Paging Kurlon

[Pittenger5]

Still cant get the RMZ to run.
On choke, runs flawlessly. Off choke, as long as I'm giving it throttle, it runs alright, lots of backfiring and the header is RED hot (have a fan blowing on it, but obv not that much air). Second I let off the throttle, backfires and dies. Ive cleaned the carb twice now, the pilot is spotless.

What do I do.

[lrrs313]

Sounds like its running way too lean. Fresh fuel? Is the air boot attached fully? Is there a hot start on the carb that is sticking? Sounds like an air leak somewhere to me.

[Kurlon]

Agreed, sounds like an air leak. I wonder if this a symptom of an FCR slide seal leak? The bike is old enough, I suspect you haven't replaced it before?

[Pittenger5]

Correct. I dont even know what that is.

- - - Updated - - -

Oh and boots are seated probably, I checked those.

[Kurlon]

Pilot jet is clear, have you blown out the pilot passages in the carb with an air compressor?

[breakdirt916]

unless there's something going on we don't know about, your symptoms definitely point towards lean...

I don't know how your carb works, but I'm betting on the needle NOT coming up. The clip either got unplugged, or you fucked the order up when you put everything back together. So now - the bike will start because *some* fuel comes through the pilot jet, and the choke will make it run normal because it gives more gas, and it runs super hot because you're lifting the slide (introducing more air) to make it lean, but since the needle is blocking all the fuel from coming up the main, no gas comes through.

here are some diagnosis tips:

1.) [air leak check] did you - at any point in time remove the carb/air boots to the cylinder? if yes - check it...if no - check it. Just make sure everything's tight

if you truly have an air leak, it would have to be between the carb and the cylinder. Otherwise the choke wouldn't really affect the operation

2.) [pilot/main/needle check] when you say "as long as I'm giving it throttle" - how much throttle are we talking? 1/4? 1/2? WOT?

3.) what kind of carb do you have? how does the choke introduce gas into the carb?

4.) [float check] with the choke on - will it run forever, or does it eventually stall? - if it eventually stalls, but will restart after a few minutes, float sticking or pin fell out. Re-check float

5.) [gas entry check] does fuel flow freely out of the fuel line?

6.) [fuel into carb check] with the fuel line connected to the carb and the gas on, and the bottom of the carb off, and the float needle not blocking fuel - does fuel piss out of the bottom of the carb? - if not, fuel clog

7.) [needle check] with the bottom of the carb off, but the throttle cable connected, does rotating your throttle lift the needle? if not, take the top of the carb off, and figure out how the throttle cable lifts up the slide, and also lifts up the needle. Usually the needle is attached by some sort of clip. Make sure it's hooked up

Actually you know what? start with step 7...

[Kurlon]

Wait, have you used carb cleaner on anything other than the jets when they're out of the carb? FCRs are stupid sensitive to the stuff. Don't ask why they used rubber bits that don't like carb cleaner but they did... I'm going to guess you need part #10 on this list: http://www.ronayers.com/CARBURETOR-C155955.aspx

Walk through on replacing it: http://crfsonly.com/howto/keihin-fcr...al-crf450r.php

While you've got the carb off, use compressed air to blow out the various passages, particularly the pilot jet circuit. Take your rubber tipped air gun and put it right to the pilot jet hole, press for a seal and then blow it clear.

Also need to make sure there are no leaks. The normal suggestion would be to fire the bike up and spray around the intake/air boots with carb cleaner. That's a no-no with FCRs. WD40 is safer, or you can use an unlit propane torch as a gas source. With either, be aware you're pumping flamables around a HOT ENGINE! Use caution. Get the bike fired up and idling on choke. Spray WD40 at the intake boot around the lip. If using a torch, open the valve but don't light it, direct the nozzle around the intake boot. If the idle suddenly changes, you found your leak. Short tests only so you don't get built up gas vapors looking for a heat source to set them off.

