Burbling hesitance below 5k

[Visitor Q]

CBR 600 FT (1996)

Hi guys, the hack has been burbling a bit at low revs, and bogging down. It used to only be noticeable when pulling away gently, where I found myself bogging until about 15mph, then it was fine.

Now it's doing it when moving, as mentionned it seems anywhere below 5k.

Still merrily does 150plus, so I don't think it's general fuellng (despite the slight smell of petrol its developed, and yes i've checked the pipe are on correctly).

My guess is the smaller of the needle jets? I've whacked ia whole 'one shot' of redex, which doesn't seem to have changed much, exept now it makes a weird kind of vibrating burble at certain revs occasionally.

What do you think? inline 4 with a sod of a carb to work on, so I'd like some other idea. I also had carb balancing done recently, any danger they fettled the wrong part?

Irritating as it kind of feels like when you have to change to reserves, but as mentioned, it's fairly random. So not suited to london traffic.

(nhs keyboard sorry)
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China traffic/travel bike vid - When I make a sweeping statement, please add the word 'statistically' in to the sentence before you bitch...
From September 2014 to January/February 2015 I will not be using any English, nor reading any. As such, I won't be on here. PM at will, but I won't be checking/posting unless in emergencies. Certainly not for the first couple of months. Please berate me savagely if I break that rule...

[carlperkins00...]

i have the same problem with my hornet 600. riding slowly (less than 15mph) it feels juddery and rough but as soon as i pick up the speed its fine.

if you find out the problem... let me know??

[Blue_SV650S]

When was the last time you changed the plugs!?!?
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The purpose of life is to fight maturity.

[Robby]

90% of carb problems are electrical. Standing tends to gum up carbs, regular use keeps them clean, all the petrol flowing through does that, and I think you replaced the fuel filter fairly recently.

Spark plugs would be my first port of call. I would also change HT leads, but seeing as these can be expensive try new plugs and a good bit of WD40 on the HT leads.

Also have a look at the reg/rec to make sure it hasn't melted away, and check that the HT leads and LT wires are secure on the coils.

[MarJay]

[Visitor Q]

Haha, I had a horrible feeling you would say that.

Guess what I replaced mine with... Iridiums

About 2 months ago.

Weird for it to suddenly cause a problem now though

The fact it would still wheelie and do 150 at strongly made me think it couldn't be fuel/air supply difficulties.

Ah well, I'll have a look.
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China traffic/travel bike vid - When I make a sweeping statement, please add the word 'statistically' in to the sentence before you bitch...
From September 2014 to January/February 2015 I will not be using any English, nor reading any. As such, I won't be on here. PM at will, but I won't be checking/posting unless in emergencies. Certainly not for the first couple of months. Please berate me savagely if I break that rule...

[temeluchus]

I doubt the iridium plugs will cause any problems. Ive run them on a variety of bikes and theyve always worked fine....I fail to understand the almost psychotic dislike for them by some members of this forum....

providing the plugs, caps leads etc are fine...

Crud in the carbs can cause the float valve to not close properly, causes rich running at low RPM.

Certainly matches up with the sudden onset, smell of fuel etc. Your fuel pump would probably prevent the puddle of fuel clue that gravity fed bods would get

I would suggest you invest in a replacement set of needles/valves.

I'd bet the clique members lives that thats your problem.

[Whosthedaddy]

Stick it on a dyno.

It'll make you smile like a Chesire cat when its belching flames from the exhausts on the overrun and the scream of the top end. This softens the blow of them telling you that its a fueling / jet size problem.

The 7R had used to judder and throw a right hissy fit when I applied the right hand in a mid gear or even as low as 1st and 2nd sometimes. It would bog down, shake the front end, bog down and then go like the proverbial poo off a shovel.

The flat spot was at 4-5,000 revs.

It turned out that it was lean at the bottom end and rich at the top (or the other way round?).

Playing around with the jet sizes may have helped a little to even things out a little but I was more than happy to live with the slight problem.

Pulling away from a slow start and bogging down, that needs sorting.

