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Post by freeqsee on Nov 24, 2023 5:42:21 GMT -5
Hello. I have a 2003 Malaguti F15 LC 50cc minarelli horizontal. Recently my engine broke so I changed my cylinder kit with a 70cc Polini sport. Now the RPMs remain stuck sometimes. Most often engine remains around 5000 RPMs while I am stopped. It doesn't accelerate by itself just remain stuck. I checked throttle cable, checked and changed reed valve but I don't know what else to check cause the problem is still there. Do you have any ideas?
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Post by oldgeek on Nov 24, 2023 6:41:02 GMT -5
When the throttle seems to hang it is a strong indication you are in a very lean condition, not good. Did you install a larger main jet in the carb when you put the larger cylinder on?
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Post by freeqsee on Nov 24, 2023 6:45:33 GMT -5
When the throttle seems to hang it is a strong indication you are in a very lean condition, not good. Did you install a larger main jet in the carb when you put the larger cylinder on? I already had a larger jet. I don't remember exactly its size, but it is above 80. It's 82 or 85 and stock was 74. |
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Post by oldgeek on Nov 24, 2023 6:59:42 GMT -5
Did you make any changes to the air input, such as remove the air box or change it?
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Post by freeqsee on Nov 24, 2023 7:25:10 GMT -5
Did you make any changes to the air input, such as remove the air box or change it? No, air box is completely stock.
Weird is that engine sounds good and pulls very good, but sometimes RPM remain high
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Post by oldgeek on Nov 24, 2023 7:42:46 GMT -5
That is peculiar. Has it done it from day one of the upgrade? Does it seem to be running hot? I still think that you need a bigger MJ or some carb tweaking such as pilot jet or needle clip move.
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Post by freeqsee on Nov 24, 2023 7:52:58 GMT -5
That is peculiar. Has it done it from day one of the upgrade? Does it seem to be running hot? I still think that you need a bigger MJ or some carb tweaking such as pilot jet or needle clip move. Yes, I have this problem from the first start after the upgrade. It's not running hot. Everything is normal.
In Polini manual says to move the needle clip by one so I did it until first start. First I thought that the problem was because of the needle so I moved it back to its stock position.
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Post by oldgeek on Nov 24, 2023 7:59:52 GMT -5
Try moving the clip down (richer) and see if it improves. A larger main jet may still be necessary to help find the issue.
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Post by freeqsee on Nov 24, 2023 9:34:07 GMT -5
Try moving the clip down (richer) and see if it improves. A larger main jet may still be necessary to help find the issue. It was moved one down at first start and the problem was the same. That's why I moved it back on top. |
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Post by aragorn on Nov 28, 2023 13:48:07 GMT -5
I would try to screw out the idle mixture screw which is right next to the screw that is moving needle. Another thing may be that you are having an air leak?
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Post by jackrides on Nov 29, 2023 14:53:44 GMT -5
Does the idle screw adjust idle speed? If not, not enough slack in cable. Next thought is air leak in intake.
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Post by freeqsee on Nov 30, 2023 10:40:48 GMT -5
Does the idle screw adjust idle speed? If not, not enough slack in cable. Next thought is air leak in intake. Yes, it adjusts the idle speed.
I am also thinking about an air leak but I have no idea where it can be. My intake is in good condition.
Today I tried it again and I noticed that RPMs remain a bit high just while moving. If I stop on a spot, RPMs go down and it idles normally.
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Post by freeqsee on Nov 30, 2023 10:42:28 GMT -5
I would try to screw out the idle mixture screw which is right next to the screw that is moving needle. Another thing may be that you are having an air leak? Do you mean the mixture screw or idle screw? |
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Post by jackrides on Nov 30, 2023 16:51:42 GMT -5
Perhaps a particle got into where the carb plugs in. Pull the crb, clean the mating surfaces well, lightly grease the surfaces, reinstall. Next, test all vacuum lines. Removeeach line and test with a hand vacuum pump to see if they hold a vacuum. Alternativly, the old fashioned way is to suck on each line (yeah, I'm serious), and put your toungue on the line and it should stick there. There is a small risk of inhaling gasoline which is bad news, so be careful.
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Post by aragorn on Dec 1, 2023 4:49:07 GMT -5
I would try to screw out the idle mixture screw which is right next to the screw that is moving needle. Another thing may be that you are having an air leak? Do you mean the mixture screw or idle screw? I mean mixture screw. I would try to screw him out a bit, it should add more fuel in idle rpms. |
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