[Pittenger5]

Jettings never been changed. No fuel blocks, no air leaks that I can find (tried the spray shit in the area test). Runs off choke with ANY throttle.
Its got to be something that the choke "bypasses". It runs FLAWLESSLY when on choke, not a single backfire, sounds perfect, but the second I push the choke button, bam, dead. Like instantly.

[Kurlon]

That points to the pilot circuit. Choke on, throttle closed, need for fuel with the main blocked by the needle is satisfied. Choke off, throttle opened, need for fuel is satisfied by the main. Throttle closed, choke off, no fuel from pilot, bike dies. If it's not the pilot jet itself it's got to be one of the air passages that feeds the pilot circuit.

Just out of curiosity, how many turns from seated is your idle mix screw?

[Pittenger5]

No idea. Never touched it.
Even when off choke with throttle I get a lot of backfiring.

[Kurlon]

No idea. Never touched it.
Even when off choke with throttle I get a lot of backfiring.

You're missing part of your fuel supply so that makes sense. Take a screwdriver, turn the pilot adjust screw in slowly, counting how many turns it takes until it just lightly seats. Then take the screw out. It'll have a spring on the end and an o-ring and washer, so make sure you get all the parts when you do it. With the bowl off, this is another spot I'd hit with compressed air. When you reinstall, turn it all the way in until it lightly seats, then back it off the same number of turns you counted before. Should be in the 1.5 to 3.5 turn range.

[Pittenger5]

Kurlon, I got a track day lined up sunday. Fix this for me.

[Kurlon]

If I was closer you know I would. :/

[Pittenger5]

Get driving and you can come to the track day too!

[JettaJayGLS]

This problem ruined racing for me last year. I got too busy, too lazy, and too frustrated and never fixed it. I no longer race. Good luck and please let me know when you find the solution. I'll be following this.

[Rada]

This problem ruined racing for me last year. I got too busy, too lazy, and too frustrated and never fixed it. I no longer race. Good luck and please let me know when you find the solution. I'll be following this.

Miss having you around buddy!!

I'll be curious to find the answer here. It was baffling last year...

[Kurlon]

This problem ruined racing for me last year. I got too busy, too lazy, and too frustrated and never fixed it. I no longer race. Good luck and please let me know when you find the solution. I'll be following this.

Let me borrow your bike some time, I'll try to sort it.

[KB]

The answer is replace the seal on the carb slide. Your welcome

[Pittenger5]

Sigh, local dealers want 25 bucks for that stupid seal, and its not in stock.
Ronayers was 13 bucks plus 8 shipping
Bike Bandit is 16 bucks and 7 shipping.

Fuck all them

[Kurlon]

Call Sudco, PN 021-726 and see what they can do. IIRC it's $16 MSRP?

[Pittenger5]

Meh, I sucked it up and went with Ron Ayers, ordered some other shit I needed anything. Just BS they do flat rate shipping for a stupid gasket.

[Kurlon]

Yeah, I have to really shop around now when looking for OEM bits, between price variations and shipping variations I never know till I total it all up who I'll be buying from. I had decent luck with boats.net (don't laugh, they've had some OBSCURE Yam stuff that everyone else listed as NLA), motosport.com, servicehonda.com and rocky mountain atv.

[nhbubba]

Oneida Suzuki
Honda of Hollywood ironically had the best rates a year or two back when I priced all the wear items for my 78 Honda. Shame I didn't press the go button on that.

My local dealer now charges me MSRP + a shipping fee.. and I have to wait a week + before they get the part in and bother to call me.. why do I bother again?

[Pittenger5]

My local dealer now charges me MSRP + a shipping fee.. and I have to wait a week + before they get the part in and bother to call me.. why do I bother again?

I dont. Ill pay a premium if they have it in stock since I can appreciate it. But they expect me to pay more than the internet shops (including 8 dollar shipping) and they have to order it to? No thanks.

[Pittenger5]

Ok, that stupid gasket is supposed to come today, so I'm gonna work on the bike tonight. Any last things I should check on the carb before buttoning it all up ... again