l/712

Same kit is also available from CRF's only

http://www.crfsonly.com/catalog/product_info.php/cPath/290_292/products_id/5146

[f0xxee]

Thought I'd give this thread a bump as I have just bought a CRF 250M after always being a big bike ride (Ducati 1198, 999s, etc, still own a 900 SS and a SR400).

I love the CRF 250M: finally found a bike that makes sense on Thai back roads! Lots of fun, comfortable riding position for my middle aged old body, and even with the IRB Cross-ply supermotard tyres stick like snot to a blanket. It handles, it brakes, its bloody good straight out of the box: and with Greenbooks for Falangs becoming a necessity (or at least around HH to avoid endless harassment) it makes sense for the price. 142K baht on the road with insurance etc. (List price 139K Baht).

THE POWER ISSUE: Mine is still a bit tight with only 300k on it (I am back offshore now, home again soon) but it needs a small lift.

There are a couple of statements made above of interest: 1 agree with, the other I don't. Firstly when the engine only kicks out about 20 hp getting a 2hp increase is 10% and noticeable. Agreed. But more can be had than 10%.

Second statement was that an aftermarket exhaust and custom ECU will do little. <deleted>!!! As anyone who has modified a motorbike since around 2004 knows, manufacturers set original ECU's as lean as they possibly can by design to meet and pass rigid exhaust emission rules in the US and Europe. Custom ECU's do not "fool" the original ECU into thinking it is reading something it isn't: they reset the air fuel mixture richer across a number of parameters. Do you use more fuel? Of course! But if you use a standard ECU, remove the snorkel from the Airbox and otherwise open the air intake side, and ad an open exhaust you stand a good chance of not only loosing power but of heat seizing your piston or burning out valves too. It will lean out the mixture more than the OEM ECU has been calibrated to deal with…

SO if you ad a properly calibrated Electronic Fuel Control Module that is set to a known exhaust you can get up to about 5 hp out of the CRM 250M. Which is a good deal better than the standard package, and If you go slightly smaller on the front sprocket you can get far better torque and top end speed too. CRF's ONLY do a package with the above, which I have ordered. (Ordered a comfort seat too for my skinny old man's ass.)

SPROCKET SIZES:

According to the Manual, the Front is 14T the rear is 39T for a ratio of 2.79:1. Pretty tall gearing for a small engine.

Available sprockets I have found on Ebay:

13T Front, Standard 39 T rear for 3:1

14T Standard Front, 40 T rear for 2.86:1

13 T Front, 40T rear for 3.01;1

13T front, 42T rear for 3.23:1

I am going to buy a 13T, 40 and 42T sprocket as it gives me pretty good scope from 2.79:1 to 3.23:1 One of those will suit the exhaust and ECU best.

ANOTHER FALACY: Shorter gearing = lower top speed. Maybe so on the Ducati 1198 with its massive power, but on a 20+hp Honda 250, the tall gearing overcomes the engines ability to top out in top hear. It can't hit the revs as the gearing is too tall. I will let you know what works best for me at my huge 86kgs, and as stated have ordered the above sprockets.

There is no need for Big Bore Kits, expensive head work etc, unless you really want to go knackers out. Doing so stresses the bottom end and loses reliability etc. As someone stated, if you want that much more bang, buy a bigger bike.

Try the above, all for around 800 USD landed in Thailand, and I will be surprised if you cannot accept the 250M as a pretty good scratcher on the back roads.

[Richard-BKK]

The thing is that the injectors for the Honda CBR250R are technical compatible with the Honda CRF250L and CRF250M but the two off-road style motorcycle use a much higher fuel pressure... something the standard Honda CBR250R throttle body is not able to handle.\

Also if you find a way to make the whole thing work, using CBR250R parts on the CRF250L or M you would need a free flow exhaust pipe that would be similar to what you would use on a 450cc. Performance is up to magical numbers, but fuel efficiency is very very low you will be looking for a gas station every time you ride your bike....

[piston broke]

Thought I'd give this thread a bump as I have just bought a CRF 250M after always being a big bike ride (Ducati 1198, 999s, etc, still own a 900 SS and a SR400).

I love the CRF 250M: finally found a bike that makes sense on Thai back roads! Lots of fun, comfortable riding position for my middle aged old body, and even with the IRB Cross-ply supermotard tyres stick like snot to a blanket. It handles, it brakes, its bloody good straight out of the box: and with Greenbooks for Falangs becoming a necessity (or at least around HH to avoid endless harassment) it makes sense for the price. 142K baht on the road with insurance etc. (List price 139K Baht).

