11cc K&B running problems.

[wswatzell]

11cc K&B running problems.

Need some help with this one.

First a little history; a friend bought a Dumas Scarab, all the running Hardware, Tuned pipe, & a brand new K&B 11cc Engine about 6 months before K&B got bought out. He assembled everything according to the instructions, & to this day he has not been able to get the engine running above 1/2 throttle, even though it is very easy to start.

What the engine does is surges or pulsates once you try to accelerate. Acts like the fuel is spraying into the carb in short spurts.

What we have tried so far.

• put my tuned pipe on engine after we determined that his pipe must be for a 7.5cc (it is a lot smaller than mine)...made a huge improvement, now able to run at 1/2 throttle compared to just an idle.
  
• We tried cleaning his carb….. improved a little but still can’t get above ½ throttle without it wanting to stall & pulsate.
  
• Tried shorting fuel lines…… no change.
  
• Took the carb out of my hydro which runs great & put it on his engine….. ran worse.
  
• Took the fuel system out of my hydro….. no change.
  
• So with my tuned pipe, carb, & fuel system. It ran worse than his original setup.
  

Our conclusion, something is “stuffed” with his engine considering that was the only original piece left. What do you think?

We are going to try my engine in his boat just to make sure that his boat isn’t jinxed. LOL!

 

[snowdog-2112]

Re:11cc K&B running problems.

Wade,

My initial reaction was that the prop was to deep in the water. Not being familiar with the Scarab I looked at it on the Dumas site and see that it's an inboard which leads me to the next step. Is the prop to big? Was the engine broken in properly? Try a richer needle setting. And since you mentioned "stuffed" does the flex shaft spin freely?

Just some ideas...hope they help.

Team Snowdog: These ideas work for inboards also???

 

[Ron Olson]

Re:11cc K&B running problems.

"Stuffed" is a term that I learned from EMS and passed it along. We have other phrases for it but this is a family site. Get my drift? My kid learned it too from Craig and is now using it. Thanks Craig!

Back to the question............................

 

[ScottVanSlooten]

Re:11cc K&B running problems.

I had the same thing with a K&B 7.5 once you can try richening it but we found that we were to rich to start with try and turn the needle in the one I had I thought I had it in all the way and found after a day of running that it was not in as far as I thought . reset it and the nexk week it ran fine Scott

 

[wswatzell]

Re:11cc K&B running problems.

We have had the needle almost all the way out to all the way in, & it ran the same?? :- I am thinking that maybe something is messed up inside the engine, like maybe the timing, or the porting on the sleeve. It acts like something is causing an inconsistent pressure or vacuum to pull the fuel into the combustion chamber. The thing is we changed everything one thing at a time with the exception of the engine itself, so that is why I think it has to be inside the engine. This engine has never run smooth. Is it possible that it was flawed from the factory?

 

[snowdog-2112]

Re:11cc K&B running problems.

Wade,

My hunch is now that the sleeve is out of alignment. Open the engine and check for proper sleeve position. If the sleeve isn't aligned properly, make it so. My bet is that's your problem.

Snowdog

 

[wswatzell]

Re:11cc K&B running problems.

Well here is an update.

He took the engine apart & he thinks the valve & the pin in the crank are miss-aligned maybe causing a delay in the rotation of the valve. he said he will look at the sleeve alignment as well.

 

[Grimracer]

Re:11cc K&B running problems.

Wade

We have had K+B carbs that do not allow enough fuel to enter the motor.

This was comon on the Redhead 45 OB.

We hooked up the fuel line right up to the carb (no Needle) still too lean.

Its just your best bet to say that if the boat quits (and all parts are still in tact) it was lean.

Mike

 

[Ron Olson]

Re:11cc K&B running problems.

I've got an idea that's what is happening with my OS .46 . It might be where that funny noise is coming from too that I thought was a rod going South. Now I've got to tear it down again..........

 

[Ron Olson]

Re:11cc K&B running problems.

Wade, I just jerked the OS out of the 'burst and guess what I found? Yeppers,the rotor disc was flappin' around in there. It was a PITA to get it back in there and aligned. That thing ought to run better now!

Anybody got any secrets to getting these puppies lined up and put in there right the first time?

Wet Paint Racing, to those in RCZone, yes I do ask questions!

 

[wswatzell]

Re:11cc K&B running problems.

Steve, my friend, is going to test his out this weekend. I hope it does the trick.

 

[snowdog-2112]

Re:11cc K&B running problems.

Did you find anything else wrong with it Wade?

Snowdog

 

[wswatzell]

Re:11cc K&B running problems.

I haven't heard. :-

 

[wswatzell]

Re:11cc K&B running problems.

Ok, here is the update. he ran 2 tanks of fuel through it & it ran perfect. He only had to play with the needle some. ;D

What it turned out to be...

He has an older style K&B with the disk valve. the crank pin that drives the valve was in the triangle valve hole instead of the notch where it belonged. so it was aligned enough to start & stay at an idle, but couldn't get enough fuel at higher RPM's.