I just installed a 38mm A/S carb it revs really nice but I cant get it to idle even when I put the idle screw all the way in. But if I have the choke on it will. Any help would be greatly appreciated. 172 main, needle on 3rd clip, not sure of pilot, air screw 2 turns out, 85 250R motor is stock bore with pro lite, v force reeds, no air box running k&n. head shaved .010, running race gas 40:1 R50

I was thinking the pilot is too big but have to see what it came with?

 

Mine main is a 189. I also have a 38mm A/S. Sounds like the carb has issues. Maybe the choke isn't disengaging completely. I would check that first. If the idle screw isn't working you may have some debris in there. I would recommend taking it apart and cleaning it real good. Inspect the choke and all the little ports for debris. I hope this helps.

 

and just a note sprayin carb cleaner around a few parts does not count as cleanin it out GOOD!!! You will have to get some torch tip cleaners or some other thing to put in there and clean it out good. and/or use compressed air to clean all the ports out. Oh and be carefull not to resize the jets either...

 

Ok thanks I will tear it apart a check out everything the carb it brand new from ESR I took it down the road today and it rips up until 3/4 throttle then starts breaking up I think the main is to small I pulled out the plug and it waslike a burnt orangish grey. I live in MI its about 60 degrees outside so I was thinking about trying a 180 but if your running a 189 in yours maybe I should get a 180,185, 189 any input??

 

Ok I took it apart and everything is working fine I had to much play in the cable at the top of the carb that was the problem with the idle. I have a 52 pilot 172 main, DEG needle, air screw at 1 1/2, I moved the needle from 3rd clip to 2nd it has better low end. I was thinking of putting a 50 pilot and moving the clip back to 3. I still am having the breaking up issue on the top end I am heading up to get a 175, 180 main hopefully that will help I rip thru the gears til 4th and shut it down coasted back to driveway and pulled plug it had greyish powder on it im running a NGK irradium BR8

Thanks for any input

 

Now im really stumped I put a 178 main in and it was running great I made a few passes and it was really rippin then it started poppin and sputtering so I kept in it and it cleared up and ran fine again I shut er off let it cool and about an hour later I fired it up and ripped it down the street it was rippin again then on my way back it started sputtering again. It runs fine one pass then crappy the next any ideas I also just put in a new piston and rings when I installed the carb?????????????[img]i/expressions/face-icon-small-sad.gif[/img]

 

check your fuel line. It may be dirty or clogged. I installed an inline filter in mine.

 

Yeah I was kinda thinking thinking that might be the problem thanks! I will check it out tommorow and let you know[img]i/expressions/face-icon-small-smile.gif[/img]

 

Well I checked it out and thats not the problem I have gone from 165 main up to a 178 main and I just cant get it right I dont know what do do anymore so I put the stock carb back on and its running good know. I am going to put the 38mm back on next week and go back to the drawing bored I put a 50 pilot in the 38mm it seems good up until top end then it just sputters and pops maybe im still not big enough on the main but I couldnt get anything bigger today the local shop was already closed what do you guys think am I way to lean on the main?? I took carb completely apart and cleaned it thourghly.......[img]i/expressions/face-icon-small-disgusted.gif[/img][img]i/expressions/face-icon-small-disgusted.gif[/img]

 

Not sure what else to tell you. My main is huge 189 and it runs great. I believe my needle clip is at the #2 spot. I don't remember what the pilot jet size is. If I can find the info I'll post it for you.