CRF250X Mega Thread

[DJ_MI]

Valve clearance check is what also came to mind. I know the '04 models and maybe the '05s had some valve issues. It's worth researching. My old '08 had a lot of hours on it and it ran strong. I made an adapter for the leak down check by gutting an old spark plug, using epoxy and a chunk of Home Depot steel pipe hammered and twisted into it. It was a complete hack job, but it worked! As you know that check will tell you a lot. I hope it's a minor issue and just a result from the pressure washing.

That’s an ingenious solution!

My understanding is that the ’04 and’05 models have softer valve seats and are more prone to having clearance issues.

I think the washing was just a coincidence. At this point I’m guessing it’s the valves. I’ll know once the gaskets get here.

 

[DJ_MI]

This was my old '08 X. They just don't get the attention they deserve. Fun bikes!

Very nice!

 

[Yinzer Moto]

So I broke the bike already. It proved to be rock solid reliable for the first 3.5 days of ownership putting some miles on it on dirt roads and at work.

On Sunday I got good 4.5-5 hours in the mud, sand and trails in Mt. Morris MI. It ran strong and was awesome. I stopped by work and washed it with a electric power washer (jwaller sees where this is going ) and then it wouldn't start afterward. I air gunned it thoroughly and fiddled with it for a while and got it started. It ran strong and I screwed around in the parking lot for a while before loading it up and bringing it home. Yesterday I was going to go for a rip and it would crank but not fire.


Symptoms:
Won't start.
Will crank and will occasionally pop and sputter.
The header pipe heats up so there's some kind of combustion going on.


Things I've tried:
I changed the spark plug and confirmed that it's sparking. The old one looked pretty rough. No change.
Inspected for loose hoses or chaffed wires. There's two disconnected hoses that appear to be vent hoses. There's no clamp marks and they aren't bulged or flared on the end like they were on a fitting.
I checked the kill switch for continuity and function. No problem there.
I drained the gas tank and the carb. I didn't find any obvious problem.
I was going to do a compression test but my tester is slightly too wide to fit down the spark plug recess.


I read that some people have better luck kick starting it when they couldn't get it running with the electric starter. I was able to get it running with the kicker but it wouldn't hold an idle. I went for a ride and it still feels strong and responsive. I shut it off a few times and tried to restart it immediately and it was hard to start each time.

I ordered a valve cover gasket and case plug o-ring earlier so I can check the valve clearance.

Anyone have any input?

Just to eliminate a variable, charge the battery fully and see what that gets you.

 

[DJ_MI]

Just to eliminate a variable, charge the battery fully and see what that gets you.

Thanks for the suggestion. I tried that and was using a multimeter to monitor the voltage.

 

[Yinzer Moto]

Thanks for the suggestion. I tried that and was using a multimeter to monitor the voltage.

I have seen it on other bikes where a weak battery can cause some wacky issues, like what you are experiencing. The bike will crank over but the spark is weak and they don’t start.

It is odd that washing caused the problem and after having time to dry out, you are still experiencing the problem. I might be tempted to start unplugging wiring connections, cleaning them, then put back together and then try starting. Just one at a time so you can pin point what may be the issue.

 

[DJ_MI]

I have seen it on other bikes where a weak battery can cause some wacky issues, like what you are experiencing. The bike will crank over but the spark is weak and they don’t start.

It is odd that washing caused the problem and after having time to dry out, you are still experiencing the problem. I might be tempted to start unplugging wiring connections, cleaning them, then put back together and then try starting. Just one at a time so you can pin point what may be the issue.

Thanks again for your input.

It's hard to say if it was the washing or the ~4.5 hours of hard riding on Sunday. I can get it started but it takes a lot of effort and oddly enough is more likely to start with the kicker (I only tried because I found other people with similiar problems who could kick it and not e-start it). Before the ride and wash it started like a champ. After the wash was the first time I tried a cold start since the Sunday ride.

I went through every connection I could find, air gunned everything, checked grounds, checked the kill switch and haven't found any apparant problems. When I washed it I used an relatively lower power electric pressure washer and kept a good distance, far enough that I can spray the radiators clean and not bend the fins and also trying to avoid the bearings and sensitive areas. I wash my KLX much more aggressively and have never had a problem, not that that means I didn't cause a problem with the X. I certainly thought it was the water at first but after a few days of airing out it seems unlikely. I couldn't confirm it but I did read somewhere that Honda recommended to someone to leave the bike out in the sun for a while. I've gotten it to run a couple times and ripped it around so it's gotten plenty of heat and airflow a few times now.

Another interesting thing is the header pipe gets hot from trying to start it, even when it doesn't sound close to starting.

I have an old cheap comp tester at work I'm going to take home and see if that one fits. I also have a leak down tester I'm going to take home and see if that will work too. If they are slender enough to fit down the hole I should have some more definitive data. Tracking shows that the gaskets will be here tomorrow so I should be able to check the valves this weekend.

Thanks again Yinzer!

 

[Yinzer Moto]

Thanks again for your input.

