2007 CRF50 Confusing Problem

I just picked up a 2007 CRF50 from someone. The bike is all stock except for a tall seat, higher bar mounts/bars, and a Red Barron throttle assembly/tube.

The owner said it had just been sitting in the garage for the past 18 months and no longer runs. He also mentioned that it might need a new throttle assembly. As he was not mechanically inclined so thought that this all meant that the carb was gummed up and simply needed a good cleaning. Upon inspecting it, the throttle was completely frozen. This was because when he routed the throttle cable it was binding against the frame. Quick fix, reroute the cable.

I also dissembled the carb and cleaned it all out, as well as the gas tank. Removed, float, needle, main jet, idle screw, and air/fuel screw. Cleaned everything with carb cleaner and resembled.

Now here comes the problem(s). I only have an 1/8th of a turn of throttle. I don't know 50s, but I would think it should have more than that. I've adjusted the throttle cable as much as possible with little effect. It looks like the cable is simply too short. This is what it looks like at the end that goes into the carb... not normal?



The other issue is that it will not want to run with the throttle on. I can it it to idle...barely. But when you hold the throttle open it will maybe increase to about 2500rpm for a few seconds and then want to die. I am thinking it could be a float issue?

I've gone through the carb twice. Removed the air filter and then the exhaust thinking it might not be getting enough air or a back pressure issue, but no change what so ever.

Anything else to check or ideas? (thank god these things are easy to work on compared to a 250F :) )


With your throttle issuse, there is a little nipple in the carb and on the throttle there is a slot that goes from top to bottom cut out. Make sure the slot on the throttle goes up and down on the nipple. You will know if it is alined correct because if it is not the throttle will be stuck and barly move. Hope this helps.

Thanks! yes slot is aligned correctly. I have some throttle (1/8th turn) and it returns as it should. I think the cable is physically too short and that is why the spring is kinked. Can anyone confirm that?

Your slide photos appear normal to me.

They do have a throttle stop screw.

Take the throttle off the bar and test it wil no tension. Meaning, move the throttle housing so it isnt binding and check to see if there is still 1/8 th turn. If there still is, then as mentioned before, check to see if that. Throttle has a stop and unscrew it. Finally, the cap can kind of go on and still not be properly seated. And the slots mentioned before can allowed the slide to "fit" but still be 180 degree in the wrong direction. The whole carb slide should easily fit in and not be visible when you reseat the cap and screw it down.

But yes, with taller bars and and aftermarket throttle housing, the stock cable is usually too short. Fast 50s makes a two inch longer cable that should work. You can call them and they will help you out for the part.

The spring isn't kinked. It just looks like that because it's compressed. If you take it off the cable and set it down, it'll be straight. I had the same concern on mine and when I pulled the spring, it was straight. Check the throttle screw to make sure it's all the way out.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Similar Content

    • By RCWSO
      I have an 07 CRF70 that I have done the filter pod modificaiton by cutting the extension tube off and I have drilled a couple of holes in the end of the exaust per some instructions on a thread here at TT.
      I have recently had some problems getting the bike to idle consistently. I am wondering if I should try and rejet the bike at all or get a needle from an older carb that is adjustable. I do have a unifilter that I can put in as well with the stock pod that I cut.
      It is not that the bike wont run or start, it just seems to only idle if I turn it up significantly but as soon as I turn it down even 1/8 of a turn it dies. But the idle that I set to keep it running well is too fast as the bike will move forward if in gear and no throttle is applied.
      Any suggestions? Jetting, needle, air screw change with an older carb?
    • By the-new-kid
      hello guys I'm like really new to this, like extremely new but I was going to buy xr-70r from a friend and drop a Lifan 125cc engine in it (here's the link: http://tboltusa.com/store/lifan-125cc-enginebrsale-price-p-1811.html ). Now the site says its a 4preed trans with normal gear set up (1-n-2-3-4), and manual front clutch, I'm wondering if I need to buy the clutch lever, perch, and cable then connect it all. Then secondly, what pip should I be looking for I'm not sure if the header would have to be a different style or what exactly.... please be patient with me I'm doing the best I can to learn... thanks
    • By anger806
      hi im new to the forum and i am running a stock 2005 crf 50f with pro tapers but no engine mods what size carburetor should i be looking for to get a little more pep out of my motor?
    • By HondaRacer37
      Hey everyone.  Darn glad to have found this forum!
      Just bought my son a 2009 CFR70 (first bike - 8 years old) and the first thing I'm doing is scrapping the factory air box for a UNI pod filter.
      I'm looking for advice on how I can open up/modify the factory exhaust for more performance.  I heard about removing the screen and drilling some holes but have not found those posts. Any specific advice would be greatly appreciated. (Found only a couple performance aftermarket pipes that were very pricey.)
      I'm thinking after the air filter change and pipe opening the main jet size may need to be increased. It's a stock 13mm Keihin carb.  What size is recommended?  Haven't looked at the stock size yet. 
      I assume the needle is adjustable on the slide (but don't know if this would do any good or be necessary anyway) and hope there is an air mixture screw somewhere because it seems the carb could use a bit of adjustment now.  Although next to the idle screw it looks like a brass cap or plug rather than a screw. (See photo attached.)
      Thanks for any advice.  It's great to be part of this group.  Ride on!
      Greg in Florida

    • By thousandbuckle
      Hello all, reaching out to you today to get some help with a small project I am trying to do.
      I just bought a 2006 CRF50 for my 3 year old and would like to rig it up with a wireless remote kill switch for those just in case moments. I have the throttle speed screw installed and will limit it that way also but want a back up until she is proficient and I feel confident.
      Since this bike does not have electric start there is no battery. I was wondering if any one has or knows how to rig up a wireless car alarm system to work as a remote kill switch. I know I will need a 12 Volt battery on the bike which I can get. I know there is a product from 3Built that does this but the range is only 250 feet and some say it is even less than that. I was thinking of a car system since the range is usually around 1,000 feet which is overkill but I prefer overkill when it comes to this topic,
      Any DIY thoughts you might have or suggestions would be appreciated.