1955 3hp Lightwin Runs Rough High Speed

[MarvK]

Hello all,

Acquired a 3hp Lightwin recently. Model 3014. It wouldn't start when I got it, so I took the carb apart, replaced the float, needle, and low speed needle because it was damaged at the tip. Took it out on the water for the first time today, it idles nice and runs fairly smooth through mid to 3/4 throttle. When I open it to WOT, it begins to run rough, like the fuel is cutting out, and even vibrates terribly. Bring it back down to mid throttle and it smoothes out again.

Is this something that sounds like the ignition is cutting out at high RPM's, or might this still be a carburetor problem? I haven't touched anything in the ignition system yet, and I don't know the history of this motor, bought it off of Craig's list.

Thanks,
Marv

 

[twocyclemania]

Re: 1955 3hp Lightwin Runs Rough High Speed

Did you try to adjust your high speed needle (either way) as it began to get rough? I'd first try opening it up; sounds like it's fuel starved. Take it a little at a time and allowing about 20 seconds or so for a reaction. When you replaced the carb parts did you replace the needle packings (two each high and low speed). Another thing you should replace is the small round seal that's at the top of the fuel pickup inside the bowl (it's surrounded by the float). The old ones are cork and probably dried out. The new ones are a rubber type and much better.

As for the ignition. It could be. You need to look at the coils. Are they cracked. If they're a semi-clear pink looking plastic they're original and definitely in need of replacement. Most of the time I manage to get away without replacing points. Just a good dressing and setting. Condensers are cheap and if you have to open up the flywheel you might as well replace these.

The 3 is a great little motor. Keep us posted.

 

[MarvK]

Re: 1955 3hp Lightwin Runs Rough High Speed

Yes, I tried to adjust the high speed needle. Turned it in to lean, then backed it out. Still ran rough.

Yes, I replaced the needle packings. I did get a kit and replaced all the packing washers an gaskets.

Yes, I replaced the rubber seal on the pickup tube. But, now I'm confused, I thought it is supposed to go on the bottom of the pickup tube, I guess it's called the High Speed Nozzle? Between the end of the tube and the bottom of the bowl? That's where the old one was at. The old one looked like the same type of material as a packing washer.

Haven't looked at the coils yet. I'm heading to the parts store today to pick up an O ring for the top of the drive shaft. When I replaced the impeller, it fell out with the driveshaft. It didn't look all that good, but I put it back in because I didn't have a replacement for it. So, I might as well pick up a couple of coils.

I do love the 3 though, but a speed demon it is not. I have it mounted on a 14ft shallow V-hull I just want to get it in tip-top shape.

Thanks

 

[Rick.]

Re: 1955 3hp Lightwin Runs Rough High Speed

I would replace all the ignition components including wires and boots. You'll be good for years that way. I just got a 55 - 3 hp johnson this year and it is mint. I did everything but a lower unit seal replacement. Have not had the time to get it out trolling yet but hopefully soon. Best of luck. Rick.

 

[lindy46]

Re: 1955 3hp Lightwin Runs Rough High Speed

Could be one coil is cutting out when it warms up. It will idle fine but will bog down at WOT.

 

[MarvK]

Re: 1955 3hp Lightwin Runs Rough High Speed

Hey Lindy, I'm not to far from you!

I'll pick up new coils, points, condensers and see if that solves the problem. Now all I have to do is find the time.

I'm still unsure about where the rubber seal is supposed to be. At the top of the pickup tube, or the bottom? Maybe that's all that's the problem?

Thanks for all the suggestions,

 

[lindy46]

Re: 1955 3hp Lightwin Runs Rough High Speed

The high speed nozzle screws into the carb body, then the washer goes on. The nozzle should have a thick washer (about 3 times as thick as a packing washer) which seals it to the float bowl. It should be thick enough that, when you go to put the bowl back on the carb, it appears that it is too thick and the parts don't meet. That is how it should be. You have to tighten the float bowl bolts to get the halves to meet.

 

[MarvK]

Re: 1955 3hp Lightwin Runs Rough High Speed

Yup, makes sense now. That will direct all the fuel through the high speed needle valve, then up through the high speed nozzle. I have it installed correctly.

Thanks again

 

[MarvK]

Re: 1955 3hp Lightwin Runs Rough High Speed

Update;

I replaced the coils, points, and condensers. The coil insulation was original and major cracked, so I'm glad it's now new.

Took it out this weekend, and still have a similar problem. 1/2 to WOT will run for about 10-15 seconds and then die. Let it sit for a minute and it will start again and do the same thing. It will however, run at about 1/2 throttle without quitting. So, I think I'm back to a fuel problem. I have a new fuel filter coming, as I assume it still has the original filter. It may not be flowing enough to maintain high RPMs.

Am I heading in the right direction?

Good news, is it doesn't seem to vibrate near as bad as before.

 

[Rick.]

Re: 1955 3hp Lightwin Runs Rough High Speed

Sounds like it could well be fuel starvation. Does it run well at high speed and then get rough or rough the second you speed up. I did not know that engine had a fuel filter. Where exactly does that go? If in the tank, how do you remove it? Rick.

 

[HighTrim]

Re: 1955 3hp Lightwin Runs Rough High Speed

As well as the filter, ensure all thefuel lines are open and clean. Good time to clean any crud from the tank.

 

[MarvK]

Re: 1955 3hp Lightwin Runs Rough High Speed

Sounds like it could well be fuel starvation. Does it run well at high speed and then get rough or rough the second you speed up. I did not know that engine had a fuel filter. Where exactly does that go? If in the tank, how do you remove it? Rick.

Filter is acually in the tank itself. It screws in from the bottom and the fuel shutoff valve screws into that, then the copper fuel line goes into the carb.

 

[Rick.]

Re: 1955 3hp Lightwin Runs Rough High Speed

Thanks for that. I never knew. Now, how is your engine doing? Are you making progress? Rick.

 

[MarvK]

Re: 1955 3hp Lightwin Runs Rough High Speed

New filter should be here tomorrow. Then, I'll have to wait for the weekend to test her out. While I have the tank off again, I'll re-check the point gap.

I'll keep you all updated. . Thanks for all the help and suggestions.

Marv

 

[MarvK]

Re: 1955 3hp Lightwin Runs Rough High Speed

Installed the filter and took her out today. Runs much better! :joyous: While I was working on it, I pulled the carb bowl and checked the float setting. I adjusted it a bit so it would sit more level. As it was, it was sitting up a little as viewed upside down.

I don't know what did it for sure, but it doesn't cut out at high RPMs now.

Thanks All,

Marv