67 Lightwin piston rings

[JasonAych]

Where can i get a set of piston rings for a 1967 Evinrude 3 hp Lightwin?

I see Evinrude online goes back to 68. Are the rings for the 68 3hp the same? I am betting they are but would like to be sure.

I had 68 psi on each cylinder. I replaced the head gasket and resurfaced the head and now I have 72 psi. I also tried to decarbon it. I think the rings are just worn. Motor looks like it has quite a few hours on it.

Thanks!

 

[F_R]

Re: 67 Lightwin piston rings

Where can i get a set of piston rings for a 1967 Evinrude 3 hp Lightwin?

I see Evinrude online goes back to 68. Are the rings for the 68 3hp the same? I am betting they are but would like to be sure.

I had 68 psi on each cylinder. I replaced the head gasket and resurfaced the head and now I have 72 psi. I also tried to decarbon it. I think the rings are just worn. Motor looks like it has quite a few hours on it.

Thanks!

Part number 378412 ring set fits the 3hp from 1952 through 1968. "Set" is for one piston.

 

[tx1961whaler]

Re: 67 Lightwin piston rings

Where can i get a set of piston rings for a 1967 Evinrude 3 hp Lightwin?

I see Evinrude online goes back to 68. Are the rings for the 68 3hp the same? I am betting they are but would like to be sure.

I had 68 psi on each cylinder. I replaced the head gasket and resurfaced the head and now I have 72 psi. I also tried to decarbon it. I think the rings are just worn. Motor looks like it has quite a few hours on it.

Thanks!

72 psi is fine for that motor. What do you think the compression should be, and why?

 

[JasonAych]

Re: 67 Lightwin piston rings

Well, I was told by a local service manager it should be up around 90-100psi. I can't seem to find anything to dispute that.

Another reason I'd say the compression is low is because the engine is slow to rev up. In the furthest "fast" position it takes a few minutes to get up to full rpms. If I partially close up the tube on the end of the air silencer it revs up faster. Just seems like a low compression to me. However, my experience is more with 2 stroke dirtbike engines.

I am fairly certain the carburetor is cleaned properly at this point. Is there only a high and low jet? Is there a midrange jet or circuit in these carbs? It idles perfect. And the fact that it eventually hits full rpm tells me the main jet is clear. I did a few plug chops and the plugs actually look a bit rich which contradicts it running better when restricting the intake.

I am open to suggestions

 

[Rick.]

Re: 67 Lightwin piston rings

A good seafoam treatment may well increase your compression numbers. It brought my 71 4HP up about 10 lbs. per cylinder. I don't have any advice on the poor performance issue. Perhaps try pumping the bulb while trying to accelerate. Best of luck. Rick.

 

[kbait]

Re: 67 Lightwin piston rings

Make sure you're getting 1/4" blue arc on a spark tester. Link/sync of carb/stator plate? In my experience, low compression doesn't equate to slow, steady idle performance. I'd definitely tinker with it before ripping it down.

 

[JasonAych]

Re: 67 Lightwin piston rings

Thanks for all your advice.

As far as the seafoam treatment is concerned, I am pretty sure it is very similar to the OMC Tuner spray treatment that I used. I also used some PB Blaster in the cylinders to free up the rings (if they are stuck). That is exactly what I did with the old 39 Elto 3hp I have which worked like a charm, that thing runs great now. The 67 Lightwin has an onboard fuel tank, no bulb.

kbait, I don't have a spark tester. Well, I have a cheap HF tester with a bulb that flashes, but that isn't the same thing as you are suggesting, at least I don't think. I am suspicious of the ignition but it looks like brand new in there. Newer style coils (purple and green). No signs of cracks. Although i am aware that is no garantee. Can I make a tester? Do I just need a ground wire spaced at 1/4"? I can rig something up if that is the case. Do I need to test at higher RPMS or wiill the spark be weak at pull start? If so, how o I do that?

As far as the stat plate carb sync goes, I though about that too. The thing is, the carb shafts have flat spots (looks to be factory on purpose) where the set screws seat. So there does not seem to be adjustment. Is there another adjustment I am missing?

Thanks!!

