CRF 250 L vs CBR 300 R

[schrauberklaus]

Hi

I did a little bit research to compare the CBR 300 Engine Parts with the CRF 250 Engine Parts to find out what Honda change and which
CBR 300 Parts will may fit in to the CRF250 Engine to give me the posibillity to improve the Engine with newer upgraded Parts for future repairs :RE

As many of you allready know the CBR 300 has a new Crank shaft with longer 63 mm stroke to get to 286cc , thats changed obviously.

But many other Parts has changed to .

The Cylinder Head as example , details i don't know yet but the Valves are the same . Valve Springs has changed and the Rockers , Cam Shaft to to follow the engine upgrade .
The Cam Chain is the same but it get a new Cam Chain Tensioner and Lifter assy.

The Flywheel/Generator has Change and the Starter gear (68T) behind with a new Needle Bearing with a larger Out Side diameter .
The Inside Diameter of that Needle bearing is unchanged , that make me belive that the Shaft diameters on the Crank are the same to the CRF.
How ever there are also new Crank shaft bearings , so outside diameter of the shafts has to be confirmed.

Clutch has changed for differend prim. Gearing and new (stronger?) Springs and a new bushing behind the Clutch basket.

Balancer Shaft has Change with new Gears on Bancer and Crankshaft . Gears has now 35T instead of 34T on the CRF
Balancer Shaft bearings change to from 6204 to 6304 bearing (bigger Out side diameter but same inside diameter).

And for the larger bearings the Crank cases has changed to .

The Piston is new to but with the same Ring Set and Pin it must fit in the CRF Bore. The new Piston has now some kind of coting on the skirts

Cylinder Bolts are Changed but with the same dimensions and the Clutch actuater Arm and Cable Holder (differnt Frame )

Gears are of course totally different .

No change on Water and Oil Pump .

 

[Forest]

quiet interesting ,i was doing such research a while ago .keep us updated with any news! cheers!

 

[bikesncats]

Nice job Klaus...very useful information. Vielen Dank!

 

[Thump]

Lots of 250 owners are thinking of simply stroking the engine but may run into difficulties.

I'm sure that Honda is smart enough to make it quite complicated and expensive to "upgrade" from a 250 to a 300 with stock Honda parts.

Not saying that it's impossible but maybe not worth the time, effort and expense.

 

[bikesncats]

There might also be some legal issues for Honda if they made the parts so that anyone could just swap them and increase the displacement...I believe in many countries nowdays the 250cc is a class limit and above that the bike would fall into a different class (insurance included)....

 

[Thump]

The main reason of course would be lost sales...

 

[schrauberklaus]

Hi

finally i got the CRF 349 L

Parts used
CBR 300 crank and balancer shaft
CBR 250 38 mm Trottle Body
Takegawa 305 Big Bore Kit , Cylinder , Piston , Cams
FMF MB/Q4
Inovate Lamda Display with LSU 4.9 Wide Band Lamda Probe in Exhoust
API tech Stand alone fully programmable ECU
CRF 450 R Fuel Injector
Hurricane Air Filter , Box with 2 inlet Snorkels and XL600R Snorkel to the Trottle Body

Yesterday everything was installed and the first Start show immediately a Problem.
It smoked like hell .

The API ECU don't have the correct mapping (have to work on this ) but that
amount of smoke could not come from a to rich running engine .

That was oil .
And i remember immediately from were it maybe come from .

Today i check my suspicion and my findings confirm it .

The Takegawa 305 cc Cylinder is not made with the 63 mm stroke of the CBR 300 Crank in mind.

Why ???

The Takegawa Cylinder has a additional lubrication hole from the oil canal (that goes through the Cylinder up to the Head and
feed the oil to the Cam bearing ) in to the Cylinder.

I I saw the hole a few days ago as i install the Cylinder the first time , thought o.k. a additional lubrication hole, but don't thought it far enough.
That little hole is at the 55 mm stroke just below the oil rings at BDC .

Now with the 63 mm Stroke the Hole is at BDC already over the second Piston Ring.

And that the Way how the oil i saw yesterday via my endoscope camera / Spark plug hole on top of the Piston came in
and produced the heavy smoking .

Unfortunately there is no way to solve this Problem other than blocking this hole of .
Fortunately there is enough meat (8mm) , so i drill the hole to 2,5 mm , 5 mm deep and cut M3 thread .
Set a brass screw with Loctide red in and cut the Screw flat with the cylinder surface.

The hole is oil-tight now , and the engine is not smoking anymore but i can only hope that this
additional lubrication is not absolut essential for this full aluminium Cylinders .
Time will tell , my risk .

