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Idle jet

13 posts in this topic

Posted

55's currently installed. Have you guys had any luck trying to sufficiently lean with the 55 or do you just go with a 45 from the get-go?

Rotax 618 in Louisiana heat

And what rpm do you aim for? 2000? 2200?

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Posted

I'm running a 45 on my 582, but then I have a clutch and almost no load on the engine at idle RPM's.

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Posted

I shoot for just over 2000 on idle with my 2.62 and E box. You can also lean the idle some with the airscrews. You can back them out 1/2 turn at a time. If you run out of travel you need a smaller jet. Also if you lean the airscrew out make sure and jam in a quick burst of throttle and make sure the engine doesn't bog as it accelerates. If it does your too lean on the bottom end. I won't say it's impossible but it's pretty tough to hurt the engine running lean at idle or just above. It'll quit from fuel starvation first. Don't test that theory in the High or Mid range though!! You can sure tell a rich running two stroke at idle if you hear one after you get yours tuned though. I saw a flightstar taxi in with a 503 on it at our airport one day and I thought his engine was going to jump off the plane it was shaking and smoking so bad. That's a good way to foul plugs and build up carbon.

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Posted

Ok. I'll get some more tuning done. Chart calls for one full turn. I'm at two turns and running smooth around 2700. Noticeably smoothed out. 3000 was about where she was previously happy. I'd certainly like to get her smooth at 2000. I was wondering how many turns out before you would consider the 45's? For some reason I have four 45's in my stock so experimenting is cheap.

Perhaps a clutch is in my future, however I know she can be better than she is now. That being said, I'm not running at idle for long anyway. After start, I will warmup at 3000

My midrange and top end seem very smooth. But I'll be going through it to confirm settings.

I did finally install a generic electric tach and reset the prop pitch accordingly. Wow. I have a new airplane!

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Posted

Shoot if you have the 45s try em. Those little buggers are expensive to buy! Most people run a tiny tach. They are $40 and double as an hour meter. Very simple to hook up.

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Posted

Tiny tach on the want list.

Ill try the 45's since I have them.

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Posted

Can I expect a smooth motor at 2000rpm with a 3:1 C box with proper jetting and leaning without a clutch?

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Posted

A lot depends on the prop you're running and the design and condition of your motor mounts.  2000 should be attainable if your prop inertia isn't too high and the mounts are doing the job.

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Posted

Moderate success! I leaned out my 55's to the point where my airscrews were about to fall out. I installed the 45's and with two turns out, she now runs smooth around 2200-2300. She was so rich that the idle was 1800 and struggling. Now she idles at 2000 with some roughness, but i bump her up to 2300 and she is smooth. I'm happy with that. Much better than 3k! Happy, happy happy....

My midrange and wot seem to be fairly well adjusted. I do have a 50deg egt split at all throttle positions other than wot. My guess would be my sliders are slightly out of sync? Tomrs project

Cooling.... New thread coming up

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Posted

with a gsc prop i could not idle below 3,000?  as soon as i installed a clutch and 45 jets i was idling at 1,400-1,500 and absolutely no effort to start the engine.  I haven't seen too many 582's run smooth without the clutch before 2,500 but that being said I do have relatively limited 2 stroke experience.

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Posted

I have the grey-head 582 with C-box 3:1.  The engine is smooth from about 3k up to wot, but the idle is rough.  On final, what would be 2300 rpm static is now 3000 rpm, and rough.  I have read lots of opinions on how to adjust the idle air screw, from 1 turn open, per the factory, to going leaner.  When I tried leaning it out, the roughness never left, but eventually the engine wouldn't run.   Where else should I be looking?  My engine only has 141 hrs on it.  What's the deal with the clutch?  Is it a centrifugal?  Does the prop not turn at idle?  How does that work out when taxiing?  I always thought the prop also serves as the flywheel.

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Posted

Yup,  prop sits still at idle unless you have a breeze and then it windmills.  The two strokes apparently don’t need much of a flywheel because they idle really nice with no load. The clutch starts to engage around 2200 RPM. You’re supposed to avoid spending much time between that and 3000 RPM. I taxi at 3000. 

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Posted

I have the grey-head 582 with C-box 3:1.  The engine is smooth from about 3k up to wot, but the idle is rough.  On final, what would be 2300 rpm static is now 3000 rpm, and rough.  I have read lots of opinions on how to adjust the idle air screw, from 1 turn open, per the factory, to going leaner.  When I tried leaning it out, the roughness never left, but eventually the engine wouldn't run.   Where else should I be looking?  My engine only has 141 hrs on it.  What's the deal with the clutch?  Is it a centrifugal?  Does the prop not turn at idle?  How does that work out when taxiing?  I always thought the prop also serves as the flywheel.

I had the same problem on a 503 that sat for several years.. I fought it for months and finally removed it based on the advice of a few overhaulers saying probably the crankshaft seals were shot from sitting.. dont mean that is your problem, could be however... 

Try to get a  couple of good known carbs and install them? or just take the ones off you have now, take them apart and see what jets are in them. That kid who had it might have messed with it, he was a dip stick in my book from talking to him, so full of BS he was... so be careful.

The clutch will only put a bandaid on your real problem. That engine should idle fairly smooth at 2200- 2300 rpm after its warm and assuming the correct jets and installed the air bleed set at 1/2 turn out..

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