1990 Evin 120 Carburetor Air Bleed Orifices?

[quinnf]

As I was cleaning and rebuilding the four carbs on my rough idling 120, I noticed one of the air bleed screws did not match the others. Each of three carbs had screws marked "41" and "50" but the fourth had "41" and "36". Service records indicate the previous owner had it in for rough idling several times and spent mucho bucks having all kinds of parts replaced, but I think maybe the problem involved someone's eyesight, well, that and a folded base gasket that I found on another carb.<br /><br />Can anyone confirm that 41 and 50 are the correct sizes for the idle and intermediate air bleed screws? Number stamped on the carburetor is 398743. Engine model #E120TLESB, Ser. #602502110<br /><br />Thanks!

 

[93bronco]

Re: 1990 Evin 120 Carburetor Air Bleed Orifices?

i have both a 1989 & 1991 parts manual this should give you an idea.<br />but that #398743 is in ??<br />-<br /> 1988 & 1989 120<br /># 41 idle air<br /># 50 intermediate<br /># 63D high speed (fuel bowl)<br />----<br />1991 120<br /># 41 idle air<br /># 50 intermediate<br /># 63D high speed<br />-<br />now here is something that mite explain the one carb<br />in 1991 they had the 140 carb setup as <br /># 37 idle air<br /># 40 intermediate<br /># 61D high speed<br />check to sea what the high speed is for that carb.<br />1990 could have used the same setup as 1991.<br />-<br />it is possible at one time that carb got replaced by someone that thought they were the same.<br />-<br />check all your carb body #s to make sure they match.<br />but i would say that the 41, 50 & 63D are correct for your motor.<br />hope that helps

 

[quinnf]

Re: 1990 Evin 120 Carburetor Air Bleed Orifices?

Yes, the bodies are all have the same part number stamped on them and the high speed jet in the bottom of the bowl is 63D on all four carbs. The 36 was in place of the 50 in one carb, so I think someone maybe picked up the wrong part off the bench and didn't bother to check with a magnifying glass. I'll order a new #50.<br /><br />Thank you kindly!

 

[Dhadley]

Re: 1990 Evin 120 Carburetor Air Bleed Orifices?

The parts book lists the 1990 the same as the 89 and 91. Now the question becomes why did someone richen up that particular mid range jet that much?<br /><br />Good luck!

 

[quinnf]

Re: 1990 Evin 120 Carburetor Air Bleed Orifices?

I'm assuming that it wasn't done on purpose. At any rate, that explains why this engine's been running so punk. The folded base gasket probably introduced an air/vacuum leak on one cylinder, the corroded low-tension coil terminal was keeping another cylinder from firing and the wrong intermediate speed orifice wasn't helping either. I'm tempted to keep removing parts to see what else is wrong with this beast. Haven't checked the lubricant in the lower unit yet. I'm almost afraid of what I might find there!<br /><br />Thanks for all your help!

 

[quinnf]

Re: 1990 Evin 120 Carburetor Air Bleed Orifices?

Update: <br /><br />Ordered #50 intermediate speed orifice to replace the incorrect #36 that someone stuck in #1 carb who knows when . In the meantime, I drilled out the #36 to the same diameter as a #50 (temporary fix) and reinstalled the carbs. <br /><br />Primed carbs, filled plastic trash can (poor man's test tank) with water and hit the starter. VROOM! All cylinders were firing, but idle still rough with coughing, sneezing out the upper exhaust and more smoke than there should have been. <br /><br />I had acquired a couple cans of DeepCreep (SeaFoam in a can) so decided what the heck? Sprayed in carbs until engine died, then sprayed more down the venturies, then appx. 5 seconds in each spark plug hole and replaced plugs, then went and ate lunch.<br /><br />After lunch, started engine, which really didn't want to start at first. Finally, enough cylinders fired to keep engine running. Dense white smoke everywhere and engine running really rough. Goosed the throttle lever several times and just as I was beginning to think I'd have to admit defeat and take it to a hired wrench, engine began to smooth out. <br /><br />Once smoke cleared (appx 3 minutes), engine settled down to a smooth purr. Water in trash can looked like someone emptied ashes from a barbecue in it. Lots of oil and black soot. Emulsified the oil with dishwashing detergent, then siphoned off and replaced with clean water. <br /><br />I've gotta say I'm a believer in SeaFoam. Really impressive difference from something that comes in a can. Despite reading about it here, I didn't think it would do anything.<br /><br />Next step is to take boat out for an Italian tune-up and see what breaks next!

 

[quinnf]

Re: 1990 Evin 120 Carburetor Air Bleed Orifices?

Crud. All that work and it was a stinking broken plug wire! <br /><br />After doing the Italian tune up, engine still was missing. Only got 4500 rpm at WOT, though it idled fine after a carb rebuild and decarboning with DeepCreep. <br /><br />This evening, I was poring thru the manual, trying to figure whether I should re-check all the electrical resistance and voltage checks I had made on the ignition system. So I popped the lid and took a look and something didn't look right. Here's this spark plug wire hanging in free space with the boot still on the plug. That explains everything. <br /><br />New plugs and wires are on order at iboats.com.<br /><br />Thank you for all your help.