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View Full Version : 70cc lifan carb settings??? help please



CrawlinMike
05-07-2012, 04:42 AM
I sold this pit bike 5 years ago and its sat since. When the guy tried starting it he messed with the carb screws. Now I got it back and cleaned the tank. Ive had the carb off at least 5 times and cleaned and disassembled every screw and microscopic jet. Last time I even boiled it all in lemon juice and water then blew out with the compressor. There is a new fuel filter and brand new fuel lines on it. I seen light through all the jets and ports so am finally ruling out a plug. I bought this new and only had a few hours on it. Ive had the screws almost everywhere and googled to death but cant find a stock carb setting or how to set. My question can you get me in the ballpark and which screw is which?? Trust me my right foot feels about broke from kickstarting. New plug too. I can get it to start but when gas applied it just bogs and dies. I can get it to Rev up if ibaby it but it dies anyways each time like its out of fuel.fed up because I know its clean as a whistle. Yes Iso have a trims but my new membership wouldn't allow me to post in the bike section. Some small trikes use this motor too I'm sure.
http://i728.photobucket.com/albums/ww288/torker86/6542d413.jpg
http://i728.photobucket.com/albums/ww288/torker86/3e445bb1.jpg
http://i728.photobucket.com/albums/ww288/torker86/bd4d1eb7.jpg

DRKCYDE
05-07-2012, 10:26 AM
Start by looking at stock 70 manual. Gives you a spot to start, and what screws do what.

http://www.oscarmayer.net/atc/manuals/

CrawlinMike
05-07-2012, 02:35 PM
Thanks so much for the link! Since my carb seems to be a Honda replica I looked through the old atc70 manual. Pretty much exact copy. I never would of got it in without this info. I'll post the picture for anyone else to see since the manual takes forever to download. I kept turning the pilot screw 1.5 turns out and 1.75 then setting the idle expecting that to be it. Now I have the missing step! Learn new stuff every day.
http://i728.photobucket.com/albums/ww288/torker86/e305d07c.jpg
If it works I'll put up a quick vid of it running smooth

DRKCYDE
05-07-2012, 02:56 PM
Then when you get to the next step, I found this one helpful too.

http://tboltusa.com/store/tech.php?pID=61/Simple+Guide+to+Jetting

You might not need different jetting but it helped me learn more specifically what each area did on a carb.

CrawlinMike
05-07-2012, 04:08 PM
That's a great link. I have made progress but after 30 secs or so it acts like it plain run out of gas. In that time I can throttle it and ride ,it has power. Then it dies like there's no fuel. I must have a problem after all with one of my jets. The float bowl isn't running out ,the last time as soon as it died I loosened the drain and it poured out telling me it's in there. I figured the carb should be as clean as new as its filtered and I seen light through all the jets last night. I may just buy a $30 replacement carb. Better that then not rideable at all. I'll tinker a little more still.

WJG1000W
05-07-2012, 07:55 PM
pull the hose of the carburetor and see if you have good flow

CrawlinMike
05-07-2012, 09:02 PM
I'm doing a 12 hr shift tonight. Some guys here at work also recommended making sure my gas cap still breathes and check the fuel cock screen. I have drained straight from the fuel switch and didnt seem too bad. Maybe it is plugged there was a tiny bit of debris in the tank from sitting. I've kicked that bike over so many times I put a hole in my tennis shoe and raked the crap out of my shin once. I'll post what I find when I drain out the gas and check it all. Thanks for all the help so far.

DRKCYDE
05-08-2012, 12:49 PM
Yeah, thought about the gas cap too. See if there is any vacuum pressure holding it tighter next time it stalls.

CrawlinMike
05-08-2012, 04:06 PM
Alright now I'm getting a little hot. Took the time to drain the tank and pull off the fuel cock and clean both screens. There was almost nothing there anyways. Also I blew out my cap. Put on a clean hose and my breath easily blew through it. Started it, let it run a little, and took off. Same thing AGAIN. For right now the sheds closed up tools left out and all. One of those just shut the lights off, lock up, and go cool off. I guess I'll be buying a new carb. Just can't believe this things hardly ever been used but this much trouble.

badass350x
05-08-2012, 04:51 PM
Dont know if its possible on that carb and not trying to say your doing it wrong, but you can put the floats upside down on some carbs! Make sure they are in there correct..

CrawlinMike
05-08-2012, 05:16 PM
Thanks for the reply. Yea this is one that only goes in one way. The pin actually slides into the back of the float before going into the carb. I'm almost thinking its a partial clogged jet. The smaller( pilot jet?) one is pretty tiny. It actually has ran best with the mix screw only 1/2 turn out. Much mOre than that it really bogs with any throttle and maybe even dies a lot faster. I even tried some alternative tuning way I see on you tube. He turned idle screw all the way in with it running and turned in the mix screw until highest idle, then backed the idle screw down until it was normal. I may play with it some more on my next day off. Tomorrow night. I get to do another 12hr shift tonight

badass350x
05-08-2012, 10:12 PM
Have to love those 12 hour shifts lol,, I do the 12 rotating day,night, 14 days a month! feel like a walking Zombie half the time,,, Just the way it is being a miner!

CrawlinMike
05-09-2012, 05:11 PM
Alright some progress!! Kind of. Speaking with a guy at work he said sounds like I'm flooding it out even at 1/2 turn out. So today I went out with a cooler head than yesterday and started it at 1/16 to 1/8 turn out. From all I read thats way lean but it seemed normal. I let it warm up and was able to hit 3rd. Gear flying down and back up the yard. About 500ft in all then started the bogging. It will run at low idle as long as I want(let it idle 20 mins on deck) but when I burp throttle or try to take off I get this fall on its face and few backfires. Any further screwed out its symptoms are worse and screwed in any it bottoms out and kills it from cutting off fuel. Here's a YouTube vid showing the problem really good. My idea next it to move the eclip on the throttle needle to the leanest setting. You guys agree?
http://www.youtube.com/watch?v=WVYDc0xahn8&feature=youtube_gdata_player
Link should work

CrawlinMike
05-20-2012, 04:44 AM
Well the carb is most likely now eliminated 100%. Got a brand new one in. Also a new spark plug. Same exact story. So after deciding to mow the yard to cool off I came back 2 hrs later and decided to adjust the plug gap. After making it just only big enough to fit some 280 sandpaper I put it back in. Ran like a frikken top- until it warmed up. I mean no bogging or anything. Still like it runs out of fuel? With the new carb I installed I put in the main needle it came with and it was just a hair larger than stock. I am NOT giving up on this bike. There's been a couple other things going on in my life right now simultaneous with this frustration that you would think had a cut and dry fix and still remain elusive. I'll die with this before I let it defeat me. Still 100% open to any more advice...... No matter how Dumb or intricate you may think it is. Again- thanks guys

RaceBannon
05-20-2012, 08:44 AM
Intake gasket/o-ring maybe? The carb sure has been off-on alot. Just a thought.

shortline10
05-20-2012, 09:44 AM
Did you check your valve adjustments ? A tight valve will have the same symptom as your video is showing !!!! Probably not even a carb issue . Make sure the piston is at top dead center and see if you have a little play in the rockers .

CrawlinMike
05-20-2012, 09:39 PM
I will check them. And the orings are good. After I adjusted the spark plug gap it had no bog. Revved right up. Until it warmed up all the way. Motor shouldn't have wear really since there's only a few hours on it. Be a few days before I get time to tinker more.