Rotax FR125

[Rick]

How often do you guys do rebuilds on the Rotax FR125s?

[LikeStig]

I put a question like this on ekarting and got alot of good answers.

http://www.ekartingnews.com/viewtopic.php?t=92198&postdays=0&postorder=asc&start=0

[Jeff Stamper]

45 to 50 hours. They run forever !

[Matt]

A top end rebuild about every 20 hrs and bottom end about 35-50 depending on how hard you run it. Plus the usual piston/ring changes as needed.

[tonyb8878]

I need help!! I cannot get the right set up for my rotax. since i got it, it hasnt run good. any tips on getting them to run good? ive got a 162 main jet in it with a k98 needle and 5.2 kg floats. any tips?

[Rick]

1. Get a weather station of some type.
2. Get software to calculate jet, needle position, floats, etc based on weather.
3. Keep carb and components surgically clean.
4. Check plug through out the day.
5. And get a racing dad to do #1-#4 for you.

:couch:

But seriously, Jeff Stamper had his running really good all year last year. The CIR juniors also do a pretty good job of tuning the Rotax. I never really got the max out of my DD2 or my FR125. They always felt like they bogged out of the corners. But I will have to learn to jet a carb for the stock honda now. I'll probably buy the software to do it.

[tonyb8878]

Thanks for the help. Unfortunatly i am on my own in racing. i dont have anyone to really help me so anything helps.

[Rick]

Read this (http://www.karting1.co.uk/new-ThePreparation&JettingoftheRotaxCarb.pdf)

[Rick]

Also, a good way to tell if you are too lean or rich is to pull the choke at WOT down the back straight under load and see how the engine reacts.

[Azzurro Kart]

There are so many little things that all need to be right most are very easy fixes if you know were to start looking. If you have any questions feel free to give me a call can probably narrow it down. They can be a pain but once you have them right there trouble free.
630-965-4354

[tonyb8878]

At last weekends norways race i made many changes to my carb on my rotax. i finally got into the 48 second range. i still cant figure out anything else to get that thing to run faster? maybe clean out the fuel pump and clean the air filter in the airbox? or maybe i just need to throw a fresh set of rubber on and maybe that will drop my lap times by a second or so? im not sure. man if i would have gotten a leopard maybe i would be up in the pack.:hmm:

[Racer Of Tomorrow #01]

yes! leopard! with the bridgestones they take a while to kick in when u first start out u dropped 4 tenths or so with new rubber then i gradually got faster

[tonyb8878]

All i can say in my oppinion is that the Rotax FR125 is a great motor. It has its advantages and disadvantages. The reason i got it was because its such a low maintinence motor and if you tune it right it can somewhat keep up. The down side is every week i keep getting blown away by leopards and PRD's. Maybe i just have it tuned wrong? I dont know yet. The rotax i got was Brian Jacobsen's rotax that he ran at blackhawk and killed the field running 2 seconds faster. But than again he has 40+ national championships.:grinyes: I dont know and i may not know for awhile until i figure out the rotax motor. that is if i can deal with running around in the back for awhile until i figure it out. :hmm:

[JET Karting - Andy Finke]

You can't expect to run out and win in the first season with a TAG. They are very unforgiving of driver mistakes.

And the Rotax was a good choice, I think.


Andy

[Racer Of Tomorrow #01]

i say u should try a couple more practice days figure it out try new things bc u cant try to figure it out on the stand and u cant figure it out on a practice session on raceday man u gotta get more time with that motor:thumbsup:

[tonyb8878]

Yea i agree. I think the rotax was a good way to go seeing that it dosent require much maintinence. Knowing me if i get a leopard ill lean it out to much and blow it up which is one of the reasons i got a rotax for my first season in TaG. Maybe ill get a second motor for next season?

[D. Harrington]

You can beat the Leopards (and everyone else) with a Rotax. Keep working on your driving and the chassis. You will find way more time there than you will find in the engine (no matter what brand).

[tonyb8878]

is there anything i can do to get my rotax better on the starts of the race? ive tried everything! i tried to raise the needle so that i can get better acceleration and ive tried loading up the motor and dragging the brake but nothing has seemed to work. I also feather the throttle because i heard if you just mash it that it will just bogg. I'm confused on what to do:hmm: any tips?

[tonyb8878]

:clap:Hey i got 10th out of 20 karts in the 66 race at norway so for my first reigonal race i think i did pretty good with the rotax.

[LikeStig]

Squeeze the fuel line on the starts.

[tonyb8878]

Yea i was reading that on ekartingnews. Ill try that. Like what do you do? just squeeze it and after the start let go?

[Rick]

Squeeze the fuel line on the starts.

What does that do?

[LikeStig]

When you squeeze it, the engine leans because the carb isn't getting as much fuel.

[Rick]

I always thought that the fuel in the bowl was sucked out until it was gone. And the rate of flow was controlled by the main jet, needle and slide.

I guess it could work if you squeeze it until the bowl runs dry. I will have to try that and see if it works.

[JET Karting - Andy Finke]

Lowering the float level leans the mixture some as well, as it's harder to pull the fuel up and into the venturi. It'd be a smaller effect than with a pumper carb, but should work some in theory.

Seems like more things would go wrong than right for a new racer though...


Andy

[Jeff Stamper]

Squeezing the fuel line on a Rotax will not help. By the time it leans out it will die due to no fuel in the bowl. And you would have to squeeze the line a lap before the start ! The bowl holds a lot of fuel. Thats a pump carb trick ! If you want to lean it out on the start, you dont raise the needle, you drop it ! Which means it goes farther in the seat. The clip should be on the top slot for the leanest setting.

[tonyb8878]

i found that out the hard way. i tried it at one of the norway races and it died on me a few seconds after the start. whoops:redface: