Rich? Lean? or Normal?

Wired the AP lever, downsized to a 55 leak, have a 45 PJ (wouldn't idle well with a 42). Just putting around my yard in first the motor acts kinda funny when decelerating.

From idle, if I give it a quick gentle twist up to 5-6k RPM, all is ok and good response, but the motor doesn't decelerate like it used to. I get some engine braking at first and then around 4k it seems that the motor gets a second life and wants to hold that RPM for a bit before the decel continues. The problem is magnified via a slight down grade.

It is almost like my idle is set too high, but I've lowered it to just over 2k and if I go lower, it won't run smooth. I tried a 42 PJ and it won't idle well with that and I don't know why. Both the 42 and 45 PJs are new, so shouldn't be plugged. Thought maybe the hotstart was stuck, but it sounds like its opening and closing again. I took it loose at the lever, so it shouldn't be messed up.

I'm guessing the problem is being caused by leftover fuel from the AP squirt getting drawn in after I turn off the throttle. What do you guys think?

I haven't really ridden it...just putted around. Too muddy to do any real riding yet.

Thanks.

my bike used to do that before i rejetted but dosent do it any more,i thought it was a leak jet issue,you said with a 42 your bike dosent idle well?even if you turn it up?

A few things. Since the problem appears to of started right after you wired the linkae, that is where I'd check first. I assume you have an 07 or older bike as the newer ones do not need this mod. Comfirm at WOT (engine off) that the linkage does not bind. Confirm your throttle cables have play in them with the bars straight a head and when turned side to side.

Next you can properly set the fuel screw and confirm correct pilot jet .

Fuel Screw/Pilot Jet

Fuel screw settings in the 'book' are recommended starting points. Every bike is different, as is the temp and altitude. Set the screw according to this method. Do it with the bike fully heated up.

Gently turn the screw all the way in. Now back it out two turns. Start the bike and fully warm it up, go for a 10 minute ride. Set the idle to speed to 1,500~1,800 RPM as best you can (I know, without a tach this is tough, just set it to were it idles relatively smoothly). Once warmed, slow the idle to the lowest possible speed.

*** When turning the fuel screw, keep an accurate 'count' of the amount you are turning it and record it in case you have to reset it for some reason. Makes life easier when you can just set it from notes Vs. going through the procedure again.***

Turn the screw in until the idle becomes rough or the bike stalls.

if it stalled, open the screw about 1/4 more turn. Restart it and slowly screw it in till you can just perceive a change.

If the screw can be turned all the way in and the bike still idles perfectly and does not stall, then you need to go down a size in pilot jet.

Now very slowly, open the fuel screw till the idle is smooth. Blip the throttle, let the bike return to an idle, wait say ten seconds. Confirm it is the same smooth idle.

If the screw has to be opened more than 3 turns to get a smooth idle, you need to go up a size in pilot jet.

If you find it does not stall with the larger jet but has to be open more than three turns with the smaller pilot jet, put the larger one in and set the fuel screw at 1/2 turn.

If the idle speed increased, adjust the idle speed knob to return the bike to a real slow idle speed. You must then re-visit the fuel screw. Keep doing this till the fuel screw is opened just enough to provide a nice steady idle at the lowest possible RPM. Once this is done, increase the idle speed to the normal one for your bike, typically about 1,800 rpm, but go by the spec in your manual.

Thanks for the replies guys! I do have a tach (Vapor) so know where it is idleing. Its weird....before I did all this work, my bike was fine with a 45 pj. It was too big because the fuel screw had little, if any, effect, but it would idle great and if I turned off the gas, it decelerated. Now something doesn't seem to be right. I'll try the 42 pj again and will go through the setting process you describe William, but it seems like something else is amiss. (perhaps its just that I haven't been able to really ride it yet).

Something else I did while I had it apart was remove a long, L shaped aluminum tube that was inside my airbox of my 06 CA version. The tube was connected to the breather that goes to the valve cover and to the plugged drain in front of the shock. I replaced the aluminum tube with the plastic connector that I removed a couple years ago from the airbox when I took off the smog pump (that opening is plugged). I can't imagine taking out the tube changing how my bike runs. All I can figure the aluminum tube did was create better suction on the valve cover but I'm not sure. I don't think the part is on a 49 state bike. The part I removed is #28 (its in the inset which I believe is only for CA bikes):

http://www.cyclepartsnation.com/pages/OemParts#/Honda/CRF250X_AC_(06)_MOTORCYCLE%2c_JPN%2c_VIN%23_JH2ME111-6M200001_TO_JH2ME111-6M209999/AIR_CLEANER/CRF250X-06-JPN-AC/2Y14KSC4KSC4F1600CB

Do you guys with 49 state bikes have part #28 and/or know what its purpose is? Again, on my CA version, it was connected to a short breather hose that goes to the T...one end of the T goes to the valve cover, the other to the drain in the clips in front of the shock. On my son's 49 state bike, he has a longer breather hose connected to the airbox where clamp 21 goes in the bigger diagram in the link above.

