"HELP" K&B 3.5 SX Problems

[SCTunnel]

I have brand new K&B 3.5 sx on a TS2. First time it was put in the water today. Can not get the carb set , it will run fine to about half throttle,any more than that and it will die.THE k&b manual says start with 6 turns out, i have went in & out but still want run over half throttle. I'm running 20% red max fuel.Can anyone give me any advise on adjusting this carb.

 

[RodneyPierce]

I have brand new K&B 3.5 sx on a TS2. First time it was put in the water today. Can not get the carb set , it will run fine to about half throttle,any more than that and it will die.THE k&b manual says start with 6 turns out, i have went in & out but still want run over half throttle. I'm running 20% red max fuel.Can anyone give me any advise on adjusting this carb.

Try 3.5 to start out, 6 turns is a ton, unless that has a different carb, which I highly doubt. Let me research here abit, but 3.5 turns shoudl be PLENTY

 

[RodneyPierce]

I have brand new K&B 3.5 sx on a TS2. First time it was put in the water today. Can not get the carb set , it will run fine to about half throttle,any more than that and it will die.THE k&b manual says start with 6 turns out, i have went in & out but still want run over half throttle. I'm running 20% red max fuel.Can anyone give me any advise on adjusting this carb.

Try 3.5 to start out, 6 turns is a ton, unless that has a different carb, which I highly doubt. Let me research here abit, but 3.5 turns shoudl be PLENTY

Standard gold carb, 3.5 turns out shoudl be enough

 

[SCTunnel]

Yes it does have the gold carb, i will try the 3.5 turning out. Thanks for the Advice Rodney.

 

[chuck]

Did you check the plug color.

 

[Mike Larson]

What prop are you running? I personally would not lean on the motor until I had a coupla tanks through it,.....With the motor being new, its more than tight @ TDC, so you have added extra friction to the equation you cannot control..... try a smaller dia/pitch prop to at least run the boat be it half throttle or not, the boat slow, accordingly,... The critical phase of achieving the p/l fit is dependant on you, right now, premature leaning it in will affect your long term engine life accordingly...... easy does it..... Try a 215, or a 440/2 to at least keep the motor running in the water ( rich) for a tank or two, it will come in to itself eventually.............. Once youve achieved proper running in, commence trimming the hull, and propping up for speed accordingly...... Good luck Mike

 

[RodneyPierce]

What prop are you running? I personally would not lean on the motor until I had a coupla tanks through it,.....With the motor being new, its more than tight @ TDC, so you have added extra friction to the equation you cannot control..... try a smaller dia/pitch prop to at least run the boat be it half throttle or not, the boat slow, accordingly,... The critical phase of achieving the p/l fit is dependant on you, right now, premature leaning it in will affect your long term engine life accordingly...... easy does it..... Try a 215, or a 440/2 to at least keep the motor running in the water ( rich) for a tank or two, it will come in to itself eventually.............. Once youve achieved proper running in, commence trimming the hull, and propping up for speed accordingly...... Good luck Mike

I do agree to a certain point, but too much fuel can be detrimental to the life of the motor also. Running th e motor overly rich will keep it from warming up like it needs to and the p&l wont break in like they should........

 

[Duck899]

I have brand new K&B 3.5 sx on a TS2. First time it was put in the water today. Can not get the carb set , it will run fine to about half throttle,any more than that and it will die.THE k&b manual says start with 6 turns out, i have went in & out but still want run over half throttle. I'm running 20% red max fuel.Can anyone give me any advise on adjusting this carb.

What prop?.....Is the hull set up as per instructions? Couple guys here run those hulls with K&B and OS engines. X-440/2 prop seems to be a good choice. My K&B runs at around 4 turns open with an X-440/3 on a leecraft. You may have a tank issue (pressure?), small pin-hole in the fuel line, pressure line, etc if it dies from lack of fuel......

Or, Is it so blubbery rich that it won't run? Lean it in to 4 turns if thats the case.......K&B puts that 6 turns open clause in there to keep people from trying to start them at 1 turn open.....

 

[SCTunnel]

Im running a 215 prop,and it must have been running to rich because i had very little heat in the motor. I took the motor apart last night and it looks fine ,piston and cylinder look good and glow plug looks like new.

 

[Duck899]

Im running a 215 prop,and it must have been running to rich because i had very little heat in the motor. I took the motor apart last night and it looks fine ,piston and cylinder look good and glow plug looks like new.

A Prather 215 is not really the prop to start with on a new K&B. The Prather is virtually the same diameter but has 2.5" of pitch vs the Octura X-440's 2.198". May not seem like much, but when your trying to get a needle on an engine and a new engine to boot, it can drive you nuts. If your just sport running, the 215 will probably be fine. The fast guys mostly use an X-440/2 or 440/3 or 437/3 for the most part. Lets the engine rev and the speed increases dramatically. Also very forgiving on the set-up. Sounds as if your just running to rich and possibly loading a new engine with too much prop. The 215 would be the prop to try after you have the boat/engine combination dialed in. Even then I'm sure if you want to go fast you will stay with the 440....

Don't be afraid to lean the mixture......Get it running so its just slightly rich on the top-end. You will do more damage running it too rich.....if its too lean, it will quit, plain and simple.....

 

[chunk t]

SC,

How's the engine run on the bench before it hits the water? Sputtering & choaking? or Runs good?... It should be sputtering and choaking out of water, once a load is on the engine (in water) it should run better.

You could have too much load on the engine with the 215 back there. I would definately run THAT prop higher than where where you think it should be (by 3/32"-1/8") in the beginning to let the engine rev-up during break-in.

Describing the engine tootling around OK but dieing when you pick up the RPMs... I'd experienced something similar myself. Traced the problem back to the fuel system drawing in air. The fuel system seal was good enough when idling around, but when the engine got serious and demanded a lot of fuel it leaned out and died. One time the fuel line barb on the carb was cross-threaded, the other the trerads were stripped-out. Replacing the carb body solved the problem both times for me.

chunk t

 

[waterbug]

Deryl

Bring that boat to the pond this Sunday....... We'll get her dun !!!

Butch :lol:

 

[SCTunnel]

Butch

I plan to be there Sunday if nothing happiens, and yes i may need some help to get it up and running.

Thanks Deryl