2008 honda crf 250r hard to start cold nad wont idle

Have you checked the CDI?

I've got a friend who had an '08 that was very difficult to start, then would run for a little while, start dying and didn't want to restart. They did all the usual valves/carb, etc., stuff to no avail. They brought it to me and we checked the electronics. The peak voltage was low and a new CDI remedied it.

Not saying that's your issue but you might want to go down the ignition system diagnostics road. The least you can do is eliminate it as a culprit if it's all good.

Good luck.

Order a new 45 pilot jet and install it don’t do anything else until you do that, I don’t care if you’ve cleaned the carb already.

FWIW, the spark on that one looked good, too. All resistances were good but the peak voltage was out of spec - so we replaced the CDI and it cured it.

Again, not saying that's what it is but it couldn't hurt to eliminate it if it isn't.

BTW, in case you need it, the stock CDI was no longer available. They got a new one from Rick's Motorsport Electrics.

No doubt and they are a process of elimination diagnosis, not direct testing. But if everything tests in spec I would eliminate that as a possibility.

A possible test to try to determine which to focus on (Fuel or Spark). With bike cold, pull the seat/air filter off the bike. Grab a can of ether, open the carb slide and give it a healthy whiff. Close the slide and give it a boot. See if it "pops" sooner than you have been experiencing. If so, chase fuel, if not spark would be up.

I assume you have disconnected the kill button from the equation. Simplify the problem.

I agree with YZ 133, sometimes cleanings is fruitless.

Good luck!

My first thought is carb/pilot jet issue. Don't bother cleaning pilot jets as it's almost always a waste of time and pilot jets are only a couple dollars. The shop I worked at, we'd always throw a 48 pilot in every Honda. I keep a 42, 45 and 48 pilot for my carbed 4 strokes just to be safe.

edit: Also check your slide “plates.” If they are worn out it will cause you issues and most people overlook them. 

Check your valves!

It's obvious who reads the OP and who doesn't.

Clean out the tank, when you change the jet in the carb.

Looks like someone may have had dirty tank / carb / dirty fuel in the past, and have replaced the hose from the tank to the carb.

Bike looks pretty tidy for a 2008, looks to still have standard side number plates in good nick an tank isn't scratched too much - which tells me it has probably done less than 100 hours.

The CDI that Village Idiot mentioned is only $125. I put the Vortex 10 Map from Tokyo Mods on my 2007 CRF 250R, that one is expensive at $600.

Yeah the others are too busy down voting your posts to pay attention. Dumb asses . 

I remember kicking the everliving hell out of my 08 back in the day. worst starting bike I ever owned. 

Have you confirmed the pilot circuit is clear?  You can change the jet, but the circuit behind can gum up and is a challenge to clear.  When you cleaned the carb, did you use a sonic tank with heat?  That's what I've had the best luck using to clean the varnish out of old carbs.

Put a new 45 pilot in , fuel screw 1.5 turns out and then update us.

This.

I actually still have my 2008 CRF250 because I cant bear the idea of selling it to someone. My 2008 Honda CRF250 never, ever, ran right. 

I had a 2005 and it was great. That was my first 4 stroke, and it started first kick, ran great and had no issues at all. Then a few years later, I bought the 2008 CRF250, brand new. That thing was a different story from day 1 of ownership...I couldnt get it started when cold.  No matter what I tried. Endless kicking. And even jump starting. By the time I got it started, I was exhausted and miserable.

However, the bike, once running, was a decent bike.  Just dont let it stall out -  that was like a 30 minute project to get it re-fired.  Checked the valves, did all the right things. 

I had Tokyo mods do the carb mod. When that didnt work, I took it back to them and had them install and jet a brand new 2005 CRF250 carb, as that was the hot set up to do back then.  That was better, but still not great. In fact, I got taken out in turn 1 at the Catalina GP in 2010 or whatever and couldnt start the damn bike.  By the time I did, it cost me about 8 mins of kicking, and I lost my class by 7 seconds. I was pissed! 

My 2008 never ran right from day 1.  It sits now in my storage covered in dust. Would love to get rid of it, so let us know if you figure out how to start it so I can sell mine.

