chowderhead72

My Feedback: (4)

I have recently purchased a O'Neill (cy) 27 with the works (ported,balanced, and billet/chrome) so far I am less than pleased with it's performance but I am not convinced it is the fault of the motor. I broke in through heat cycling and various rpms for a tank and a half. The motor was difficult to tune after break in; it would run great top OR bottom take your pick. after two more tanks I tried to fine tune. I was somewhat successful after abot two hrs of fiddling; it will run great for about two minutes and then acts like it is too lean. After two minute bubbles begin to form in the large gas line and about the same time the engine begins to run terrible. To test my theory I would run it hard for two minutes and when it started to lean out I would push tje prime button two or three times; this would solve the problem for a few minutes but once the float was empty it would run badly again. I have check the fuel tank and both lines for leaks and found nothing, I am stumped! I ask you these questions:

1.Under normal operating conditions are there any bubbles in your fuel line?
2.Has anyone had a similar problem with one of these engines?
2.a.What did you do to solve the problem?
3.could I have a faulty carb
4.Do I need to keep my idle abnormally high? (to avoid loading and for overall fuel metering) I read Pigfly's post on the walbro carb but it really didn't answer my questions at actually created more. Not his fault great post just not excactly the info I need.
5. Suggestions? I'll try anything!

randyg-rcu

not normal. I'd keep looking for leaks somewhere, either the lines, carb gaskets, etc. also could be your lines are touching the engine and getting too hot. Also could just be you need a card rebuild kit, or other easily fixed carb problems.

--Randy

badz

My Feedback: (1)

My CY Engines the idle is rather high compared to a zenoah one that I got...but I've never seen bubbles in my fuel lines...maybe ya crossed the fuel hoses? Got the pickup on the primer end of the carb and primer line on pickup end of carb?

chowderhead72

My Feedback: (4)

The carb and engine are brand new. So you are saying there should be no bubbles? Is the tank supposed to be pressurized like a nitro? Could it be the gas cap? My old engine ran fine untill it sucked up alot of dirt through an airfilter I thought had been oild but had not. The carb came with the engine so I dont know what to do.

chowderhead72

My Feedback: (4)

Interesting thought! the fittings are two different sizes so I don't think I could have screwed that part up but I will look. Now the black tube is the prime circuit(pressure) and the clear is the supply,correct?

badz

My Feedback: (1)

The fuel line that goes to the primer bulb is usually unfiltered...it just dangles into the fuel...the main pickup line thats on the bottom of the carb has the fuel filter on it inside the tank....they don't really pressurize like a nitro...I guess they build a little up but not much....2 stroke fuel will bubble and foam up also when mixed rich...like yours more then likely is cause of break in...I'd almost bet you got a small leak in a line or they are reversed....ya can always give a shot of carb cleaner around the hose connections and all to find leaks easier....the engine will bog out some from the cleaner...or do a easy test...drop 2 pieces of new fuel line into a jug of fuel...hook em up and fire it...see if the bubbles go away...that for sure will let ya know if it's a line

randyg-rcu

Nope, the tanks aren't pressurized. in fact, they should be vented to the atmosphere (normally done in the cap, but I don't know about your engine). The carb has a built-in fuel pump to suck the fuel into it...

--Randy

StefanL

I had the exact same problem, and I located the problem in a small hole in the primer bulb fuel line.

The engineĀ“s performed much better, but some of the problem still persisted. So I rerouted the bulb line, it had gone on the outside of the muffler, and got heated that way. Now the bulb line goes under the pullstart, and engine performance is much better now. I hadnĀ“t thought that heat might be a problem, but in hindsight I can see that it most likely affected the engine.

Stefan

icecreamslick

My Feedback: (9)

This a bit of a stretch, but brand new nitro motors, straight from the factory, sometimes have small leaks and will not tune properly. [] If you check all of the lines and gaskets and still have the same problem, you might try this:

Empty the motor of fuel and pinch off the return hose. Set the piston at TDC. Then, force air (blow) into the fuel line while brushing soapy water onto the outside of the motor. If there is a leak in the housing, you will see bubbles forming in the soapy water, over the leak. Then, you just doctor the boo boo with high temp sealant.

...it's just a thought, but sometimes when all the likely solutions fail to solve the problem, the unlikely ones are all that you have left.

Monstrous

check your breather pipe isnt kinked or caught up anywhere

Monstrous

voo2doo

I had bubbles in mine! Then Micheal took him away
Vo0[&:]

ammdrew

the black line is the supply, the yellow is return, the bulb only fills the carb then pumps the exsess out the yellow line.

chowderhead72

My Feedback: (4)

What size is the black supply line? I want to replace it with clear.