Page 1 of 3

About to pull the carb to clean - any tips for a first timer

Posted: Mon Mar 07, 2016 12:33 pm
by Deanzo

Done around 250 hours on my 2012 250X

Other than installing the JD Jetting kit (left the carb on the bike to do that)soon after I got it, I've done nothing to the carb.
And over all given no real issue (still a wee bog when I snap the throttle hard)


The bike will now not idle, it's up and down and will in the end die.....its a mess!
Also, the idle screw does nothing now unless I turn it a lot (it was/used to be great for fine turning)

Thinking the slow jet needs a clean (though I'm just going to change it out.)

But as I damaged the hot start cable a year and a half or so ago (damaged between the rocker cover and gas tank, no longer works, but has never been an issue, just can't "open" the hot start)

So thinking I'll pull the carb to give it a clean, change the hot start cable, change the slow jet, and install a #50 leak jet as I always wanted to try that for the last little bit of my bog.

Other info,
Throttle cables snap back and seem to be working fine.
New gas every week/use a tank per week.
Bike was fine (other than a wee bog)this is a new issue.

Thanks Dean

Re: About to pull the carb to clean - any tips for a first t

Posted: Mon Mar 07, 2016 4:51 pm
by crfsonly
Hi Dean,

Don't use any carb cleaner where it can make contact with any of the rubber parts of the carb. Pilot jets are very difficult to clean without an ultrasonic cleaner. My recommendation is to replace the pilot jet at a minimum. Even the smallest change in the orifice size and the pilot circuit won't function correctly. The main jets are more easily and successfully cleaned.

Replace the floating valve seal and make sure the seal and the plate are installed correctly. We have a how-to article you can use.

I would work to get the hot start repaired. Replace the hot start nut with our billet version. The stocker is plastic and breaks easily. Check our how-to for how to install it and clean the hot start plunger.

Check your AP diaphragm. These can degrade and when they do the rubber flakes off. You want to replace it before this happens.

Keep in mind the screws are made at a butter factory. Use the correct size screw driver, straight on and with a lot of force or the heads will strip. Replace them with the hex head cap screws we offer.

Clean and check the float bowl height. A lot of people don't know that the float height controls the head pressure at the jets. This can affect mixture as a result.

Good luck!


Posted: Mon Mar 07, 2016 5:31 pm
by JimDirt
I would also recommend checking the needle itself for wear ,if there is any discoloration on it i would replace it and the Needle Jet (the long tube the needle goes into and what the main jet screws into) , if either are worn (mostly the needle jet wears more than the needle so if the needle shows wear , the needle jet is most likely ovaled out and needs replacement) , the wear can and does cause erratic idle , where you set it , then rev it a couple times and its off , then reset it again , then rev and its off again , usually to the point of usually dying at idle , then you adjust it and the idle and its now way too high

Posted: Tue Mar 08, 2016 11:48 am
by Deanzo
For the AP diaphragm, is it best to just order this kit, or do I just need the diaphragm on it's own (couldn't see that listed) ... ts_id/3932

Checked around, almost all carb parts are indent only into New Zealand (20+ Days)

So I'd say I'm just going to order,
The 3 jets (to cheap to not just change them)
The diaphragm and floating valve seal.

I'm going to pull the hot start cable altogether and install another choke knob, this way I lose the cable but could still use the hot start if I ever needed to, and that part is in stock here :)

Pulled the shock and swing arm off last night (doing the swing arm and linkage bearings as well) will get the carb out tonight and look at the parts Jim listed before ordering.

But getting parts, and pulling the carb is a right pain, so changing out high wear parts now just seems the smart way to go.

On a side note, the intake boot seal wasn't as good as it should have been (came off way to easy, I've put it on and off a few times so know how it should feel) has me thinking thats maybe where some of the dust was getting in, I'll be keeping a close eye on that going forward.

Posted: Tue Mar 08, 2016 12:07 pm
by crfsonly
The only way to get the diaphragm is the complete kit. The needle is also only available in the JD Kit. On the intake boot, I always apply a very thin amount of grease to the lip of the boot. This allows it to slide on to the carb easier for a perfect fit. However, you still have to physically verify the boot is fully seat 360 degrees before cinching it down.


Posted: Tue Mar 08, 2016 1:03 pm
by Deanzo
What about the R&D Power Bowl 2 ... ts_id/2520

Is it as good as it makes out ?

Being able to try/test leak jet sizes on the fly would be cool.

And I take it you put the OEM diaphragm, spring into it's AP cover ?


Posted: Tue Mar 08, 2016 1:07 pm
by crfsonly
Deanzo wrote:What about the R&D Power Bowl 2 ... ts_id/2520

Is it as good as it makes out ?

Being able to try/test leak jet sizes on the fly would be cool.

And I take it you put the OEM diaphragm, spring into it's AP cover ?


