Rotax Max Fuel system issue


(stamatis stampelos) #22

Well I’m just have bought a pre evo rotax engine and this conversation here is a great overall help.

Many thanks mates.
Cheers from Greece


(Christopher Ramnauth) #23

Daniel, the colder it is go bigger on the main jet to start with. Use the IW24 Denso spark plug.

40:1 is ok, i personally run more oil to help lengthen engine life, you give up a little power but its barely noticeable. The more important thing is running good oil. My recommendation is to run a 100% synthetic oil that is ESTER based…there are different types of synthetics, the one you’re wanting to get is the ester ones. In your end of the world you’d probably be looking at the motul kart grand prix or something equivalent.

Stamatis, welcome…feel free to ask any questions you may have on the rotax engines I’ll try my best to help.


(Daniel Wilkinson) #24

Sorry not replied sooner guys, I’ve recieved all the parts for the carb so il have a session tomorrow sorting it out. Got some fresh fuel too as im sure the can I’ve got is about 4 months old saving it for the old strimmer.
Not had chance to get any other oil yet so il only mix a small amount up and use that for the time being, just means more cleaning from what I gather of the powervalve? Would you recommend using 30/1 or more?
New spark plugs are genuine rotax ones however I do have a good iw24 still in the engine just needs a clean up points are good. However Il order a few spares.

Ordered and fitted a smaller fuel tank aswell (being a shorty the 5l tank was just to wide for me reaching pedals comfortably) so now the fuel supply side is completely new/rebuilt.


(Christopher Ramnauth) #25

You will be fine using the remainder of current oil you have. You can switch to the ester based synthetic after if you want, its not absolutely necessary but I use it because its the best trade off you can get in a oil in terms of burn cleanliness and lubrication/protection.

I personally run my rotax at 32:1 however you need to be cognicant of the fact that as you use more oil/fuel you actually lean your air/fuel so theoretically speaking you need to jet the carb a bit richer to keep the same air fuel ratios. The difference between 50:1 and 32:1 is only 1% however and personally I’ve not seen much need for different jetting, this could however be different for you with your atmospheric conditions. If you’re gonna run 32:1 maybe go a little richer on your float setting to 2.75mm vs 3.0mm. Then find optimum jetting for main jet, needle clip and air screw as outlined above.

You can clean up your current plug and set the gap to 0.7mm, get spares because once those plugs foul they need replacing most times