01 Robbins Engine Loses Power

[mgray70]

01 Robins loses power after getting warm. Motor seems to run ok, just weak. Both clutches are opening and closing like they should. Before I got it, someone had put a new carburetor on it, and adjusted the valves. I rechecked the valves, and they are set to .004. I did a compression check, and both cylinders are just under 75psi.
I'm a sparky, and new to the gas side. Just wanting to make sure I'm not missing anything. Is it time for rebuild? Anything else to check?

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[trig123]

Originally Posted by mgray70

01 Robins loses power after getting warm. Motor seems to run ok, just weak. Both clutches are opening and closing like they should. Before I got it, someone had put a new carburetor on it, and adjusted the valves. I rechecked the valves, and they are set to .004. I did a compression check, and both cylinders are just under 75psi.
I'm a sparky, and new to the gas side. Just wanting to make sure I'm not missing anything. Is it time for rebuild? Anything else to check?

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Hold the throttle wide open with your hand and check the compression again. I doubt it would run at all with compression that low but it might.
By manually holding the throttle wide open we will know for sure it compression is your problem.

Pull one of the small wires off coil where it don't try to start before you check the compression. Leave one spark plug in also when testing
These engines are known to pull the intake valves into head.

You can look at threads on the two middle valves where you adjust valves and if you see lots more than the other two then you have found the issue :)
The carburetor. I don't know which one was bought. Cheap ones give me lots of problems. I have a box full of them here at my shop.

[mgray70]

Originally Posted by trig123

Hold the throttle wide open with your hand and check the compression again. I doubt it would run at all with compression that low but it might.

By manually holding the throttle wide open we will know for sure it compression is your problem.



Pull one of the small wires off coil where it don't try to start before you check the compression. Leave one spark plug in also when testing

These engines are known to pull the intake valves into head.



You can look at threads on the two middle valves where you adjust valves and if you see lots more than the other two then you have found the issue :)

The carburetor. I don't know which one was bought. Cheap ones give me lots of problems. I have a box full of them here at my shop.

Thanks, the compression tester I have is a cheap one, I don't know if it's accurate or not.
I'm not sure about the carburetor either, but the motor runs smooth, doesn't really even seems like it boogs down any. Just weak feeling.
I did the compression test with one plug on in and both plug wires off.

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[mgray70]

I decide to test the gauge best I could with my compressor. 150psi at the compressor = 135psi on my gauge. It seemed to be about 15psi difference across the board while pumping up.
Would it be kinda safe to say that I have around 90psi compression? I know that's not the most accurate way to check it, but it's all I have right now. Gonna get me a better gauge.

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[trig123]

Originally Posted by mgray70

I decide to test the gauge best I could with my compressor. 150psi at the compressor = 135psi on my gauge. It seemed to be about 15psi difference across the board while pumping up.
Would it be kinda safe to say that I have around 90psi compression? I know that's not the most accurate way to check it, but it's all I have right now. Gonna get me a better gauge.

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I can't say for sure. Can you borrow or maybe rent a better compression tester ? and don't forget to make sure throttle is wide open when testing.

Can you remove the valve cover and upload a picture here where you adjust the valves. It would be interesting to see how much those intakes are worn.

You can identify if the carburetor is OEM by removing the air box and look
inside throat of carburetor. You will see a 13 or 15 stamped on it if its an OEM and nothing if china version. 13MM - Venturi or 15 -MM Venturi.

I have found when using the OEM that the 15 MM ones run better on the Pre Mci engine than the 13 MM which came on the MCI engines. I have installed many of these also and just speaking on what I have noticed. Ezgo still has them but they are pricey but well worth it.

[mgray70]

Originally Posted by trig123

I can't say for sure. Can you borrow or maybe rent a better compression tester ? and don't forget to make sure throttle is wide open when testing.



Can you remove the valve cover and upload a picture here where you adjust the valves. It would be interesting to see how much those intakes are worn.



You can identify if the carburetor is OEM by removing the air box and look

inside throat of carburetor. You will see a 13 or 15 stamped on it if its an OEM and nothing if china version. 13MM - Venturi or 15 -MM Venturi.



I have found when using the OEM that the 15 MM ones run better on the Pre Mci engine than the 13 MM which came on the MCI engines. I have installed many of these also and just speaking on what I have noticed. Ezgo still has them but they are pricey but well worth it.

