weired cold warm up

[Roadstar]

When i start my 07 after sitting over nite , it starts perfectly but has this kind of miss (small backfire) kind of sound . When it warm up all is perfect , just when cold. Now it is all stock with just an ECU recall, and was woundering if i did the Barbarian mod would that help it out.

 

[wfooshee]

If you're talking about a backfire noise on overrun (coasting in gear) then it's normal. It's air being allowed into the exhaust header to consume unburned hydrocarbons, an emissions requirement. Only happens when cold, because the richness required for cold running puts a lot of unburned fuel into the exhaust pipe. It's basically combustion in the exhaust pipe, and makes the popping sound.

This is what that maze of rubber hoses on the top of the engine is for.

 

[Roadstar]

If you're talking about a backfire noise on overrun (coasting in gear) then it's normal. It's air being allowed into the exhaust header to consume unburned hydrocarbons, an emissions requirement. Only happens when cold, because the richness required for cold running puts a lot of unburned fuel into the exhaust pipe. It's basically combustion in the exhaust pipe, and makes the popping sound.
This is what that maze of rubber hoses on the top of the engine is for.

This is only when first start up not on road , if i start & go it`s no problem , just if i let it warm up without even touching the throttle . (kind of whirrrrrrrr bop whirrrrrrrrr bop). It does it for a little bit & all calms down & it runs like a buzzy top (another problem i`m working out also) still love this bike though.

Also why doesn`t this reply show up , unless i`m on lo-fi ??

 

[copron]

Mine does that to........sounds like an occasional missfire......then it settles down and idles right.

 

[ShinyPartsUp]

I can't really say my '06 does that. Maybe a throttle body sync. might help?

 

[Geezer]

Maybe it's time for a set of plugs. How many miles on the bike?

 

[Roadstar]

Carbs were re-synced & new plugs installed , & i sure don`t want to start throwing cleaners in the tank & hurt anything. If it runs like this for the rest of it`s long life i`d be fine with it, if the bike was carbed , but having F.i. it should run floorless. oh! bike has 21,000mi on her

 

[ShinyPartsUp]

Carbs were re-synced & new plugs installed , & i sure don`t want to start throwing cleaners in the tank & hurt anything. If it runs like this for the rest of it`s long life i`d be fine with it, if the bike was carbed , but having F.i. it should run floorless. oh! bike has 21,000mi on her

I'm just guessing, and I'm no mechanic. But...

If this is recent, you might try throwing a tank of good, fresh and brand named gasoline in the tank to see if it helps. Another possibility is the sync wasn't done as well as it could have. Is the idle set high enough? 1100 rpm is a place to start.

 

[J Paul]

My 08 has a noise on cold start that may be mistaken for a backfire.What I have determined is happening is a lite miss when started and you can hear the primary gears banging(?) when it misses and the backlash is taken out momentarily.After she runs a bit and gets some heat in her the miss is gone and so is the noise so I haven't worried about it. Jeff

 

[Roadstar]

J paul it could be the same (who knows) ?? Well i went out & since i didn`t use the bike for 2 days , i decided to do the Barbarian jumper mod. Numbers were 5 , 18 , 18 , 21 , so i upped all by 7 and it fired right up & didn`t do it (this time) but did notice a little more rich smell when running (idling with open big garage door) I`ll give it a couple of days of running & maybe drop the numbers a little. (anyone go up less than 7 on the C O with a benfit to the running of the bike).

 

[ShinyPartsUp]

J paul it could be the same (who knows) ?? Well i went out & since i didn`t use the bike for 2 days , i decided to do the Barbarian jumper mod. Numbers were 5 , 18 , 18 , 21 , so i upped all by 7 and it fired right up & didn`t do it (this time) but did notice a little more rich smell when running (idling with open big garage door) I`ll give it a couple of days of running & maybe drop the numbers a little. (anyone go up less than 7 on the C O with a benfit to the running of the bike).

I did the mod and your current scenario sounds familiar. A little rich starting should not be a problem. Watch for deposits inside the cans or blackened plugs over time just in case; otherwise the bike should be good. I don't know how Aussie Environmental controls are, but here in the US everything runs so lean out of the box it is a pain. Hope you found your fix.

To answer your question: Yes, others have enrichened the cylinders by less, and some more for the Barbarian Mod. I remember some going up 3-4 and getting satisfactory results for them.

 

[Roadstar]

Well i took it for a quick spin & it feels nice , it had a crisp throttle responce & seemed to be just happy tooling along. So , so far i`m happy & after the ride i figured i`d just check to see if the sliders were loose (bike felt vibratty) & i found the left slider was loose . HMMMM

 

[dustyrains]

My 06 has always done this. I think it is normal. Does it maybe three times on a cold start during the first minute or two of warmup, then smooths right out. Kinda sounds and feels like "klunk".

