Engine power loss

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Engine power loss

Postby Emerica1975 » Thu Jul 07, 2022 12:00 am

Finally got an air filter for my 1956st. Engine is rebuilt and runs good. (Except for it seems to run too hot) I finally got a repop air filter and put it on and I can barely get moving in first gear. The engine doesn’t even want to rev. But if I take the air filter off it runs good. Any ideas?
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Re: Engine power loss

Postby Emerica1975 » Thu Jul 07, 2022 1:08 am

I didn’t word my question very well I realized. My 1956 st engine runs good until I put the air filter on. When I put the air filter on It keeps the engine from having any power and will barely rev. I adjusted the metering pin and that helped a little but the engine still doesn’t have its usual power. I’m wondering if I need to check ignition timing. I just don’t want to remove the head if I don’t need to. Has anyone had this problem?
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Re: Engine power loss

Postby KJohn » Thu Jul 07, 2022 5:57 pm

You should be able to blow through the air cleaner pretty freely. If not, take the air cleaner apart. Is there any chance there is some packaging material in there?
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Re: Engine power loss

Postby Emerica1975 » Thu Jul 07, 2022 9:18 pm

The filter is free from debris and i can blow through it easily.
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Re: Engine power loss

Postby HarryM » Thu Jul 07, 2022 11:27 pm

Check your CHOKE off (open). The tear drop shaped end on the air cleaner. The purpose of the choke is to close off all or some of the air to the carb to give a richer fuel mix for starting only. MUST be open to run.
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Re: Engine power loss

Postby 250_Sprint » Thu Jul 07, 2022 11:58 pm

Apparently the reproduction air filter is too restrictive.
If the engine starts, idles, responds to twist grip input and will respond under load (riding down the street) with no air filter and does none of that WITH the reproduction air filter, there is something wrong with the reproduction air filter.
Try connecting an air filter from a modern day 125cc engine. A lawn mower engine for example could be fitted. It may look ugly, but most experiments do look ugly and unpolished.
Keep us posted.
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Re: Engine power loss

Postby Emerica1975 » Fri Jul 08, 2022 1:07 am

I’ll try the other filter idea and let you know what happens.
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Re: Engine power loss

Postby troymessina » Sun Jul 10, 2022 10:23 am

If you like the look of your air filter, you can buy different kinds of foam or wire mesh packing and pack it yourself. Start with a little and add until you start to lose power. Then, back off the packing. You probably want as much filtering as you can get without the engine suffering from lack of air. I think the original filters were metal mesh.
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