Crf150r 2008 wont idle

[Joe08]

Hi i’ve just bought a CRF150R 2008, and the bike wont idle. When i got there he was having trouble getting it to idle. Anyway i went on it but he said i had to keep on revving it in order for it to stay alive. It was fine didn’t fully open it up so couldn’t identify any other isues but i did give it some throttle but seemed fine.

So i bought it and got it home and still my self cant get it to idle. Everytime i start it it will start up and just die, and then when i go to give it throttle it just bogs out. Only the occasional time it will start up and i can keep it going but it will eventually die.

So the guy said you have to ‘prime’ it twice before you start it so i do that and it start up  a bit longer and dies and then i go to go give it throttle and it bogs out no matter what.

So then i put the choke on starts right up but idles high but then as soon as i take it of choke it dies and then i go to give it throttle and it bogs out. Then only way to keep it going is to choke it and then hold the rev and turn choke off and just keep revving it like i did when i first went on it at the guys house.

I’ve looked at some suggestions on Youtube and the internet and i can’t find much, people were just saying it could be a clogged pilot jet or needing a need a new pilot jet or to change it or the air/fuel mixture screw, but the problem is i cant find it and i wouldent know how far to turn it out nor how to know what pilot jet size to get.

So i was just wondering if anyone out there could help me fix this ASAP. Not really looking to do to much maintenance as i dont wanna break anything before ive properly riden it.

Thanks Joe

[Danceswithtrees]

         Your pilot jet is plugged.  Loosen the clamps on the carb boots, spin the carb so you can get at the bottom, remove the plug and you'll see two brass jets.  The narrower one with the screwdriver slot in it is the pilot jet, pull it out and preferably replace it with a 42 or 45.  You may be able to clean it but it's a very small passage through it and once they're plugged can be difficult to clean, and the bike will run better, start easier with a little bigger pilot. 

[Joe08]

6 minutes ago, Danceswithtrees said:

         Your pilot jet is plugged.  Loosen the clamps on the carb boots, spin the carb so you can get at the bottom, remove the plug and you'll see two brass jets.  The narrower one with the screwdriver slot in it is the pilot jet, pull it out and preferably replace it with a 42 or 45.  You may be able to clean it but it's a very small passage through it and once they're plugged can be difficult to clean, and the bike will run better, start easier with a little bigger pilot. 

Ok thanks for the help. Do you tjink you could send my to a direct link to it preferably a 45? If thats ok?

[Danceswithtrees]

You're in the UK so don't know where you're going to shop.  Here's a link to rmatv https://www.rockymountainatvmc.com/p/2896/24375/Pro-X-N424-21-Series-Keihin-Pilot-Jet-?v=2017-HONDA-CRF150R-Expert

Pro X N424-21 Series Keihin Pilot Jet 45

 

[Joe08]

1 minute ago, Danceswithtrees said:

You're in the UK so don't know where you're going to shop.  Here's a link to rmatv https://www.rockymountainatvmc.com/p/2896/24375/Pro-X-N424-21-Series-Keihin-Pilot-Jet-?v=2017-HONDA-CRF150R-Expert

Pro X N424-21 Series Keihin Pilot Jet 45

 

Ok will take a look now

[Joe08]

26 minutes ago, Joe08 said:

Ok will take a look now

I can’t find any in the uk its just says cannot be sold to a international seller

[mlatour]

1 hour ago, Joe08 said:

Not really looking to do to much maintenance as i dont wanna break anything before ive properly riden it.

Quite the opposite if you want a reliable and long lasting bike,

keep in mind this is a high performance MX race bike, not a recreational trail bike.

 

Meaning frequent oil & filter changes, air filter servicing and valve train adjustments are all part of the ownership.

 

The more you put aside routine maintenance, the more it will cost you later.

[Joe08]

1 minute ago, mlatour said:

Quite the opposite if you want a reliable and long lasting bike,

keep in mind this is a high performance MX race bike, not a recreational trail bike.

 

Meaning frequent oil & filter changes, air filter servicing and valve train adjustments are all part of the ownership.

 

The more you put aside routine maintenance, the more it will cost you later.

Yes saying that, obviously ill do the maintence as in every to 2 hours change oil change air filter e.t.c, and normal maintenance but i just dont wanna rip the thing to pieces before ive taken it out because im learning on all the new parts this is my first proper bike.

[mlatour]

Unless you have proof is was done somewhat recently,

at 9 years old that FCR carburetor would no doubt benefit from a refurb:

new jets, all passages cleaned, new float, serviced accelerator pump etc.

 

Many little wear items that add up to make for various driveability issues:

hard starting, won't idle, bogs on acceleration, tends to flood etc.

