60' lark 40 and new 2-stroke oil

[surlyjoe]

I have just gotten my 60' lark 40 horse back together after a complete overhaul, and am totally confused about what oil/fuel ratio to run. I bought it as a basket case and have only started it a couple times on the stand I have seen posts saying 50:1 with the new oil, and ones that say NO WAY! you gotta run the 25:1 like they spec'd back in the day.<br /><br />I surely dont wanna screw up my new/old motor, but I also don't wanna pollute any more than i have to...<br /><br />what about 30:1 or 40:1 I assume it will run with any ratio between the exremes.. TIA!!!

 

[jimmbo]

Re: 60' lark 40 and new 2-stroke oil

Some engine made prior to 1964 could run on the 50:1 ratio. These were the engines that had anti friction bearing throughout the power head. Engines that used friction bearings(bushings) must use more oil, 24:1 or 16:1 ratios were common. As for your engine, it has the nedle bearings in the con rods and wrist pins. So you should be able to run 50:1 but... <br />Well you just spent a pile of coin on this engine. Why risk your investment by being cheap with the oil? Use a GOOD TC-W3 oil, csn't go wrong using Evinrude/Johnson XD30, Better yet XD50(more detergents).

 

[surlyjoe]

Re: 60' lark 40 and new 2-stroke oil

Thanks Jimmbo! I am using penzoil tc-w3 right now at the recomended 25-1. is this crap oil? I only have a couple quarts, I will get the OPMD stuff next time.<br /><br />so would running say 38:1 just to be safe, seem silly?

 

[walleyehed]

Re: 60' lark 40 and new 2-stroke oil

The top and bottom bearing/bushings are the important ones...If it doesn't have ball/roller bearings top and bottom, the proper clearance is maintained by the 25;1 oil mixture.

 

[MCM]

Re: 60' lark 40 and new 2-stroke oil

Hi, If this was just rebuilt/overhauled you should do a search for "breaking in new motor", the search feature doesn't appear to be working at the moment though. Also here's a post from the FAQ section of the forum.<br /><br /> http://www.iboats.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=36;t=000007 <br /><br />As I recall running double oil mix during the breakin is part of the procedure, but as I mentioned you'll need to do a search for the proper procedure. Someone else here may be able to post the info though.<br /><br />Hope this helps some

 

[walleyehed]

Re: 60' lark 40 and new 2-stroke oil

I'd get a manual or take the word of Joe Reeves, Paul Moir, or JB, if one of those folks would post on that. But, if it has any bushings on the crank at all, I would stay with 24-25:1 until I knew other-wise for sure..<br />The Penz TC-W3 is just fine.

 

[JB]

Re: 60' lark 40 and new 2-stroke oil

OMC specified 24:1 for ALL OMC engines built before 1964, needles or not. There is no way I would run 50:1 in your engine.<br /><br />There is no crap oil that is rated TC-W3. Any TC-W3 oil will do a good job. "Cheap" has nothing to do with the quality of the oil. Price is driven by advertising and marketing. I use WallyWorld SuperTech TC-W3.<br /><br />Good luck.

 

[surlyjoe]

Re: 60' lark 40 and new 2-stroke oil

I tend to lean towards your theory JB. the oil is cheap enough, and it will mostly be in the delta, so I think I will probably try 30:1 for this winter and then check the bearings in the spring, and maybe try 35:1 if all looks good.

 

[walleyehed]

Re: 60' lark 40 and new 2-stroke oil

Let's remember on break-in (first 10 hours) we need a ratio of around 12-15:1=2 quarts per 6 gallons on the first 10hrs..avoid WOT and continuous settings for more than a few minutes at a time for a given RPM...No WOT for the first couple of hrs.

