Yes Clayton, they look new, but the engine tries to start, it starts a little, but doesn’t really want to start. And when it happens while driving, it just won’t start anymore. The second I put a new one in, it starts again, everything is normal, and my rotax works great. These are the NGK racing plugs, recommended by rotax, the one that replaces the Denso iw31.
They all come with the correct gap and I check, 0.6 mm, so according to the recommendations, I leave them like that. You tell me if I’m better off putting them at 1.0 mm. Soon I’ll test them all, I bought a good quality spark plug tester, blue flame ok! red flame no, otherwise no flame at all.
I have a Preevo engine and not an evo. As long as I haven’t put a new spark plug back in, there’s nothing to do, I can’t start again, can’t start anymore, only intermittently. They are still spark plugs at around $9 US, cheaper than Denso, but they are starting to cost a lot for spark plugs and I would especially like to find the problem with that. Thanks
Maybe they loook new , but they also loook super rich from fuel also . Did you get any spark if you try them outside of the cylinder with the spark plug on them ?
ok! stamatis. I’ll check them all soon with a good tester I just got. The last one I blew was when I warmed up my rotax with the back lifted and spun the engine a bit to unclog it. Wouldn’t it be better to go right away and have it warmed up and unclog on the track. My mixture was at 2% before this outing, but this time it was at 2.5% last time and it was smoking a lot.
You told me to put it at 2.5%, that’s what I did, but I see that it’s stuffing more.
At least initially
Its not the oil, period.
Looks like its overfueling like hell, or you notletting it rev up suficiently
Do you have any video at all?
Re the plugs it could be:
Overfueling (ie more than it would by just being jetted too rich). Something like the inlet needle sticking or floats although you’ve already looked at floats.
Not being driven hard enough to clear out and get heat into the plug. If it’s not being driven hard you will get a lot of smoke and oil coming out, even with the smallest amount of oil in your fuel.
Idling for too long before or after a session.
Also: You can clean a fouled plug by heating it with a torch. Do not, ever use a wire brush though. Spark plugs (specifically insulator core) are self-cleaning once they get up to temp (I think it’s around 700c.)
Spraying with ether works too if it’s just oiled up.
Perfect! Thanks Bjørn
I’ll see what I can do
Thanks James, I’ll be taking it out in 2 days, I got my new plugs. I’ll try not to idle it for nothing and go straight to the track to warm it up and then open the machine. I’ll see if I blow another plug then.
You can warm it up in the stand, but you should be giving it some revs and using the brakes to load the engine and burn fuel.
Just don’t sit in the pits before and after running with it just idling.
Thanks for your advice Clayton
I should try this tomorrow
Hello, guys. I wanted to give a little feedback for all the help I got from you and a big thank you. My rotax max is doing very well now and I am very happy with it. I have been riding for 4 days on the track, without any problems, it works well, I don’t idle it for nothing anymore, and I still run with the same spark plug, hooray! A charm. I had to change my clutch, because my repair gave way, it broke again, and I am now with the new EVO clutch, which I bought. According to the track I ride, my 13 teeth was too big, so I went with a 12 and they tell me that I should even go to 11, and my rear sprocket has 82 teeth. I also met the mechanic of the track who helps me a lot and with whom I take over a lot of things. I arrive at the end of the straight line at about 11,800 rpm, and I find that the engine turns really fast, so I’m afraid of wearing it out for nothing and especially if I go with an 11 tooth. Is it true that it can turn up to 13 or 14,000 rpm without problem and without damage. That’s my only question. Thanks!
Good news! Yes 13 to 14000 rpm is just fine for Rotax. It stops making maximum power after 12500 so going to 13 or 14 isn’t going to cause harm and is preferred.
Yes, ok! thanks Clayton