Horse Newbie 7,168 #1 Posted November 24, 2020 (edited) @lynnmor @WVHillbilly520H I am having some issues to say the least. I was having surging issues on my 20 hp Onan (520h). So I bought a cheap carb off the net. Got it on and the rpms go through the roof...had to slow the engine down with the choke... The governor linkage is rubbing slightly against my crankcase breather. Can I bend the linkage rod a small bit so that it does not rub ? See pic. Edited November 24, 2020 by Horse Newbie Share this post Link to post Share on other sites
Horse Newbie 7,168 #2 Posted November 24, 2020 The surging is gone but the engine tries to run at way over 4000 rpms according to my tach. I shut it down before it blew. What would I have to do to get the rpms down enough to check things out ? Share this post Link to post Share on other sites
WildHorses 393 #3 Posted November 24, 2020 (edited) The cheap chines carbs (and even occasionally the originals) can come in not set correctly, missing parts or with incorrect parts. I would check the original verse the new carb to make sure nothing obvious is missing or dramatically different in shape or size. You may need to adjust the needles like in any carb even if everything is correct. There are a lot of youtube videos on Onan carbs surging and they'll generally give you a good idea on how to set the carb and what it should look like. You may have bumped the governor arm or linkage as well that may have something to do with it. I would explore that as a last possibility though. This video shows the governor moving (properly I believe). Edited November 24, 2020 by WildHorses 1 Share this post Link to post Share on other sites
Horse Newbie 7,168 #4 Posted November 24, 2020 So the way I understand it, the linkage rod on the governor has to move easily and un restricted by even the slightest bit... So would I make the problem worse by bending the linkage slightly so it wont rub the crankcase breather assembly ? Share this post Link to post Share on other sites
WVHillbilly520H 10,376 #5 Posted November 24, 2020 5 hours ago, Horse Newbie said: So the way I understand it, the linkage rod on the governor has to move easily and un restricted by even the slightest bit... So would I make the problem worse by bending the linkage slightly so it wont rub the crankcase breather assembly ? Yes unfortunately... Also they have to be in the correct hole (check Onan service manual) the carb itself has little to do with the racing RPMs its in the governer adjustment. 1 Share this post Link to post Share on other sites
lynnmor 7,484 #6 Posted November 24, 2020 I don't like the way that linkage is so close to the breather and I have bent some slightly. I would never use a cheap Chinese carburetor, just clean the old one if possible or buy a used one. My guess is that you have the linkage installed wrong, post photos of your linkages, both throttle and governor. 2 Share this post Link to post Share on other sites
Horse Newbie 7,168 #7 Posted November 24, 2020 14 minutes ago, lynnmor said: I don't like the way that linkage is so close to the breather and I have bent some slightly. I would never use a cheap Chinese carburetor, just clean the old one if possible or buy a used one. My guess is that you have the linkage installed wrong, post photos of your linkages, both throttle and governor. @lynnmor @WVHillbilly520H I will post detailed pics of linkages later today after work or tomorrow. I'm 99% sure I have the linkages the way they were with the original carb. Lynnmor I know what you are saying about the Chinese carbs , but I thought I would give it a try since my original carb was so grimy. The linkage rubbing the crankcase breather HAS to be affecting the governor operation...I'm sure of that. I did read the Onan manual about adjusting the governor. I read where it said to remove end of the linkage from hole in the bracket (wrong term), push the linkage and the bracket toward carb as far as it would go, and then put the rod back in the hole that it is closest to... The end of the linkage went past the end of the bracket so for now I just put it back where I found it until I can learn more and get some more info. from you guys. Share this post Link to post Share on other sites
WVHillbilly520H 10,376 #9 Posted November 24, 2020 I'm not gonna knock or praise the Chinese carbs (as I have had decent luck with the Kohler/Carter versions) but sometimes the ethanol has "eaten" away the original castings that they can't be rebuilt or PO did some really stupid things trying fix them (like wiring repairs to the 520s for example) and you are taking just a big a chance on a used one as well, and its really hard sometimes to justify spending O.E. new prices for replacement parts (carbs fuel pumps coils ect) when initial investment was that price, if you trying things on the cheap to see if it helps your situation I say go for it... Keep the original and try rebuilding it later... I'm not at home to look at my 2 for the linkage placement but I will try to get some pics later today. Share this post Link to post Share on other sites
