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Honda CRF250F - Modifications
March 16, 2019 version

 Introduction 

 Modifications 

 Documents 

 Fuel Injection 

 Break In 

Click pictures to  supersize.

ALERT - Break-in starts tomorrow, Sunday, March 17.

See Break In 

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I modify most motorcycles that I buy. As a must-do mod, I replace the stock handlebars with aftermarket bars that I have used for many years. I like the rise and set-back, and they are aluminum, of course. I find that there are other small tweaks that I prefer, and apply those as appropriate. And I usually remove plastic that I consider useless. In particular, side number plates.

Guiding principles:
Preserve and enhance reliability (survival in the back-country)
Street-legal (DS) equipment to obtain street licensing (connect trails and areas)
Reduce weight.
Improve performance.
Enhance comfort.

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So on with the show, if I can just find some room to work.
  
  
  
  
  
Bored reading? Take a break.
  
Video of Race in Brazil:
CRF250F wins the 5th Challenge...

NOTICE    -    Bank Angle Sensor Ignition Cut-off System

Your motorcycle's banking (lean angle) sensor system is designed to automatically stop the engine and fuel pump if the motorcycle is overturned.

Before restarting the engine, you must turn the ignition switch (key) to the OFF position and then back to ● (ON). The engine will not restart until you perform this procedure.

Page 28 of the 2019 CRF250F Owner's Manual. 0750.2018.09.K


ramz note: the BAS (bank angle sensor) function check shows:
 Start the engine.
 Incline the bank angle sensor approximately 60° to the left or right.
 The bank angle sensor is normal if the engine stops after a few seconds.
 
Page 4-32 of the 2019 CRF250F Honda Service Manual 61K9900, September 2018
 
60° !?? I'm gonna have to disconnect the BAS when I ride the 'fun' trails.

  

                                         Alphabetical table of contents 

Air box 
Dual Sport mods 
Gearing/Sprockets 
GPSr mount 
Handlebar, grips, and handguards 
Headlight 
Horn 
Kouba Link 
Manufacturer labels and stampings 
Mirror 
MoJavi saddlebags 
Muffler 
Seat bolt lock washers 
Seat Concepts seat 
Shifter bolt 
 
Side number plates 
Skidplate 
Tach/Hour meter 
Taillight and license plate holder 
Throttle cable 
Tie-down brackets 
Tires 
 
 

Modifications are shown below in roughly the order I did them.

I live in Salida, a small town in central Colorado. The nearest motorcycle shop is 60 miles away (Gunnison) with more shops in the front range 100 or more miles away. So I do most of my shopping online. I buy Honda parts from one or more of the online vendors shown in this list on the Introduction page. I buy non-Honda parts from Amazon , Rocky Mountain ATV/MC ,  MotoSPORT.com , and other online vendors as I encounter them in Google searches for specific products. I do not endorse nor disparage any vendor or parts they sell. I buy parts, install them, and report any features and/or problems I find. There are certainly many other vendors who sell perfectly useable products - Google is your friend.

 

Weigh-in

The first thing I did when I got my 250F home was empty the gas tank and weigh the bike. It weighed 248 pounds. The bike was stone stock, no mods. All fluids checked and topped up, and the gas tank was empty.

About that number. I weigh bikes using a WalMart scale I bought 20 years ago. I don't use the scale in the house; it's strictly used to weigh things in the garage, so it gets very little use. I check its accuracy now and then by weighing myself at Dr appointments, and then coming home and see how close my scale is to the Dr's scale. It's usually within a pound or two.

So why don't my numbers match Honda or Yamaha or other moto maker's numbers? Can't really say. But I don't really care. I only care how heavy my bikes are comparing one to another. So how does 248 pounds compare?

CRF230F - 233        CRF250F - 248        CRF250L - 298

This is great! These numbers are for brand new bikes, fully set up to ride, with no fuel. No matter what mods I do (adding and removing weight), these numbers represent a base weight that is probably 95% of the finished modified bike weight.

Furthermore, the weights relate to the intended use of these motos thusly:
CRF230F - primarily technical-single-track trail riding (TST), with some dirt-road dual sport. Base 233 lbs.
CRF250F - primarily dirt-road dual sport with some TST. +15 lbs - excellent.
CRF250L - primarily dirt-road dual sport with some easy trail riding. +65 lbs - heavy, but the only choice I had.

The 50 pound drop from the 250L to the 250F should make for a very fun DR/DS experience.


