Best Performance Carb Upgrade for 142f??

[Milkedglass]

I want an upgrade but will it help any?

Can I use a good "2 stroke" carb or are their better ones for 4 stroke. Thanks!

Have a new cleaner and poo poo exhaust

 

[bakaneko]

You can use 2-stroke carbs on a 4-stroke but I believe you need an adapter for the intake manifold. I like the 4-stroke carb because adjusting the mixture is done via a screw versus having to take apart the carb for many 2-stroke carbs. Not sure about performance though.

 

[KCvale]

I haven't found anything better than stock.
A 2-stroke will work but it doesn't give you any more power.

What will give it more umph is to loose the stock exhaust, put an NGK plug it it, better air cleaner, and run you engine vent hose to a catch can opposed to back into the carb.

I don't usually do the catch can part, SBP has a nice chrome air cleaner with an input for the engines vent tube.

That's all I have found too nudge a little more power out of these little 4-stroke engines.
After that it's how you put the power to the ground.
Gears change everything ;-}

 

[Milkedglass]

Interesting. So can you adjust or swap out the stock carb jets? Didnt seem like it when i opened it up? I'm running pretty lean based on my plug chop (white tip) with NGK plug and sbp air filter plus poo poo.

Beautiful setup there!! How do you like the jackshaft kit and does the chain hold up well enough? What kinda top speed does that get you? Thanks

 

[Rico glover]

A 2 stroke carburetor does increase power compare both and you will see how the stock carburetor have a lot of obstructions in the way opposed to the Dellorto 2-stroke replica better top end and mid range.

 

[Rico glover]

Dellorto replica

 

[skyash]

If it's a 142f with over head cam can't you file some off the lobes to increase power in the old cam days they filed it off by hand on car cams it works I got a v tec motor that changes cam at 5400 rev from a slug to a racer sounds like a motorbike. I got a 142f and haven't found eny difference in mods the plug might of helped 1 percent if that the muffler did nothing stock to just a straight pipe oil helps a bit 4 or 5 kph with roil oil from newways even 10kmh best mod I have done.

 

[HeadSmess]

i thought the 142f was a standard pushrod, single cam lobe type engine? all of mine have been such...means you cant modify the cam profile unless you really know what you are doing. maybe change the angle of the followers, maybe change the ratio of the rockers, but any changes to the cam will affect both intake and exhaust timings. cant change much at all on the 142f.

no, there are not any readily available carbs to stick on them either. i once made an adaptor to take a slide carb from a pitbike engine, and the results were much the same as standard. mediocre (i was having issues with the original carb, it simply wouldnt run...made the carb mod, it still wouldnt run properly. left it outside for a year or more, got a new stock carb, and it behaved itself after that... very strange, but thats beside the point...)

in the words of KCvale, the best carb IS THE STOCK CARB.

all you can do to them is some minor porting, clean up the airflow through the square, highly turbulent ports, and modify the exhaust.

its definitely best to leave the 142f alone and take it for what it is.

you want a modifiable (4stroke) engine, you use a b&s 6hp sidevalve engine with aftermarket kart racing parts...

 

[Milkedglass]

Well I can stick to the stock carb but mine doesn't have an air fuel mix screw to adjust. My plug is bright white so I gotta be way too lean, yes? This worries me as I assume it should but..?

The Dell carb copy looks nice and I was indeed looking at that. Better overall design and at least I can adjust that one, even if not much mid/top upgrade.

But I'd prefer a stock adjust if anyone knows how to richen the fuel mix. Idle adjust screw is all I have. The needle jet has another slot to the right but ? and the main jet has no apparent way to remove or swap. Thanks for the input all. Except for this lean carb issue the bike's all set!

 

[KCvale]

Beautiful setup there!! How do you like the jackshaft kit and does the chain hold up well enough?
What kinda top speed does that get you? Thanks

Thanks for the Kudos, here is the other side to see the drive train.

I prefer an internal shifting hub but the 7-speed is hold up.
It does over 40mph with the gears ;-}

i thought the 142f was a standard pushrod, single cam lobe type engine?

It is, and adjusting the valves with the push rods is pretty easy from the top under the silver plate covering them.
There are 2, one for intake and one for exhaust.