A dyno run is less than a few rounds of drinks on a Friday night. It gives answers straight away and gives some bragging rights for power / torque...
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Current : MSX 125 Past : CBR 900RR Monkeybike : c50 LAC : ZXR750 H2 : FZR600 : ZX7R P3 : YW100 : TRX850: Trophy 900 T309 : GSXR 600 L0: Monkeybike : XJ6S Whosthedaddy

[Visitor Q]

[Irezumi aka Reuben]

Bad plugs/lead normally show up as problems when higher up the rev range.

Probably carbs like you originally thought. Needles can go after a while (I think yours is an older bike that correct?) in which case needles can sometimes need changing, or very carefully smooth off the ends. Some people think that's stupid, but it works.

[bladerunner]

what the hell does burbling mean? is it not running on 4 all the time..and if it's running rough up to 8K now...not long till it wont start if it is plugs. did you fit cooler plugs than std? I know I had to go a grade hotter on the old blade after it was dynojetted as otherwise it just killed the plugs in a matter of weeks


filing that....check your airfilter aint clogged...the carbs are clean and set up correctly see if they need balancing even if it's just been done....the ht leads aint shorting out somewhere...usually when it's raining that one etc etc
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Current bikes...cbr929, KDX200's, Rd125lc mk2, RGV250's

[temeluchus]

[Visitor Q]

[Mr Hammers]

[mr rip]

when was the airfilter last cleaned/changed?

it sounds like a blocked or choked idle/pilot jet, or the air ways surrounding them, making it run too rich at the bottom end,

my armstrong gets a bit fluffy at the bottom of the rev range when the air filter's due for a clean,

it can make riding in traffic a nightmare as you wind it on & nothing happens untill you give it some more & it takes off

if it's the air ways, redex wont help, they'll have to be blown out with an airline
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never criticise a man until you've walked a mile in his shoes, then when the muck hits the fan you'll be a mile away & you'll have his shoes

[Visitor Q]

[mr rip]

it runs better at first because it's acting like the choke is on but when it gets warmed up it's just too rich & so it starts to misbehave
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never criticise a man until you've walked a mile in his shoes, then when the muck hits the fan you'll be a mile away & you'll have his shoes

[Finglonga]

[bladerunner]

Hmmm if it was plugs then they usually start off bad and maybe get a little better once warm. Honda type plugs are bad for going west if the mixture is rich and once flooded they don't come back to life so well as most plugs do!

Burbling to me is the kinda noise a V4 or V8 chevy engine makes
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Current bikes...cbr929, KDX200's, Rd125lc mk2, RGV250's

[Visitor Q]

Note title JUst the sound, to me, would be burbling. But yes, hesitant.

The weird thing is, it barely seems to affect performance. It's not lurching about, and the bikes not been (more) unstable when it happens mid corner

It just really sounds/feels like its dying.

Not so good.

Honda reckoned 150+ vat + coolant to CHECK the needles. I think not.
____________________
China traffic/travel bike vid - When I make a sweeping statement, please add the word 'statistically' in to the sentence before you bitch...
From September 2014 to January/February 2015 I will not be using any English, nor reading any. As such, I won't be on here. PM at will, but I won't be checking/posting unless in emergencies. Certainly not for the first couple of months. Please berate me savagely if I break that rule...

[temeluchus]

its not going to be the needles.....

its gonna be crud in your float bowl....

[Visitor Q]

[Blue_SV650S]

[temeluchus]

[Visitor Q]

So do you think its just number 3 cylinder that is occasionally running rough, which is why it isn't affecting performance /that/ much when it (briefly) happens?

Ok, will WD40 the crap out of the HT leads.

Does that plug seem indicative of a problem for certain? Can I escape cocking about with the airfilter whilst hungover?

How do I check the HT leads are working WELL. I could stick a spark plug in each of them and check it has a good spark against the frame... but as mine still starts and runs fine most of the time
____________________
China traffic/travel bike vid - When I make a sweeping statement, please add the word 'statistically' in to the sentence before you bitch...
From September 2014 to January/February 2015 I will not be using any English, nor reading any. As such, I won't be on here. PM at will, but I won't be checking/posting unless in emergencies. Certainly not for the first couple of months. Please berate me savagely if I break that rule...