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The first mod - Tie-down brackets

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I found these several years ago, and have been installing them on all of my bikes since. They are SO convenient to use, and make securing the bikes a breeze. Two different brands are shown here: I was trying one of each out on my 250L to see which one I liked best. They're pretty much the same, and I never swapped one or the other back so they would match up. Meh.


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Shifter bolt - my favorite mod

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I moved the shifter up two notches, and replaced the shifter pinch bolt with a longer bolt and a lock nut.


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Air box

Yes, I did an air box mod; opened up the inlet about 50%.
My 250F needs all the air it can get; trail riding elevation starts at 8,000 feet.

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There is a cast-in divider; I used it as my cut line. Finish opening size - about 1 3/8 x 1 5/8 inches.

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Seat bolt lock washers

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I lost a seat bolt on my CRF230F about 10 years ago, and after this mod, I never lost another. Works for me.


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Throttle cable

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I have always removed the push throttle cable from dual-cable throttles. I have never experienced a stuck slide due to high vacuum on the engine side of the carb slide.

After removing the cable, the pull cable needs minor readjustment. Plug the empty hole in the throttle cable cover with Shoe Goo or something similar. Plug the empty hole in the throttle drum cover on the carb with an M6x?? flange-head bolt with a locking nut on the inside.

The throttle operates almost effortlessly.


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Tach/Hour meter

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This Moose Tach/Hour meter mounted in front of the fuel tank shows:
 Total hours of operation
 Current RPM
 Maximum RPM
 Number of engine starts

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Wire wrap connection on spark plug wire; no soldering required.
No battery required.


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GPSr mount

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With no speedometer on the 250F, nor even a simple odometer, I took the easy way out, and mounted up a Garmin Montana 610. The mount is not wired to the battery yet; I will add power when I install the dual-sport wiring harness.

Note: The stock handlebars are shown here because the new Pro Tapers have not yet arrived.

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The large black plastic wrap-around piece is the Garmin AMPS rugged mount with the power cable removed for now. You can buy it from Garmin or from any one of several aftermarket GPS parts vendors. The black mounting plate is Kydex, my favorite plastic for making custom parts for my motos.

There's a small 2 x 2 inch sorbothane pad up against the back of the GPSr for vibration isolation and as a friction interface to prevent the GPSr from rotating on the cross bar.

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The brake hose is nowhere near the unit; it's a perspective effect. I can slide the unit left or right along the crossbar as desired. I think I'll go for far left to keep it out of my forward-looking field of view.


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Handlebar, grips, and handguards

I like the ProTaper SE in CR High, and installed them on the last 5 bikes I've owned. This time I went for the platinum grey look - and I like it. The SE (at 812 g) weighs 111 grams less than the stock Honda bars (at 923 g). I feel less vibration with aluminum bars over steel bars.

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Handguard Bar End Mount kit used to mount handguards to handlebars.

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First I trimmed the bars to width, which is about 30 inches or line #2 mark on the bars. Then I installed Handguard Bar End Mounts. I tapped the aluminum bars with an 11-xx tap. The bar end mounts are coated with locktite and then screwed into the handlebar ends. The handguard mounting bolts screw into the mounts with more locktite that yields a very firm, locked-in result.

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Trial fit.

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Looking for an LED headlight to keep power draw to a minimum; there's only 209 watts at 5,000 RPM to be had.


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Skidplate

No one is selling CRF250F skidplates! But I gotta have a skidplate!
Not that skimpy stock one, but a real skidplate.

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I looked through my old parts bin, and lo and behold, I found an AXP skidplate. Could it work? I clamped it to the frame rails in front and under the engine, and by golly, it fit. I'll drill the mounting holes later this afternoon.

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I got the skidplate mounted. Sano.


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Gearing/Sprockets

MotoSPORT has front and rear sprockets for the CRF250F. I bought a selection.

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I remove the sprocket cover so mud doesn't jam up in there and ruin my chain. I was surprised to see how little room there is between the chain and the case protector. I don't think a 14 tooth sprocket will fit in there...

If you look in the lower left corner of the picture, just above the shifter arm, you can see a circular black something - that is a seal covering the hole where the neutral switch wire comes out of the tranny. You can see the black insulated wire snaking it's way up the engine to a wire bundle near the top of the picture.

The area where the wire comes out of the tranny is covered by the lower part of the sprocket cover. If I remove the sprocket cover, I expose the wimpy wire and seal to all sorts of debris from the chain. So I decided to keep the sprocket cover on the bike, but to cut some of it away so mud and other debris can still find a way out. Picture coming.