Horse Newbie 7,168 #10 Posted November 24, 2020 @lynnmor @WVHillbilly520H What does the spring on the linkage do... just keep the slack out of the linkage ? Share this post Link to post Share on other sites
Horse Newbie 7,168 #11 Posted November 24, 2020 6 minutes ago, WVHillbilly520H said: I'm not gonna knock or praise the Chinese carbs (as I have had decent luck with the Kohler/Carter versions) but sometimes the ethanol has "eaten" away the original castings that they can't be rebuilt or PO did some really stupid things trying fix them (like wiring repairs to the 520s for example) and you are taking just a big a chance on a used one as well, and its really hard sometimes to justify spending O.E. new prices for replacement parts (carbs fuel pumps coils ect) when initial investment was that price, if you trying things on the cheap to see if it helps your situation I say go for it... Keep the original and try rebuilding it later... I'm not at home to look at my 2 for the linkage placement but I will try to get some pics later today. I concur with what you say, and I did buy the carb on Amazon that you sent me a link to in another conversation. Not pointing the finger please know that ! The description said OEM but I got a Chican carb. I thought OEM meant Original Equipment Manufacturer but I guess I should have known that would be too good to be true. I do still have the original carb and I may try to rebuild that one if I cant get this Chican carb to work out. I have straightened out all of the wiring issues and all seems to be well with that... All instruments seem to work and all dash lights are working. I was feeling pretty good about that still knowing that the carb was going to be a pain for me because of my lack of knowledge about small engines, or for that matter engines in general. I do fine changing stuff like a coil, water pump, brakes, etc., but I need more experience in diagnostics and understanding of mechanics. I still try to do most of my work myself because I know I'll do it the best I can instead of paying top dollar to someone who will do a halfway job. I am going to stick with this because I want to experience riding my horse. I will admit taking the whole top of the engine off, trying a carb, being disappointed, then having to take it apart again to try the original again is something I am not looking forward to but its going into winter, my shop is heated, so I have plenty of time to work it all out. Share this post Link to post Share on other sites
WVHillbilly520H 10,376 #12 Posted November 24, 2020 51 minutes ago, Horse Newbie said: I concur with what you say, and I did buy the carb on Amazon that you sent me a link to in another conversation. Not pointing the finger please know that ! The description said OEM but I got a Chican carb. I thought OEM meant Original Equipment Manufacturer but I guess I should have known that would be too good to be true. I do still have the original carb and I may try to rebuild that one if I cant get this Chican carb to work out. I have straightened out all of the wiring issues and all seems to be well with that... All instruments seem to work and all dash lights are working. I was feeling pretty good about that still knowing that the carb was going to be a pain for me because of my lack of knowledge about small engines, or for that matter engines in general. I do fine changing stuff like a coil, water pump, brakes, etc., but I need more experience in diagnostics and understanding of mechanics. I still try to do most of my work myself because I know I'll do it the best I can instead of paying top dollar to someone who will do a halfway job. I am going to stick with this because I want to experience riding my horse. I will admit taking the whole top of the engine off, trying a carb, being disappointed, then having to take it apart again to try the original again is something I am not looking forward to but its going into winter, my shop is heated, so I have plenty of time to work it all out. Its all good like I said I have bought the cheap carbs bolted them on and it took off no adjustments needs then I have gotten a couple and they leaked worse than the original or linkages not quite right either way you are trying and working with what you got. 1 Share this post Link to post Share on other sites
lynnmor 7,484 #13 Posted November 24, 2020 Read this thread I believe you have the linkage installed wrong, the photos will guide you. Share this post Link to post Share on other sites
Horse Newbie 7,168 #14 Posted November 24, 2020 33 minutes ago, lynnmor said: Read this thread I believe you have the linkage installed wrong, the photos will guide you. Yes sir ! The linkage may very well be wrong... Don't know yet... Will have to read what you said in "this thread". But I did put it back where it was...you can tell where the rust stain is in that one pic... Thanks for you fellars help ! Share this post Link to post Share on other sites
