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I have a 2015 Toro V-twin (with 225 hrs) and it seems the compression release may not be working. I have checked the battery and all connections. Spins fine with no spark plugs. I have adjusted the valves to the tight end of specs .004 inch intake, .006 inch exhaust. It still mostly stops when I try to crank it. Does anyone know how the CR works on Toro branded engine or if I can tell if the CR is working without taking engine apart? Should there be a visible "bump" of one of the valves from a mechanism on the cam?

Really need the engine model and spec numbers to look up the engine but normally one rocker(valve) will move slightly just before TDC compression. It is to note not all engines have ACRs just which engine was used.

Thank you for your reply. From what I have read it is a Chinese Loncin engine branded as Toro. From their features tab: "Automatically decompression structure can ensure an Easy starting. less battery current are consumed." I can't find anything about the ACR so thought it might work differently from other engines.

I looked closely and could not see any rocker movement before TDC on either cylinder. Would ACR typically be on intake or exhaust? Would it typically be on both cylinders?

Looking at Exmark service manual for this engine it doesn't say which it is. But normally it would which valve that is closest to sump (oil) pan on a vertical engine. And it really depends on the camshaft design if it is on both. The only image I found of the 140020072 camshaft doesn't show ACR side.

But if you don't see any movement on any of the valves I would say the ACR on the camshaft has failed. But finding a camshaft you need the Toro model number of the equipment so you can look-up the parts list for their part number. I not able to find listed the Loncin PN at any of my vendors in the USA.

The Toro model # is 74760. 133-1568 is the CAMSHAFT, it Replaces 127-9269. From pictures, can you tell anything about the cam and how the ACR functions from that? The pictures I saw, of new parts, did not show ACR mechanism but I did see a notch on the inner face of the cam that would likely be for the ACR. That makes me think ACR may not be included. Could it be a separately available part?

dtestin said:

I have a 2015 Toro V-twin (with 225 hrs) and it seems the compression release may not be working. I have checked the battery and all connections. Spins fine with no spark plugs. I have adjusted the valves to the tight end of specs .004 inch intake, .006 inch exhaust. It still mostly stops when I try to crank it. Does anyone know how the CR works on Toro branded engine or if I can tell if the CR is working without taking engine apart? Should there be a visible "bump" of one of the valves from a mechanism on the cam?

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I'm in the exact same situation. The starter can't overcome the compression. I have also researched the replacement cam and I don't see a decomp mechanism on it. I have been down this road many times with other engines and can usually fix it with valve adjustments, or a new cam, but I don't see how a replacement will help on this engine. Any progress on yours?

glennmac said:

I'm in the exact same situation. The starter can't overcome the compression. I have also researched the replacement cam and I don't see a decomp mechanism on it. I have been down this road many times with other engines and can usually fix it with valve adjustments, or a new cam, but I don't see how a replacement will help on this engine. Any progress on yours?

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The original starter was bad on mine. It would barely turn over but always started. Starter looked like someone had been in it previously. I got a new starter but I also messed with carb and valves along the way. I had it running good but it didn't want to restart when hot. Played with the carb some, now it cranks fine but doesn't want to start. Just ordered the Pilot air jet kit as the o-rings were bad on mine. Not sure if that will help any but worth a try. The float in my carb was sticking to the carb body and not letting any fuel in.

Maybe this manual on the Loncin Twin will help you out. https://www.toro.com/getpub/117255

Apparently Loncin is no longer providing Toro with the ACR style camshafts. Based on engine serial number.

Rivets said:

Maybe this manual on the Loncin Twin will help you out. https://www.toro.com/getpub/117255

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Thanks so much for that!