416 adventures......

[bowtiebutler956 650]

 Glad you got it running Martin!!   Does that carburetor have a main jet adjustment needle? I don't have any experience with that model of Onan, but I've had plenty of engines that surged until air fuel mixture was set right.

 

Matt

[Martin 2,132]

Nope, that's the frustrating thing, a k series would be running right 30 seconds after it's fired up. I have a couple spare carbs, might swap out a jet, can't find any vac leaks anywhere at all....

Choking slightly doesn't help, so I think it's only off a little.

In the second video it's almost running right, I ran it for 10 min or so and it's getting better. Starts with just a quick turn of the key too....

Sent from my iPhone using Tapatalk

Edited June 10, 2014 by Martin

[km3h 543]

Ain't the beer cold?????

[Martin 2,132]

i have been doing a little reading on the surging. i thought id dealt with most of the Nikki carb issues in the past but this one I'm going to try tonight when i get home. specifically the last statement by kpinnc here.....

 

 

Yep. The bowl is the whole carb body. I love my Onans, but this was a bad design. All Nikki 6100 carbs are the same way. Just different size throats for different HP. Briggs used them for a while too, and most of the core parts are interchangeable.

To be 100% sure Duke, I'd take the carb off and clean it properly. You can remove all the parts that a soaking would damage (gaskets, float & plunger, etc...) and re-use them. No need to remove the butterfly plates. They won't be harmed by soaking it.

Check the float plunger tip for a "ring" where it seats in the inlet. It should not have one, and should still be soft and pliable.

Remove the jet plug from the side (the metal plug), but not the jet itself (#6). There's also the idle jet inside on the top (#5). You can remove it with a screwdriver and clean it after you take the top of the carb off. It's not adjustable- so just seat it back in there when you've cleaned it.



You may also want to replace the float while you're in there. They contribute quite a bit to the surging, and they don't shut the gas off the way they should because they get kinda "waterlogged". That will cause some blue smoke when you throttle up and rough running any other time.

 

 

 

 

i really only put an upper gasket in this carb as it was running really nice way back in this thread. I guess its worth a try, i have a new float and needle sitting on the shelf.......

[AMC RULES 37,134]

Humm...does this read right to you Martin?   

"Check the float plunger tip for a "ring" where it seats in the inlet. It should not have one, and should still be soft and pliable."

[Martin 2,132]

Yeah, that's sometimes why they have flooding issues. The ring is a wear point and once they get like that they never really seal that well again. Mine looked ok, but I think it will get a new one with the float, they come as a kit.

Sometimes I should just go and replace all this crap right from the get go, maybe avoid some bs down the road. I figure it was running good before, and the parts looked ok, so why change them out. I guess turning it into a trailer queen raised its standards, no longer is used parts good enough for it!!!!!!!

Sent from my iPhone using Tapatalk

[ol550 830]

Can't believe you went for a test drive with no seat or blanket.    

[Martin 2,132]

Mike, it was more like a mini blanket. I was afraid I would catch the large red blanket in the belt.

Always remember, Safety First!!!!!

[Martin 2,132]

well, this Onan is challenging me, big time.

pulled the top off the carb, removed power jet, idle jet and float. gave it a real close look over. main jet had some small specks of something in behind it and i thought great, thats the problem, give it a real good blow out, closely inspect all the jets, holes etc and put it back together. well it still runs like crap......

 

to be fair, no it doesn't run like crap, but its still not how it should be. and its not how it was before i pulled this whole thing down. i can get the surging out of it but at the expense of running rough, like mixture adjustment when you find the lean and rich limits. just starts to splutter very slightly every few seconds and then it will be continuous but very minor. it has plenty of power though. i can get it to surge for a few seconds if throttled up from idle, but it gradually looses the surging after 5 seconds or so and settles into its faint rough running state, either at idle or high speed, but they aren't the same though. the idle is more of a slight choke out, whereas the high speed is a stumble every 2 to 3 seconds. I've checked for leaks in all the obvious places on the carb and manifold.

 

the one thing that i found and can't get any info on is the power jet size. the jet in this carb has 120 stamped in to the flange. i have a couple carbs around and went hunting for jet sizes. only one carb had a power jet in it and that was a P216 carb from a 1997 Miller welder. emissions carb with the accelerator jet on the side. this jet had 114 stamped in it and looked slightly smaller in the opening. maybe because it is an emissions carb they used a smaller size jet i don't know. ( just a fyi- a p220 uses a 134).