 

[Roadstar]

Hey dustyrains , did you do the Barbarian jumper mod on your bike or is it still stock ?? I`m going to let my bike sit over nite again & see how it is in the morning (i`m sure it`ll be better)

 

[RadioHowie]

Hey dustyrains , did you do the Barbarian jumper mod on your bike or is it still stock ?? I`m going to let my bike sit over nite again & see how it is in the morning (i`m sure it`ll be better)

Don't expect too much from the BJM. I personally think it's a bunch of voodoo that does little, if any good in overall performance or smoothness of the motorcycle, although it DOES carry about 200,000 metric tonnes of placebo effect for those who have done it. I'll probably get shot at and missed, **** at and hit, for suggesting the BJM is a sugar pill, but in the greater scheme of things, it's a drop in the ocean.

And I wouldn't expect any change in a cold idle misfire from the BJM, either. When the bike's cold (and that means less than 2 bars on the temp-o-scope) sometimes a cylinder doesn't fire because the fuel load doesn't vaporize well, the piston hits a "dead hole" and the misfire occurs. It's SO normal on a motor with almost zero "flywheel effect" that it should be ignored, UNLESS it continues to miss on a fully warmed up motor. And increasing the mixture will only create more vaporization issues on a cold motor.

If it runs like this for the rest of it`s long life i`d be fine with it, if the bike was carbed , but having F.i. it should run floorless.

You're putting WAY too much faith in F.I. The biggest problem with bikes, carbed or F.I.'d, is the "zero flywheel effect."

There's just not enough inertia in the spinning bits of a motor with no flywheel to keep the motor spinning smoothly when a cold-engine misfire occurs. That's why an 1100rpm idle has been suggested over and over and over again on the forum. Keep the revs up 'til the motor warms up and ignore the occasional fart/bump/clunk right after a cold start.

Why does my wore-out, 15 year old Honda Civic idle so smoothly at 600rpm when cold, when my state-of-the-art motorcycle farts and clunks occasionally until the temp is up to normal? Easy-peasy....the Civic has a 45 pound flywheel smoothing out the rotation of the motor. The FJR has **** for inertial assistance.

And on a final note, I'll put up a set of Keihin FCR flat-slide carbs up against any F.I. system any day of the week for overall smoothness and performance gain, if you can stand the rattle those carbs produce, and don't mind dicking with them constantly. LOVED they way they transformed my ZRX. HATED the way they sounded like an old Mercedes 240 diesel with all the slide clatter.

 

[mcatrophy]

...

If it runs like this for the rest of it`s long life i`d be fine with it, if the bike was carbed , but having F.i. it should run floorless.

You're putting WAY too much faith in F.I. The biggest problem with bikes, carbed or F.I.'d, is the "zero flywheel effect."

There's just not enough inertia in the spinning bits of a motor with no flywheel to keep the motor spinning smoothly when a cold-engine misfire occurs. That's why an 1100rpm idle has been suggested over and over and over again on the forum. Keep the revs up 'til the motor warms up and ignore the occasional fart/bump/clunk right after a cold start.

Why does my wore-out, 15 year old Honda Civic idle so smoothly at 600rpm when cold, when my state-of-the-art motorcycle farts and clunks occasionally until the temp is up to normal? Easy-peasy....the Civic has a 45 pound flywheel smoothing out the rotation of the motor. The FJR has **** for inertial assistance.

And on a final note, I'll put up a set of Keihin FCR flat-slide carbs up against any F.I. system any day of the week for overall smoothness and performance gain, if you can stand the rattle those carbs produce, and don't mind dicking with them constantly. LOVED they way they transformed my ZRX. HATED the way they sounded like an old Mercedes 240 diesel with all the slide clatter.

Have to agree with RH.

The main reason why many manufacturers go to FI is because of the emission regulations that force them to run very controlled lean mixtures. The lean mixture exacerbates the potential for misfiring, and, as he says, the light flywheel makes this very noticeable, often leading to a clunk due to backlash in the drive train.

Why the light (non-existent) flywheel? No car-type clutch. Also the rotational inertia of a heavy flywheel would be the biggest restriction on first gear acceleration. (Yeah, RH, I know my Gen II can't accelerate as fast as your Gen I 'cos it's heavy, high geared, has a computer-controlled clutch, the wrong tyres, [wrong spelling of tires,] the original CCT, ridden by an incompetent ...)

 

[RadioHowie]

Have to agree with RH.

You are slipping, my Anglo friend....

2nd time today you've agreed with me. Your reputation is at risk.

 

[mcatrophy]

Have to agree with RH.

You are slipping, my Anglo friend....

2nd time today you've agreed with me. Your reputation is at risk.

No, you're wrong. I don't have a reputation :uhuh: . Well, not one worth preserving.

 

[dustyrains]

Hey dustyrains , did you do the Barbarian jumper mod on your bike or is it still stock ?? I`m going to let my bike sit over nite again & see how it is in the morning (i`m sure it`ll be better)

Mine is still bone stock.