 

Your first priorities though is replacing the pilot jet and cleaning the passageway above it

to fix the won't idle problem. Then, checking the valve clearances.

Edited March 11, 2018 by mlatour

[bosox5150]

First check your air filter is clean. I've had 2 of these bikes & the idle issue is a pain. Does it stall with a small blip of the throttle off idle? You MUST read the fcr lean bog post here on this site. The issues are related.

 

Heres the short version of what is needed,

1. Either a new leak jet (I believe I ended up with a size 58) or the R&D power bowl or cheaper boyseen quickshot 3. The power bowl has an adjustable leak jet and is best but pricey.

2. A Tokyo mod or Merge racing accelerator pump spring. (this eliminates the o-ring mod discussed in the linked post)

3. Honda Accelerator Pump Kit: Has an Updated accelerator pump cover, improved diaphragm, longer rod. All this is a plus for that carb. Honda 16021MENA01

5.  R&D Air screw, this makes the air screw adjustment easy to do with a re-located screw just like the idle screw. This is a must!

4. If also hard to cold start try a 40 pilot jet.

 

IN 2012 there was a design change to the carb and both the improved Accelerator Pump Kit & stiffer pump spring where added. you could just try & find a used carb from a 2012 or newer crf150r or rb & not bother with steps 2 & 3.

 

At the very least trya 58 leak jet, 40 pilot & R&D Air screw.  I also needed a 138 main jet but jet sizes may be different for your climate/elevation.

 

Good luck, hope this helps!

 

 

Edited March 12, 2018 by bosox5150

[Joe08]

6 hours ago, bosox5150 said:

First check your air filter is clean. I've had 2 of these bikes & the idle issue is a pain. Does it stall with a small blip of the throttle off idle? You MUST read the fcr lean bog post here on this site. The issues are related.

 

Heres the short version of what is needed,

1. Either a new leak jet (I believe I ended up with a size 58) or the R&D power bowl or cheaper boyseen quickshot 3. The power bowl has an adjustable leak jet and is best but pricey.

2. A Tokyo mod or Merge racing accelerator pump spring. (this eliminates the o-ring mod discussed in the linked post)

3. Honda Accelerator Pump Kit: Has an Updated accelerator pump cover, improved diaphragm, longer rod. All this is a plus for that carb. Honda 16021MENA01

5.  R&D Air screw, this makes the air screw adjustment easy to do with a re-located screw just like the idle screw. This is a must!

4. If also hard to cold start try a 40 pilot jet.

 

IN 2012 there was a design change to the carb and both the improved Accelerator Pump Kit & stiffer pump spring where added. you could just try & find a used carb from a 2012 or newer crf150r or rb & not bother with steps 2 & 3.

 

At the very least trya 58 leak jet, 40 pilot & R&D Air screw.  I also needed a 138 main jet but jet sizes may be different for your climate/elevation.

 

Good luck, hope this helps!

 

 

Ok thanks this is very helpful im going to have a look around

[Joe08]

8 hours ago, Joe08 said:

Ok will take a look now

Will this be ok?? The size is a little different or does it have to be the exact same??

[BoMadsen]

As long as you get something that fits the Keihin FCR MX carb, you should be good ?

Just FYI, you can find a kit containing many different jets for just about double of what a single jet will cost you. 

[mlatour]

Go to your local Honda motorcycle dealership and order part # 99103-GBF-0450 JET, SLOW  which is the genuine Keihin part.

Don't mess with aftermarket 'equivalent' copies that can sometimes be questionable. 

Best way (not the cheapest though) to rule out as many variables to carburetor problems is to refurbish it using only OEM parts.

'do it once, do it right'...

Edited March 12, 2018 by mlatour

[luv2ride2]

Joe there are a lot of variables that could cause this problem. If you don't work on these on a regular basis I would suggest taking it into you local dealer.

Be careful if you Loosen the clamps on the carb boots & spinning the carb so you can get at the bottom. You can potentially break your hot start plunger. It has plastic threads and breaks easily. Good luck!!

[bosox5150]

Thats a pilot jet, not a leak jet. The leak jet is inside the bottom of the bowl & looks like this one below. Part number would be Keihin N424-52-058 for a 58. luv2ride2 is correct in that this is fairly technical stuff if you have not much experience wrenching, however we all have to start somewhere. I would also recommend you pick up a honda service manual for your 08 crf150r, a service manual not an owners manual. This is always my 1st purchase after any bike! He is also correct in making sure you keep your air boot and intake seals nice and tight when you are done. There cannot be any gaps or air leaks around your boots or you will have much worse problems. Its easier to remove the carb for all the items I listed which requires you to remove the hot start nut, throttle cables, sub frame. You can do it by twisting the carb on the boots (loosen the clamps) or by letting it hang on the hot start and throttle cables but personally I would remove it completely and give it a good cleaning as well. Again it could be other things causing your idle issues ut I know that both my crf150r's needed the things I listed so I'm betting most do.

