Carburetor problem / issue

Hey guys, I hope you can help me. 
I have a crf450r 2007. My carb have problems when I want to start my dirtbike, most of the time I can't start it with kickstart, someone needs to pull me with a car, and when I'm using my bike if I'm on a curve, and I slow down the bike, it goes off. Some people tell me the reason what it happened is because the "valve, throttle" part: 16112-MEY-A11 is not working as it should. Some one can tell me if it is the reason why my carb isn´t working as shloud? or what else can it be?
I really appreciate your time! thank you.

Well there are a few things to check... some are easy...others a little bit more involved..

Once it's started, does it idle fine on it's own?

1 - Check your carb adjustments (Fuel screw, Idle Knob)

2 - Check valve clearances - if the are off enough, the bike can be hard to start for sure

3 - Wouldn't hurt to check compression and spark plug

4 - That "Valve Throttle"(Glorified Slide) can wear from rubbing on the slide slots/tracks plus there is a special oring'ish type seal on that slide that has a tendency to wear out, but it's not that expensive to replace. If I remember correctly, if that seal is bad or there's excessive wear on the Slide, low end performance can suffer, but I wouldn't think it would keep the bike from starting (?)

To get the carb off you have to remove the rear shock (At least you do on my 08) not hard just a pain. once you have the air box boot off (With the carb still attached to the intake boot and gas still hooked up) look in the rear of the carb and twist the throttle to make sure the accelerator pump is working - there's a small jet that sticks up behind the slide that squirts gas through the venturi as the slide lifts up - has nothing to do with starting the bike or anything, but while you're in there you'd be money ahead to check it out ;)

 

my gut is telling me it's a compression issue though (Valves or rings)

20170728_181850.jpg

check your valve clearances first

22 hours ago, S.O.A.N.Z said:

check your valve clearances first

That's the first thing I thought as well. :thumbsup:

Depending on how slow you're going into/thru the curve, it may be the result of the 04-08's lighter (by roughly 4.5 ounces) flywheel.  You can put a flywheel from a 02-03 on it or heavier flywheel and that should help. It will help stalling and hook up better on, for example, hard pack but it won't rev as freely (which is why Honda went to a lighter flywheel in the first place).

You should be able to just clean the throttle valve but, yes, the floating valve set/seal (# 16 on fiche) should help low throttle performance.  Make sure you install the seal correctly (see pic) if you change it. Also, always keep carb cleaner from the throttle valve area whenever you clean the carb. It'll damage the seal.

IMG_3665_web.jpg

Edited by HRC27
On 3/11/2017 at 11:22 AM, WERNER1 said:

Well there are a few things to check... some are easy...others a little bit more involved..

Once it's started, does it idle fine on it's own?

1 - Check your carb adjustments (Fuel screw, Idle Knob)

2 - Check valve clearances - if the are off enough, the bike can be hard to start for sure

3 - Wouldn't hurt to check compression and spark plug

4 - That "Valve Throttle"(Glorified Slide) can wear from rubbing on the slide slots/tracks plus there is a special oring'ish type seal on that slide that has a tendency to wear out, but it's not that expensive to replace. If I remember correctly, if that seal is bad or there's excessive wear on the Slide, low end performance can suffer, but I wouldn't think it would keep the bike from starting (?)

To get the carb off you have to remove the rear shock (At least you do on my 08) not hard just a pain. once you have the air box boot off (With the carb still attached to the intake boot and gas still hooked up) look in the rear of the carb and twist the throttle to make sure the accelerator pump is working - there's a small jet that sticks up behind the slide that squirts gas through the venturi as the slide lifts up - has nothing to do with starting the bike or anything, but while you're in there you'd be money ahead to check it out ;)

 

my gut is telling me it's a compression issue though (Valves or rings)

20170728_181850.jpg

I really apreciatte your time, I´ll check it, and when my bike starts, I can not let go of the accelerator because the motorcycle turns off, is embarrassing :/ but, once it start, its easier to start again, already remove the carb from the dirtbike! 

21 hours ago, HRC27 said:

That's the first thing I thought as well. :thumbsup:

Depending on how slow you're going into/thru the curve, it may be the result of the 04-08's lighter (by roughly 4.5 ounces) flywheel.  You can put a flywheel from a 02-03 on it or heavier flywheel and that should help. It will help stalling and hook up better on, for example, hard pack but it won't rev as freely (which is why Honda went to a lighter flywheel in the first place).

You should be able to just clean the throttle valve but, yes, the floating valve set/seal (# 16 on fiche) should help low throttle performance.  Make sure you install the seal correctly (see pic) if you change it. Also, always keep carb cleaner from the throttle valve area whenever you clean the carb. It'll damage the seal.

IMG_3665_web.jpg

Thank you bro! I will check it! I apreciatte your time!

My pleasure man. :thumbsup:

Yeah, So Valves first (And a Compression check after you get the valves set within specs) 

Since the carb is off, I'd just go through it with a fine tooth comb - seeing as it's not idling on it's own, and IF the valves or correct, then you'd start looking at the Pilot circuit as well as the Fuel screw circuit - those two have the most effect at start up and Idle 

Also check your choke as well.

