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CBR125 2004 Problem


Adsh
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Hi guys,


having an issue with my bike hope someone can help me! Its not running very well at all, like its got a misfire idles like crap and has trouble starting...


So far I have cleaned the the carb and the jets one was blocked, replaced the spark plug and still runs crappy I have brought a new air filter coil/lead and fuel filter hopefully that fixes it, am I missing anything else that it could be?


Thanks


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Hi ,when did it start with this issue, is it new or something that got worse, have you cleaned any vacuum pipes from the tank, is the insulator clamp from the carb to the cylinder head tight,and what did the spark plug look like when you took it out, just a few things to try to eliminate fuel problems first :wink:

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Hi


Thanks for the reply, the problem came all of a sudden.


I cleaned out the pipes and the cylinder is tight the spark plug was bad when I took it out, black all over the end, could it be a bad batch of fuel as it was straight after I filled the bike up?


Thanks

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The black plug means that it was running rich, have you tried a petrol additive for cleaning the fuel system like this

http://www.ebay.co.uk/itm/STP-Petrol-injector-cleaner-fuel-system-cleaner-additive-200ml-Improves-Power-/121734541156?hash=item1c57f1af64:g:1OQAAOSwLVZV0yBI" onclick="window.open(this.href);return false;

it will help clean through the system and give a better idea where the problem is,it could be a rich running problem by the look of the spark plug :wink:

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Hi have you got a workshop manual for it, as you will need to look at mixture screws, but they dont just move on their own ,there could be another reason , when you took the carbs off to clean did you set up the carb or just clean the jets. also check that the choke cable is releasing fully when off :)

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Hi

Have you cleaned the pilot the tiny jet and the main jet, what colour is your plug ? Is it coffee colour ? White means lean sutty/oilly is running rich.


Is it running all standard parts ? What size jet are you running ?

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Had another bash at it.tonight, cleaned the carb again small jet was blocked again! Put a new fuel filter coil and air filter still runs bad and i have no idea what to do now! Plug is new clean and fine. When it was running the more revs i gave it the worse it ran. Could it be over fueling or bad fuel?

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Had another bash at it.tonight, cleaned the carb again small jet was blocked again! Put a new fuel filter coil and air filter still runs bad and i have no idea what to do now! Plug is new clean and fine. When it was running the more revs i gave it the worse it ran. Could it be over fueling or bad fuel?

 

clean all the fuel lines empty fuel refresh the fuel put redx in see if this helps i was getting this same problem with my bike it was bad fuel had water and fuel mixed done above and solved the problem

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  • 3 weeks later...

So, bittersweet news!


the bike is running loads better after the fuel change! the bad news is, it struggles to start and if I try to start it with the choke it floods before it is warm if i rev it too much it stalls.... I am going to get the valve clearance done as I guess that could be the problem as I have no idea when it was last done

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Still think it's a problem with the carb Adsh, have you tried squirting carb cleaner around the rubber connector from the carb to the cylinder head, if the revs increase there's an air leak there, those boots do dry up and crack letting in air causing erratic running, the engine idle should be running at 1400 when warm is it doing that, try to get the engine warm and check the choke is shutting completely off when you turn it off, after its got warm take out the plug and check it again to see if its black or a good colour a picture would be great if you could send one :thumb:

[attachment=0]CV Carbs.pdf[/attachment]

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Hi Adsh, is not such a problem as you think it is, not sure but I think you carb is a 28mm, you have only got to measure it and look at a new one, yours should be a Keihin but Mikuni will do as well as long as its CV, will have a look on E-bay, but if the rubber boots are shot you will still have the same problem, what do they look like :wink:

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Success, the dodgy running is sorted and it starts fine to the pin out of the carb and gave it all a clean, i guess it was getting stuck! But.... again 1 solved 1 appears.. its now running at 4k revs on idle, 7 with the choke open

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All sorted an running perfectly again! back to £4 a week in fuel is nice lol although someone tried to kill me last night on the ride home but I guess thats life on two wheels!

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Well done Adsh, looks like lucks on your side all round :thumb:

 

I wouldnt go that far, head gasket went on my Impreza.. :(


This is becoming more of a project thread! I have decided to do a bit more tinkering and replace the sprockets and chain, is there any difference in what they do, as I see on fleabay there are ones that are "performance" etc.


I have noticed recently in 6th gear my bike slows down, is this common for the cbr125?


Thanks again :)

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