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I cut out part of the sprocket cover, and will see how it works like this. I can cut more off later.

The neutral switch wire is well protected at this point.


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Side number plates

Those who know me, know that I don't like number plates on bikes that I register for street use. They make the bike stand out too much, they don't do anything for performance, and they just cost money to replace after you fall on them. So I always take the number plates off and make replacement Kydex covers, as appropriate.

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Kydex panel forthcoming...

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Make a mockup on the bike using a piece of manilla legal folder.

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Cut a piece of black Kydex using vanilla pattern.

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Clean up the black piece.

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Heat, trim, and shape.

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Looks passable; fully functional.

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Now what?.

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I removed the shrouds, and that left the ignition coil exposed.

On the left it's bolted to the frame bracket in the stock position.

On the right, I moved it to the inboard side of the bracket, for protection.

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Then I covered the bracket and coil with Kydex.

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The right side with the nice air box cover is done; no Kydex panel is necessary.

I also removed the plastic cover over the rear brake master cylinder.


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Muffler

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I removed the exhaust pipe heat shield, and the metal tab on the side of the muffler. I ground the rough spot on the muffler smooth, and painted it with some heat resistant paint. BTW, the complete muffler and s-bend weighs 5 lbs 11.4 oz (excluding the 3 bolts and 1 nut). A stock CRF230F muffler and s-bend weighs 5 lbs 10.4 oz (excluding mounting bolts).


The exhaust diffuser is inside the spark arrestor; they cannot easily be separated.
But some nimnul will try...

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I used my DeWalt proctoscope to look into both ends of the muffler/s-bend. No catalytic anythings were seen, just open all the way through without any obstructions. Silencing appears to take two forms: some kind of metal mesh lining against the inner surface of the outer walls and perforated pipe in many places. But no chambers or doubling back exhaust gases paths.

Initial rides at the dealers parking lot and in my 2 acre yard (3 laps) were surprisingly noisy. Even though the CRF230F and the CRF250F are both rated 82 dBA, the 250F is considerably louder. Not as bad as the 230F with the exhaust diffuser removed, and altogether not that bad to listen to. We'll see what all-day exposure to the melody will do to my sensitive ears.


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Dual Sport mods

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Yahooo, most of the DS parts have arrived!

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Headlight

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Waiting for lens/bulb

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Mirror

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Horn

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Taillight and license plate holder

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Kouba Link

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MoJavi saddlebags

I estimate that the small 1.6 gallon fuel tank on the 250F will yield about 60 to 80 mile range, depending on terrain and throttle application. For longer rides, I will mount up the MoJavi saddlebags with 1 or 2 fuel canisters, depending on my expected ride length. The following piece is taken from my CRF250L mods page, and will be modified with pictures of the 250F and the mounted bags as soon as I take that first long ride.

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Giant Loop makes Mojavi Saddlebags and here's what they have to say about them:

"Specifically designed to carry just the essentials needed for a day trip or trail ride, the MoJavi Saddlebag is the slim, trim bag for inner tubes, tools, fluids and other "save a ride" necessities."

These bags are the shiznit. I bought the original design for my WR250R and now have the newer model for the CRF250L. These have an optional tool pouch.

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The black canister is a Touratech 2 Liter Spare Fuel Canister. They fit nicely in the Mojavi with some room left over. Two of these adds over a gallon of extra fuel - GREAT! I will carry these when I go on longer rides to get my range up over 150 miles.

Mojavi™ Saddlebag - about $212.  Giant Loop
Touratech 2 Liter Spare Fuel Canister 070-0580 - about $28.  Touratech



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Tires

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The best tires for riding trails in the Rocky Mountains are full-on FIM-specified competition trials tires. Yep, trials tires. Run them at low pressure with tubeless rims and no better traction can be found. Rocks - easy peasy; slimy rocks and roots - laughing all the way! Hard-pack, soft-pack, and slimy dirt - goes without saying. Their only weakness is deep mud. The knob spacing is so small that mud packs in and traction drops significantly.

The top-of-the-line setup is very expensive. Trials tires are expensive and wear out quickly. Tubeless rims are like gold. So riders have found cheaper, less-capable setups, and traction is only slightly reduced. Still better than knobbies!