 

im not really sure where to go from here, i guess i could try the 114 and see what happens, really got nothing to lose. last resort at this stage is a new carb, but i really would like to get this one sorted. the only other thing that is different is the intake is not the one i used on this engine when i got it running. it is slightly different with the carb flange and was the one i sealed up. I'm going to take a look at this tomorrow and do a more thorough look for leaks. it doesn't seem to be running lean though, when its surging, slightly pulling the choke only makes it worse, which tells me that maybe its running slightly rich.

 

heres another video of it today before i pulled the carb apart........

 

Edited June 11, 2014 by Martin

[km3h 543]

When you took the intake manifold apart and put it back together are you absolutely sure that it is completely sealed? Common sense says that the engine ran perfectly before doing any work on it so it should run perfectly now using the same size jet. I don't believe it is a faulty carburetor. Are you sure that the valves are adjusted properly?

[Martin 2,132]

When you took the intake manifold apart and put it back together are you absolutely sure that it is completely sealed? Common sense says that the engine ran perfectly before doing any work on it so it should run perfectly now using the same size jet. I don't believe it is a faulty carburetor. Are you sure that the valves are adjusted properly?

 

thianks for your input. much appreciated. i thought a lot about this at work today while working in the sauna and considered your points. what if the manifold had a slight leak before and was being masked by a carb that was running slightly rich? the reason I'm still saying the carb is slightly rich is i couldn't adjust a smooth idle with the idle mix screw without almost being closed and then it just wouldn't run smooth (reasonably) at all. i know most of this stuff was on the engine before its clean up, but a lot of things have changed since then, the resealed manifold (not the one on the engine, but another i had), gaskets, clean intake and exhaust path, valves adjusted, which by the way i checked over and over before sealing the engine, new plugs, new coil and other ignition components, etc etc.

just for giggles tonight when i got home i changed out the main jet. but not before doing a bunch of reading on the subject on wfm and a few other tractor sites that the machines use Onan engines.

 

from the info gathered the 120 jet was used in the P218 carb (#205 venturi). the P218 also has the same displacement as the P220 at 47.7 cu in. i couldn't find definite info regarding the P216 size main (pre accel pump Nikki) and all can gather is that they were used on the P216 carbs with the #205 venturi as that was what the carb had when i got it through Mike (sorekiwi). i think i remember him saying it was on a 516 wheel horse but I'm not 100% on that. now i have a P216 emissions Nikki carb that does run a 114 jet. apparently this was done to cut down on emissions.....

 

anyway back to the P218, its displacement is 47.7 cu in. and the P216 is 43.3 cu in.

now I'm thinking if going from the 18hp carb to the 20hp carb (with the same engine size) the jet size increased from 120 to 134, why would you expect an engine with 4.4 cu in less displacement to be ok with the same size 120 jet? there was probably 1000s of engines made that were ok with that, but obviously mine was not enjoying that size jet in it now. i had a 114 so why not try it.....

 

so i did, the results are night and day from how it was. still not perfect but this engine is still basically a 580 hour engine under all its shiny parts. remember this isn't a rebuild, the bores were cleaned up with scotchbrite and you only need to go back to the beginning of this ordeal.....

 

here.....   

 

to see how bad it was. i don't think i really got close ups of the bores from water damage either, so I'm surprised that it runs as nice as it does here......

 

[km3h 543]

My old ears can't hear anything wrong with that engine. It does not sound like it is surging. Send me your address and I will drive from Maryland up there and take it off your hands.

Seriously though if you feel that it is running as good as it should then it probably is. I have a 416H with 528 hours on it. I know it is not up to factory new condition, but it is good enough for me.

[Martin 2,132]

yes, about the only surging it has now is sometimes when you throttle up quick it might just correct itself once or twice, but its getting better. it doesn't quite run like the other 416 (with approx 580 hours too...), but I'm sure with time it will settle a little more. it took some good loading up on that one to make it run as good as it does now. i think this one just needs some time. maybe i will get myself a heavy roller and pull that around for a while. i can't see myself hooking up a deck to it and letting the grass undo all the work I've done to it........

thanks for your input

Edited June 12, 2014 by Martin

[leeave96 487]

yes, about the only surging it has now is sometimes when you throttle up quick it might just correct itself once or twice, but its getting better. it doesn't quite run like the other 416 (with approx 580 hours too...), but I'm sure with time it will settle a little more. it took some good loading up on that one to make it run as good as it does now. i think this one just needs some time. maybe i will get myself a heavy roller and pull that around for a while. i can't see myself hooking up a deck to it and letting the grass undo all the work I've done to it........

thanks for your input

I can't remember, but are there low and high speed jets that one can adjust on these Onan carb's? For some reason, I'm thinking maybe yes, but also seem to recall that the 1997 year makes we're not adjustable? And if there are high and low speed jets that are adjustable, can one adjust out the surge?

