Martin 2,130 #51 Posted March 29, 2014 Ed, i would take the top off the carb and give it a look. easy to do that first rather than removing the manifold and separating the carb. i did 416 #1 that way and has been fine ever since... look here.. Share this post Link to post Share on other sites
Ed Kennell 35,967 #52 Posted March 29, 2014 Id be interested to see how this does ... Keep us posted on it please IMG_2541 (640x480).jpg Added a few vent holes to help cool the rear cylinder. May also be my heater when I get the cab built. I could not believe the amount of hot air even at idle. Will definitely make a good heater with the cab on next winter. Can't wait to blow snow in the warm dry cab. Share this post Link to post Share on other sites
jackhammer 544 #53 Posted March 29, 2014 Maybe your on to something there Ed ,, Sounds like it will work great for you Share this post Link to post Share on other sites
Ed Kennell 35,967 #54 Posted March 29, 2014 Thanks for the link Martin. The pics will be a great help. No work on the 520 tomorrow though. Tomorrow is the PeeeAaa trout season opening day, so I will be baiting hooks for grandson(s). 1 Share this post Link to post Share on other sites
motox25 36 #55 Posted March 29, 2014 Definately sounds like your carb, onans are very sensitive when it comes to even a small amount of garbage in them. Mines doing the same thing, I'm planning on draining my float bowl and giving it a deep clean. Yours sounds like one or more of the tiny holes on the idle jet are plugged (the small jet facing you when you take the bowl off) 1 Share this post Link to post Share on other sites
Ed Kennell 35,967 #56 Posted March 29, 2014 Well the trout fishing ended early ....the rain moved in about 10AM, but Grandson Jacob caught a few before the rainout. With the fishing rainout, I got a little time on the Onan this afternoon. I took the top off the carb and pulled the float out and could see some varnish crud in the bottom of the bowl. After looking at the two bolts fastening the carb to the manifold, I decided to take the carb off. I only had to remove the exhaust pipe heat shield and pull the oil filler pipe and tip it outside the muffler. This made enough room to use an open end wrench to get the bolts out. I think I got the carb totally apart and nothing seemed to be blocked. I do have a couple questions. The carb/ manifold bolt on the muffler side had a fiber washer on it , the other one did not have one. I really don't see a need for this washer on either bolt. Was this just a mistake by the PO ? I found this small sst washer loose in the bowl. It does not fit any of the bolts. It is the right size for the main jet, but if I put it on the jet needle with the spring, the needle will not bottom out before the spring gets tight. Was this another error by the PO ? The only holes that I am not sure are open are the three small holes under the edge of the throttle plate when it is nearly closed. I could not get the carb spray nozzle pipe sealed on these holes to be sure they are open. Are these three small holes connected to the larger main jet hole just below the throttle plate ? 1 Share this post Link to post Share on other sites
Martin 2,130 #57 Posted March 29, 2014 (edited) Ed, the small washer goes with the main jet ( that jet that screws in inside the bowl) not sure what you meant by the jet needle with the spring, maybe the idle mixture screw? I would find another washer for under the head of the carb mounting bolt. every one I've pulled has two flat washers on the bolts (steel though). the one thing that concerns me is the surface of the venturi in your last pic where the 3 small holes are, looks like some small damage or nicks in the bore? those 3 little holes there go up into a passage behind the expansion plug on the side of the carb. you can flush them from one of the top holes in the carb. Edited March 29, 2014 by Martin Share this post Link to post Share on other sites
Ed Kennell 35,967 #58 Posted March 30, 2014 Thanks for the answers on the washers Martin. Yeah, I did mean the idle mixture screw. I'm new on these carbs and don't have the nomenclature down. I'll see if I can get the three small holes open. So these three holes do not connect to the idle mixture opening, correct ? You are correct, there are some marks in the area of these three holes... looks like someone would have scraped that area, maybe trying to deburr the holes ? . Do you think I should try to polish the damaged area with some fine emery cloth ? Share this post Link to post Share on other sites
Martin 2,130 #59 Posted March 30, 2014 (edited) i would try and clean up that area a little. pull the throttle shaft and plate and clean the bore. I'm not 100% on if they are connected by a passage with the idle screw, they probably are in some way. the idle mixture screw has a hole all of its own in the bore. when the needle is bottomed you can just see the tip ever so slightly in that hole. i haven't really studied which passage goes where. i should know by now, as I've cleaned a few of these. without going out there and looking at one i have apart i couldn't tell you for sure..... i just make sure that i squirt carb cleaner in each and every hole and it comes out its respective passage/hole at the other end clean. Edited March 30, 2014 by Martin Share this post Link to post Share on other sites
Ed Kennell 35,967 #60 Posted March 30, 2014 OK, thanks again for your time and support Martin. 1 Share this post Link to post Share on other sites
Ed Kennell 35,967 #61 Posted March 30, 2014 OK, got the three small holes open, took the throttle plate and shaft out, and polished the throat. Put her back together, set full choke, 1/4 throttle and cranked her over. It took about 10 revs, but when the bowl filled and she got a taste of fuel, she lit up and purred with no sign of surging at idle or full throttle. To all that helped convince me to clean the carb. 1 Share this post Link to post Share on other sites
Ed Kennell 35,967 #62 Posted August 30, 2014 (edited) Well, I have been working on this 520 since March 2014, and I think I have it finished ready for the snow. It was a tractor that was given to me to take along to the Big Show and try to get a couple hundred bucks for which the PO said he would split with me. After tinkering with it for a few days and getting it running, I knew I wanted it for the hyd lift to make a snow machine, so I bought it from him for the $200. I need to thank everyone that helped to walk me through all the problems ... especially Martin. It wouldn't be here without your help. In addition to all the wiring repairs, carb cleaning, R/R replacement, I have vented the belt guard to cool the back cylinder and made a housing to catch the heat and route it into the cab that I picked up at the Big Show this spring. Thanks to Mrs. K for her alterations to the canvas to fit the heat houser. Added fused aux. power strip for cab lights Also added a foot control so one hand is free to operate the hydro lift. Loaded the tires and added double Vee bar chains. I raised the fender/seat pan 2" and moved the foot rests forward 2" to get more room for Me and the tire chains. Just picked up the tall chute this week. Made a hand crank for the chute control, but will add a motorized chute later. Need to add some mirrors inside the cab as my neck movement, due to arthritis is limited to about +/- 10 degrees. And last but really important, I added a red holder for my coffee mug. again for all the help and for looking. Edited August 30, 2014 by ekennell 1 Share this post Link to post Share on other sites
Martin 2,130 #63 Posted August 30, 2014 direction control linkage is interesting there, Ed. good idea..... i like the results of all your work, i bet you will enjoy yourself this winter! Share this post Link to post Share on other sites
km3h 543 #64 Posted August 30, 2014 (edited) Great job Edited August 30, 2014 by km3h Share this post Link to post Share on other sites