A step down from competition trials tires are DOT trials-like tires. These tires have the same knob spacing and similar knob shape as competition trials tires, but the rubber is harder to facilitate limited use on roads. Traction is reduced, but still better than knobbies. The sidewall is stiffer than trials tires, so some traction is lost there also. A benefit of this tire is the ability to hook up trails with connecting road sections.

Recently, some tire manufacturers have come up with hybrid tires. These tires have more space between the knobs to help clear the mud and the rubber is very soft, like a competition trials tire. Their sidewall stiffness is somewhere between trials and DOT tires. Some consider the hybrids to be the ultimate for dirt road and trail riding. Unfortunately, most of the rear hybrids are full size 4.00-18 and when used on smaller-frame motorcycles, they raise the rear end and quicken steering beyond comfortable.

In lieu of tubeless rims, riders use the less expensive Nuetech TUbliss tire system. I tried it, then I switched to mousse several years ago for maximum reliability,

So what tires do I use on my trail bikes?

For the front, I use a Pirelli MT43 DOT. I like a stiffer sidewall on the front so I can push the tire to help with steering. I also like to ride rocks aggressively - less effort in the end. Inside the tire is a mousse. Now yer talkin 'aggressive in the rocks'. I have no fear on where the front-end goes in rocks.

For the rear, I normally use a SHINKO Trail Pro 255 Radial 110/90R-18. For the 250F, I'm going with the Maxxis hybrid. I will adjust frame geometry as best I can to deal with the larger-profile rear tire. I hope the traction improvement will be enough to offset the geometry complications. I will use a mousse in this tire, also.

Stock Tires

Text on stock front tire

PIRELLI SCORPION XC
MID HARD   HEAVY DUTY
80/100-21
51R NHS
TUBE TYPE
XE 078B   3718

Text on stock rear tire

PIRELLI SCORPION XC
MID HARD
100/100-18
59R NHS
TUBE TYPE
XE 079B   361B
 
New Trials-like Tires

Text on the MT43 front tire

PIRELLI MT43
PROFESSIONAL
E3 75R-0055466
2.75-21
-
45P
PLIES: TREAD 2 POLYESTER
SIDEWALL 2 POLYESTER
MADE IN BRAZIL
-
DOT XE 23 E144   1916
MAX LOAD 165 kg (364 LBS)
AT 230 kPa (33 PSI) COLD
TUBELESS
ON TUBE TYPE RIM FIT A TUBE

Text on the MAXXIS rear tire

TRIAL MAXX
MAXXIS
E4 75R-0008079
4.00R18
M-7320-1
M/C 64M MST RADIAL
TREAD 2 PLIES NYLON + 2 PLIES KEVLAR
SIDEWALL 2 PLIES NYLON
MADE IN TAIWAN
LOAD RANGE B
DOT UYDD   1818
MAX LOAD 280 kg (617 lbs)
AT 230 kPa (33 psi) COLD
TUBELESS
-

Other tire-related details.
The front rim is a DID 21 x 1.60; the rear is a DID 18 x 1.85
Durometer-A tire readings are (Fr,Rr): stock 65 and 75; new trials-like 65 and 50.
Yep, 50!!! Like velcro.


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Spare Parts

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As mentioned previously, it's a long drive to the nearest Honda Dealer, so I order spare parts that I'm likely to need, short of a complete engine rebuild.
 
That $41 spark plug is an expensive spare, but if the one in the bike quits on me, I gotta have a spare handy.
 
Footpegs? Hit a big rock in the trail and I can limp home and replace it, to ride the next day. Same goes for the chain guide.
 
Air filter? Yep, gotta have a clean and oiled air filter on standby.


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Seat Concepts - pending

I talked to the lady at Seat Concepts. A CRF250F seat is not on their radar now.
'Call back in a coupla weeks.'
Yeah. Got it. Please stand by.


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Manufacturer labels and stampings

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Rear fender.
 

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Swingarm.
 

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Rear shock.
 

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Bottom of muffler.
 

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Frame by fuel tank.
 

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Low on engine case.
 

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17 character VIN struck into the metal surface of the steering tube (behind numberplate).
My bike's serial number (in these pictures) has been rendered illegible.
 

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Vehicle identification sticker affixed to the steering tube showing VIN, date of
manufacture (mm/yy), model year, and other required information.
The sticker is shown as two parts due to difficulty getting it all in one photo.


Items on the To-Do list... 
A short ride 
Fork bleeders 
Forks 
Miscellaneous removals 
Tank bag 

 

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