If someone has already the Takegawa Kit and think to go bigger , think twice .
Don't forget to check that hole .




Just want to let everyone know about this befor somebody try the same combination .



Second find was the CRF Air Snorkel to the Trottle Body .

The CRF Snorkel is inside 38 mm and fit to the CRF 36 mm Body depend this body is 38 mm on the inlet side .

The CBR 250 38 mm body is actual 41 mm on the inlet side and that give a sharp step and produce unwanted turbulence.

One way to solve this will be to grind the Snorkel out to 41 mm but lead to a very thin wall .



I have a hole Box of different Snorkels and find out that the Snorkel from a XL600R can be easly made to fit the CRF .

The XL Snorkel is much bigger from the inlet side but has the same oval shape and the CRF Airbox opening need to cut about

2,5 cm wider .

The connection on the Trottle body is just a little bit to small depend the Body has a sharp protrusion on the outside
where the rubber hook in . The protrusion was quickly removed and then the XL snorkel fit over the 38 mm CBR Body
(with a little coaxing and a warm handshake to the 30-year-old rubber)

Looks then like this .

Again a step , but this time the other way around depend the XL Snorkel is much bigger .
So i shape the inlet of the Trottle body like a Carburator inlet .

Now it look installed like this.

I don't know if that makes a difference , but i like it much more then the step up connection on the CRF Snorkel

 

[CraigBKK]

Interested to see how it rides Klaus.

 

[prince666]

If anyone can make it work Klaus it's you mate, be interesting to see some dyno figures after its done.
Good luck

 

[schrauberklaus]

Today i dit a first Test , just 150 m loop but it feels very strong from Idle.
More like my XR400 not like the CRF Engine befor.
But still some small Problems that need to be solved befor i can try a longer ride .

 

[schrauberklaus]

O.K. CRF 350 L done, finish

I work on the mapping for the API ECU now for more then 10 days and the Powermap is finish .

And Powerfull it is.

How much Hp i don't know , the next Dyno i know about is in Bangkok .
That may need a while to get there .
If anybody know a closer one to Phuket , please let me know .

The last days i change the Radiator depend the Engine was getting a litte hot when ideling on a red light .

So i install this .

From ebay , made in China for 130 USD with 32 mm depth nearly 1/3 thicker then the stock rad and nice quality.
Fits even with my IMS tank.

But even that rad was not able to hold the temp at a level that the Temp Warning light dosn't come on at traffic stops.
Depend the Water flow was blocked by the CRF's Thermostat and to much water was circulating over the Bypass directly back
to the Pump and get never cooled by the rad.
After i replace the Thermostat with a selfmade Alu Plug (I recommending that Mod also for Slow speed heavy Engine load with a 250 and stock Rad )
the water flow over the rad is much better and therefore the cooling to .

Its a simple swap between the Thermostat and the Plug without any drilling or what ever and the Thermostat Gasket is Rubber so no Problem to do with the same Gasket . Tell me if you want to know details .

Now the 349 Engine is running between 80-85 °C water temp. by quite more quickly runs over the roads .
Offroad i not test jet .

But i guess not much more depend the Power is so good it dosn't need much trottle to get up most of the tracks.

The steepest road here i know is maybe 40° and 350 m long . A nice sign on top say
Old Cars or inexperienced drivers please take another road

That road i can now drive easyly up in 4 gear at 4500 rpm .
And thats not with a 13 T and not with a 14 T , they are now useless .
I run now 15 T in front and 40 T in the back .
And on the flat the CRF does even with the 15 T Powerweelies .
In first its difficult to do a quick start depend the front wheel jumps right in to the air if i give a little bit to much trottle .

Honda claim for my XR400 SM 30 PS and 33 Nm of Torqe and 145 kg .
The CRF 350 has similar weight but more Power and Torqe , for sure .

And depend on the road i am mostly in 6 gear even in town the Gas consumption is at under 4L /100km with the Power Map
Thats less as i need with the modifyed 250 engine.
If the ECO Map is finish (the API ECU can do 2) i guess even less.

It was a lot of work , it had some difficultys and Problems i had to solve but is worth the time and money i spend.

 

[schrauberklaus]

O.K. , back on 349 cc .

BB Kit arrive last saturday , check clean and repaint the cylinder , lowered the compression and relieved the Piston by 12 gr.
Installation was painless , 140 km done already no problems .

And i notice now something that i was not aware of as i install the Takegawa Kit .
With the 63mm stroke of the CBR300 Crank the Piston skirt leave the bottom of the Sleeve for 3 mm at BDC.