 

[R.Johnson]

Re: 60' lark 40 and new 2-stroke oil

That powerhead is full roller bearing, including the wrist pin's. There is really nothing to check on a roller, or needle bearing! they don't wear in, or out, like a shell bearing, or a bushing. There has been quite alot of discussion here on the pre-63, 0r 64 engines as to what is the proper mix. I have a pair of 18 HP engines, a l957, and 58. I have been running them on OMC 50:1, and carbon guard additive for I don't know how long, neither has ever shown any sign of trouble. When you say the engine has had a complete overhaul, that can mean many thing's to many people. I've had people say complete overhaul, when what they meant was complete tune-up. If that engine has been properly rebuilt, and were it mine, I would run 50:1, and prop it at the high end of the scale, after proper breakin. Keep in mind though, I'm speaking for myself here. Every time the topic of oil, or lubrication come's up, someone is going to argue that more is better, I don't mean to open that can of worm's.

 

[walleyehed]

Re: 60' lark 40 and new 2-stroke oil

I'll NEVER say more is better...in fact, I run my 200 Rude at close to 60:1<br />R.Johnson, I respect you highly, but I must ask, why do you believe roller/needle bearings don't wear???<br />OMC and most all manufacturers recommend replacing all rod bearings-both ends, any time the engine is down...<br />I've built alot of engines, RJ, and the last one caught me. I re-used 2 caged bearings because they looked perfect, on a V6...well, one of them bit me hard. It cost me about 450 bucks in parts and my time to rebuild again.<br />I'll never do it again without new bearings.

 

[R.Johnson]

Re: 60' lark 40 and new 2-stroke oil

Kenny: I certainly agree with you. I should have went on to explain this more fully. As I said with shell bearing's, and bushing's, they don't wear the same, but when a roller, or needle fail, the result is usually a catastrophe. One problem with roller's, or needle's, any fault can sometime's be very hard to see, if at all, even with magnification. If there is a fault, the piece's are going to fly, as you found out. On your engine, I wonder where that chain of event's started. What bearing on your engine let go, and what did it all damage. On a crank journal, I believe they only allow .0002, .0003 wear. If it has been properly lubed, you will seldom see this much, unless it show's damage to the naked eye. I have found the same with roller's, or needles, but it would be easy for a bad one to get by you.

 

[JB]

Re: 60' lark 40 and new 2-stroke oil

We have a lot of guys on here who know a lot about oil and bearings, etc.<br /><br />We also have a lot who at least think they know better than the people who designed and built the engines.<br /><br />I experimented a lot in my kart racing days and blew up a lot of engines finding out that I didn't know better. I also got away with some dumb stuff.<br /><br />I might be inclined to experiment still, but I will never recommend that a member use anything other than the manufacturer's specifications.

 

[R.Johnson]

Re: 60' lark 40 and new 2-stroke oil

JB: As I said in my first post, I was speaking for myself, and what I have found with my own engines.I well realize the maker's know there engines' better than I. But then! an engine called Ficht, come's to mind.

 

[surlyjoe]

Re: 60' lark 40 and new 2-stroke oil

rebuilt to me means all new rings bearings seals and gaskets ,hoses.diaphrams and lockwashers. pretty much eveything I could find that is a "wear" item with the exception of the lower end gears which mic'd out OK. I was amazed that almost every part for this motor is obtainable new or NOS!<br /><br />roller bearings do show the wear, dust differently and not as pronounced, but still very visible.<br /><br />I have wrenched on pretty much everything in my 42 years and used to burn up quite a few yamahoppy YZ-250 motors back in my racing days by mixing too thin for the extra performance, but a bike is one thing, its alot harder to push a boat back to the trailer

 

[MCM]

Re: 60' lark 40 and new 2-stroke oil

Scrumbler, your a man after my own heart, if you're going to do something do it thorough. There's nothing worse than cutting corners only to cut your own throat doing it. JB's deffinately one to pay heed to when it comes to advise on these motors. I think walleyehed is right in there as to the break in procedure as well.<br /><br />Best of luck and Happy Holidays and a great New Year to you and yours.

 

[surlyjoe]

Re: 60' lark 40 and new 2-stroke oil

thanks man! I started thei restoration in october and we are hoping for our re-christening on new years day. I'll be sure and take some pics =)

 

[MCM]

Re: 60' lark 40 and new 2-stroke oil

Cool, look forward to them

 

[BillP]

Re: 60' lark 40 and new 2-stroke oil

I'm with JB on this one. Use the ratio OMC specified and live with the extra oil. Don't try to outsmart the guys who made your motor.