THE POWER ISSUE: Mine is still a bit tight with only 300k on it (I am back offshore now, home again soon) but it needs a small lift.

There are a couple of statements made above of interest: 1 agree with, the other I don't. Firstly when the engine only kicks out about 20 hp getting a 2hp increase is 10% and noticeable. Agreed. But more can be had than 10%.

Second statement was that an aftermarket exhaust and custom ECU will do little. <deleted>!!! As anyone who has modified a motorbike since around 2004 knows, manufacturers set original ECU's as lean as they possibly can by design to meet and pass rigid exhaust emission rules in the US and Europe. Custom ECU's do not "fool" the original ECU into thinking it is reading something it isn't: they reset the air fuel mixture richer across a number of parameters. Do you use more fuel? Of course! But if you use a standard ECU, remove the snorkel from the Airbox and otherwise open the air intake side, and ad an open exhaust you stand a good chance of not only loosing power but of heat seizing your piston or burning out valves too. It will lean out the mixture more than the OEM ECU has been calibrated to deal with…

SO if you ad a properly calibrated Electronic Fuel Control Module that is set to a known exhaust you can get up to about 5 hp out of the CRM 250M. Which is a good deal better than the standard package, and If you go slightly smaller on the front sprocket you can get far better torque and top end speed too. CRF's ONLY do a package with the above, which I have ordered. (Ordered a comfort seat too for my skinny old man's ass.)

SPROCKET SIZES:

According to the Manual, the Front is 14T the rear is 39T for a ratio of 2.79:1. Pretty tall gearing for a small engine.

Available sprockets I have found on Ebay:

13T Front, Standard 39 T rear for 3:1

14T Standard Front, 40 T rear for 2.86:1

13 T Front, 40T rear for 3.01;1

13T front, 42T rear for 3.23:1

I am going to buy a 13T, 40 and 42T sprocket as it gives me pretty good scope from 2.79:1 to 3.23:1 One of those will suit the exhaust and ECU best.

ANOTHER FALACY: Shorter gearing = lower top speed. Maybe so on the Ducati 1198 with its massive power, but on a 20+hp Honda 250, the tall gearing overcomes the engines ability to top out in top hear. It can't hit the revs as the gearing is too tall. I will let you know what works best for me at my huge 86kgs, and as stated have ordered the above sprockets.

There is no need for Big Bore Kits, expensive head work etc, unless you really want to go knackers out. Doing so stresses the bottom end and loses reliability etc. As someone stated, if you want that much more bang, buy a bigger bike.

Try the above, all for around 800 USD landed in Thailand, and I will be surprised if you cannot accept the 250M as a pretty good scratcher on the back roads.

So, having fitted the performance stuff - what diferences did you notice ???

[f0xxee]

Thought I'd give this thread a bump as I have just bought a CRF 250M after always being a big bike ride (Ducati 1198, 999s, etc, still own a 900 SS and a SR400).

I love the CRF 250M: finally found a bike that makes sense on Thai back roads! Lots of fun, comfortable riding position for my middle aged old body, and even with the IRB Cross-ply supermotard tyres stick like snot to a blanket. It handles, it brakes, its bloody good straight out of the box: and with Greenbooks for Falangs becoming a necessity (or at least around HH to avoid endless harassment) it makes sense for the price. 142K baht on the road with insurance etc. (List price 139K Baht).

THE POWER ISSUE: Mine is still a bit tight with only 300k on it (I am back offshore now, home again soon) but it needs a small lift.

There are a couple of statements made above of interest: 1 agree with, the other I don't. Firstly when the engine only kicks out about 20 hp getting a 2hp increase is 10% and noticeable. Agreed. But more can be had than 10%.

Second statement was that an aftermarket exhaust and custom ECU will do little. <deleted>!!! As anyone who has modified a motorbike since around 2004 knows, manufacturers set original ECU's as lean as they possibly can by design to meet and pass rigid exhaust emission rules in the US and Europe. Custom ECU's do not "fool" the original ECU into thinking it is reading something it isn't: they reset the air fuel mixture richer across a number of parameters. Do you use more fuel? Of course! But if you use a standard ECU, remove the snorkel from the Airbox and otherwise open the air intake side, and ad an open exhaust you stand a good chance of not only loosing power but of heat seizing your piston or burning out valves too. It will lean out the mixture more than the OEM ECU has been calibrated to deal with…

SO if you ad a properly calibrated Electronic Fuel Control Module that is set to a known exhaust you can get up to about 5 hp out of the CRM 250M. Which is a good deal better than the standard package, and If you go slightly smaller on the front sprocket you can get far better torque and top end speed too. CRF's ONLY do a package with the above, which I have ordered. (Ordered a comfort seat too for my skinny old man's ass.)