And thats on the Takegawa (pic. middle ) and on the original CRF250l Cylinder (pic. right)
The only one where the Piston stay at BDC inside the sleeve is the BB Cylinder where the Sleeve is 4 mm longer.

No idea how it is on the CBR300 Cylinder .
My CRF run with the stock cylinder and 63 mm stroke the last 7 weeks without problems.

BB Kit installed with wiseco Piston at 11,2/1 compression .

 

[CRFMike]

Hi Klaus I am interested in some more detail about the thermostat mod you did as my CRF runs very hot at low speeds !!! Thanks for all the helpful info you have been posting. And great to meet you in Kanchanaburi last weekend.
Michael


"After i replace the Thermostat with a selfmade Alu Plug (I recommending that Mod also for Slow speed heavy Engine load with a 250 and stock Rad ) the water flow over the rad is much better and therefore the cooling to .

Its a simple swap between the Thermostat and the Plug without any drilling or what ever and the Thermostat Gasket is Rubber so no Problem to do with the same Gasket . Tell me if you want to know details."

 

[KTMphil]

Klaus very kindly made a parts list of the full conversion. The prices of everything are not on this list yet, buy we will try find out the full total.

CRF350L Parts List

From model

From

Part

Local

CRF450R

Partzilla

8

no

INJECTOR ASSY., FUEL

16450-MEN-A51

$85.55

CRF450R

Partzilla

9

no

SEAL RING, INJECTOR

16472-MCW-000

$1.55

CBR250R

Partzilla

8

yes

need to be mod. For better flow

Throttle BODY SET

16410-KYJ-902

$61.84

CBR300R

Partzilla

1

yes

CRANKSHAFT

13000-K33-D03

CBR300R

Partzilla

11

yes old can be used to save money

KEY, WOODRUFF (25X18)

90742-KYJ-900

$1.39

CBR300R

Partzilla

9

yes old can be used to save money

NUT, LOCK (16MM)

90235-KYJ-900

$0.00

CBR300R

Partzilla

10

yes old can be used to save money

WASHER (16MM)

90434-KPS-900

$1.38

CBR300R

Partzilla

6

yes , new updated Part original CRF250

Part can be used

GEAR, BALANCER DRIVE (35T)

13417-K33-D00

$0.00

CBR300R

Partzilla

2

yes

SHAFT, BALANCER

13421-K33-D01

$0.00

CBR300R

Partzilla

5

yes

KEY, WOODRUFF (4MM)

90741-KFB-000

$2.07

CBR300R

Partzilla

1

yes , new updated Part original CRF250

Part can be used

GEAR ASSY., BALANCER DRIVEN (35T)

13410-K33-D00

$0.00

XL600R 83-85

Partzilla

8

maybe

Second Hand on E-bay

TUBE, R. AIR CLEANER CONNECTING

17222-MG2-000

$27.47

Partzilla

12

maybe

XL600R 83-85

Second Hand on E-bay

DUCT, AIR CLEANER IN. (NOT AVAILABLE)

17240-MG2-000

$23.33

CRF250L

where ever

FMF Q4 and Megabomb

yes

Different exhoust need remapping

about 30000-35000 THB

CRF250L

Partzilla

14

yes

SHIM, TAPPET about(2.450)

Yes need first to be messured befor order

14939-KT7-???

$6.10

CRF250L/CBR250

Takegawa

Slipper clutch kit

no

CBR250R（MC41-1000001～）

CRF250L（MD38-1000001～）

CRF250M（MD38-1100001～）

Item no.02-01-0074

39800 yen

CRF250L/CBR250

Takegawa

Sports Camshaft

no

CBR250R（MC41-1000001

Item no. 01-08-0056

38000 yen

CRF250L big Bore Kit 305 cc

Bill Blue or CRF's only (same)

Cylinder with bigger sleeve

no

Piston and Head need mod. For

Wiseco Piston , Rings , clips and pin

Headgasket is Paper , better

11,2-11,5 comp. ratio

Head and base Gasket

For 305 cc Kit

Takegawa

Head and base Gasket

2 layer metall Gasket from Takegawa

Item no. 01-01-0327 and 00-01-1060

440 yen each

CRF250 L

Gaskets only if the old one break

yes

price ?

Grinding bits for modification

Dremel

many different

yes

all about 100 USD

CBR250/CRF 250L

API Bangkok

Stand alone ECU inc.programmer kit/cable

yes

about 7800 THB

CRF250L

Hurricane

Hi Flow Airfilter

yes

better Foamfilter ?

price ?

maybe

CRF250L

DRC

Radiator hose kit (Silicone)

yes

Stock don't fit winner radiator

price ?

