auto mixing

[TravisD]

hey i have a suzuki ds80 two stroke and i took it off the old bike and am making a mini go kart/ bar stool racer, ok easy enough
but i wanted to make sure,

this engine i have has its own oil fuel mixing setup, now should the oil syestem throtle be tight or wat? at the moment i have it as tight before it pulls the arm on the oil mixer thingie, is that right??

just making sure, its still a good motor, just a bit bashed up,

havnt started it in like two years and started on the 2nd kick!!
easier to start then when it was on the bike lol!!

 

[mike75925]

not familiar with the ds, but in general, you don't want any slack in your oil injection pump's cable. unless you are running a lil rich on oil anyway. you can save yourself some space and a lil weight by blocking off your pump and going pre-mix(no longer need the oil tank). blocking off the pump is fairly simple, remove the pump and it is usually a plate that bolts/screws (you could make your own plate) right in place of the pump. if going this route remember to take apart the 'splitters' case and remove the oil pump cable. depending on how the oil is introduced you may have to plug a spigot on the carb. rejetting is usually not necessary, that is in my experience.

 

[TravisD]

yea i thought of that and easy to do, but i still want the oil mixer so its easy for stupid kids and then i wont have to mix the fuel... it will do it it's self!! the oil tank doesnt bother me wooo,


anyway so while im hear wat fuel oil ratio is good for a dirt bike engine like this?

 

[modelengineer]

I'd be running pre-mix.

If that oil pump fails, the engine is toast.

Probably 25:1 or 32:1, but a guy I know runs special $100/Litre race 2-stroke oil in his KTM-300 exc. I think he runs 50:1.

 

[TravisD]

so stuff the pump? hmm but theres nothing wrong with it..... but if u think its a good idea,

 

[modelengineer]

Well, I had a DS-80 and the oil pump worked fine, but I had a Honda 50cc with a broken oil pump, so it can happen. The problem is that if the oil pump fails you won't notice at all (unless you can feel the heat from the engine), the engine doesn't run lean or anything, it just gets hotter and hotter and then seizes. No real warning.

Since you're transplanting the motor I would do away with the oil tank. Using the oil pump is a small risk, but with big consequences.

 

[jr dragster T]

Be careful. Sometimes the oil pumps will feed vital parts like the crank bearings where pre-mix wont always get enough lubrication.

 

[modelengineer]

Ah, I hadn't thought about that...

 

[jr dragster T]

Yeah, Gotta be carefull about that. I'm pretty sure 440 race sleds run oil into the crank bearings.

 

[dpaxson]

I've heard of people removing the oil injection system on dirt bikes all the time. as long as the engine is crancase induction which basically every two stroke is, the bearings will get lubrication. just run a fairly high oil ration like 32:1 and you should be fine

 

[Kenny_McCormic]

Not necessarily, on my 250 the PTO side crank bearing is fed directly by the pump, the other side relies on crankcase pressure to force some mix(it also injects at the intake) through the bearing. The case would need to be modified to run without the oil pump and I suspect its set up that way because just sucking oil though isn't enough.

 

[Kaptain Krunch]

Just look at the injector, if its only got 1 hose going to the carb/intake than its fine, if there is more than 1 hose leave it. I got a sled engine for free once, was seized up because one of the oil injector hoses was melted.

 

[mike75925]

by leaving the oil tank on, on account of kids, could go wrong. regular motor oil could be used or not even filled.

 

[TravisD]

just so u know there is only one hose, i check for all them before to see if i could remove it and yes i can, one single hose goes to the carb, but if i remove it do i have to block that hole where the oil used to be injected into the carb? and no kids will be riding this thing lol, only me MAHAHAHAHA

so u say i should use 32:1 ratio?

i dont know the ratio for this bike

 

[Kenny_McCormic]

Kids also like to run straight gas through 2 stroke engines, which is why the injector is there. Even my dumbass sister can handle keeping the injector tank full of the correct oil on her PW50.

 

[mike75925]

but?

 

[Kaptain Krunch]

by leaving the oil tank on, on account of kids, could go wrong. regular motor oil could be used or not even filled.

Lets just say anyone can make mistakes, and there is no way to completely fool proof anything. The point of removing the oil injector tank is to make sure the oil injector doesnt break and kill the engine, which i have seen happen before, i've seen them mess up in many different ways. Its really a matter of, do you trust yourself, or the oil injector pump more?

 

[mike75925]

very true, when i was a kid they kept two stroke gas next to the two stroke vehicles.

 

[jr dragster T]

Just because theres one hose going to the carb doesnt mean the crank bearings dont require oil. There may be small passages in the block to bring oil to the crank bearings just like my 125.

 

[Kaptain Krunch]

Just because theres one hose going to the carb doesnt mean the crank bearings dont require oil. There may be small passages in the block to bring oil to the crank bearings just like my 125.

If the hose is going directly to the carb, then i dont see why having it be premix would change anything? Isnt your 125 a 4 stroke?