SPROCKET SIZES:

According to the Manual, the Front is 14T the rear is 39T for a ratio of 2.79:1. Pretty tall gearing for a small engine.

Available sprockets I have found on Ebay:

13T Front, Standard 39 T rear for 3:1

14T Standard Front, 40 T rear for 2.86:1

13 T Front, 40T rear for 3.01;1

13T front, 42T rear for 3.23:1

I am going to buy a 13T, 40 and 42T sprocket as it gives me pretty good scope from 2.79:1 to 3.23:1 One of those will suit the exhaust and ECU best.

ANOTHER FALACY: Shorter gearing = lower top speed. Maybe so on the Ducati 1198 with its massive power, but on a 20+hp Honda 250, the tall gearing overcomes the engines ability to top out in top hear. It can't hit the revs as the gearing is too tall. I will let you know what works best for me at my huge 86kgs, and as stated have ordered the above sprockets.

There is no need for Big Bore Kits, expensive head work etc, unless you really want to go knackers out. Doing so stresses the bottom end and loses reliability etc. As someone stated, if you want that much more bang, buy a bigger bike.

Try the above, all for around 800 USD landed in Thailand, and I will be surprised if you cannot accept the 250M as a pretty good scratcher on the back roads.

So, having fitted the performance stuff - what diferences did you notice ???

Sorry for the very long long time between responses:

OK it was worth it: The bike all of a sudden had some torque that was badly missing new from the dealer. Partly the ECU and Exhaust, but I suspect at least 50% was going to the 13T front Sprocket.

HOWEVER: after about 6 months the novelty wore off: I found myself wringing it's neck and wishing it had more poke. Also riding down to PKK from HH at 120kph showed up the weakness in the stock sussies. Everything bottoms out on potholes at 120kph.

Honestly? I would like the set up I had for getting around BKK or the city: pokey enough in the bottom 3 gears and comfortable when not challenged by speed. But in the country a 400 at least is needed.

I ended up selling it. And a car and buying a R1200GS BMW. In the end its the best bike for Thailand.

[piston broke]

Sorry for the very long long time between responses:

OK it was worth it: The bike all of a sudden had some torque that was badly missing new from the dealer. Partly the ECU and Exhaust, but I suspect at least 50% was going to the 13T front Sprocket.

HOWEVER: after about 6 months the novelty wore off: I found myself wringing it's neck and wishing it had more poke. Also riding down to PKK from HH at 120kph showed up the weakness in the stock sussies. Everything bottoms out on potholes at 120kph.

Honestly? I would like the set up I had for getting around BKK or the city: pokey enough in the bottom 3 gears and comfortable when not challenged by speed. But in the country a 400 at least is needed.

I ended up selling it. And a car and buying a R1200GS BMW. In the end its the best bike for Thailand.

R1200GS BMW. In the end its the best bike for Thailand.

mmm.......maybe you were expecting too much from a 250cc single ??

As far as the R1200 GS being "the best bike for Thiland ? - maybe on a long long road, but as soon as you are in any sort of traffic, its like trying to handle a 2 wheel bus...

And the cost with the crazy import taxes...............

Maybe the CB500X is a better all round compromise ??

[SwedeOnSamui]

Hi. I'm not reading all the tips so I don't know if someone already told you about it. Easy way is to see yourself so one link explaing them and one to order them...

(maybe better film somewhere ells, but after 0:40s is when you see it)

http://www.drpulley.info/shop/

Regards

Jacob

Edited June 26, 2015 by SwedeOnSamui

[STUDMEYER]

The thing is that the injectors for the Honda CBR250R are technical compatible with the Honda CRF250L and CRF250M but the two off-road style motorcycle use a much higher fuel pressure... something the standard Honda CBR250R throttle body is not able to handle.\

What does fuel pressure have to do with a throttle body? Curious comment...

The ONLY difference between the CBR250 throttle body and the CRF250 Throttle body is the diameter.

If you're worried about switching injectors, then don't switch injectors. The CRF250L injector fits in the CBR250 throttle body. Again, the ONLY difference is the diameter. It bolts up the same. The throttle cable links the same. The injector fits the same.

On a side note - Anyone know what chain is required for a 13/42 combo?

On another side note - I just installed a 13T front sprocket in 5 minutes. I bought it at SangChai in CM - Its in a weird hiding spot in the cornert, so better to ask the girl to get it for you. It's actually made for a CRF - not the AX1 sprocket - no redrilling, no messing around, just take the old one off, and put the new one on.