CRF250L

Winner racing via e-bay

32 mm Radiator

http://www.ebay.com/itm/WINNER-RACI...ash=item5d427b1cb2:g:BpwAAMXQVhFSA0PQ&vxp=mtr

142,50 usd

no

 

[schrauberklaus]

Hi

Phil , don't forget that all the prices for CRF/CBR 250/300 are from Parzilla USA .
I just use them to give you a overall idea of the cost .
The local prices are a little cheaper .

Mike , the cooler you can find on E-Bay (radiator CRF250 from Winner Racing if i remember correct ) , the thermostat replacement i must mesure in the next days then i let you know .

 

[schrauberklaus]

O.K.
here are the details about the thermostat mod.

Thats the Thermostat in the CRF250L Engine .

The smaller Disk where the arrow point goes towards the right side of the Engine or first in by the installation.
The Pic show the Thermostat cold and closed .
If it warm up the small disk and a larger one under the big Disk with the rubber Gasket move together .
based on this pic they move to the left .

Now, the head of the CRF has 2 water return channals from the Thermostat housing .
One sit direct behind the smaller Disk of the Thermostat and the Disk is in cold situation about 8 mm in front of the beginning of this Channel that lead from the Head through the cast of the cylinder and right casing staight back to the Water pump .

And thats the way about 95% of the water flows if the engine is cold . The radiator connected to the Thermostat cover
gets only a little bit water through a 3 mm hole next to the big disk in the Thermostat .

If the Engine warms up both Disks move and the bigger disk opens the way to the rad. and the smaller disk close at the same time the direct channel back to the pump .

unfortunately it seems that the small disk never close the direct channel to the Pump compleatly and even if the Engine is hot (thermostat fully open at 81°C) some water run back the direct way to the pump and get not cooled down by the rad .
At the Pump both streams get mixed together again and the hotter water from the direct connection heat up the colder water comming from the rad.
Therefore the cooling is not as efficient as it could be.

Why Honda design it like that and if this is a leak from production of the Thermostats or on purpose i don't know .

But at my tests i see clearly that the engine is running colder (my CRF has a Koso instrument with some Engine and Water temperature sensors) if the direct channel is blocked off and the water run to 100% over the rad.

And to do this i remove the Thermostat and install a aluminium rod in its place to plug of the direct Channal and keep the Radiator Channel open .
see pic below .

The tapered end goes in the bore of the direct channel and block it to 100% the spring get pressure when the thermostat
cover is in place and hold the Plug in place , the rubber gasket comes with the Thermostat and need to be installed to seal the cover .
simple , easy to replace .

But this is a mod for Engines that run in warm weather and permanent under load .
I had this plug still in place as i start my trip to the north of thailand 2 month ago and find out that with 10°C outside temperatures like i had it a few times in Nam Nau and Mae Salong the engine (with my bigger Rad. ) is running to cold .
Temp. max 58°C at Nam Nau in the Fog the hole Day depend with visibility of 2-5m its hard to drive fast and keep the engine under load.
So in CM i replace the Plug with a new Thermostat and with the bigger Rad. the temperatures are still fine .
Here in Phuket and in april and may i will see if the rad. can still hold the temp. or i need to put the plug in again.

 

[KTMphil]

Very useful, thanks Klaus.

 

[Chazsmash]

Very useful, thanks Klaus.

Great information Klaus.

I intend to fit a CBR300 clutch in my 2016 CRF250

Can you confirm that the total parts needed are;
Clutch plates
Springs
Spring bolts

Thanks in advance

 

[schrauberklaus]

Yes , but i would change the steelplates too (very cheap ) and don't forget you need 5 full size friction disks from the CBR300 and not the full Kit like the CBR300.

See updated Parts list .

