Engine Problems

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BradZ

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Swan Hill, VIC
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  1. Bashing
Hey all, finally got my parts after about a month. Fired the rig up, and its running terribly. Whenever i punch it, it struggles and splutters dropping in revvs. I have no idea what the problem is...Plug is black, meaning its a bit rich, temps are ok, little bit low. LSN seems fine, did the pinch test. I'm lost.. Help. :( Nothing has been touched needle wise..
 
Could just be that the fuel gummed up in the carb/fuel filter from when you ran it last. Or the ambient temp changed so much that your tune is out of whack. Did you try a new GP?
 
You need to get the HSN tuned right before you can use the pinch test. Get it to where it takes off quickly without bogging and plenty of blue smoke, then move on to the LSN.

It sounds like it's rich on the HSN and after you get that tuned you'll need to retune the LSN.

Hope that helps :)
 
When it starts, let it warm up. How does it idle and what's coming out of the pipe. It sounds like it's stinking rich on both needles.
The LSN needs to be leaned for good take off, and the HSN for WOT. Do the adjustments only when the engine is up to temp, and do a pass or two between adjustments till you get it right.
 
Thanks for the help. The temps haven't changed much. And last time i ran it i neer had a problem. Rolex, when it idles a heap of fuel is spittng out the exhaust. And aren't you meant to tune LSN for good takeoff??

EDIT: can't retune as my T/B servo stopped working.. :angry: Looks like another month long wait for that aswell :angry::angry:
 
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Leaning the LSN will give you a good takeoff as well as stop the fuel spitting during idle. Leaning that will also raise your temps too high if you go too lean. When you get the electronics working, let us know what you get.
 
Ok made some progress. I went out and pulled my receiver apart, only to find that all the ports have three prongs, except for the T/B. One of the three had bent so far it didnt plug in, so i bent it back and plugged it in. Hooray!! It works, badly but it does work! Now......I plugged steering into t/b and t/b into steering and this time the t/b was good and the steering actually worked but twitched. Hmmm, i got it going good enough to run and i leaned both needles a bit, as Rolex said. Now, the bogging became a little bit less but not much at all. Throttle response was pretty bad, if i punched it, it would either 1. bog down or 2. accel to a certain rpm and stay there then rise to full. Temps got to 220F at best. And when it was idling as i was temping it, the fluctuated in revvs a lot and almost cut out on me once or twice. First it would rise a tad for about half a second and jolt foward or it would drop in the same way. I'm lost...
 
Lean it some more, sometimes running too rich will cause the temps to be higher than norm. Start with leaning the HSN to get it clear after 1/4 throttle.
Then go after the LSN for idle to 1/4 throttle.
 
Thanks, its actually 10:43PM over here so i should be in bed. But yeah lol.
Do you consider 220F to be higher than normal? I always thought that was pretty low
 
I don't worry until 280F depending on the engine. I tune first for perfromance, temps last.
 
Alright, just driving it then and i've leaned both needles another turn or so each. First i turned the HSN a bit and it ran good with a little bit of bogging, leaned it further and its terrible again. After pinning it from a stop it stalled on me.. Help?
 
ARGH!!!! I have no idea what to do anymore..
At idle it spits fuel but also wants to move foward occasionally.
I lean the LSN now its spluttering and gurgling under power and now it dies ALL THE TIME!!! Hard accel and bam it shuts off WTF?!?!?!?!?!?
 
ARGH!!!! I have no idea what to do anymore..
At idle it spits fuel but also wants to move foward occasionally.
I lean the LSN now its spluttering and gurgling under power and now it dies ALL THE TIME!!! Hard accel and bam it shuts off WTF?!?!?!?!?!?

TOO LEAN, it's starving for fuel and lubrication. Go back a full turn on both since that's the amount you say you turned them correct? Look at the needle like a clock, divide it up into 12 equal increments and go one hour at a time. And start with the HSN, don't even worry about the LSN yet until it pulls properly on top end. Then you can adjust the LSN, and ultimately your idle. And keep in mind that it's gonna bog off the line while dialing in the HSN, this is normal and you'll take care of it after getting the HSN set properly. A full turn of a needle on a motor that is close to a good tune can be WAY too lean just FYI.
 
Thanks ill try that

EDIT: HPIguy, your a legend! I did what you said and it runs great now! Thanks!!!:D:D:D:D:D
 
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Just wondering, i've been hammering the buggy round the backyard.
And the temps only got to 220F at best. It had street tires and wet grass so no traction and i had it at high RPM most of the time. Why is the temp so low??
 
Ha ha, I'm no legend. I've just been fortunate enough to have some good people teach a few things over the years, the rest you learn the hard way or from great forums like this one. What is your particular motor supposed to run at for optimum temperature and do you have a temp gun? Keep in mind also that it's much better to err on the rich side and give up a little performance than err on the lean side and seize an engine. Especially in the conditions you describe....i.e. wet grass and spinning a lot you're probably not getting enough forward momentum and speed to air cool the motor much. If it's running strong, I'd check what the engine manufacturer reccomends temp wise, and use a temp gun for that last little bit if it were me. But that's just my $.02 worth.
 
I have a temp gun, how else would i know it runs 220F? :p:
Factory says nothing about it, hey occasionally like very rarely it'll bog slightly on hard accel, richen LSN a tad more? I richened both needles by 3/4 turn.
 
I have a temp gun, how else would i know it runs 220F? :p:
Factory says nothing about it, hey occasionally like very rarely it'll bog slightly on hard accel, richen LSN a tad more? I richened both needles by 3/4 turn.

Like I say, that last little bit of performance can be hard to get sometimes. Just go out and mess with it, in one hour increments as described above. It took me forever to get my S25 "just right". And about the time I did, I had to tear it down and work on it. LOL
 

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