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Fym 110 Carby upgrade

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Hey TT

I have a Fym 110 with alot of mods done to her 1 of which was a 125cc big bore kit but she has a stock carby 22mm i think could anyone suggest a bigger and better carby for me and would i have to get a new intake manifold thing? and i dont want to spend too much on it as ive spend enough already.

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Hello danielxr, 

 

I have an SSR 125 cc, it came with a 22 mm carb on it.  It seems to work fine.  I did do some enlarging of the intake manifold, but not the actual head intake, that size stayed the same, I got a power gain just from the manifold work.  

Probably if you put on a bigger carburetor, lets say a 24 or even 26 mm, minor gas volume increase will be the result, or small horsepower gain, due to the fact that the head intake would need enlarging too, and even then, the piston will only pull in so much gas fuel mixture, you would end up leaning out the larger carburetor to about the same as the 22 mm size... .

 

Other fixes might be needed:

Do make sure that none of the gaskets or connections of your intake overlap, or overhang into the manifold, reducing the volume of the intake hole, even as much as 2mm can be increased by making sure you have a clean flow to the engine from the carb.  I have a metal intake manifold, I cleaned up the inside of it with a dremel tool, enlarging it just a little, about 1 mm, then I put "golf Ball", divots into the metal with a small round tip dremel tool, so the inside ends up looking like the outside of a golf ball. This allows more air to flow into the cylinder, increasing power.  Be careful not to make divots too deep, or you will punch through to the outside of the manifold, and a J B Weld patch will be needed.  

  Basic rule is, get more gases out faster, get more volume of burnable gas into cylinder, (breath better).   You should be using the best aftermarket air cleaner you can find, and the best spark plug available.

Worn chain, or wheel bearings can have an effect on overall power to the ground too.. Also make sure your brake pads do not drag when you spin the wheel with bike on a stand, it should go around one and a half turns as minimum, with medium turning force.  

Good luck, I hope this helped some.

Gary

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Hello thanks for the info!

i currently have a UNI filter copy from China and use genuine uni filter oil and i got a iridium spark plug new renthal chain and sprockets not long ago, also no brakes rub at all but the problem i have is when i cold start i have to turn my idle screw up over 1/4 of a turn to get it to idle but once it's warmed up it idles high and i turn it down 1/4 of a turn roughly till idle smoothens out, ive checked my jets several times but i think theres a problem in this carb, im thinking of just getting a 24mm carb. but i will have a look at the gasket overhang when i next have carby off.

thanks again.

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danielxr,

Sorry I lost my previous post.    I had same problem with idle adjusting over and over.  The SSR Tech guy (Rick), said our problem is with the AIR-Fuel mixture screw, located on the bottom of the carb bowl, completely out of sight. Turn carb sideways, adjust the screw out about 3/4 of a turn. (richer) mine is set at 1 and 1/2 turns out from dead in stop point.  The bikes come lean for smog reasons.  This will give you steady idle, and reduce any backfire on deceleration.

Sounds like your doing everything else perfect, keep it up.

I want to know how your new 24mm carb works out for you, if you don't mind posting the results of that change. 

 

I will attempt to post a picture of the air fuel screw for you.

I also have a picture of the "golf ball dimple" procedure to your metal air intake manifold. this really helps air flow and power.Air fuel screw.JPG

intake dimples.JPG

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