<

CRF350L Parts List
From model	From	Part	Local
CRF450R	Partzilla		no
		INJECTOR ASSY., FUEL
		16450-MEN-A51
		$85.55
CRF450R	Partzilla		no
		SEAL RING, INJECTOR
		16472-MCW-000
		$1.55
CBR250R	Partzilla or Honda		yes
	need to be mod. For better flow
		Throttle BODY SET
		16410-KYJ-902
		$61.84
CBR300R	Partzilla or Honda		yes
	need rebalncing for Piston weight
	if 305 cc Piston	CRANKSHAFT
		13000-K33-D03
CBR300R	Partzilla or Honda		yes
			old can be used to save money
		KEY, WOODRUFF (25X18)
		90742-KYJ-900
			yes
		$1.39
CBR300R	Partzilla or Honda		old can be used to save money
		NUT, LOCK (16MM)
		90235-KYJ-900
			yes
		$0.00
CBR300R	Partzilla or Honda		old can be used to save money
		WASHER (16MM)
		90434-KPS-900
		$1.38
CBR300R	Partzilla or Honda		yes
		GEAR, BALANCER DRIVE (35T)	new updated Part original CRF250
			Part can be used
		13417-K33-D00
		$0.00
CBR300R	Partzilla or Honda		yes
		SHAFT, BALANCER
		13421-K33-D01
		$0.00
CBR300R	Partzilla or Honda		yes
		KEY, WOODRUFF (4MM)
		90741-KFB-000
		$2.07
CBR300R	Partzilla or Honda		yes , new updated Part original CRF250
			Part can be used
		GEAR ASSY., BALANCER DRIVEN (35T)
		13410-K33-D00
		$0.00
CRF rally 2017	Partzilla or Honda	TUBE, R. AIR CLEANER CONNECTING	yes
	Second Hand on E-bay	from 2017 CRF Rally
XL600R 83-85	alternative	TUBE, R. AIR CLEANER CONNECTING	maybe
		17222-MG2-000
		$27.47
	Partzilla		maybe
XL600R 83-85	Second Hand on E-bay
		DUCT, AIR CLEANER IN. (NOT AVAILABLE)
		17240-MG2-000
		$23.33
CRF250L	where ever	FMF Q4 and Megabomb	yes
	Different exhoust need remapping	about 30000-35000 THB
CRF250L	Partzilla		yes
		SHIM, TAPPET about(2.450)	Yes need first to be messured befor order
		14939-KT7-???
		$6.10
CRF250L/CBR250	Takegawa	Slipper clutch kit	no
		CBR250R（MC41-1000001～）
		CRF250L（MD38-1000001～）
		CRF250M（MD38-1100001～）
		Item no.02-01-0074
		39800 yen
	or
CBR300	Parzilla or Honda	Clutch friction Disks
		5 x 22201-MGZ-J01	yes
		Clutch Steel Plate
		4 x 22321-KYJ -902	yes
	shorter and Stronger then CRF or	Spring
	Takegawa	5 x 22401-K33-D01	yes
		plus 5 x 1 mm washer
Or Barnett , Clutch or whatever
CBR300	Partzilla or Honda	Flighwheel
	lighter then CRF250	31110-K33-D01	yes
CBR300	Partzilla or Honda	outer valve spring
	stiffer then CRF250	4 x 14751-K33-D01	yes
		Inner Valve Spring
		4 x 14761-K33-D01	yes
CBR300	Partzilla or Honda	Arm in Valve Rocker
	0,5 mm more lift	14430-K33-D00	yes
		Arm EX. Valve Rocker
		14440-K33-D00	yes
CRF250L/CBR250	Takegawa	Sports Camshaft	no
		CBR250R（MC41-1000001
		Item no. 01-08-0056
		38000 yen
CRF250L big Bore Kit 305 cc	Bill Blue or CRF's only (same)	Cylinder with bigger sleeve	no
	Piston and Head need mod. For	Wiseco Piston , Rings , clips and pin	Headgasket is Paper , better
	11,2-11,5 comp. ratio	Head and base Gasket
For 305 cc Kit	Takegawa	Head and base Gasket	2 layer metall Gasket from Takegawa
		Item no. 01-01-0327 and 00-01-1060
		440 yen each
CRF250 L	Partzilla or Honda	Gaskets only if the old one break	yes
	Side covers	price ?
Grinding bits for modification	Dremel	many different	yes
On Piston and Head		all about 100 USD
CBR250/CRF 250L	API Tech Bangkok	Stand alone ECU inc.programmer kit/cable	yes
		about 7800 THB
CRF250L	Hurricane	Hi Flow Airfilter	yes
	better Foamfilter ?	price ?	maybe
CRF250L	DRC	Radiator hose kit (Silicone)	yes
	Stock don't fit winner radiator	price ?
CRF250L	Winner racing via e-bay	32 mm Radiator
	http://www.ebay.com/itm/WINNER-RACI...ash=item5d427b1cb2:g:BpwAAMXQVhFSA0PQ&vxp=mtr
		142,50 usd	no

 

[Chazsmash]

Thanks fr the response. Just to clarify the parts to be ordered;
5 x bolts
5 x springs
5 x friction plates
5 x steel plates
1 x gasket

 

[schrauberklaus]

As shown in the Parts List , you need only 4 Steel Plates .