Carb issues/questions

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linuxman51

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Preface: I understand how carbs work fundamentally, however I do not apparently get along with them at freaking all.

The scenario:
I'm told this carb came off a CN250 (or whatever the sort-of GY 250cc engines are called), it looks to be a 30 or 32mm carb, and it's been jetted for E-85 (although.. on a 200cc gy with e-85 a stock 250 jet should have been pretty close... anyway).

When I got the engine bolted up, it was pouring fuel out the overflow on the carb.. Ok, float may be stuck, float needle may have trash in it, this part of the game I'm decent enough at. So I get the bowl off, notice some crud in there, and decide to try out this lemon juice trick I'm seeing all the cool guys doing. Took the plastic top off the carb, pulled the slide and it's gasket out (tried to get all the rubber stuff off so it wouldn't get damaged, basically).

Did the 50/50 10 minute carb cook-off challenge, rinsed it out real good with water, hit the butterfly with wd-40, re-assembled, and boom, works like a champ.Well sort of. kart runs, no more dumping fuel.

Fast forward 3 weeks, kart has sat up for a little while (if you call 2 weeks sitting up), and after replacing the starter gear (other thread), it's leaking fuel out the overflow again. Filter is clean and clear tank didn't have any crud in it that I saw, so I dunno what the deal is- and to add insult to injury I can't seem to nail down exactly which carb it is to get parts for it.

I noticed while it was running and leaking today that when I rev it, the slide never comes up, I think that may be an issue yes? the diaphragm looked good but it could be bad...


Would I be better off going back to the stock carb and jetting it up to run with the hotter setup, or if I should stop dorking around and swap the efi on (which I do understand and can get to bend to my will :stir: ) ? Or hey I'm open to option C as well.. I'd just like to get it running well enough to get a good baseline before I really start playing with it.
 

OzFab

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You may have already answered this but, why did you change the carb in the first place?

My guess is the needle or seat is damaged or the float is set too low... which is all but pointless information since yo udon't know wher to buy replacement parts; I'm only guessing but, have you tried contacting a dealer?
 

2SlickNick

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Stock 150cc carbs are 26 mm. sounds like you went to the big pumper carb.
but regardless I always thought leaking from the overflow was due to float needle as those do wear out, maybe float level is out of wack and needle isn't seating. check this out.... http://www.allthingsmoto.com/forums...carburetor-float-level-more-commentary-13608/

If that doesn't help well....
then maybe you answered your own question. Go back to stock 26mm carb and jet up.

you can even adjust needle height on some of these carbs for more performance. I used this vid for that ...https://www.youtube.com/watch?v=c-Byj1RBr-Q&feature=youtube_gdata_player
You can upgrade a lot on these carb before moving to the big pumper.

Just some suggestions. Good luck!
 

linuxman51

volvo spaz
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You may have already answered this but, why did you change the carb in the first place?

My guess is the needle or seat is damaged or the float is set too low... which is all but pointless information since yo udon't know wher to buy replacement parts; I'm only guessing but, have you tried contacting a dealer?

I didn't replace the carb, it came with the engine I'm using (stroked high compression gy6 running e85).

Turns out that it came with a spare carb in the box of parts I got with the engine, I replaced the slide and needle and it's behaving MUCH better now.

Stock 150cc carbs are 26 mm. sounds like you went to the big pumper carb.
but regardless I always thought leaking from the overflow was due to float needle as those do wear out, maybe float level is out of wack and needle isn't seating. check this out.... http://www.allthingsmoto.com/forums...carburetor-float-level-more-commentary-13608/

If that doesn't help well....
then maybe you answered your own question. Go back to stock 26mm carb and jet up.

you can even adjust needle height on some of these carbs for more performance. I used this vid for that ...https://www.youtube.com/watch?v=c-Byj1RBr-Q&feature=youtube_gdata_player
You can upgrade a lot on these carb before moving to the big pumper.

Just some suggestions. Good luck!

Both good links, thank you! Pretty sure it's a CVK carb (found the spare one and it had that cast in the side). As said above, I robbed the parts carb (That looked really clean actually, just didn't have a jet in it) of it's slide and needle, both looked far better than what was in the carb on the kart. Much better across the board, more torque from a stand still, no real 'lag' midway through the rpm range, gets to top speed much faster than it did previously.

:cheers2:
 
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