carb adjustment

[mike_1984]

hiya guys, adjusted my carb needle this morning to allow more fuel in as running lean from new air filter, lowerd needle to the bottom grove and re-assembled it all

tried to start and this happens:

https://www.youtube.com/watch?v=YhTI157xzr8&feature=youtu.be

same with choke in or out... any ideas?

[Joeman]

You done something wrong!

Put it back as it was and try again.

Moving the needle one notch won't kill a bike.

[mike_1984]

Thtas the order im rebuilding it, with the speed cable through the spring and hooking underneth in the notch.

the casing can sit high or low in the carb chamber but im sure it should be low down not higher?

shoulda left this alone me thinks

[Joeman]

Is that how it came apart?

All you needed to do was move the little clip one notch towards the pointy end of the needle!

Take the air filter off, put it all back together and look inside the end of the carb. Make sure when you twist the throttle the needle and silver part move up and down.

[mike_1984]

Is that how it came apart?

All you needed to do was move the little clip one notch towards the pointy end of the needle!

Take the air filter off, put it all back together and look inside the end of the carb. Make sure when you twist the throttle the needle and silver part move up and down.

 

cheers joe i'll check that now and yeah thats how it came apart im sure, the manual says it goes back togther that way to.

[mike_1984]

Is that how it came apart?

All you needed to do was move the little clip one notch towards the pointy end of the needle!

Take the air filter off, put it all back together and look inside the end of the carb. Make sure when you twist the throttle the needle and silver part move up and down.

 

it does move when i use the throttle yeah,

https://youtu.be/qKCo5Qv7Ads

is that working right? just looking at that gap when its sat .

[Joeman]

That big hole looks odd. Does it have the hole in the slider both sides? Can you turn in 180degrees?

[mike_1984]

the hole is just in one side gonna try turning it round and see, i think it sits higher if i turn it, will check now and post results. setup like this it still dosent start .

[mike_1984]

it can sit other way round but it only goes this low down , does still move with throttle though.

[Joeman]

Google image search I found this:

http://www.yellow13bikebreakers.co.uk/ekmps/shops/yellow13bb/images/yamaha-sr125-carburettor-%5B3%5D-10340-p.jpg

No hole.

So was right the first time

[mike_1984]

Google image search I found this:

http://www.yellow13bikebreakers.co.uk/ekmps/shops/yellow13bb/images/yamaha-sr125-carburettor-%5B3%5D-10340-p.jpg

No hole.

So was right the first time

 

its here on this pic though, and the manual shows the slight incave on the chamber goes towards the right, on the pic you can see were its marked from resting on a pin, other way round it wont rest on anything

wonder if something else has buggerd up since i moved the carb?

[Joeman]

Yeah that's what I meant, the hole is outwards..

Anyway, with the filter off, try putting you hand over the carb to choke it more, see if that's starts.

[mike_1984]

Yeah that's what I meant, the hole is outwards..

Anyway, with the filter off, try putting you hand over the carb to choke it more, see if that's starts.

 

omg joe that worked!! thanks man!

just re adjusted the needle and set it back up, runs fine hopefully that will stop her running so lean and engine wont get so hot.

Thank you so much Joe i woulda been stumped without your help

[Joeman]

That's why I thought the hole looked odd. Looks like it will let too much air through..

See if you can adjust the carb to make the slider go down more. Looks quite open in the video.

[mike_1984]

That's why I thought the hole looked odd. Looks like it will let too much air through..

See if you can adjust the carb to make the slider go down more. Looks quite open in the video.

 

yeah it was sticking i found some gunk stuck near the bottom holding it open got rid of that when i re-fitted it she sounding lovely now! and such a nice day i think i may just have to go for a lil ride out, purely for testing reasons ofc...

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^^

[Joeman]

Sounds good, glad it's sorted, makes me want a project bike now!

[mike_1984]

Haha im glad too just done a quick run out up a duel carrigeway, 60mph into headwinds and not full revs so defo improvment, would drop to 55-even 50 in headwinds at times

still feels a lil hot, though im not sure how hot is too hot, water fizzles off instantly when it touch's the main engine, however last night before adjusments it did the same on the cam shaft (no longer does)

took 2 and a half hours to cool last night to a touchable amount gonna see today how long. At worst i can fit my old airbox and filter have got them handy but will see

Sounds like an absolute beast when you open the throttle now hahaha see people looking expecting a big harley or something and its me on an ancient 4 stroke 125

[mike_1984]

took about 40 mins to be able to hold hands on for more than a second or so. still warm but not burnng hot , running too hot still maybe?

[Joeman]

Take the plug out (when's it's cool enough!) And see what it's like. If it's running too lean the plug will let you know .

[mike_1984]

just waiting on my sparkplug removal socket coming in post so i can check, in the meantime any other symptoms i can check?

I read about a water test flick a bit of water at the engine block and if it fizzles its too hot.

before the carb adjustment water did fizzle, now it dosent so running cooler for sure but still seems hot.

Can touch it for a few seconds before the heat becomes too much and not taking 2 and a half hours to cool now

I cant feel the heat of the engine when im riding, and no noticeable burning smells or engine issues , Shes running like a dream throttle is a lot more responsive power is there a lot quicker than before

If she is running to hot and my needle is low as can be now, the soloution would be chaning the jets to let more fuel in but am thinking is it worth getting into that much tuning (its a slow four stroke end of the day lol)

tldr: ways to tell engine too hot aside from sparkplug.

[Joeman]

Digital laser thermometer. That's what I use.

Cheap from Lidl.

But engines do get hot, it's just what they do!

My bike regularly runs 90 to 100 degrees Celsius and I feel he heat bellowing out from under me, but that's normal.

[mike_1984]

Digital laser thermometer. That's what I use.

Cheap from Lidl.

But engines do get hot, it's just what they do!

My bike regularly runs 90 to 100 degrees Celsius and I feel he heat bellowing out from under me, but that's normal.

 

im prety sure shes fine heat wise now had a good run out and still hand touchable on the lower engine just the main block was a bit hot but not fizzing water hot cooled down in 20 mins

on the back of all this tinkering do you guys think its worth chaining the jets while im at it? can get this kit for £30

http://www.ebay.co.uk/itm/232226728249?redirect=mobile

would it give any benefit you think considering my engine is only 12bhp? (apparntly though i dont think its that high imho)

[Joeman]

Have you ever seen what comes in a jetting kit?

You will cry if you spend 30quid on one and you don't get any gains

[mike_1984]

Have you ever seen what comes in a jetting kit?

You will cry if you spend 30quid on one and you don't get any gains

 

Ive just had a google of them hmm lots of small screw in type things... im assuming a lot of fiddly take the carb to pieces and rebuild type stuff on a very low chance of gains? lol

[Mr Fro]

Usually carb kits have a few main jets, a new needle and maybe a slow jet/screw.

I've fart-arsed around tuning mine and with dyno time found that even with exhaust, induction and engine mods, the original carb settings were best.

I probably spend 2-3 hunge plus loads of time finding that out too.

If you can whack open the throttle from say 3k rpm to red line in 3rd gear without any bogging or flat spots then you've got it about right.

Carb fiddling is pretty easy and if you're going to do it just change one thing at a time!