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General control line discussion => Open Forum => Topic started by: kevin king on June 29, 2025, 09:46:04 PM

Title: ST 35 Combat's sleeve orientation
Post by: kevin king on June 29, 2025, 09:46:04 PM

Anyone know the correct way to reinstall the sleeve on a ST 35 Combat engine? One side of the sleeve has 2 windows, the opposite side has one big window. When viewed from the engine case exhaust port. Thank you.

Kevin

Title: Re: ST 35 Combat's sleeve orientation
Post by: Massimo Rimoldi on June 30, 2025, 12:02:13 AM

Hello.
In all 2S engines the highest window is the exhaust one, the lowest one (or ones) is the transfer window.
In your case the single window is the exhaust, the two coupled ones are the transfer ports.

Massimo

Title: Re: ST 35 Combat's sleeve orientation
Post by: kevin king on June 30, 2025, 05:26:38 AM

Thanks Massimo! H^^

Title: Re: ST 35 Combat's sleeve orientation
Post by: Paul Smith on June 30, 2025, 06:22:48 AM

Very true. 
In all 2-stroke engines it is necessary to allow the hot compressed exhaust to leave the combustion chamber before the cool low pressure incoming charge can enter. 

Title: Re: ST 35 Combat's sleeve orientation
Post by: Motorman on June 30, 2025, 07:54:47 AM

 I seem to recall ST made some sleeves where the exhaust and transfer opened at the same time. The one big window is the exhaust and the two angled windows are the transfer ports. Make sure you get the conrod with the chamfered side forward. The cut out in the back plate goes on the transfer side.

MM :)

Title: Re: ST 35 Combat's sleeve orientation
Post by: Massimo Rimoldi on June 30, 2025, 09:13:53 AM

Quote from: Motorman on Yesterday at 07:54:47 AM

I seem to recall ST made some sleeves where the exhaust and transfer opened at the same time. The one big window is the exhaust and the two angled windows are the transfer ports. Make sure you get the conrod with the chamfered side forward. The cut out in the back plate goes on the transfer side.

MM :)

What you are talking about is the "Supertigre Transfer Ports" (Travasi SuperTigre) configuration which is the case with Kevin's sleeve.
Even in this case there is a small difference between the exhaust opening and the transfer ports, a few degrees but they are there. The engine MUST start unloading before putting fresh charge into the cylinder.

Massimo

Title: Re: ST 35 Combat's sleeve orientation
Post by: Howard Rush on June 30, 2025, 11:04:16 AM

The side with the angled cut is the bypass side, opposite the exhaust.