582 tuning problem

[Methusala]

Yesterday I was test flying my Thruster after engine rebuild. Engine runs very sweetly with egt's in general within 10degs. However, climbing out at 6300rpm, all was well with both at around 610. Upon reducing power to 5800 one cylinder ran to 642degs while the other was around 620. Both carburetors are jetted identically so wondering why the difference? Any suggestions?

 

 

[Yuri Gagarin]

Yesterday I was test flying my Thruster after engine rebuild. Engine runs very sweetly with egt's in general within 10degs. However, climbing out at 6300rpm, all was well with both at around 610. Upon reducing power to 5800 one cylinder ran to 642degs while the other was around 620. Both carburetors are jetted identically so wondering why the difference? Any suggestions?

Out of sync carbs will do that. At full throttle the slides are well clear of the inlet, when set at cruise one might be set higher than the other.

 

 

[facthunter]

Check cable adjustments at various positions of throttle opening and idle screw at idle on both with air cleaner off looking directly at slides. You should have equal free play in each outer cable with throttle closed and they should open equally. The idle stop should be equal too as to how much it opens the slide in the throttle closed position . Having said that two strokes do different things with slight port variations of size and shape and the flame pattern could vary depending on where you locate the probe(s) Nev

 

 

[Yuri Gagarin]

Also, I found that when I had two of the cone style air filters on my inverted 582 the EGT's would "change", then when I fitted the single oval style air filter to stop the carbs from flooding at idle (the carbs shaking) I noticed that the EGT's settled down as well.

 

 

[robinsm]

take off the air filter, get someone to slowly operate the throttle (with the engine NOT running) and see if they are opening at the same gap.

 

 

[Methusala]

Thanks for your suggestions. Will check all these adjustments carefully. Don

 

 

[facthunter]

Check slide cutouts are equal in both carbs as well. Nev

 

 

[Downunder]

Any pushing/pulling on the cables and outer sheath will affect length and therefore position.

 

Maybe something was leaning/pushing on them? a leg, arm or foot?

 

 

[shafs64]

interesting topic

 

 

[Methusala]

Could be the needle jets need to go up 1 size. They control mixture up to 3/4 throttle. Altitude is 2500 and I think atmospheric pressure was quite low on the day (we had a small gale the next day).

 

 

[spacesailor]

Also a blanked port on the left of each carburetor, check the rubber is good.

 

spacesailor

 

 

[M61A1]

A mercury manometer is too insensitive to measure the small amount of vacuum on the 582. I use a simple home made manometer using two lengths of clear tube off a nebuliser,(about 2000mm long each) zip tied to a piece of electrical conduit about 1500mm long. I stick that into a drink bottle with a bit of water green coolant and so I can see it and attach a tube to each carb at the primer port. It sucks the water coolant mix up about 500-600mm, which makes it really easy to read and set. Quite sensitive too.

 

Adjust the idle stops first to get even levels and correct idle speed, then open the throttle slightly and then adjust the cable adjusters to get an even level.

 

Making sure, as FH said, check that your cables are properly seated in the adjusters and haven't been pulled out.

 

I can tell when my carbs are out of balance when my egts are not even.