05' 450r Backfiring-help

[OReilly]

Hey guys,

I've been having trouble with getting my R to idle and it backfires on decel. I read all the threads regarding upping the pilot jet to a 50. After installing the 50 pilot jet, it still acts up the same way and I have the A/F screw on the 50 pilot turned out almost 4 full turns.

Question is have any of you need to up your pilot to a 52 (stock is 48) to stop the thing from backfiring on decel and idling right. Its driving me nuts, I have the idle screw turned up high enough so it won't stall when I'm riding thru tight trails and using my clutch.

My valves are shimmed/adjusted properly. Is there any way it could be my valves themselves not seating properly. I was going to take the head off and get the valves lapped. I just don't want to rip down the head if I don't have to.

Any help would be great.

Thanks!

[ghott]

I would look for an exhaust leak if I were you.

Make sure there is no leaks from the headpipe to head. Did you put a fresh copper crush gasket on recently, or the last time the headpipe was off?

Are the header bolts tight?

Also check to see if there are any leaks around the midpipe.

Definitely take your A/F Mixture screw back in. 3 turns out MAX. Any more, and the risk of it falling out while riding is greatly increased.

If you can't find any exhaust leaks, Try a 52 pilot. The 52 pilot in 04/05 450R's is not unheard of. So I would think it would be worth a shot.

Can you give us a list of specs to maybe try and get a feel for your jetting?

[OReilly]

Mods include HRC kit with the needle on 3rd clip with 185 main jet, HRC lid and snorkel and a white bros E2 slip on.

I know the guy I bought it from did have to put a new crank (OEM installed) in it and put a new Wiseco stock compression piston in it so there is a chance he didn't replace the copper crush gasket when he re-installed the pipe. That could explain the popping but would the crush gasket effect the idle?

Plug is golden brown and I am not losing any performance at mid and top at all and actually runs great at mid and top ends but the idle is issue is driving me nuts as is the popping on decel.

[ghott]

With your mods, I would imagine a 48 pilot would be just fine...BUT...every bike is different.

My money would be on an exhaust leak.

Check and see if those header bolts are lose. And you might want to try a new gasket.

Other than that...I'm out of ideas :(.

[OReilly]

Hey all,

I bought this 05' and the previous owner stated he put an HRC kit in. I did verify the kit was installed when I adjusted the valves (looked at the cam), and cleaned the carb and air filter (HRC snorkel, lid, jet, and needle are installed. He also gave me the old stock cam).

What I am not sure of is if he installed the HRC header or not. How can I tell the difference between a stock header and the HRC header? I am having the head ported in a few weeks and also wanted to know if the stock header will effect or hurt my porting. I have a White Bros E2 slip on and love it.

[ghott]

There is no HRC Header for the 05' machine.

Thats only 06/07's.

[ricks450]

DO YOU HAVE A A/M CAM? IF YOU DO. THE IDLE CURCUIT ON THE 05 CARB WORKS OFF THE VACUME OF THE ENGINE, SO WHEN YOU PUT A CAM WITH ALOT DURATION IT TAKES THE VACUME AWAY AT A IDLE. MY BIKE DID THE SAMETHING SO HAVE BEEN THROUGH THIS. AND I HAD TO FIGURE IT OUT MYSELF. I DONT PAY PEOPLE TO DO MY WORK ON MY BIKE ITS TO EXSPENSIVE. TO GET THE BIKE TO STOP BACKFIRING ON DECEL YOU NEED TO PUT A BIGGER MAIN JET IN IT. YOUR RUNNIG LEAN. YOUR CYLINDER IS TO HOT. YOU NEED A BIGGER MAIN JET IN IT TO COOL THE CYLINDER DOWN. WITH THE IDLE CURCUIT ON THE CARB WORKING THE WAY IT DOES IT SUCKS (IMO).IT AS BEEN AWHILE SENCE I HAVE BEEN IN MY CARB BUT SEEMS LIKE THE SLOW JET WASNT REPLACEABLE. YOUR NOT GOING TO CHANGE IT UNLESS YOU DRILL IT. BUT YOU CANT GO TO BIG IF YOU DO YOU MESSED UP. I KNOW I BOUT A STAGE2 JET KIT AND IT DID NOT COME WITH ANY SLOW JETS. IF YOU HAVE BIG CAM IT LOPES RIGHT AT LOW IDLE? I DIDNT LIKE THAT MY SELF SO I TURNED MY IDLE TO ABOUT 1750 (RPM). BUT YOU CANT GO MUCH HIGHER THEN THAT BECAUSE OF THE WAY THE CARB WORKS. MOTORS HAVE A VACUME AT IDLE, IT GOES AWAY WHEN YOU GIVE IT GAS. THEY MADE THE CARB WORK OFF OF THAT SO WHEN YOUR IDLEING ITS IN THE IDLE CURUIT. WHEN YOU GIVE IT GAS IT TAKE THE VACUME AWAY IT SWITCHES TO MAIN JET CURUIT. THE CAM IS TAKING AWAY THE VACUME ITS NOT GOING TO OPERATE THE WAY IT IS SOPPOSE TO UNLESS YOU CAN CHANGE THE SLOW JET. BUT I DONT THINK YOU CAN FROM WHAT I REMEMBER. I KNOW HOW THAT CARB WORKS. I AM CHANGING MINE. IT IS A PAIN (IMO). I WHAT SOMETHING YOU CAN ADJUST.WHAT MAIN JET ARE YOU RUNNING? AND WHAT DO YOU HAVE AFTERMARKET?

