new build problems

[brylon644]

Just took out my new superjet I rebuilt over winter. Ran good for 5 mins then ran like crap for 20 mins. Ran a mixture between 33 to 1 and 40 to 1. Pulled the plus twice. Rear cylinder seems to be lean or not getting fuel at all. What would be the reason for this?... carbs were cleaned and rejeted 3 weeks ago. Its a whole new motor besides stator, carbs and reeds. Where should I start?

 

[Rushford_Ripper]

Rode with him today, rear cylinder plug was real white and the front cylinder plug was just where is should be.

 

[amitchell]

Does the rear piston crown have any fuel on it when you look down the hole? Did you clean the carbs or rebuild them? individual fuel pumps?

 

[brylon644]

From what I could tell the crown didn't have fuel. Carbs where cleaned and rejeted, not rebuilt. Single fuel pump. I will also add that The motor was rebuilt last year after the rear cylinder started losing compression. They guy who rebuilt it said it looked like it was overheated. Just so everyone knows its a 62t motor with stock 38 carbs.

 

[badvinny]

Pressure test the motor is my recommendation.

 

[brylon644]

Leak down or compression? I assume u mean leak down

 

[JetManiac]

Go through your carbs again.

 

[brylon644]

Went through the rear carb today. Everything was very clean on them. Besides the leak down test is their anything else I should look for? Or could the carb be plugged internally?

 

[amitchell]

You can shoot carb cleaner or WD-40 in the jet orifices and see if it comes out the carb bore. The little plastic aerosol tubes fit perfect in the carb holes.

 

[brylon644]

You can shoot carb cleaner or WD-40 in the jet orifices and see if it comes out the carb bore. The little plastic aerosol tubes fit perfect in the carb holes.

Thanks for the tip.I will check it tomorrow.

 

[CRJ]

ill suggest the obvious. i assume you made sure that the jets match in both carbs? did you try adding fuel to the rear cylinder to see if you get a change, as the rear does work harder than the front? do you have even compression?

 

[JetManiac]

Went through the rear carb today. Everything was very clean on them. Besides the leak down test is their anything else I should look for? Or could the carb be plugged internally?

Slave carb (front 38) has a restrictor in the back cover that often can get clogged but doubt that is your problem.

 

[brylon644]

ill suggest the obvious. i assume you made sure that the jets match in both carbs? did you try adding fuel to the rear cylinder to see if you get a change, as the rear does work harder than the front? do you have even compression?

Yeah both jets match and I have an even 185 compression in both cylinders. Did not try adding fuel to the rear.

 

[Rushford_Ripper]

Didn't you say when we were out that it ran fine for a few minutes then started acting up? I would bet there is something plugging up the carb.

 

[CRJ]

id back flush the lines and the carb. also check you dont have sticky reeds

 

[brylon644]

Lines are all new and cleared before installation. Could the reeds be the problem?

 

[Rushford_Ripper]

Worth a check....