On 6/11/2017 at 7:34 AM, WERNER1 said:

Yeah, So Valves first (And a Compression check after you get the valves set within specs) 

Since the carb is off, I'd just go through it with a fine tooth comb - seeing as it's not idling on it's own, and IF the valves or correct, then you'd start looking at the Pilot circuit as well as the Fuel screw circuit - those two have the most effect at start up and Idle 

Also check your choke as well.

Already disarms my carburetor, when looking at the throttle valve, is very worn from the edges and has a lot of play for wear, is this normal? I can send pics, if you want 

By all means, post pics here if you can (Should be able to upload directly from you PC or phone if they're not too big.. ) The more eyes on it the better..

IMO - wear on the slide it's self shouldn't cause it not to start,... the washer/oring under the plate of the Throttle Valve would have a bit more of an effect as that is what essentially applies tension to that plate and seals everything, but physical wear on the slide body shouldn't have that much of an effect. AND, if it was sucking a little bit extra air, you could compensate a bit by your fuel screw (Another 1/2 or so turn out...?) then it would probably just run/idle a lot faster ... again, all this is my opinion and theory :D

I would still concentrate on the Valves and compression to make sure you have a base line starting point...

yes they are loose, its normal.  Sounds like the pilot jet is stopped up to me.  If it has the std 42 in it, throw it away and get a 45...you can thank me later.  I dont know why honda sent them out so damn lean.  Also get a thumb type idle mix screw as adjusting them on the bike with the stock slotted type is a total pain in the butt. 

On 7/11/2017 at 10:06 AM, WERNER1 said:

By all means, post pics here if you can (Should be able to upload directly from you PC or phone if they're not too big.. ) The more eyes on it the better..

IMO - wear on the slide it's self shouldn't cause it not to start,... the washer/oring under the plate of the Throttle Valve would have a bit more of an effect as that is what essentially applies tension to that plate and seals everything, but physical wear on the slide body shouldn't have that much of an effect. AND, if it was sucking a little bit extra air, you could compensate a bit by your fuel screw (Another 1/2 or so turn out...?) then it would probably just run/idle a lot faster ... again, all this is my opinion and theory :D

I would still concentrate on the Valves and compression to make sure you have a base line starting point...

I take some pics of my carb, so, here's the link on google drive: https://drive.google.com/drive/u/0/folders/1mIk_cLXSviZQOtEMmQy4BnaKJ7iXs56B 
I'll apreciatte your time, if something is wrong please tell me 

So "Yes", there is some wear on the slide,.... BUT, I don't really think that would keep the bike from running in and of it's self. 

Have you checked the valves yet?

One fairly easy test to try since you have the carb off - re-assembly the carb (Make sure to clean out all of the jets and ports first!) install the carb on the intake (You don't even have to hook up the throttle cables or gas line) then take a small squirt bottle with some gas in it and squirt a couple of small squirts into the back of the carb (Maybe lift of the slide a bit and squirt one shot in there) then try and kick start the bike. It should fire right off if everything else is good to go (Valves / compression )

Other ponts of interest would be the oring behind the plate of the slide, and possibly the accelerator pump diaphragm  - inspect those really good to see if they need to be replaced...

On 9/11/2017 at 1:52 PM, WERNER1 said:

So "Yes", there is some wear on the slide,.... BUT, I don't really think that would keep the bike from running in and of it's self. 

Have you checked the valves yet?

One fairly easy test to try since you have the carb off - re-assembly the carb (Make sure to clean out all of the jets and ports first!) install the carb on the intake (You don't even have to hook up the throttle cables or gas line) then take a small squirt bottle with some gas in it and squirt a couple of small squirts into the back of the carb (Maybe lift of the slide a bit and squirt one shot in there) then try and kick start the bike. It should fire right off if everything else is good to go (Valves / compression )

Other ponts of interest would be the oring behind the plate of the slide, and possibly the accelerator pump diaphragm  - inspect those really good to see if they need to be replaced...

I cleaned everything, put everything again as it was, the engine turned on, and it stayed that way, I used it for 5 or 6 minutes to warm it up and when I use the clutch and loose the throttle goes off, I changed the jet from 42 to 45 , maybe my problem is with the float, I have read in several parts how to put the correct level but I do not know how, this is embarrassing, I spend a lot of my time on this, taking their advice but I do not know what I did wrong, I need to check the valves, but the curious thing is that the first time I turned it on, after reinstalling the carburetor, the engine was running without any problem, but when accelerating (in neutral) black smoke came out of the muffler, otherwise I remember smoke black means gasoline, thank you guys, apreciatte your time....

On 9/11/2017 at 1:52 PM, WERNER1 said:

So "Yes", there is some wear on the slide,.... BUT, I don't really think that would keep the bike from running in and of it's self. 

Have you checked the valves yet?

One fairly easy test to try since you have the carb off - re-assembly the carb (Make sure to clean out all of the jets and ports first!) install the carb on the intake (You don't even have to hook up the throttle cables or gas line) then take a small squirt bottle with some gas in it and squirt a couple of small squirts into the back of the carb (Maybe lift of the slide a bit and squirt one shot in there) then try and kick start the bike. It should fire right off if everything else is good to go (Valves / compression )

Other ponts of interest would be the oring behind the plate of the slide, and possibly the accelerator pump diaphragm  - inspect those really good to see if they need to be replaced...