[Martin 2,132]

up until they used the emissions carbs you could still adjust the idle mixture, which actually adjusts not just at idle but the mid and high to a certain extent as well. the adjustable main jet was done away with some time ago, none of the performer engines had that.

 

the surging can be caused by a number of different scenarios. one thing to remember is surging, or hunting, is just a result of a governor trying to compensate for a lean or rich condition for whatever reason. lean could be carb blockage, leaking intake, something that is allowing air to be sucked in the engine intake path almost always below the throttle blade. rich could be an out of adjustment carb or in my case a main jet just slightly too big for the engine for whatever reason. a too sensitive governor adjustment will cause it as well.

 

all the governor is doing is trying to fix a condition it sees. the rpm starts to drop for whatever reason, governor kicks in momentarily to compensate, now its over compensated and backs off, but then the condition rears its head again and compensation kicks in again. this just keeps going on until the condition causing it disappears. a governor can be made to mask the surging but it will not do its job properly in that situation. you could adjust it so there is no sensitivity at all, but its there for a reason and needs to be working properly.

the governor can be the cause of the problem too by not having the sensitivity correct or a mechanical condition inside the engine. 

 

typically surging can't be adjusted out by idle mixture adjustment alone, i guess if the adjustment was way, way out maybe, but usually to be surging in a typical Onan scenario, its usually something more than an out of adjustment mixture screw....

Edited June 12, 2014 by Martin

[Desko 610]

IMHO I think it runs great giving its past history of sitting out and water in the bore over time it'll clean itself up. Keep up the great work.

[MalMac 1,331]

I am not saying this is the cause but I have fought with Onans doing what yours is doing and have done all kinds of carb work on them. I know this has been mention before but this darn junk gas we get now a days. This junk gas can masquerade as all kinds of problems. Even the high octane and even the non-ethanol gas is not what it use to be. I have seen problems change from tank full to tank full. Like I said you may very well have a crab problem or gov. problem but don't rule out the junk gas because it can fool you.

[Martin 2,132]

yes, good point, the junk gas is always a problem. i am very careful nowadays, only buy premium from one station i know is ethanol free. i try to stay consistent all the time. 

sometimes when I'm at a 2 or 3 day show, i need to buy from somewhere else, but 99% of the time its the same pump at the same station....

 

thanks for your input......

Edited June 13, 2014 by Martin

[Martin 2,132]

finally got my peterson tail lights today.....

got them fitted with the correct wire and 'bullet' terminal to plug into the factory harness. i had some old taillights that the wire was still good on, but the bulb holder had gone bad, so i cut the wire from two of them, crimped the 3/16 female spade terminal on the end and installed them on the seat pan.....

 

heres the lights i used, peterson 135R clearance lights from trailer.com, they are 2 bulb units and run about $4.50 ea.

 

 

 

old tail light next to the new, the old donated the wire to connect them with the correct terminal

 

 

 

connected to tractor harness, used one of those clips that like to bite the paint, but seem to hold the excess wiring under the seat pan out of the way of moving parts....

 

 

looks like i need to get the steering wheel sorted, i need a seat and then decals. i think I'm almost done!!!!!!

 

 

 

 

[Torino 14]

I have an Onan on a 520 that runs excellant and have one on a JD 318 that I have never got to run right.  While reading this thread I wondered if there where any other good carbs that could be put on these Onans to replace the Niki?

[Martin 2,132]

the nikki carbs are really not the problem. 99.9% of the problems that people here on the forum deal with, would in my opinion be fuel related. i can't recall many complaints of the carbs being worn out. they are a finicky carb compared with a carter on a kohler, but they are no more finicky than an automotive carb. imagine an automotive (older) carb under the same conditions as a nikki on an onan. dirty gas, bad filter, sporadic use, running it on gas that has sit in a container for a few days or weeks, etc etc.

if one is running right after a total fuel system clean and only fresh clean gas along with decent filters are used, along with regular use the problems i think would be almost non existent

my other 416 that is running had problems when i first got it running, but since then regular use and decent gas, that tractor hasn't missed a beat since. starts quick, plenty of power and smooth running.....

 

sometimes finding the issue when running bad is the real frustration.......

Edited June 13, 2014 by Martin

[ol550 830]

Just thinkin them rears need a trim.  

 

 

 

 

 

[Welsh Wheelhorses 8]

416#2 next?

[Martin 2,132]

416#2 next?

 

maybe, but not for a while. i need a rest.......

[dbartlett1958 96]

Martin,

You make all us 416 owners proud!