 

[kbait]

Re: 67 Lightwin piston rings

The linkage has the flat spots so it only goes together in one way/position. The cam on the armature plate that makes the carb open is adjustable. There should be a mark on it where it's first supposed to contact the follower connected to the carb linkage when plate is advancing. That's the link/sync.
I made a tester, and here's a pic, I hope. Just like you described, and if you search this forum, there is a post on how to do it. Mine is more primitive-wood block, screws, tape, 2 removable tips from old spark plugs..haha, works great though.. Good luck!

 

[kbait]

Re: 67 Lightwin piston rings

Oh.. recoil will spin it plenty fast to get test, even if pulled kinda slow.. If the spark isn't consistent, remove points, file their faces up shiny and re-install to .020". I'm sure the 'top secret files' has the detailed procedure, located at the top of the forum.
Also, be sure you're getting a good 'gravity feed' of fuel from the tube to the carb. Sometimes when the tank gets low, the fuel won't pass easily through the filter in the tank, and cause headaches. When you re-test, make sure tank is pretty full.
I still believe if it idles really well, it should get to higher rpm's w/power,and w/o the hesitation described.

 

[JasonAych]

Re: 67 Lightwin piston rings

Can't seem to find the link for the spark tester.

Your primitive tool is cool. I like that kind of stuff. I have you beat for primitive. I made a flywheel puller out of a old cable pulley from my garage door. Next time you ar at home depot stop by the garage door parts. Look at the pulley kits they sell (around $5). You'll notice there are six holes around the pulley. Well 3 of them (with a tiny bit of filing) happend to line up the same as the 3 threaded holes on the flywheel. Welded a nutsert in the center, ground the end of the bolt to be rounded and presto ... or you can go to Harbor Freight and get one for $15 (10 on sale). Wasn't an option at 10:00pm when i needed it.

Thanks!

 

[JasonAych]

Re: 67 Lightwin piston rings

Already cleaned up the points and set them.

 

[kbait]

Re: 67 Lightwin piston rings

You got me beat on primitive. I like that yours was cheaper than the cheap puller I bought!! I bow humbly..

 

[kbait]

Re: 67 Lightwin piston rings

If you already did the points, I'd assume that it's getting fine spark, as your description didn't really fit w/intermittent loss of spark issue. Make sure you're getting a good flow to the carb, float is set level to the inverted carb body, make sure the float valve is good by blowing in the fuel line with carb upright(air will pass), and inverted (air will NOT pass..), good needle o-ring packing (I use #47 plumbing o-rings from truValue). Start again w/high speed 3/4 turn out, and low speed 1.25 turns and adjust from there. It should rev up from idle to throw the water all over really quickly (in barrel).

 

[JasonAych]

Re: 67 Lightwin piston rings

Had the carb apart about 20 times now bending the float tab in increments. Bent to the point that I was getting no gas then back to the point it no longer shut the fuel off. Never found a sweet spot (where it would run better).

The float is cork. I resealed with a product called "Seal all" which supposedly can stand up to ethenol, gasoline and oil. 2 thin coats to make sure it was sealed. Let it cure for 2 days. Test floated it for a few hours. Seems good.
I intend to get a new float sooner or later. Just don't want to spend money on that until I get it running right.

On thing I am going to try is replacing the plug wires. I just remembered I have some copper core plug wire (6 or 7mm) left over from a motorcycle project. One of the wires on it now has a tiny chunk out of the insulation. I am skeptical because I was brave enough to test it with my finger (not really it was by accident). No shock nor did I see any spark jumping in the dark when running.

 

[kbait]

Re: 67 Lightwin piston rings

The 'sweet spot' for your float adjustment should be huge, so maybe that's not the culprit. Are you sure it's running on 2 cylinders when idling? You can take the plug boots off one at a time when running to check (rubber handled pliers, or just take one off at a time and start it up). If it's just on one, it'll idle nicely, and perhaps when you try to rev it up it starts hitting on both? Otherwise, maybe it has a vacuum leak somewhere else around the powerhead? I'm not sure how that problem would present itself.. There's sure not that much to those 'lil gems, so have patience, and keep on asking the experts (not me, haha). If the high speed jet is slightly obstructed, maybe that'd cause the problem, but you'd think fuel going through would keep it free. Also, is the nozzle clear (brass tube)? Just brainstorming.. Keep us appraised!