I will check all that tomorrow and post. I did hold the throttle wide open at the pedal for several seconds until the gauge didn't increase anymore. I have another gauge coming.
I would be willing to bet the carburetor isn't oem. Who carries the OEM carburetor? You can't always tell by the price! Some folks charge OEM prices for China parts. I'm a Red Hawk dealer. What do they carry, if you know?
I also have another 295 that needs rebuilding. I told the lady that I haven't done one before, but she's gonna let it be the Guinea Pig for me. It's an older cart that if I fail, she's not really worried about it, but she would like to have it running. I've watched several videos, and it don't look that bad, but this cart with the issue in this thread is a much nicer cart. I want to have one under my belt before I attempt it.

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[trig123]

Originally Posted by mgray70

I will check all that tomorrow and post. I did hold the throttle wide open at the pedal for several seconds until the gauge didn't increase anymore. I have another gauge coming.
I would be willing to bet the carburetor isn't oem. Who carries the OEM carburetor? You can't always tell by the price! Some folks charge OEM prices for China parts. I'm a Red Hawk dealer. What do they carry, if you know?
I also have another 295 that needs rebuilding. I told the lady that I haven't done one before, but she's gonna let it be the Guinea Pig for me. It's an older cart that if I fail, she's not really worried about it, but she would like to have it running. I've watched several videos, and it don't look that bad, but this cart with the issue in this thread is a much nicer cart. I want to have one under my belt before I attempt it.

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The carburetor is probably aftermarket. Look for numbers stamped on it inside Venturi. I got friends that think the $20 carburetors will make their cart run great. I just laugh when they come to me asking for help.

I am not sure about a Red Hawk. They may be fine. I have been told that the Red Hawk ignitors work great.

I get them from Country Cat but not sure what they have left as far as the Pre-Mci. I know they have one for the 350 that is $129 with free shipping. It has the # 90 jet.

I bought one in 2021 and put it on my Pre Mci 295 and it runs fine with the new Pre Mci 350 carburetor on it. It actually cranks better and so far I haven't noticed it running rich.

Interesting to see what the actual compression is after using another tester. Post a picture of under you valve cover if you get time. My bet is your intakes are worn.

These engines are easy to rebuild. Plenty of good ezgo gas techs here to help out.

[mgray70]

Originally Posted by trig123

The carburetor is probably aftermarket. Look for numbers stamped on it inside Venturi. I got friends that think the $20 carburetors will make their cart run great. I just laugh when they come to me asking for help.



I am not sure about a Red Hawk. They may be fine. I have been told that the Red Hawk ignitors work great.



I get them from Country Cat but not sure what they have left as far as the Pre-Mci. I know they have one for the 350 that is $129 with free shipping. It has the # 90 jet.



I bought one in 2021 and put it on my Pre Mci 295 and it runs fine with the new Pre Mci 350 carburetor on it. It actually cranks better and so far I haven't noticed it running rich.



Interesting to see what the actual compression is after using another tester. Post a picture of under you valve cover if you get time. My bet is your intakes are worn.



These engines are easy to rebuild. Plenty of good ezgo gas techs here to help out.

Had a busy day and didn't get to it, but I will. Thanks for info. I guess if it's the valves, it wouldn't be bad at all to remove the head and just rebuild it?

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[trig123]

Originally Posted by mgray70

Had a busy day and didn't get to it, but I will. Thanks for info. I guess if it's the valves, it wouldn't be bad at all to remove the head and just rebuild it?

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I have replaced the intakes on a few and got away with it . Most of the time everything needs rebuilding. Some that I just replaced the valves on ended up leaking oil in different places from blow by. So the answer is yes. Best to remove the engine anyway to remove the head so just rebuilt it while you got it on the table.
These engines are easy to remove.

[mgray70]

Originally Posted by trig123

I have replaced the intakes on a few and got away with it . Most of the time everything needs rebuilding. Some that I just replaced the valves on ended up leaking oil in different places from blow by. So the answer is yet. Best to remove the engine anyway to remove the head so just rebuilt it while you got it on the table.

These engines are easy to remove.

I'm gonna pull that practice engine next week hopefully, and tear it down before I actually order the rebuild kit. I've watched a few videos, and ordered a service/rebuild manual, that in came today.

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