giantsean 59 #1 Posted July 6, 2019 Hey All, Just picked up a C101 yesterday, more or less stock. Overall in great shape save for an annoying hunting issue at anything above idle (idle is nice). I'm guessing it's fuel related but could use some more ideas. Pulled the plug and found it a little sooty, did a compression check... 105 (I know it has the automatic pressure relief so not sure what the spec is... that was the top at least). Cleaned plug, put back in, shot in some carb cleaner, adjusted the governor shaft but not any springs, mucked around with the high/low screws. It's a bit better from where I started but still not normal. I noticed if I let it warm up it would run a little better/smoother and go longer without stumbling, but it's still not right. I shot some carb cleaner around the throttle/choke shafts and the gaskets to see if there were any air leaks, seems ok. The PO told me that he hasn't run it in a bit and that this is not something it had been doing before winter, so thinking maybe bad gas. The fuel line to the pump also looked pretty awful, so was going drain the tank and change out the lines next. Then I can try going through the carb and maybe playing with the governor springs. He told me he had done new points and it also has a replacement coil and condenser (I got the old parts with it), plus when it is not stumbling it actually seems ok. No smoke or funny smells. I took a video if it helps. Any suggestions appreciated, and thanks!!! My_Movie.mp4 Share this post Link to post Share on other sites
troutbum70 857 #2 Posted July 6, 2019 Maybe dirty carb or timing off a bit. Share this post Link to post Share on other sites
953 nut 57,969 #3 Posted July 6, 2019 7 hours ago, giantsean said: not something it had been doing before winter, so thinking maybe bad gas. The fuel line to the pump also looked pretty awful, so was going drain the tank and change out the lines next. Replacing the fuel line and running ethanol free gas will be a good starting point. https://www.pure-gas.org/ While the engine is running at near full throttle (air filter off) give it a few good sprays of catb. cleaner into the air inlet. Also, add some SeaFoam to the new fuel at double the recommended rate for a couple tank fulls. Share this post Link to post Share on other sites
ebinmaine 70,789 #4 Posted July 6, 2019 13 minutes ago, 953 nut said: Replacing the fuel line and running ethanol free gas will be a good starting point. https://www.pure-gas.org/ While the engine is running at near full throttle (air filter off) give it a few good sprays of catb. cleaner into the air inlet. Also, add some SeaFoam to the new fuel at double the recommended rate for a couple tank fulls. I'll second that. Replace ALL the fuel lines. Remove and clean the carb. Use E0 fuel. 1 Share this post Link to post Share on other sites
peter lena 9,092 #5 Posted July 6, 2019 agree with ebinmaine on the fuel issue, that seafoam in both the gas as well as the spray in soaker type , has really worked for me. i regularly add stabil to fuels and it has helped to eliminate my fuel issues. i also find that you have to go back and repeat repairs to cronic areas.. having done that , has eliminated the problems i had , pete Share this post Link to post Share on other sites
Shynon 7,475 #6 Posted July 6, 2019 probably needs a carb cleaning. But with the sooty plug I would warm up the motor then at wide open throttle adjust the high speed jet. Probably running rich causing the hunting. Share this post Link to post Share on other sites
pacer 3,175 #7 Posted July 6, 2019 I'm in the 'clean the carb' group! Surging/hunting is more often than not a fuel prob and with it having been sitting up for a while (no doubt with that wonderful ethanol fuel!) then the carb is very likely to be gunked up, especially in the high speed jet metering area. And of course, cleaning the whole fuel system is also a good idea... Share this post Link to post Share on other sites
rmaynard 15,927 #8 Posted July 6, 2019 I'm going to agree with those who say clean the carburetor. The main jet tube is hollow and has about 6 tiny holes in it. You should be able to pass air through all the holes. Soak the carburetor in a good cleaner over night, blow it out and then reassemble with a new float valve, splash guard, and bowl gasket. Set the main jet and low speed jet screws to the Kohler manual settings. Then, fine adjust as described. When it is running smooth again, be sure that the idle speed is at least 1100-1200 rpm. Anything lower and you risk not having enough lubrication. 1 Share this post Link to post Share on other sites
Stubby 19 #9 Posted July 11, 2019 Once you get it clean try to run rec gas through it. More expensive but 90 or 91 octane and 0 ethanol. Share this post Link to post Share on other sites