 

[JasonAych]

Re: 67 Lightwin piston rings

That high speed jet is clear. I am positive.

Absolutely firing on both cylinders at idle. Pulled each wire one at a time and it made a big difference. Didn't do that yet in the fast or greater position. Actually I did for the plug chop but did it so quick I am not sure it made a difference.

 

[JasonAych]

Re: 67 Lightwin piston rings

... nozzle is clear too

 

[kbait]

Re: 67 Lightwin piston rings

Spark sounds fine, and if it was cutting out when you tried to speed up, you'd have noticed. Spark and plugs are likely fine. Doesn't sound like the plug wires are shorting w/throttle position, for the same reason. Stick w/the fuel side, and I STILL think your compression is fine, and not a reason for this issue. I'd make sure the gasket around the nozzle is good, and can't leak, and scrutinize the high speed jet. I use a little flashlight and some air duster and perhaps a bit of your engine tune (I use amsoil powerfoam.. same diff). You can poke it with a THIN wire, not making the brass hole bigger, but my headlamp shone (shined) through the jet usually suffices for me, unless no light gets through.. Be sure the needle packing is good. It should run. Dumb question, you using FRESH 24/1 fuel mix?

 

[JasonAych]

Re: 67 Lightwin piston rings

My gut is with you. Just not adding up at the moment.

It is a 67 so I am using fresh gas and 40:1 as manuals for that year recommend. Especially since the main jet is fixed (no adjustment) for the 67. I actually tried 24:1, 32:1, 40:1, and 50:1 (current recommendation at BRP) with not much of a change (seamed to get a tinny bit worse as i went down in ratio). I really wish it had an adjustable high speed. Would take a lot of guess work out of this whole thing.

Great minds think alike. Did the wire thing as well as used a little blue LED to shine through the jets. It is all clear and perfectly round and clean. The seals/gaskets in the carb are the grey rubber type with lots of flex to them. I am confident they are sealing. I did the same exactly thing with the needle packing that you mentioned using o-rings.

The tank had the petcock strainer/filter cut off. I put a brand new inline Briggs + Stratton strainer/screen type filter.

Just to throw some other things out there that I have discounted: It is a 67 with a 63 fuel tank and side covers. The block has the 67 model number in the freeze plug so i am fairly certain everything with the mechanical part of the engine is 67.

Being that there are some swapped parts, how would I know if the carb is 67 and not 62 or older (adjustable main) with the 67 dummy plug (isnead of needle) in it? There is a horizontally positioned brass jet in the main jet circuit which would meter gas from the bowl to the main jet throat.

 

[kbait]

Re: 67 Lightwin piston rings

Sorry.. 50/1 for a '67. And if the frost plug says '67, it was originally fitted with a fixed main jet carb, like you have now. I believe any carb from '52-'67 would fit and work, and the earlier ones had an adjustable main jet. I've never had any trouble with the fixed jet models. Do you have the screen that fits between the air silencer and carb? I've heard that leaving that out could lead to a leaner condition, as the incoming air would have less resistance. That sounds feasible, as you could compensate the low speed setting w/adjustment, but at higher rpm's, you get what you get through the fixed jet. With that being said, I've run many different 3hp's w/fixed jet in a barrel and no air silencer or screen attached, and they've never had the issue w/hesitation when advancing throttle (unless I forgot to re-install the linkage, haha). Try misting some mixed fuel into the carb throat when you're throttling up to see if it stops hesitating. If it performs better, it's obviously running too lean on the high speed circuit (even though it shouldn't be..). You could get a carb bowl w/adjustable jet at that point, and it would obviously fix the hesitation. I've had great luck w/Tim's outboard in Hackensack, mn 218-682-2331. I get used coils from them too ($10 each if you get 6 or more.. and they test 'em). Nice prices and quick shipping.
I'm still thinking that it's not just the jet that's wrong though. Almost has to be an air leak somewhere. When running at the issue point, you could try misting fuel mix around carb base, powerhead base, etc to see if you can find some kind of vacuum leak. You definitely have a head-scratcher! Post back after you've messed around some more, and I'll continue to blather on.. haha.