It's hard to say if it was the washing or the ~4.5 hours of hard riding on Sunday. I can get it started but it takes a lot of effort and oddly enough is more likely to start with the kicker (I only tried because I found other people with similiar problems who could kick it and not e-start it). Before the ride and wash it started like a champ. After the wash was the first time I tried a cold start since the Sunday ride.

I went through every connection I could find, air gunned everything, checked grounds, checked the kill switch and haven't found any apparant problems. When I washed it I used an relatively lower power electric pressure washer and kept a good distance, far enough that I can spray the radiators clean and not bend the fins and also trying to avoid the bearings and sensitive areas. I wash my KLX much more aggressively and have never had a problem, not that that means I didn't cause a problem with the X. I certainly thought it was the water at first but after a few days of airing out it seems unlikely. I couldn't confirm it but I did read somewhere that Honda recommended to someone to leave the bike out in the sun for a while. I've gotten it to run a couple times and ripped it around so it's gotten plenty of heat and airflow a few times now.

Another interesting thing is the header pipe gets hot from trying to start it, even when it doesn't sound close to starting.

I have an old cheap comp tester at work I'm going to take home and see if that one fits. I also have a leak down tester I'm going to take home and see if that will work too. If they are slender enough to fit down the hole I should have some more definitive data. Tracking shows that the gaskets will be here tomorrow so I should be able to check the valves this weekend.

Thanks again Yinzer!

Use caution with the compression test, in the sense that it might have auto decompression. So you might get shockingly low readings but that would be normal with an auto decomp valve. Honda probably has a procedure to bypass the auto decomp or has the low compression spec listed somewhere.

Some of the symptoms you list could indicate a valve adjustment is needed, as others have pointed out.

 

[DJ_MI]

Use caution with the compression test, in the sense that it might have auto decompression. So you might get shockingly low readings but that would be normal with an auto decomp valve. Honda probably has a procedure to bypass the auto decomp or has the low compression spec listed somewhere.

Some of the symptoms you list could indicate a valve adjustment is needed, as others have pointed out.

Thanks.

Yes, it does have auto decompression. The manual says comp spec is only 57 psi @ 800 RPM so it's accounting for the decomp system. It even states that high compression readings can be caused by a faulty decompressor cam.

Had I not realized it had the auto decomp and only got 57 psi I definitely would have been pretty shocked.

 

[Bearcat]

DJ-MI, in case you can't find a proper adapter that fits. Here's a pic of the adapter I made to get down in the CRF's sparkplug well. If you have the means to weld the old plug onto the pipe that's even better. Mine has the inference pipe fit with a bfm and twisted in with vise grips, and epoxy for sealant. Use eye protection for the leak-check and stand clear! It worked.

Edit: I can't remember if that picture is the actual CRF adapter. I have a few others of various lengths for frame clearance issues when connecting the air source.

 

[DJ_MI]

DJ-MI, incase you can't find a proper adapter that fits. Here's a pic of the adapter I made to get down in the CRF's sparkplug well. If you have the means to weld the old plug onto the pipe that's even better. Mine has the inference pipe fit with a bfm and twisted in with vise grips, and epoxy for sealant. Use eye protection for the leak-check and stand clear! It worked.

Very cool! Thanks for the picture. It helps visualize it.

 

[jwaller]

So I broke the bike already. It proved to be rock solid reliable for the first 3.5 days of ownership putting some miles on it on dirt roads and at work.

On Sunday I got good 4.5-5 hours in the mud, sand and trails in Mt. Morris MI. It ran strong and was awesome. I stopped by work and washed it with a electric power washer (jwaller sees where this is going ) and then it wouldn't start afterward. I air gunned it thoroughly and fiddled with it for a while and got it started. It ran strong and I screwed around in the parking lot for a while before loading it up and bringing it home. Yesterday I was going to go for a rip and it would crank but not fire.


Symptoms:
Won't start.
Will crank and will occasionally pop and sputter.
The header pipe heats up so there's some kind of combustion going on.


Things I've tried:
I changed the spark plug and confirmed that it's sparking. The old one looked pretty rough. No change.
Inspected for loose hoses or chaffed wires. There's two disconnected hoses that appear to be vent hoses. There's no clamp marks and they aren't bulged or flared on the end like they were on a fitting.
I checked the kill switch for continuity and function. No problem there.
I drained the gas tank and the carb. I didn't find any obvious problem.
I was going to do a compression test but my tester is slightly too wide to fit down the spark plug recess.


I read that some people have better luck kick starting it when they couldn't get it running with the electric starter. I was able to get it running with the kicker but it wouldn't hold an idle. I went for a ride and it still feels strong and responsive. I shut it off a few times and tried to restart it immediately and it was hard to start each time.

I ordered a valve cover gasket and case plug o-ring earlier so I can check the valve clearance.

Anyone have any input?

Oh man! That sucks!

I guess with dirt bikes and dual sports, w#sh is a four-letter word. I haven't w#shed my CRF250RX and doubt I ever will now!

 

[DJ_MI]

Oh man! That sucks!

