CRF's Only Forums

Howdy folks,

I'm new to the site. Lots of great info here. It's really good to have such a place as a sounding board for ideas.

After a 30 year hiatus from dirt biking, I just purchased a 2007 250X, so I could ride with my daughter who just bought a CR85. The 250X is in like new condition, and looks to rarely have been ridden. Except for a melted RHS number plate, the bike looks like it's right out of the crate. But that's where it ends. It's super hard to start, runs rough and somewhat poorly when it runs. It also has highly variable idle speed, when it will idle.

I found that if I pull out the choke and pump the throttle 3 or 4 times, it will usually start easier. But it will not idle when cold and I have to keep pumping the throttle until it warms up. So, based on this, I'm assuming that it's running pretty lean, or that it needs a very rich start.

I was also thinking that if it's running lean, the muffler might be running hotter than normal, thus the melted number plate. I read where some folks drill holes in the rear baffle plates. I was wondering about how this affects performance and maybe the muffler heating.

I was just looking for a little feedback on my plan of action, to get this thing running.

1. Replace the gas - Done.
2. Clean the carb - I have no ideal how old the gas is.
3. Install a JD jetting kit (read about that here)
4. Open the air box
5. Check the valve clearance.
6. Maybe drill holes in the baffle plates in the muffler
7. Oh... it needs a new battery also.

Does this sound about right, for a long term action plan? What about a near-term action plan. I assume that the mixture screw will help a little. I was planning to play around with that next. This thing really runs poorly. So I don't think it's ever been worked on. I think the previous owner probably couldn't get it running right and decided to get rid of it.

I'd also be curious to hear about others with the number plate melting issue.

Thanks in advance for the information.

Yes - very good plan. I would recommend cleaning the carb and especially the pilot jet before any other mod's. That is probably [ 99% guarantee ] where the running poorly issue is. Then proceed with the mod's. Remember the mod's you described absolutely require richer mixtures as you do them. If it starts and runs well after the carb cleaning leave the valve checks for little further down the road.
Many will tell you to just buy a new pilot jet. Some say they can't be cleaned = that's not true but you make the choice,

Just my opinions of course.

Awesome. Thanks for the info. I have an ultrasonic cleaner that I use for small items like this. I'll give a cleaning a try. If not I'll replace it.

My preference would be to leave it stock. But only if I can get it running decently. I don't need supersonic performance. Just rideability.

Any thoughts on the hot muffler/melting number plate? it seems to run hot, but I really have no frame of reference.

Welcome to the site !!

Is it a stock muffler ?? , if so it should have a couple of rubber grommet/bumpers that keep the muffler metal from touching the number plate , if they are missing , then i would think that is the issue , the muffler does get pretty hot , so without those bumpers , this will be a constant issue

Unless you shim out the number plate at the bottom hold down bolt , which you sometimes have to do with a aftermarket muffler , which will require a longer bolt and a nut or something to shim the plate away from the muffler , but if the muffler is stock , then just go to the dealer (or eBay) and get the rubber bumpers and you should be good

It should be part #11
http://fiche.worldofpowersports.com/yel ... %20MUFFLER

There should also be a stick on heat shield (looks aluminum) on the underside of the number plate , part #6 , as well as another rubber bumper , part #7
http://fiche.worldofpowersports.com/yel ... DE%20COVER

Thanks for the welcome and the reply. Lots of great information here.

My bike does have the stock muffler. It appears to be completely stock. It looks like I have all the grommets and the aluminum heat shield.

It's clear that melting has been a problem with this bike, as this melted number plate is not the factory plate. So I have a feeling that the original one melted and was replaced, and the new one also melted. This new one is all white and it appears that the stock one has red at the top, that blends with the seat.

I want to replace this number plate with a new one, as it's the only thing on the bike that shows that it's even been ridden. But I want to solve this melting mystery before replacing it.

Thanks for that info. The exploded view was super helpful.

You need to check the muffler to make sure its pointing straight back , and not pushed/pointed to the right , there has to be a reason its melting , its not a common issue unless something is bent or installed incorrectly , i have never melted a plate on my 450X and i even have a 450R muffler on it with no bumpers , and it still does not touch the muffler , i personally use UFO plastics , i feel the fit is as good as OEM but at a much lesser cost , they have them in all colors from white with red on top , to all white , to black , to all red , but either way , the side cover should NOT touch the muffler at all ,

Look behind the bike from a distance (5-10 ft) , and be directly behind it and look at the relationship of the rear fender center to the center of the rear tire , they should align exactly , if they do not , its likely that the subframe is bent and its putting enough pressure on the muffler that its pushed/pointing out too much , and that is causing the issue


Bottom line is , the muffler should not touch the number plate

These are pictures i found on Google , i could not find a direct rear picture , but these will give you a idea of what the gap should be between the number plate and the muffler

Hope this helps some

Stock muffler


Stock Muffler with Aftermarket End Cap


Aftermarket Muffler

Yep, this is puzzling to me. There is plenty of room between the number plate and the muffler. So I can't imagine why it's melting, unless there is an abnormal amount of heat in the muffler.



Here's a shot of my number plate



I also noticed that there is some melting on the underside of the fender. Note that the melting is occurring in the area behind the color division on the muffler (the hotter side). So it's clear that there has been some significant heating of the exhaust.



Also note the heat line and the nice golden color of the end of the muffler. That color puts the end of the muffler at over 400F and the blue end at temperatures over 600F. Without good airflow, I can see why this might be melting.

I checked to see if there were any restrictions in the muffler. There weren't. So I have to assume that the bike must be running really lean. That's a little scary. A friend suggested looking at the spark plug, which I'll also dig out and examine.

I have a feeling solving my carb issues will probably fix the heating issues.