The only solution I found was to buy a new bike - in my case a Yamaha YZ250F, and that thing has been a dream, as have several more since the Honda.

I will say there is a "technique" to starting the 2008 - top dead center, no throttle, and kick like your life depends on it. you might get lucky. But it still sucks to even think about it now...even reading this post I get winded and bummed out at how bad that bike was. 

Is the rubber boot from the engine to the carb tight, sealed, and not cracked or anything? If you raise the idle, and back out the fuel screw does anything improve?

try roughly 1 turn clockwise on idle knob and 1 turn counterclockwise with the fuel screw on bottom of carb.

also I checked your location and noticed you’re in Finland I believe? If so I’m truly not sure of the conditions there and fuel, maybe like you said try a 48-50 pilot if the 45 was an improvement maybe you need a little more on your side of the pond!!

Are you installing the carb slide cover on upside down?  It is possible and actually looks like it should be "the wrong way" intuitively.

Check the parts diagram and ensure the "floating valve set" is assembled properly.  This will cause it to run, but like shit...

Assuming you checked timing etc ?

possible cam gear not aligned properly

i may have a cam I could send you if you want to try that . If you want I can throw it in the mail . Easy swap to just rule out one more item 

I can’t imagine what it could be knowing you bought it brand new and it was like this from the beginning . 

I had an 08 for a couple of years.  It was very difficult to start even with new SS valves.  Here are my suggestions.  I did all these at once so I’m not sure exactly which ones fixed the starting issue.

1. Start with Procircuit’s jetting specs. You may need to fine tune from there, but I have found that their settings are really good. For some reason the 08 jetting specs are not listed but the 09 are.  MJ=172, PJ=42, Stock needle=#3 clip, Fuel Screw=2, Leak=48.  Starter jet = stock (68).  These settings worked better than everything else I tried which included a JD kit settings.

2. Your bike is 16 years old, time for a new “Mid Body” carb gasket kit (EBay).  Honda’s OEM carb kit (Usually part #1 on the carb diagram) You will get all the carb O-rings you need.

3. The carb slide plate cover rubber seal.  You can order the individual seal from 08 yz250f parts diagram.  

4. Make sure the AP pump is squirting properly.  Lots of videos out there (Check thumpertalk.com)

5. I put a R&D float bowl on.  It got rid of a slight bog I had when riding whoops.

6. I installed a new OEM decompression mech.

7. New OEM cylinder and piston kit and timing chain.

8. I installed a new needle jet holder (the part the MJ screws into)

9. Make sure the hot start plastic piece that screws into the carb is not cracked.

I fixed a similar issue once with a new mid-body gasket like garagedog above mentioned. The rubber had deformed which restricted the pilot circuit, cleaning or replacing the pilot jet alone would not solve the problem.

To answer this question that everyone just skipped right over... YES, that missing washer can absolutely cause the issue you are having. 

The washer is what keeps the o-ring in proper place and seats/seals it in the cavity of the carb.  Without that washer, the oring can get deformed and either restrict gas flow or allow an air leak into that circuit.

The #1 thing to do on any FCR carb 4-stroke is put on an EZ-adjust fuel screw so that you can actually adjust the thing later on while running.  Buy an aftermarket one and make sure you put the spring-washer-oring in proper orientation.  Blow out the passage in the carb well with carb cleaner before installing and put a small dab of anti-seize on the threads.

Note that this aftermarket one has an additional o-ring to seal the cavity on the carb and prevent dirt from getting in.

Maybe someone with more knowledge can confirm or deny the possibility of the plate on the carb slide being on backwards . My 06 450 ran the same way and It ended up I put the plate on the slide on backwards.

Not sure if your referring to my response but I was speaking to mxnick post, not the op. 
 

Hello, I had CRF250 2006, the bike was really hard to start when cold. I figured it out this way -> hop on the bike, twist the throttle 5-7times, then pull the choke and kickstart the bike. Let it run for a while, plug the choke and go to the track. It worked for me, tryout these steps on your CRF, maybe it will work for you as well.