It's outstanding! If you can swing the cost it works great. It still relies on a good AP but with the adjustable leakjet cover you can dial in the pressure for the strongest squirt possible. Yes, uses the stock diaphragm and spring.


Posted: Wed Mar 09, 2016 1:40 am
by Deanzo
Almost too embarrassed to post this......

The bowl was pretty clean to be fair, which is something......

After taking the the slow jet out, can see a little bit of grit in the slot it goes into. Not the best....

The inside of the top of the carb, in, on and around the walls and throttle valve area. utterly disgusting!!

I hate to think what I have done to my piston and head :(

Just waiting to hear back from Ken on a part that isn't listed that I'd like, then I can place my whole order.

Posted: Wed Mar 09, 2016 7:37 am
by JimDirt
Man that sucks , that sounds like a poor sealing air filter issue :cry:

You need one of these , best investment i have made as far as keeping valves lasting and keeping the carb clear of dirt sucked thru the intake tract ... ts_id/3205

Posted: Wed Mar 09, 2016 11:00 am
by crfsonly
If the air boot was not properly installed it could be the culprit. The filter set up is not ideal for ensuring a positive fit. The Pro Seal is a good product to help with a better filter seal. My preference is the Twin Air Powerflow system. It does a few things I really appreciate. 1. It provides an absolute perfect seal every time. It locks onto the bridge in the air box so you know when you have it installed correctly. No reaching around the back to check, no twisting the cage to hopefully find proper alignment, etc. 2. No need for filter grease which makes clean up and easier. 3. Easier to get in and out of the air box. 4. No backfire screen and the Powerflow replacement filters are designed to fit the cage.

Here's a link to a review we did on this product: ... erflow.php

It's pricey but well worth it if you ride enough to get tired of regular air filter maintenance. ... cts_id/511


Posted: Wed Mar 09, 2016 11:26 am
by Deanzo
When I first got the bike, and start changing out items.

I never liked how the backfire screen didn't push hard into the airbox.
I changed that out to the no toil Super-Flo cage, that seemed to make a much better seal.

What I think I've done somehow :(
Is the last time I had the rear of the bike up (months and months ago)
I didn't seal the boot back onto the intake of the carb right.

In the past, I've had to undo the screw on the clamp, go in with needle nose pliers to pull on that little tab on the boot as I'm lifting the back end up to get it to pop off.

This time......

I undid the bolts of the sides and the top one, moved the rear up a little so I could put the side bolts back in there holes (do that with everything to keep track of them) went to undo the screw on the clamp, and saw the boot was off!!!!!!!
Clamp with done up.
What I think I have done, was when I had put it on, I didn't put it on all the way and I have done the clam up on the end lip, and not over/past it. and it's popped off, when the bike is sitting on the ground it "looks ok" but when riding I bet it will be opening and closing letting all that dust in :(

After Jim pointed out the pro seals the other week, I put them on all 3 of my CRF's lol
Not that I have an issue with mine or the wife's R's, but I want to keep it that way.

Posted: Wed Mar 09, 2016 11:52 am
by Deanzo
Now I'm not going to post a picture of the inside on the top of the carb as I'm to embarrassed!

But you know how I said the hotstart hadn't worked in about a year and a half.

Check out what it left behind after I unscrewed it...


My poor sad little bike...


Posted: Wed Mar 09, 2016 2:39 pm
by JimDirt
Wow , that's definitely some rust in there :shock:

Looks like its time to pop the carb off , for some deep cleaning :oops:

I don't know what the temp is like over there right now , but if its on the cold side , what you can do before you slap it back together next time , is to use a Hair Dryer on the boot itself before you lower the subframe , that way the rubber is softer when your putting it on , it will help it go over the carb end and when you tighten the clamp it will actually be a tighter seal because the warmer rubber is softer and the clamp will squeeze it down tighter

What i personally use to assist in installation is a long thin flat screwdriver to go around the boot as i am putting it on , you can reach in from the front of the frame spar on each side pointing back towards the rear of the carb and push/pry the boot over the lip if it hits and tries to bend/fold (use a small flashlight so you can see in there) , i also hold the large part of the boot that is on the back side of the frame spar and wiggle it back and forth as i am pushing the subframe down the last few inches , but heating the boot where it goes over the lip of the carb helps the most !!!

Posted: Wed Mar 09, 2016 3:08 pm
by Deanzo
I know right, I was shocked when I pulled the hotstart off...

Yea, cleaning starts tonight.

That's for the tip, still summer here, but I'll be doing everything under the sun to make sure I don't do that again.

The few parts I can get here have been ordered.

And have just now placed my order with Ken, what the hell, I ordered the Power Bowl as well :)

Posted: Thu Mar 10, 2016 7:23 am
by Astro_Eric
I'm just getting started with my 250X. But I'm going to check a few things, carb boots, clamps and grease a round the air cleaner.

Thanks for the informative post & good luck getting everything cleaned-up.