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2008 CRF250X carb tune questions

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I'm a complete beginner mechanic and a rider returning to the sport after 33yrs off the moto. Got back into it for father son time and we're loving it!

I picked up a brand new 2008 CRF250X. Yep you read that right some rich guy bought it and road it around the block and parked it for the last 10yrs. It still has chalk marks on the tires!

 

I got it and took it straight to the shop to have carb cleaned and external air / fuel mixture screw installed. Went and road it today and it doesn't seem to be running correctly. The shop also said they removed the smog equipment?? Anyhow the bike has an inconsistent idle and feels like it surges at low speed tech trails. When dead cold it doesn't need to be choked to start. When warm it starts only with hot start lever engaged. After riding downhills at idle it would stallIMG_1482.jpg out at idle and would stall after idle then rolling on throttle. Is it just the mixture is to rich? Any help is appreciated. I'm done with taking it to the shop. Just want to learn how to do it myself. Shop was like $350 for a carb clean???

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Well first, congrats on a find like that.

As for the $350, yes, shops can be expensive and you can save a ton of money doing work yourself, which is really not all that difficult.  I would add though that ease of maintenance was not the primary goal of the CRF's; they are competition racing bikes.   The carb takes some effort to remove and is not as simple as one would think (nothing difficult, but it takes time).

 If you plan to do your own work, you should get a shop manual ($50).   The owners handbook is not bad, but it doesn't go into the same level of detail as the shop manual.   You won't need to spend a ton of money on tools to do the majority of the required maintenance for the moment.  Right off you'll need a metric hex set for your socket wrench, a good set of metric sockets, a torque wrench, and a spoke wrench.     That will cover you for a long time.     If you end up really getting into the motor and suspension later on, you'll spend  need to spend at most a couple hundred on tools (you'll save yourself far more than that in not taking it in)

In stock trim, the bikes are very lean (for emissions) and typically don't run well.   The simplest route is a JD Jetting kit.  For $85, you get a handful of jets, two multi-taper needles, and instructions on what to use for what conditions.   You can buy the same jets far cheaper and regular Keihin needles and save money, but really it's well worth it in my opinion.   JD jetting does dyno testing of all the setups and that's what the $85 is paying for.   Most find their setups spot on.

Doing the smog block off was OK, but if your in CA, your going to have a problem.   Removing it does not effect performance, but it does eliminate backfire on decel, and shave 1 lb off the bike.

 The other thing you'll want to do is pop the snorkel off the air box, and poke some holes in the top at the very least.   Many cut-off the entire top of the air box. The snorkel is held on by two pop rivets.   Just drill them out to remove it.

 After doing those two things, you'll find the bikes runs very well, runs cooler, and has added power.

 Change the oil about every 10-15 hours and when you do, do NOT use the transmission check bolt as described in the manual.   Instead, measure the oil out and poor it in through the large inspection plug.   The check bolt strips out easily as it's only 7ft/lbs (some manual are mis-printed with 9ft/lbs as the spec), so best to avoid it.

 Clean the air filter often, especially if riding in sand, and use a thin layer of grease on the form gasket.    Getting the element in and out is a real challenge at first.  It's a compound movement and takes a few times before you get it figured out.  After that, it is easy. 

 Think that covers it for the moment, other than going out and having some fun with your son.:ride:

Jim.

 

Edited by Jim Dettman
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Well that's a shame the shop blew what should been an simple job.

I'd think it very temping to take it back and make them fix it. On the other hand if they blew it the 1st time, I see being hesitant to take it back to these guys.

There is no reason that bike, with that history, shouldn't have run great with just new replacement main and slow jets. I think stock for California 08 was 132 main, and 42 slow/pilot. Even better would be a 45 slow/pilot and about a 140-160 main. Pretty easy to install with the carb still on the bike. You need a small screwdriver and a small 6mm socket or this...

https://thumpertalk.com/shop/Motion-Pro-FCR-Carb-Tool-08-0181-p4451888.html

There is a a tiny o-ring, washer and spring on the air/fuel screw, I wonder if they messed up and didn't put on the little o-ring or washer. Otherwise, I think they assembled the carb incorrectly. That will be hard to figure out for someone who hasn't worked on this carb a few times. Do an internet search for "Keihin FCR Carb Rebuild With Ty Davis Racing". He has a good tutorial for taking apart and putting together the carb, with great pictures.

