curayjusdad 0 Posted February 17, 2011 I picked up a used 2007 CRF 80 off of Craigslist back in November for my son. It had a harrrrrd time starting at the seller's home, so I was able to get him to knock some off the price figuring that I could clean the carb and get it going. Well, I cleaned the carb back in November and we went for one ride in the desert. At that time, it was having a hard time idling. I had to adjust up and down the idle screw. It also had a hard time settling down to idle (slow to go from revving to idle). We garaged the bike after the ride in November and I got it out to ride last weekend. It showed the same symptoms of high/low idle as it got warm and ridden. I'm wondering if I should clean and rebuild the carb for second time (being more thorough) or should I consider taking the top off and looking at the valves to see if they need adjustment or replacement. It's acting like the throttle needle/slider apparatus is sticking (the needle is inside a sliding cylinder that moves up and down in the carb body when the throttle is turned). The idle screw seems to adjust the height of the sliding cylinder. I'm looking for advice on which seems the most likely course of action to smooth out the idle problem. Clean and rebuild the carb or do a valve job. Thanks for your help. Rob.. P.S. other than the idle problem (and being a little hard to start), there are no other obvious problems. No smoking. The spark plug looks like the engine is running a little rich (dark sooty/damp). Share this post Link to post Share on other sites
ADV Bum 205 Posted February 17, 2011 I would bet it is all carb. Soak and clean the carb real good. Some new gas. I am dealing with this issue with my pee wee machines. Shutting gas off, running carb dry and using gas treatment is the best routine. Share this post Link to post Share on other sites
Papa Smurf 0 Posted February 17, 2011 I would also check valves. It is super easy after you do it once. These Honda air-cooled 4-strokes are easy to work on, NO SHIMS just a adjuster screw and a nut. I had a 230L basically same motor, just bigger. It took me less than 30 minutes the first time I did it. Most of that time was removing/putting on tank. The idle is most likely the carb, but hard starting sounds suspiciously like valves. I would bet a nickel one is too tight. Share this post Link to post Share on other sites
ADV Bum 205 Posted February 17, 2011 New spark plug wont hurt either. That was the latest culprit on the kids knockoff quad(thanks Mimi). Share this post Link to post Share on other sites
Spaugh 1 Posted February 17, 2011 "It also had a hard time settling down to idle (slow to go from revving to idle)." sounds like a lean idle circuit have you adjusted the fuel screw? heres a link if you haven't played with it. http://www.thumperfaq.com/fuel_screw.htm Share this post Link to post Share on other sites
robertaccio 412 Posted February 17, 2011 make Xtra sure the Pilot J is not clogged or semi blocked, as well as the above, Always start from all good, new plug, valves set,fresh fuel, clean airfilter, clean carb, good oil, verify cam chain as well. Be sure to check the OEM jet spec, or if aftermarket pipe airbox mods, check jetting spec for the mod stuff. Share this post Link to post Share on other sites
DigDug 0 Posted February 17, 2011 "It also had a hard time settling down to idle (slow to go from revving to idle)." sounds like a lean idle circuit have you adjusted the fuel screw? heres a link if you haven't played with it. http://www.thumperfaq.com/fuel_screw.htm Lean idle circuit (could be low speed jet or fuel screw). The other thing it could be is that the needle, in fact, is sticking. Check the slide for free movement as well as the clip on the needle. On my 450, the needle wore and the gap the clip fit into was widened out - causing the exact same problem. That was UNTIL the clip let loose and the needle stayed down, requiring a trailside fix. Share this post Link to post Share on other sites
bikeslut 1 Posted February 17, 2011 "idle jet" My DRZ sat too long, and was having starting and idling problems... cleaned the carb, and the jets... still was rough I put in the stock idle jet, and it works great. I really thought I had cleaned the jet well enough, but sometimes, you just have to replace it Share this post Link to post Share on other sites
dirt dame 561 Posted February 17, 2011 I actually use a number drill to clean the pilot jet, along with carb dip and compressed air. Just be sure that the number drill that you use is not larger than the hole in the pilot jet. Share this post Link to post Share on other sites
jbw 0 Posted February 17, 2011 Question: Does it only have trouble cold starting or does it also have trouble hot starting? Yeah, cleaning the pilot jet on some bikes (DRZ) is very difficult. Replacing is a better idea if clogged. Other thoughts to add onto the already good suggestions: It also could be an air leak on intake. Or as simple as the idle being set too high. Share this post Link to post Share on other sites
curayjusdad 0 Posted February 17, 2011 All, Thanks for the input and suggestions. I will be doing a more thorough carb clean and rebuild first and then checking to see if the valves are tight. The spark plug has two rides on it, so that should be good. This may be my Sunday project. Rob.. Share this post Link to post Share on other sites
curayjusdad 0 Posted February 17, 2011 Question: Does it only have trouble cold starting or does it also have trouble hot starting? It has trouble when cold. Hot starting is pretty good for me. My son has less leg strength, so harder for him, but he is learning. When cold, it will not idle well and I have to futz around with the choke. Share this post Link to post Share on other sites
bikeslut 1 Posted February 17, 2011 http://www.thumpertalk.com/forum/showthread.php?t=745013&highlight=xr80+jetting I didn't read all 10 pages, but sent you a PM Share this post Link to post Share on other sites