[OReilly]

I replaced my slow jet (pilot jet) with no problem. It screws in and out with a screw driver and is located right next to the main jet location. Not exactly sure why I would have to drill anything. It runs fine at mid and top end. The came is an Honda HRC drop in cam so I know its not radical enough to cause this rough idling. I know carbs fairly well and how they work and I don't see how the main jet has anything to do with idling since the main jet doesn't even function until 1/4 to wide open throttle and at those ranges on my bike, I am perfect.. I know I'm not lean on the main since my plug is perfect in color (nice toast color brown).

I'm now thinking my hot start valve is not seating all the way down hence it is sucking air at idle creating the lean issue.

[ghott]

Intake boot, and carb-to-head boot attached properly? Those clamps tight? All electrical connections good to coil/cdi? Kinks in the wires? Cuts in the wires where it could be touching the frame?

I'm running outta ideas...:(

[86250rbanshee]

Hva you at all drained any fuel and checked it to see if any water in it?

[ricks450]

I NOT SAYING THE MAIN JET HAVES ANYTHING TO DO WITH YOUR IDLE, IT DOESNT. YOUR SPARK PLUG MIGHT BE CRISP BROWN. BUT TAKE OFF YOUR HEADER PIPE AND SEE WHAT COLOR THAT IS. RIGHT WHERE IT CONNECTS TO THE CYLINDER. LOOK INSIDE.SEE IF ITS WHITE. MY BIKE RAN FINE FROM MID TO HIGH TO BUT AS SOON AS I LET OFF THE THROTTLE IT STARTED BACKFIRING. SO WHAT I DID IS PUT A BIGGER MAIN JET IN IT TO COOL THE CYLINDER DOWN. IT STOPED BACKFIRING. DOES YOUR A/F SCREW DO ANYTHING (RPM CHANGE) WHEN YOU TURN IT IN AND OUT. IF IT DOESNT YOU NEED TO PUT A BIGGER MAIN JET IN IT IM GOING TO GO GET MY CARB AND TEAR IT DOWN TO LOOK AT THE IDLE CURCUIT TO FREAHING UP ON IT. FROM WHAT MY MANUAL IS SAYING YOU CAN CHANGE YOUR SLOW JET. THAT IS A REAL GOOD THING. MAYBE MY JET KIT HAD SOMETHING TO DO WITH THE SLOW JET. IM GOING TO LOOK.

[ricks450]

Originally posted by ricks450
I NOT SAYING THE MAIN JET HAVES ANYTHING TO DO WITH YOUR IDLE, IT DOESNT. YOUR SPARK PLUG MIGHT BE CRISP BROWN. BUT TAKE OFF YOUR HEADER PIPE AND SEE WHAT COLOR THAT IS. RIGHT WHERE IT CONNECTS TO THE CYLINDER. LOOK INSIDE.SEE IF ITS WHITE. MY BIKE RAN FINE FROM MID TO HIGH TO BUT AS SOON AS I LET OFF THE THROTTLE IT STARTED BACKFIRING. SO WHAT I DID IS PUT A BIGGER MAIN JET IN IT TO COOL THE CYLINDER DOWN. IT STOPED BACKFIRING. DOES YOUR A/F SCREW DO ANYTHING (RPM CHANGE) WHEN YOU TURN IT IN AND OUT. IF IT DOESNT YOU NEED TO PUT A BIGGER MAIN JET IN IT IM GOING TO GO GET MY CARB AND TEAR IT DOWN TO LOOK AT THE IDLE CURCUIT TO FREAHIN UP ON IT. FROM WHAT MY MANUAL IS SAYING YOU CAN CHANGE YOUR SLOW JET. THAT IS A REAL GOOD THING. MAYBE MY JET KIT HAD SOMETHING TO DO WITH THE SLOW JET. IM GOING TO LOOK. NOT TRYING TO SAY YOU DONT KNOW HOW CARBS WORK. JUST TRYING TO HELP.

[ricks450]

WHATS UP PUNISHE-R. IM GOING 5OO BORE 12:5.1 . HELL WID IT RUNNIN CAM2.

[OReilly]

I'll try anything at this point to get this thing to idle. It sucks riding thru the trails and when you pull in the clutch it stalls. I can deal with the small popping in decel if only I can get it to idle.

I have a 185 in it right now, should I get a 190 or 195? My local shop only sells them in 5 increments so a 192 isn't readily available.

[GPracer2500]

I think you know the answer regarding the main jet. ;) It has next to nothing to do with idling.

What affect does your idle adjustment screw have? Could it be as simple as having the idle turned down too low?

It that's no help I'd focus on either an air leak on the intake side or a partially clogged pilot circuit. It's probably worth removing the carb and cleaning it with carb cleaner and compressed air just to eliminate that as a possibility.

If this is an 04/05 then don't overlook the hotstart mechanism as a possible air leak source.

[ricks450]

when you turn your idle adjustment does it go from low idle to a really high idle with no in between?

[OReilly]

That's exactly what it does and vice versa. When it is too high, I turn it just a little and it drops down quick with no in between.

[ricks450]

did it start doing this when you put in your cam?

[ricks450]

Originally posted by ricks450
did it start doing this when you put in your cam? that no in between is the carb swicthing curcuits. you have no control over it wants it starts doing that. you can almost just touch the idle ajustment and dramatic change in idle. ?

[ajay002]

quick ?.. did you pull out your hot start and plug the hole...?? if you did that will cause it. mine was doin that.. so i unplugged the hole.. pulled the round metal thing off the end of the hotstart. pushed it all the way in the hole then put the fitting where the cable goes in on the carb.. put the rubber grommet that fits over the cable back on the fitting and put a screw in it and just left the cable off. it sealed it like it should have and runs fine now>>> try that if you took off your hot start..