I guess with dirt bikes and dual sports, w#sh is a four-letter word. I haven't w#shed my CRF250RX and doubt I ever will now!

Yeah, it's a bummer but I knew what I was getting into. It's an old bike with unknown history.

I really don't think the washing did either of our bikes in.

 

[DJ_MI]

So I did some more investigating last night.

Throttle position sensor is within spec.

I traced the two loose hoses. They are vent hoses and aren't the problem.

The coil pack secondary resistance is good @ 5.67 kOhms. However, the resistance across the connector terminals is 0.7 ohms. The spec range is 0.07-0.10 ohms which puts mine at 7x what the upper limit should be.

Does anyone thing this could be the cause of my hard starting issue?

 

[Bearcat]

RMATVMC shows new caps at $25 aftermarket and $50 for OEM. The resistance reading sounds high for sure. You probably already tried grounding the spark plug to the outside of the engine. How bright was the spark when kicking it over? Does the bike cut out when running and things heat up? Maybe the lead wire to the cap is breaking down? Check for cracks on the plug too.

Did you get chance to check the valve clearances yet as well as the leak down?

I went through the school of hard knocks chasing a supposed jetting issue at quarter throttle on an old XL600R... Turns out the brand-new aftermarket coil was bad. It would start to stumble under load when things heated up, just about the time I was one mile from the house. I installed a 35 year old OEM coil and it solved the problem. The "new" bad coil would test good when cold on the bench. The 35 year old coil tested bad yet worked great, go figure! Coils usually work or they don't, I think it's rare to have an intermittent problem.

 

[DJ_MI]

RMATVMC shows new caps at $25 aftermarket and $50 for OEM. The resistance reading sounds high for sure. You probably already tried grounding the spark plug to the outside of the engine. How bright was the spark when kicking it over? Does the bike cut out when running and things heat up? Maybe the lead wire to the cap is breaking down? Check for cracks on the plug too.

Did you get chance to check the valve clearances yet as well as the leak down?

I went through the school of hard knocks chasing a supposed jetting issue at quarter throttle on an old XL600R... Turns out the brand-new aftermarket coil was bad. It would start to cut out under load when things heated up, just about the time I was one mile from the house. I installed a 35 year old OEM coil and it solved the problem. The "new" bad coil would test good when cold on the bench. The 35 year old coil tested bad yet worked great, go figure! Coils usually work or they don't, I think it's rare to have an intermittent problem.

Thanks Bearcat.

Yes, it sparks. I don't have anything for comparison, but the spark seemed okay. It runs good once started and warmed up. I replaced the plug with a new one.

I didn't check the valves yet. The gaskets are on my porch according to the tracking so I'm hoping to get it done this weekend. Which reminds me, I have to grab my feeler gauges before I leave work.

I'm going to call around and see if I can find a coil locally, if not I'll order it from RMATV. Also, I ran out of time last night to see if my leak down tester fits so hopefully I'll get those results also.

It's a bummer having problems, but I've learned a lot about the bike and will be better prepared should I have problems out in the wild.

Thanks again for your help!

 

[Bearcat]

That which does not kill us only makes us stronger! I still suspect a valve adjustment is due!

 

[DJ_MI]

That which does not kill us only makes us stronger! I still suspect a valve adjustment is due!

For sure.

Yeah, I agree. The more I research the more I think it's the valves. If nothing else, they need to be checked since I have no idea when they were last checked or adjusted.

 

[North ride]

For sure.

Yeah, I agree. The more I research the more I think it's the valves. If nothing else, they need to be checked since I have no idea when they were last checked or adjusted.

If it is the older Honda valve issue get the head rebuilt. With aftermarket stainless steel valves and good seats. Then it will be super solid.

Kibblewhite used to be the valves and seats of choice. Not sure currently what people are using.

 

[DJ_MI]

I checked the valve clearance…

Exhaust was slightly over spec. The intake was 0.000. I couldn’t even fit a piece of Starrett 0.001 tape in there!

Anyone have suggestions for a good machine shop?

I found some people like this place:

Fastheads - dirt bike cylinder head service

Fastheads deals exclusively in dirt bike cylinder heads and valve train components for all brands. New and service options available. 435-668-7776

fastheads.com

 

[Bearcat]

I checked the valve clearance…

Exhaust was slightly over spec. The intake was 0.000. I couldn’t even fit a piece of Starrett 0.001 tape in there!

Anyone have suggestions for a good machine shop?

I found some people like this place:

Fastheads - dirt bike cylinder head service

Fastheads deals exclusively in dirt bike cylinder heads and valve train components for all brands. New and service options available. 435-668-7776

fastheads.com

I clicked on the fastheads link and thought the stainless $499 option seemed like a good way to go for trail riding requirements.

Do you think a valve adjustment with thinner shims will get you through this season of riding? Then go big with the head work over the winter? Your bike looks low hour in those clean pics. My '08 was hammered, in spec and running great as a trail machine. Dropping a valve can be catastrophic but if there's life left for another adjustment, it's something to consider.