Thanks.

Dave

my bike used to do that before i rejetted but dosent do it any more,i thought it was a leak jet issue,you said with a 42 your bike dosent idle well?even if you turn it up?

Right...I opened the fuel screw about 2 1/4 turns and it was rough. I could get it to run smooth, but that was with the idle turned up too much so it was running on the main jet I think. Saying this makes me think plugged pj :smirk: but after about 6 jet changes (I tried some old ones first) I never have seen any dirt in the bottom of the 17mm plug. When I pulled the new 42 from the bike, I couldn't see through it, but could after blowing through it so I think it was just a drop of fuel in the orifice? Those dang things seem impossible to clean out for some reason.

I haven't had a 42 in my bike in years but could swear it used to idle ok with a 42, but I went to a 45 to help with the bog. I thought with the AP linkage wired, I could go to a 42 like most others on the forum.

The only other thing I did (that I didn't mention in the previous posts) was replace the carb bowl and AP cover screws with some hex head bolts.

Dave

May want to recheck your fuel screw 0-ring and washer. the o-ring can get damaged on install and cause the adjustment to be inconsistent.

Recheck your tps adjustment also after you find your correct idle speed. If the adjustment is incorrect you could end up with a hanging idle speed from timing advancing too much at idle.

May want to recheck your fuel screw 0-ring and washer. the o-ring can get damaged on install and cause the adjustment to be inconsistent.

Recheck your tps adjustment also after you find your correct idle speed. If the adjustment is incorrect you could end up with a hanging idle speed from timing advancing too much at idle.

Ok...will do. I did drop the dang washer and o-ring out of the carb accidentally (somewhat surprised I found them)...surely I didn't install them wrong? O-ring on tip...washer towards screw head. How do I check the tps adjustment? I unplugged it at electrical connector vs disconnecting from bike.

Oh....forgot to repsond to William about throttle cables...they move smoothly and don't hang up.

you actually have to reset your tps with a volt meter...or at least thats what the manual suggests,i did the ccc mods and rejetted and my bog was worse,i ended up having to retime the ap pump and reset my tps using a volt meter as suggested,my bike straigt rips now,no hesitation,no hanging idle, 3rd gear wheelies with ease

Ok...thanks slaydirt. I saw the electrical diagnostic stuff at the end of my service manual but never really looked at it.

I think my AP is good...it was squirting about 10' and that was before the smaller leak jet. I couldn't see it hitting the slide at all. Didn't observe any binding in the linkage either and there was no gap between lever and rod at WOT.

I'm still wondering if the 'hanging idle' isn't related to residual fuel from the squirt....but nobody seems to be thinking along those lines. Honestly, it seems that on a trail ride, it could be problematic if in technical stuff and blip the throttle to clear something and then want to decel but the motor keeps on going a bit :smirk:. Looking at 3 days of rain beginning today, so likely can't try it out until Sunday.

someone will correct me if im wrong but you should still have a little gap still at WOT,thats what one of my issues was i had adjusted the the AP arm with no cap...pretty sure thats where my hanging idle came from,it was either that or my tps needing to be reset

I don't see anything about resetting the TPS in the service manual. All I did was unplug it and replug it in. Could that somehow mess it up?

The road was dry earlier so I took it for a spin. Doesn't idle right nor run right. Hangs on decel in comparison to my son's. Actually doesn't even accelerate as well as his. Jetting seems off... All I did was wire the AP pump arm, change the clip on the needle from 4 to 3 and change the leak from 65 to 55 :smirk:. Well...I changed that suction hose connection to the airbox too but all I really did was remove the aluminum tube.

I guess I'll check jets to see if plugged, go back to 4 on the needle and try new fuel and if that doesn't do it I'll pull the carb and see what I messed up. I guess I'll check the TPS too since thats easier than pulling the carb, but I don't see anything about resetting it.

