Pre Mix vs Injecting in '95 Sportster

[kringdoo]

This season my '95 Sportster has started smoking at startup. The longer the duration between use the more smoke. After reading a few threads, I've come to the conclusion that it might be a worn rotary seal or similar. I'm considering draining the oil injection system and just doing a premix until the end of this season when I can bring it back and work on it prior to storage. MY QUESTION IS: Will I wreck something else by doing premix and will this fix the initial smoking problem on start up?

Tremendous Thanks in Advance!!

kringdoo
:hurray:

 

[seadoomanls]

It will smoke still. If you premix at a forty to one ratio thY is at WOT. So naturally at idle it will be running a tad eich thus causing the excessive but bearable smoke

 

[CypherAZ]

It will smoke still. If you premix at a forty to one ratio thY is at WOT. So naturally at idle it will be running a tad eich thus causing the excessive but bearable smoke

not to mention your plugs will foul easier more often.

 

[roneagan@cfl.rr.com]

If you go to premix you will still need to keep some oil in the tank.. The oil from the tank lubes the rotary valve. I wouldn't worry about it to much.. My 98 has one engine that will do it after sitting for a long time, but runs great..
It is a lot of work to fix the seals, romove engine split case etc.. Just keep running it until you really need to pull the engine.. Seem the more I use mine the better it gets..

 

[RX951]

Mixing at 40:1 with a good oil like Amsoil Interceptor will suffice. You should not experience accelerated plug fouling either.
I also suggest if you take the oil injection pump out of service, you should loop your oil lines in order to keep the rotary gear in a bath.

 

[seadoosnipe]

Rotary gear?...

Mixing at 40:1 with a good oil like Amsoil Interceptor will suffice. You should not experience accelerated plug fouling either.
I also suggest if you take the oil injection pump out of service, you should loop your oil lines in order to keep the rotary gear in a bath.

It seems for the most part, your questions are finding answers. But, I'd like to chime in on one point that RX951 made.

People who bounce around in forums, looking for answers I'm sure recognize RX951. He's no stranger to working on these 2 strokers. But, I must disagree just a bit on looping the oil lines to the rotary.

I've heard and seen where this is done but I do not recommend it for a couple reasons. First, if you look at the design, it's set up that the bottom oil line from the tank feeds the bottom side of the rotary chamber. The line you see at the top of the oil tank is a gravity vent. That oil level will change with the changing level in the tank and the expansion from the oil as it's heated.

This was designed because of oils natural change in volume as the viscosity is thined. Hypothetically, if that chamber holds 5 ounces of oil at room temperature, then when it's heated, viscosity of the oil thins as it expands. Now, that chamber volume may be 5.5 ounces. Where is that extra volume going to go?

Second, if you loop that line over, so that the rotary chamber can't breath, when the oil is heated it will build pressure. The weakest link in that chamber is the rotary seals. If you build pressure to the point you blow the seals, you'll be replacing the crankshaft. I haven't found replacement seals for sale anywhere plus, you have to split the crank to put them on.

I really believe that because that sounds like a simple solution to lubricating the rotary chamber, if it was feasible, then the engineers from Rotax would have designed it that way. There may be Seadoo owners who have done it this way for years and had no problems. But, it's in my opinion that it is not the way Rotax intended for it to be lubricated. It's not something I'd recommend doing..... :cheers:

 

[seadoosnipe]

No problems...

I run my ski like that also since i run premix. I have done this for over 3 years with zero problems. You can run the oiil lines hooked to the oil tank if you want but i have seen were the gromet to the bottom of the oil tank starts to leak oil.

You can run the oil lines looped over for 5 years and you may never have a problem. Your geographical location may also play a part in the ability to use this with no ill affects.

Logically speaking, if this was technically a good idea, don't you think the engineers from Rotax would have already done that.

I could demonstrate this with one of my beakers, since they have accurate measurements by the mils. If you have 25 mils of oil which is cold, it is thick, correct? When you warm that oil, it not only thins, it expands. Most evey motor that I've worked with, has some type of ventilation system for oil to expand and contract. One engine system I work with actually uses an electrostatic precipitator in the vent line. Because as this oil is heated, the temperature is high enough that it creates a vapor. That vapor passes across the precipitator to render the vapor harmless, since it's in an environment where people are working.

The point is, if you understand the properties of oils expansion and contraction, heat and viscosity, then you'll see why there is a need for the rotary chamber to be vented. Will it blow out every rotary seal to every engine that uses the loop over as described? No, it won't. But, it's not designed to be in a closed loop system.

Anyone with a rotary chamber and oil system can loop their oil lines if they like, I just recommend you don't do it. I also don't recommend getting rid of your oil pump and go premix. Why? I know how much a gallon of oil cost and how much more oil you'll be wasting by premixing, rather than using in oil injection. It's really not that hard to test and ensure your oil injection works properly, rather than just dumping it.:cheers:

 

[RX951]

If you loop the oil line, its typical and common practice that a 3" Gap if left for expansion. This will be fine. Racers have been doing this for years.

 

[seadoosnipe]

Experience...?

If you loop the oil line, its typical and common practice that a 3" Gap if left for expansion. This will be fine. Racers have been doing this for years.

Of course, race engines are not pleasure craft, used on a daily basis, they are reserved for specific events for a predetermined amount of run time.

But, it seems you have first hand experience with this practice. If you think the pressure created from expansion will not put excessive pressure on the rotary chamber systems seals, then I guess it could be an acceptable practice (I'm sure there are a lot of people who have done it). I don't do it or recommend it but with your vast knowledge and experience, I will take your word that you know what your talking about. I believe that will allow members to decide what is right for them. Keep the oil tank or ditch it and loop the oil lines together..........:cheers: