Need .15 nitro tuning help!!

[iqraceworks]

I've had a few nitro trucks in the past, and never had much problem tuning them. I can usually get the high and low speed jets set with no problems, and normaly never have to adjust it much after that.

I recently bought a used HPI Rush EVO with a .15 motor. I've got it set up about as good as I can, but I still seem to be having problems. It runs fine during the fist 1/2 tank of fuel or so.....then it seems to get really doggy on the bottom end. Top end stays good, but accelerating from a stop just bogs the motor down. I've tried leaning and richening the low speed jet, but I can't seem to find a setting that gets rid of the low end bog. It only does this after I've ran it for a while.

Any tips? Does that sounds like a jetting problem, or a motor problem?

Thanks

 

[Rolex]

When it starts to get boggy, what is the engine temp?
When it's warmed up and below half tank, do the pinch test. Pinch the fuel line shut and count the seconds to see how long it takes before the engine speeds up and then stalls.

They tend to lean out a bit on the last half of the tank, and that's where you should be adjusting your settings.
You might have to richen the HSN along with the LSN to properly meter the fuel flow.

 

[Racer 1966]

Sounds like the signs of a worn engine, my Traxxas .15 acted the same way before replacing the piston/sleeve.

 

[Xotix]

do you still have?

I just put a new Kyosho .15 on my used Kyosho car, and I seem to have a problem tuning it. From a few posts here I see running it at a full tank, and running it at a half tank does make a difference. Any suggestions? Also are
fuel filters a good investment, or are they just air leaks waiting to happen?

How do you set up a Kyosho .15 nitro engine? Anybody...please.

 

[MrClean]

You may have an air leak in the tank, might be around the filler cap or the seam where the 2 halves of the tank are 'welded'. I think it's also possible that a leak could be in the hose coming from the exhaust to the tank. You can remove the tank, submerge it in water, plug one hole with your finger and use a piece of tubing and blow into the other hole. You should see bubbles coming from where the leak is, if you have one.

I think fuel filters are a necessity (IMO). There is a greater chance of a piece of dirt/foriegn material getting into the tank and making it's way to the engine then there is of the fuel filter causing an air leak.