I cleaned everything, put everything again as it was, the engine turned on, and it stayed that way, I used it for 5 or 6 minutes to warm it up and when I use the clutch and loose the throttle goes off, I changed the jet from 42 to 45 , maybe my problem is with the float, I have read in several parts how to put the correct level but I do not know how, this is embarrassing, I spend a lot of my time on this, taking their advice but I do not know what I did wrong, I need to check the valves, but the curious thing is that the first time I turned it on, after reinstalling the carburetor, the engine was running without any problem, but when accelerating (in neutral) black smoke came out of the muffler, otherwise I remember smoke black means gasoline, thank you guys, apreciatte your time....

The carb has an accelerator pump and will discharge black smoke from the exhaust while throttling it.  this is normal. 

Your issue sounds valve lash related, mainly the intake valves.  It is common when the intake valve lash is too tight, once the motor warms up (thermal expansion of the valves, cam, head, ect) the lash will go to 0 or even less than 0 preventing the valves from closing all the way.  My 06 450R did this.  It would start right up, idle smooth with choke, then remove choke and it would idle for maybe 5-8 more seconds and die.  It would NOT kick start again till it cooled off.  It would roll start but would not idle properly.  My valve lash was .0015" when cold and would go to .0000" when hot.  I reshimmed my intake valves as the exhaust were spot on at .011".   Once this was done, the bike started easy, ran great, and would idle normally and not shut off.

Note, be very careful when tightening down the rear most valve cover bolt (towards the carb) as it will snap off very easy and then you will have to remove the cam/rocker assembly and get it extracted.  Ask me how I know...

 

45 pilot

Stock main jet

Needle in middle clip position

Mix screw 1.750-2 turns out.  Then can adjust once its hot.

4 hours ago, KeyKeeper said:

The carb has an accelerator pump and will discharge black smoke from the exhaust while throttling it.  this is normal. 

Your issue sounds valve lash related, mainly the intake valves.  It is common when the intake valve lash is too tight, once the motor warms up (thermal expansion of the valves, cam, head, ect) the lash will go to 0 or even less than 0 preventing the valves from closing all the way.  My 06 450R did this.  It would start right up, idle smooth with choke, then remove choke and it would idle for maybe 5-8 more seconds and die.  It would NOT kick start again till it cooled off.  It would roll start but would not idle properly.  My valve lash was .0015" when cold and would go to .0000" when hot.  I reshimmed my intake valves as the exhaust were spot on at .011".   Once this was done, the bike started easy, ran great, and would idle normally and not shut off.

Note, be very careful when tightening down the rear most valve cover bolt (towards the carb) as it will snap off very easy and then you will have to remove the cam/rocker assembly and get it extracted.  Ask me how I know...

 

45 pilot

Stock main jet

Needle in middle clip position

Mix screw 1.750-2 turns out.  Then can adjust once its hot.

thanks bro, i will check my valves, and my 42 jet was broken, was a real deal to get off of there! (that was like 2 or 3 months ago), and I have the same 45 pilot, stock main jet, needle in middle clip position and mix screw 1 3/4 turns out, one thing more, when I want start my bike, it does not want to start, because the spark plug gets wet...

As in it smells like gas when you pull it out and it's wet?

In regards to the black smoke, there will be a little bit when blipping the throttle in neutral, but it shouldn't be a whole lot,.. more like barely noticeable (?)

If the plug is wet, sounds like the carb is puking gas internally..

Do NOT throttle it when you start it.  4T motors do not want throttle to start like the 2T engines do.  

Cold = choke, kick 2 times slowly but smoothly, then lock kick starter on top dead center (compression stroke) and kick the heck out of it.  Repeat if it dont start.

Hot = pull hot start and kick from top dead center again.  If no start, release hot start and kick

Do NOT twist the throttle...they flood super easy.

intake valve lash per manual = .008"  ( set to .005" or .006" for quieter motor)

Exhaust valve lash per manual = .011" ( set to .009" or .010" for quieter motor)

1 minute ago, WERNER1 said:

As in it smells like gas when you pull it out and it's wet?

In regards to the black smoke, there will be a little bit when blipping the throttle in neutral, but it shouldn't be a whole lot,.. more like barely noticeable (?)

If the plug is wet, sounds like the carb is puking gas internally..

I believe I´ve problems with float, any advice to put in correct way?

 

2 minutes ago, WERNER1 said:

As in it smells like gas when you pull it out and it's wet?

In regards to the black smoke, there will be a little bit when blipping the throttle in neutral, but it shouldn't be a whole lot,.. more like barely noticeable (?)

If the plug is wet, sounds like the carb is puking gas internally..

 

Float Level - Typically when folks adjust the float level wrong, it's to the Lean side, AND, typically when it's set too high, (Fuel Not shutting off) it should run mostly out of the vent(s)? But, here's a good vid on adjusting the float on these types of carbs...

 

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