I have a 97 Sport 400L. It is in the shop getting a rebuild due to spinning a rod bearing and trashing the motor. I have a couple of questions. First of all what do I need to do to ensure a proper and safe break in period? Secondly I have removed the oil injection and am going to start mixing my own fuel,I presently use Spectro 2T 2 stroke oil which is safe to premix.Is this a quality oil and if so is the correct mixture 40:1 or should I mix it richer especially during the breakin period?

Thanks,
J Prentice

 

Sport400LSC,

I'm might be mistaken, but I'm not sure how your 400 spun a rod bearing.....the rod bearing on the 400 is a needle bearing, and spinning a bearing is usually referring to journal bearings, like on 4-stroke engines. Regardless, it is being rebuilt.

For break-in: First off, make sure you are jetted plenty rich.....up a couple sizes on the main jet, and set the needle one notch richer than normal. Setting it rich may not be required, but is a good idea to ensure the piston doesn't get too hot while the clearances are still real tight. Depending on what piston you go back with (stock or wiseco), the break-in may be different. With wiseco pistons, you need to take it really easy for the first 4 to 5 hours, but I understand that the stock cast piston requires less break-in time (about 1 hour). More so with the wiseco, you always need to allow the engine to warm up to operating temperature (even after break-in) before you're hard on it at all. This will prevent cold seizure.

You will probably find that oil preference is like religion to most people........lots of people prefer what they are running, and this is either from excellent service they have had in the past from "their" oil, or based on the recommendation of someone who has had great service from a certain oil. Most 2-stroke oils that are sold at atv dealerships specifically made for 2-stroke atv's will be good-quality oils. That being said, find one that you are comfortable with and stick with it. As far as break-in oil ratio, since you are using premix, just mix it at the ratio you plan on running after break-in. Rick Ritter of RCR recommends 32:1, using Klotz Supertechniplate, since his experience is that it will mix with any fuel, and stay in suspension well. He works on the polaris 400 2-stroke engines constantly, so his opinion is based on much experience. I personally use Amsoil, but that is my preference. Like I said, pick an oil that has a good history, is readily available to you, and stick with it. One other note, many people confuse a rich oil to gas mixture with a rich fuel mixture. When you mix a higher oil to gas ratio, say 20:1, you are actually creating a leaner fuel mixture, which requires richer jetting to allow the same amount of fuel versus running 40:1. Hope this helps.

Waylan

 

Waylan,
Thanks for your help.I understand what you are saying about the bearings being needle bearings.My saying " spun a bearing " is my mistake.I just know that the bearing is not where it is suppose to be and it caused alot of trouble, haha !!!!As for my jetting , I rejetted to a bigger jet that came with my RCR Stage 1 kit. Do you think this will be suffecient?

You said Rick mixes 32:1 using the Klotz , If I continue to use the Spectro will the ratio still be the same? I have used the spectro for about a year with no problems and it says it is safe to premix so unless I decide to go with a synthetic oil I would like to stay with the Spectro.Also do you know what the pros and cons of using synthetic 2 stroke oils? I have a 2500 truck that I use to tow with and run synthetic in it but am not sure about the 2 stroke. Thanks for taking the time to help.

J. Prentice

 

You might want to call RCR for his advice on jetting for break-in. The larger jet sent to you with the Stage 1 kit was to compensate for the pipe and better airflow. An even larger jet would probably be best to ensure things stay cool during break-in. I'm no engine builder, and I'm only going on wise recommendations for my rebuild. If there's any time that jetting needs to be rich, it is during break-in.

The 32:1 ratio is just what Rick has seen the least trouble with. I have run it in my Xplorer before with good results. It didn't want to foul plugs at all, and I'm sure it was more than adequate lubrication. For Spectro or other 2-stroke oils, you can probably look on the bottle for the oil manufacturer's recommendation. If it recommends 40:1, and it has worked very well for you in the past and you feel comfortable with it, I don't see a problem sticking with it. Keep in mind that if you do change to 32:1, you are essentially leaning the fuel ratio, which may also require fatter jetting. With 2-stroke oil, what you want to achieve is adequate engine lubrication, without plug fouling. You also want to run an oil that burns fairly clean, leaving few deposits. If this oil satisfies these requirements, then you should be happy with it. If it has any castor oil in it, I would be weary of using it in freezing temperatures, as the castor will fall out of suspension. Most oils with castor in them warn of this.

Petroleum vs. synthetic........I'm sure you're at least a little educated on the pros of using synthetic oils.....higher tolerance to heat, better lubrication, yada yada yada. The main downfall of some synthetics is that they don't protect the engine components from corrosion during storage as well as the petroleum products. This is not true with all synthetic oils, as Amsoil boasts excellent protection for off-season storage. Again, oil preference varies greatly from person to person, as well as oil-to-gas ratio. Go to macdizzy.com, and look for posts on oils. You'll see so many different brands that different people are loyal to. You can even do an internet search to find out how these oils are tested, and what ratings an oil should have marked on the bottle to make it suitable for your engine's requirements. Hope this helps.

Waylan

 

I am tired so I will keep this brief. I have used Amsoil Premix 100:1 for almost 15 years and never had any engine trouble from any 2 cycle. That includes lawn mowers, weed eaters, chain saws, boats (115 hp Yamaha & 10 hp Johnson), motorcycles (Honda CR500, Husky XC530, ...) and ATVs. They all get their gas from the same gas can.

Call Darrell or Mike at HPD (who is "THE NAME" in Polaris high performance) and ask what they have raced exclusively forever. He'll say Amsoil 100:1 premixed to 80:1. I agree because I have been there and done that too.

Chunky