So with the non-adjusting needle of the '07 250X, would it be better to get a JD kit, or just stick to the stock jetting? - Probably been answered a million times here.

My thoughts were that the JD kit might offer more flexibility, if I decide to modify the airbox and/or muffler. Is that a logical approach?

Thanks for the feedback.

I have never seen a plate or fender melted like that before

And yes , if you open up the airbox , then you will lean it out more than it is , so fix the issue before going that route

If the jetting is stock then its going to be real lean , that is how they are from the factory to pass emissions , so either just replace the jets , and needle , or get the JD kit , depending on what your budget allows , , as it will give 2 different needles , one for cold weather and one for warmer/hot weather , and a few different main jet sizes , i think they only come with 1 size pilot jet , but usually the stock main jet is too small , so it will need to be replaced no matter what , and depending on elevation , the pilot could also be too small

I would also suspect the needle to be causing a lean issue as well , it will most likely be set around where the 3rd clip position from the top position would be , so it would mean the needle takes more throttle input to allow more fuel to richen the system , by means of the taper and needle length , so a adjustable needle will allow you to fine tune the fuel delivery as well

The Fuel Screw i would replace with a R&D Flex Jet , it will make minor tuning much easier , and you will be able to adjust the fuel mixture while sitting on the bike , so it makes it real nice for tuning on the trail if needed (elevation or Temperature changes require fuel screw adjustment) , so that is the direction i would go , then report back with your findings , just do small adjustments/changes so you know what does what for better or worse

Once again, thanks for the info, Mr. Dirt.

I'll dig into the jetting. I was reading that beginning in 2007 (the year of my bike), the needle no longer has slots. So if I want to make adjustments here, I'd need to replace it.

This may be a ridiculous question, but where are most folks getting jets? I'm probably not using the right Google search, but I've only located the jetting kits, not actual OEM jets. Are new needles also available? When they open this morning, I'll call a couple of our local motorsports locations and see what they carry.

I had found that remote flex fuel screw. I like that one over the other aluminum ones I've seen.

I'll definitely report on my results. Thanks again for the detailed info.

You can get any of the parts right here , or you can get them at your local dealer , any Honda dealer will have jets in stock (usually , but some do not have all sizes and they will need to order them) , they also should be able to get a adjustable needle as well (it would be for a different year obviously)

JD Jet Kit:
http://www.crfsonly.com/catalog/product ... ts_id/1096

Adjustable Needle:
http://www.crfsonly.com/catalog/product ... ts_id/3673

Individual Jets:
(Leak Jet) http://www.crfsonly.com/catalog/product ... ts_id/4028

(Pilot Jet) http://www.crfsonly.com/catalog/product ... ts_id/4975

(Main Jet) http://www.crfsonly.com/catalog/product ... ts_id/5734

R&D Flex Jet:
http://www.crfsonly.com/catalog/product ... ts_id/2792

Any local shop has jets. I buy all my jets from Rockymountainatvmc.com.
Even for the Triumph !

Awesome. Thanks for the info.

I'll reply here, when I get things sorted out, hopefully this weekend.

For those following this, I had some time to work on my very low hours '07 250X.

I first did the in-bike air box mods. I had an attachment for one of my soldering irons that is designed precisely for this purpose. It worked great.



I also installed the JD jetting kit (MJ from 130 to 158). My carb didn't tilt as much as one's I'd seen in videos. So I had a little tougher time getting it done. But I made a couple custom tools to help out.

With the jetting kit, I bought a JD mixture screw. But when I went to look at this, I didn't see a way to get the old mixture screw out. I assume it's supposed to have a screwdriver slot, which it doesn't. To me, it looks like the previous owner broke off an aftermarket mixture screw in the carb body.

These are bottom views of the carb, using a little makeup mirror to see.





Is that what I'm seeing (a broken mixture screw)? If so, I guess I'll have to pull the carb to get this out.

I also checked the plug, and it looked good. I was expecting it to look burned. But it was light brown, with a little black char.

Even with the broken mixture screw, I fired it up. It started on the 3rd kick and idled, which it's never done before. So I took it for a quick spin. It pulls a lot harder, is very smooth and doesn't backfire any longer. All around a huge improvement. I think the idle mixture is not quite right, as the RPM is a little variable. But still, a big improvement!

I was hoping not to have to pull the carb. But I don't see any other way to get the mixture screw out. Any thoughts?

Its not broken , its Honda's way of complying with the EPA and its ridicules governing over off road vehicles , having to comply with California's ridicules control over every other states emission standards , they dont want you to be able to richen the engine , although Dealers have the tool that adjusts it , but a aftermarket fuel screw is better and easier to use anyway , i personally like the R&D Flex Jet , and have one on both my bikes

You can use a RED electrical butt connector like this http://www.delcity.net/store/Vinyl!Insu ... s/p_805413

Just heat it up a bit and push it on the screw , let it completely cool , and it should just unscrew , make sure you get all the parts out , Spring , Washer, O-Ring

Also , if you lay the bike on its side resting on a crate or something to keep it from just laying on the ground , you will have a better view of the bottom of the carb and it just helps when you don't want to go thru the hassle to remove the carb , if you have a Car Jack Stand lying around you can put that under the grip and it will hold the bike just fine

Are you kidding me? I can't believe that. But I guess that's good news. I was thinking that I was going to have to drill and use an ez-out to get it out.

I'll give your method a try. I'm sure I have some of those butt connectors here.

Thanks also for the tip on laying the bike over. Seems obvious, but didn't dawn on me to do that.

I'll work on the mixture screw tomorrow, hopefully. But I feel like I'm about 90% there. It runs so much better.

Thanks a lot for all the tips and tricks. It's been like 30 years since I've worked on a bike. They are quite different these days.