Good Luck

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Thanks a ton fella's! I watched countless youtube videos on setting air fuel mixture and took her out for another spin today.  I warmed up on fire roads for about 20min then followed rockymountainatv.com instructions on how to setup proper air / fuel mixture.   The bike is now dialed.  Isn't stalling or surging, and no revving on idle return.  @Jim Dettman thanks so much for the response and suggestions on tools.  This is a fun journey.  @motonuttois thanks for the jetting suggestions but I have no idea what the numbers mean. The bike is running great for now.  Once I become a little stronger rider I think I'll do the airbox mod and re-jet with JD kit.  For now everything is fine.  I don't need anymore power.  I did this hill climb today that scared the shit out of me, but I did it! 

So now I'm thinking with the bike being brand new (I've put 3hrs on it) should I be following break-in procedures??  Also what do you guys think about my wish list?? 

WISH LIST:

Radiator braces - all the reviewers say this is the achellis heal of this bike. 

Airbox mod and JD jetting kit

Lowering link - I'm 5'7" and feels like for trail riding this would really help. 

Some sort of bag to keep tools and a tube in.  Maybe something to hold phone, keys, wallet.  

Trail Tech Vapor computer

Maybe a street legal kit (on the fence about this one) 

BTW.... I'm in Washington. Not Ca. 

Happy trails! 

 

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<<o now I'm thinking with the bike being brand new (I've put 3hrs on it) should I be following break-in procedures??>>

Just change the oil and filter soon.

<<Also what do you guys think about my wish list?? >>

Pretty much right on with what others look to do, but I would add:

1. Get springs (front and rear) that are correct for your weight and riding style.    The bike stock is sprung for 160lbs rider.

2. Make sure you set the sag on the rear.

3. a slight gearing down.   Most go slightly lower.   A cheap way to try it is to get a 13 tooth front sprocket, which requires no change in chain length.    That is worth 3-4 teeth on the rear sprocket.   Most find that too low and will use a 14 tooth front (stock) and then go up 1-2 on the rear.   That does require a longer chain though.  Some are happy with the 13 on the front and stick with that.

One other comment; on your lowering link, you'll throw the bikes geometry off if you do only that.   I can sympathize with it being too tall (I'm 5' 9", with a 30" inseam) and you have a few options:

1. Lowering link and spacers  in the front to lower the bike evenly.

2. Shaving the seat foam down (gives about 1"), or buying a gel seat.

3. Lowering the subframe (makes the rear of the seat come down).

4. A combination of any of the three.

I've put up with mine, but I'd ride a whole lot better I think if I could really get a foot down when I need to.  I've fallen over a number of times because I can't.

Jim.

Edited by Jim Dettman
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Nice bike! That's what my 15 yr old son that is 5' 9 chose for his first big bike. His sixth bike btw so enjoy the buy and sell process... anyway. His is an '08 too and it came with a fmf q4 muffler so I'm not so sure what powers difference that made but the seller said it was stronger. The bike ran flawlessly. After a few months my son wanted to do the mods. Air box and cut the pink wire the o ring in the ap circuit was already done too. We were surprised by thrower increase of these simple mods. He's going through 2 tires to my one. But he's 15. It ran lean with a 155 main so we settled with a 160 at 1000 ft in north Georgia. Can't remember the pilot. Didn't touch the leak jet. He gets every hole shot in our hare scramble series then hits a tree.

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5 minutes ago, BTD123 said:

He gets every hole shot in our hare scramble series then hits a tree.

Ah....to be young once again...sigh. 

Jim.

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That's hilarious! I'm thankful my 10yr old is very cautious and not aggressive.   Watching the kids progress and have breakthrough moments on the Moto has to be one of the coolest parenting moments.   

Speaking of Hare Scramble I'm looking into doing some local poker runs.   Something easy but fun...... This whole moto thing is taking over my brain. 

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That's hilarious! I'm thankful my 10yr old is very cautious and not aggressive.   Watching the kids progress and have breakthrough moments on the Moto has to be one of the coolest parenting moments.   
Speaking of Hare Scramble I'm looking into doing some local poker runs.   Something easy but fun...... This whole moto thing is taking over my brain. 

He was about 10 when I got rooster for the first time and we started moving at a good pace. At 11 he got his rm 85. He got really good on that bike but outgrew it. He can't take me on the MX but he's faster through the woods. Regarding the hare scrambles, there's a class for everyone and they're very family friendly. Watching the kids grow in size and skill including his friends, is something amazing. It truly creates an unbreakable bond. Sharing the excitement, surviving the danger of the moment. I cancelled our race plans this weekend due to storm damage here but I think we're back in now.
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Update... bike is now dialed! Carb tune is perfect, suspension is setup. We just hit three days of track and trails and it never failed! Love this bike!

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