madmax93

I have a km baja and it ran fine for a while but now it will just die out after about 2 min of run time.
I changed the spark plug but it is still dieing out. Its the 30.5 engine.

tapkoote

what kind of intake manifold
some times the plastic ones will warp
and leak air after getting hot.
check the engine for air leaks.
tap

Johnnysplits

Exactly how much time is that? Is it new? Have you adjusted your carb properly after breaking it in?

madmax93

is the manifold in between the carb and the head?

and yes it was bought new used about 2 weeks time over a 3 month
span. I will try to tune it since i have not since i broke it in.

tapkoote

is the manifold in between the carb and the head?

The intake manifold is the little block between carb and head
some times those mounting bolts will loosen up and create an air leak when warm
at least on a zenoha they can.
Take that block off ,lay it on a flat surface to see if it rocks corner to corner
if it does it's warped.
tap

Lars from Norway

And before doing anything else, fire it up and spray some start gas around the mating surfaces for the carb to insulator/insulator to cylinder to eventually locate where the leaks are. You should hear the engine differ in revolutions when doing this, IF there are any leaks.

Johnnysplits

There's your problem man!! It's probably running way too rich and you have to start leaning it out.

madmax93

I sprayed some starting fluid on the carb manifold and the engine cut out.
The manifold is plastic so i am gooing to replace it with a metal one.
Also going to get rid of that crappy air filter.

tapkoote

madmax93

I changed the manifold and the condition worsened, so I adjusted the
needles and still the same (it would start and then die). Then I noticed that
the primer bulb was not filling with gas, so its a walbro carb next.
Although I do not regret getting the new manifold because when I
first started it up and started to run it, i noticed a difference in pep.

willclark77

My Feedback: (2)

Check the gas cap.  If it runs for a minute then stalls because it's running out of fuel can be because the vent in the gas cap is clogged.  Next time it stalls immediately pull the cap off.  If you hear a little vacuum whoooosh sound, there's your problem.  Or better yet, just try a new cap or fix that one then try it.

madmax93

Thanks for the advice willclark. I will try that if I still have a problem after I replace the carb,
which brings me to a question. How does the little black connector that is connected to the carb
come off? Its the one that pulls the throttle in and out.

willclark77

My Feedback: (2)

I actually really liked the km carbs I've used.  I'd imagine they can be hit or miss.  You might get a good one or might get a turd.  Pretty much every one that I've taken completely apart and did more than cleaning never worked right after.  They're just really sensitive.

If you're talking about the little clip I'm thinking of, there's a trick to it.  I'd have to look at it on one of mine to remember.  I'm at work right now (shhhhh).  You'd probable be better off removing the linkage from the carb where it screws to the throttle shaft that goes through the carb.  It's a little phillips screw and it can be a pain in the butt to get the arm back on right.

madmax93

Well, its running great now with the manifold and carb, new orange gas cap
on the way. It was still doggy with the needles at 2 on high and 1 1/2 on low, so
I decided to lean it out more, thinking that I might ruin the engine but after I leaned
it out it started to get crazy fast and idles fine now. Thanks for all the help guys.

willclark77

My Feedback: (2)

Awesome!  That's still plenty rich on the carb settings.  Post some vid and we can tell you if she sounds tuned ok.

madmax93

Ok, runs good but I am having a problem with the steering servo. The original
one that came with the car started to shake back and forth so I replaced it.
The one I bought came from China and worked for about 4 runs but now its
doing the same thing. I replaced the battey with a battery holder running
4 new AA batt. and that ran for 10 min before it started to act up again.
Is the servo bad? Should I replace it with an HPI one?
Oh, and I switched out the receiver and its still doing it so its not the receiver.

tapkoote

Hitech servos are spendy but worth it
I had that same thing on a boat, turned out to be the transmitter.
try other radio gear if you've got it.
tap

madmax93

I am using a flysky radio. I am going to get a new 3 channel setup to try.

madmax93

I tried it with new radio gear and it still was the same.
So I tried a throttle servo and it did not do it. It worked as normal.
I know I cannnot use a throttle servo, so my next question is, why are there
three leads on the steering servo?

Lars from Norway

Is that rechargeable batteries or regular alkalines? Anyway, using reachargeables will only give the servos 4,8 volts, which in turn will make the servos not reach their full potential and torque. Using alkalines will give the servos 6 volts, but not last as long as the rechargeables as they are much lover rated in milliamperes. The best you can do is to use a high milliamperes (at least 3000 mAh) 6 volt pack. The use of the 4 AA battery holder can be the source to your problem with the servo(s) acting up. Get a Hitec HS 805 MG for the steering, this is a great reliable and reasonible priced servo.

The three leads are for plus, minus and signal, as on every other servo on the market.