I am restoring a 1996 yamaha timberwolf 250 2x4 and need to know what adjustments can be made to the carburetor. The only adjustment I see is the idle screw located on the side of the carb. Is there any other adjustments that can be made externally? On the same note what adjustments can be made internally? I have searched the internet and can't find the right info.

 

Yes they are an pilot mixture screw[idle mixture] .located in an horseshoe bend in bowl and the srcew is external. turn in until slightly stops and turn out prolly 2 1\2 turn and run engine til operate temp then turn in slow until you hear engine idle drop [approx 25rpm] then turn srcew out one round and that is your idle drop and it should reved up and fall quick without an feather drop if carb is clean and in good shape..Good Luck..

 

papa hogg, i found out why it wouldn't crank last night....air box filled up with fuel...in the process of taking it off and looking at everything. gonna make sure all areas are clean and then put back together. if you know whats causing this go ahead and reply, i'll check back later to make sure what you say hasn't been over looked.

thanks.

 

Got everything on carb cleaned and put back together both screws are in their 2 1/2 and 5 1/4 positions. not sure what to think on the carb now. it still puff exhaust but no crank, only turning over...

 

318 motorsport - have you checked compression? may have tight values don,t letting the compression make an conbrustion.... you got new plug?

 

Brand new plug. I got to thinking it sounds like a loose timing chain when being turned over...think I need to tear into the crankcase and check it out?

 

double checked spark plug for proper gap as well. it fired up yesterday and ran for a bit till i killed the ignition but it was running hella rough....and backfired once when i let off gas, thats when i cut it off...thats whats making me think it might have jumped time. its probably original timing chain...over 18 years old. probably time.

 

To papa hogg or 318 motorsports: I adjusted the carb yesterday. turned mixture screw out 2.5 out. runs ok. not sure about further adjustment. you said on first response to let idle, then turn screw out until rpms drop approx 25. then turn one complete turn out from that point? Is that correct? Also, what should the idle screw be set at during this adjustment. I set the mixture screw at 2.5 out and adjusted the idle screw to this setting. It runs but not well. I adjust the idle up it idles to high. Turn it down and it wants to cut off. Just wanted to check before further adjustment. I also saw something about 5 1/4. What is this for? Idle screw? Thanks

 

Yes that is for the horizontal Idle Screw on the side of the carb.

 

Huntingflordia yes start with 2.5 turns, you should crank atv and adjust idle speed [if you don,t have an tach to use to set rpm,s at 1000 plus or minus 100] put in gear idle down until atv don,t crawl in gear as the engine starts speeding up during adjustment keep idling down speed to make sure you in the idle curcuit when you get the good idle speed than turn mixture screw in slow and focus on sound of engine dropping bout 25 rpm,s than from that point turn adjustment mixture screw out one full round... You should have a great idle drop... touch throttle and revv up and let idle you should have an crisp fall and not an feather like fall back to idle...Good Luck.....