Horse Newbie 7,168 #15 Posted November 24, 2020 @lynnmor @WVHillbilly520H Lynnmor, I did read the thread you suggested above. My linkage is in too far at the carb like what was described in the thread. I will put it in the farthest loop on the linkage. That should move the linkage away from the crankcase breather. You can see in the pictures I posted above that the linkage was wrong at the carb ( based on the rust stains ). I will move the linkage and see what happens... ONE QUESTION THO... My spring on the carb end is in the same hole as the linkage...( only one hole in cheap Chican carb )... Would you guys just use the hole that the linkage is in for the spring also, or would you drill a hole in the little doohickey for the spring ? The linkage may be wrong, but it was "New to Me" like that. I am learning a lot ! Thanks, Tim Share this post Link to post Share on other sites
lynnmor 7,484 #16 Posted November 24, 2020 I would drill a hole and smooth the edges so the spring would have less wear. 1 Share this post Link to post Share on other sites
Horse Newbie 7,168 #17 Posted November 24, 2020 And is the spring just to keep the linkage from having slop ? Share this post Link to post Share on other sites
Horse Newbie 7,168 #18 Posted November 24, 2020 14 hours ago, WildHorses said: The cheap chines carbs (and even occasionally the originals) can come in not set correctly, missing parts or with incorrect parts. I would check the original verse the new carb to make sure nothing obvious is missing or dramatically different in shape or size. You may need to adjust the needles like in any carb even if everything is correct. There are a lot of youtube videos on Onan carbs surging and they'll generally give you a good idea on how to set the carb and what it should look like. You may have bumped the governor arm or linkage as well that may have something to do with it. I would explore that as a last possibility though. This video shows the governor moving (properly I believe). @lynnmor @WVHillbilly520H Do you guys think this governor is working properly ?...I don't. Choke cable is not hooked up I noticed... Share this post Link to post Share on other sites
lynnmor 7,484 #19 Posted November 24, 2020 51 minutes ago, Horse Newbie said: @lynnmor @WVHillbilly520H Do you guys think this governor is working properly ?...I don't. Choke cable is not hooked up I noticed... It appears that the mixture is too lean, that is the way they act when dirt blocks some of the fuel flow in the carburetor. Did I see the coil dancing around. Share this post Link to post Share on other sites
Horse Newbie 7,168 #20 Posted November 24, 2020 (edited) @lynnmor @WVHillbilly520H So I got home today and started looking at the linkage... So if I don't put the linkage all the way on like I found it ( and where rust stain is), then I don't have a good "hook" on the end. (See pics) Lynnmor think I should go ahead and put it in at the first curve/hook in the linkage ? Edited November 24, 2020 by Horse Newbie Share this post Link to post Share on other sites
Horse Newbie 7,168 #21 Posted November 24, 2020 (edited) @lynnmor @WVHillbilly520H So I got home today and started looking at the linkage... So if I don't put the linkage all the way on like I found it ( and where rust stain is), then I don't have a good "hook" on the end. (See pics) Lynnmor think I should go ahead and put it in at the first curve/hook in the linkage ? Edited November 25, 2020 by Horse Newbie Share this post Link to post Share on other sites
lynnmor 7,484 #22 Posted November 24, 2020 9 minutes ago, Horse Newbie said: @lynnmor @WVHillbilly520H So I hot home today and started looking at the linkage... So if I don't put the linkage all the way on like I found it ( and where rust stain is), then I don't have a good "hook" on the end. (See pics) Lynnmor think I should go ahead and put it in at the first curve/hook in the linkage ? Of course. 1 Share this post Link to post Share on other sites
Horse Newbie 7,168 #23 Posted November 25, 2020 20201124_173621.mp4 20201124_173903.mp4 20201124_173942.mp4 20201124_173720.mp4 20201124_174031.mp4 20201124_174115.mp4 Share this post Link to post Share on other sites
Horse Newbie 7,168 #24 Posted November 25, 2020 First video it would not crank because of the pto safety...scared me for a secound...lol Share this post Link to post Share on other sites
Horse Newbie 7,168 #25 Posted November 25, 2020 I did put it in at the curved part as shown on the above pic and it cranked and ran. Still may need to tune it a bit... I will have to come back to you guys and get some help with that. But for now I'm gonna go to the other topic I started about why it won't move after the hydro oil change. Thanks a million Lynnmor, WVHillbilly520H, and everyone else who shared their knowledge ! Share this post Link to post Share on other sites
