still messing with the looper - fuel pump?

[Dhadley]

Re: still messing with the looper - fuel pump?

Sounds like you may have an air leak on that cylinder. Stick a toothpick in the idle jet on that carb to see if it picks up (make it rich to overcome the air leak). Remember, the front half of a looper is an X design. The lower left carb runs the lower right cylinder and so on.

 

[tal]

Re: still messing with the looper - fuel pump?

I'll give it a shot tomorrow. Funny thing is, I already checked for air leaks with carb cleaner. One place I did notice it took in carb cleaner was around the throttle butterfly shafts, but all the carbs sort of did this. I figured this was normal since there has to be a certain tolerance to allow the throttle shafts to rotate. When sprayed liberally with carb cleaner it did have an effect though.

Once I realized this I steered away from the shafts and sprayed around the bases of the carbs which yielded no change.

 

[Dhadley]

Re: still messing with the looper - fuel pump?

Check around the side plates on each carb body.

 

[tal]

Re: still messing with the looper - fuel pump?

Finally, a nice day that's not raining and freezing cold.

Here's what I got: If I stick the toothpick in the idle jet (small one) it will slow and bog down the engine. If I stick the toothpick in the intermediate jet (larger one) the engine runs smoothly without the huff or miss sound. Once I remove the toothpick from the intermediate jet, the rpms race up a bit then slow back down with the miss/huff. What does this mean? I'm about to pull the carb off and look inside. Not sure why the intermediate plugged would help the idle quality and not idle jet.

 

[tal]

fixed?

fixed?

Alright, I pulled that carb off, had a look at the little aluminum side plate that covers the low speed passages. It sort of looked a little warped like it could be leaking. I took it off and the plate itself seemed fairly straight. I pounded on it a bit to be sure it was straight but I don't think that accomplished anything. I ran a copper wire through all the holes again and blew air to be sure everything is clean. I replaced the carb bowl gasket with a new spare I had because it looked a little twisted and squished out in a couple places. I made sure not to over tighten and only make snug. Then I put the carb back on and fired it up in my little test trough. It was rough to get going but once it warmed up I was able to let it idle for 20+ minutes without any miss or huff.

Judging by the toothpick method I would assume the carb was pulling air through one of the gaskets I rearranged/replaced. I was able to turn my idle screw all the way in which resulted in an a perfectly smooth idle of around 900 rpms in my test trough. It does not provide full back pressure but is better than the water hose. I will readjust the idle the next time I have it in the water. So by the way it was idling yesterday it appears the problem is fixed but I'm not 100% confident in what I did to fix it.