 

 

 

Consider this also,

FCR Float Bowl Stainless Steel Allen Bolt Set 00-009 $6.50 mergeracing.com ,  the float bowl screws are very soft and strip easy so these are much better and have allen heads, If you get the R&D air screw you won't use one of the long ones as the air screw has one in place that will thread into the left rear corner of the bowl. These also do fit the R&D power bowl if you splurge for that.

https://mergeracing.com/product/fcr-stainless-steel-allen-bolt-set/

 

Another great addition is an ALUMINUM hot start nut, it elminates the possibility of breaking the threads. There are many too choose form like tokyo mods, pro circuit, zip ty racing etc. I prefer the ones with a knurled edge as shown, they are easier to start the threads with the little grips. You can use just about any FCR type Hot start nut as there all the same. Be cautious though Aluminum won't break (easy anyway) but it will strip if you cross thread it. Seems like a lot of cost for it all but if your gonna do it, do it right.

 

Edited March 12, 2018 by bosox5150

[Joe08]

21 hours ago, bosox5150 said:

Thats a pilot jet, not a leak jet. The leak jet is inside the bottom of the bowl & looks like this one below. Part number would be Keihin N424-52-058 for a 58. luv2ride2 is correct in that this is fairly technical stuff if you have not much experience wrenching, however we all have to start somewhere. I would also recommend you pick up a honda service manual for your 08 crf150r, a service manual not an owners manual. This is always my 1st purchase after any bike! He is also correct in making sure you keep your air boot and intake seals nice and tight when you are done. There cannot be any gaps or air leaks around your boots or you will have much worse problems. Its easier to remove the carb for all the items I listed which requires you to remove the hot start nut, throttle cables, sub frame. You can do it by twisting the carb on the boots (loosen the clamps) or by letting it hang on the hot start and throttle cables but personally I would remove it completely and give it a good cleaning as well. Again it could be other things causing your idle issues ut I know that both my crf150r's needed the things I listed so I'm betting most do.

 

 

 

Consider this also,

FCR Float Bowl Stainless Steel Allen Bolt Set 00-009 $6.50 mergeracing.com ,  the float bowl screws are very soft and strip easy so these are much better and have allen heads, If you get the R&D air screw you won't use one of the long ones as the air screw has one in place that will thread into the left rear corner of the bowl. These also do fit the R&D power bowl if you splurge for that.

https://mergeracing.com/product/fcr-stainless-steel-allen-bolt-set/

 

Another great addition is an ALUMINUM hot start nut, it elminates the possibility of breaking the threads. There are many too choose form like tokyo mods, pro circuit, zip ty racing etc. I prefer the ones with a knurled edge as shown, they are easier to start the threads with the little grips. You can use just about any FCR type Hot start nut as there all the same. Be cautious though Aluminum won't break (easy anyway) but it will strip if you cross thread it. Seems like a lot of cost for it all but if your gonna do it, do it right.

 

Well today i have checked the pilot jet and it was a bit clogged, so it runs a tiny bit better. Then i adjusted the air screw to 1.5 turns which is was orginally on 2 turns out so i did it to 1.5 didnt really make much of a different. So i tried holding the choke half on and it idles amazing but if i give it throttle it gets stuck and slowly goes down.

i think if i put the new pilot jet in it should be alright, what do you think.

Fyi i already order one yesterday 

Thanks

Joe

[Danceswithtrees]

1 hour ago, Joe08 said:

Well today i have checked the pilot jet and it was a bit clogged, so it runs a tiny bit better. Then i adjusted the air screw to 1.5 turns which is was orginally on 2 turns out so i did it to 1.5 didnt really make much of a different. So i tried holding the choke half on and it idles amazing but if i give it throttle it gets stuck and slowly goes down.

i think if i put the new pilot jet in it should be alright, what do you think.

Fyi i already order one yesterday 

Thanks

Joe

Yes very well might be all you need, but a thorough carb cleaning would also be a good idea at this point.  Won't take much time, not hard to do and your bike will love you for it.  Btw I don't even bother trying to clean pilot jets, they're cheap just replace them.

[Joe08]

15 minutes ago, Danceswithtrees said:

Yes very well might be all you need, but a thorough carb cleaning would also be a good idea at this point.  Won't take much time, not hard to do and your bike will love you for it.  Btw I don't even bother trying to clean pilot jets, they're cheap just replace them.

Ok cheers will do in future. Ill test the pilot jet to see it works then do a thorough carb clean.