Dave

do you have the manual that came with the bike?i bought a service manual for 25$ from the dealer...i took my tps sensor out of the carb so i had to reset it

do you have the manual that came with the bike?i bought a service manual for 25$ from the dealer...i took my tps sensor out of the carb so i had to reset it

Yes...I have both the owners manual and service manual. I've done some research and think I know what you mean about resetting it. You mean turn it so that get the appropriate resistance at closed and WOT. I didn't take mine loose from the carb, so I'd think the setting should still be good. That said, I am going to check it to see if it is in spec.

Whatever I've done it seems to affect my bike across the range of throttle settings and the TPS could be culprit. I don't know why all of a sudden though. Saying that....I wonder if it got turned somehow in the disassembly/reassembly process? Looks like only one bolt holds it on.

Dave

Your TPS likely didnt move.

However turning your idle speed screw too far in will change the TPS reading at idle. Make sure your TPS sensor reading at idle is within spec. If not try lowering the idle speed until your within acceptable range first.

The TPS sensor only affects ignition timing. You could always unplug it and see if your hanging idle problems go away.

I suspect you have internal carb problems causing most of your problems. The TPS sensor may only be adding to your idle trouble but still should be checked.

If you pull your carb apart remember do not get carb clean on the slide valve seal. It will swell up and not allow the slide to seal.

a bike doesn't hold an rpm because of too much fuel. It does it because of the throttle plate still being open. When you rev your bike it opens the throttle plate, it doesn't just add fuel without air. If you add fuel without air (witch is what some of you are saying is happening) you would just have a bike that idles down, but is rich. My bet is you have a stuck throttle cable.

If you had the slide out of the carb, you may have put the floating valve back in upside down. It's easy to get wrong; many riders have done this.

FloatingValve.jpg

Keep the ideas coming! Going to start simple and get new fuel...then start checking crap. I hope its simple.

Dave

Update - found 2 problems...still not how I'd like it to run though.

#1 - apparently my son had removed my fuel screw while the carb was sitting on the bench and reinstalled because the washer was missing! I was like :smirk:!! Fortunately, just the day before I vacumed the shop with a nearly empty shop vac and I found the washer! :smirk: Reinstalled.

#2 - my TPS (presuming I'm doing the testing right) is out of spec. With the carb on the bench, I get 3k ohm resistance across blue/black (the outer terminals). Spec is 4-6. No amount of moving the TPS to one end of its 'range' or the other will change this. I put it back to where it was (it was marked with green paint). What is the significance of this? Its not a cheap part so don't want to replace it unless I need to. There is lower resistance as you open throttle and less as you close it but I don't think the other diagnostics (where you take the first reading and multiply by .13 and .15) matter if the first measurement is out of spec. Right?

Net, net...its better with the fuel screw washer, but not perfect yet. Bike seems to run about the same with TPS unplugged but not sure. Maybe this dang TPS has been my problem for years and hence why I've never been able to get it jetted just right? Remember...I thought I was close to nirvana before I started all this, but had a little bog.

Rick....I didn't have the slide out, but thanks for the idea.

Thanks.

Dave

Edited by dmac1

Another update -

TPS evaluation - I don't understand the manual. It gives you a spec of 4-6kohm. And a formula.

A = Blue and black wire terminal resistance. I get about 3 kohm. (but if I set my meter to 10 instead of 1k I get the same reading (on both mine and my son's bike).

B = Idle speed throttle position sensor resistance calculated via:

A x (.13 - .15) = B

So, if A = 3000, B is in the range 390 - 450. Do I understand correctly that B is supposed to be between 400 - 600?. I'm no electrician and don't understand this stuff.

The manual, after giving an example resulting in 650-750, says:

Adjust the TPS so the resistance between the yellow and black terminals is the calculated resistance. What calculated resistance?

And on page 17-9 it says check resistance between yellow and blue and it should decrease with opening of throttle and decrease if closing. Mine does. I understand this part!

Update -

Turns out my 35 year old volt/ohm meter was reading incorrect resistance. Bought a new digital multimeter and confirmed my suspicion. Adjusted the idle setting per the formula in the manual and all is well! :smirk:

Thanks guys for your help!

Dave

(PS - its a good thing my TPS wasn't out of spec because there are NONE in the USA. A guy at a big shop in Denver said US Honda is helping their Japanese brethren due to continuing supply problems in the wake of the earthquake and tsunami)..

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