FG Monstertruck - Engine Problems!

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MrFnisse

MrFnisse

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Hi guys, having a problem i just cant solve with the engine on my FG-MT.
Never had problems with the engine before, though the car had been standing unused for almost 2 years. I disassembled the entire car for a complete clean up since it looked like poop. Brought down the engine to and cleaned it out also, piston, cylinder etc. It was in fine condition no scratches on piston or on the cylinder walls.
Went out to give it a go with my girlfriend, it started fine but was a bit "boogish" or what you should call it. Mostly when throttling from 1/3 -> Max. It just went out from there. I tried every possible combinations with the High and Low needle the entire night but it just went from bad to worse. Eventually i had problems keeping it from stalling out on idle.

Then i got pissed and turned out the low needle really far and also the high needle then it went a bit better, but still unreliable. Anyone have any guesses what might cause this. I checked gaskets, there seems to be no leaks. Though i have ordered a new gasket set and will change them all anyways just to be sure. I checked the plug and there seems to be a spark, albeit a tiny one, but don't know how clear the spark should be on such a small engine?
Might it be the piston ring that need to be changed, though it feels like there is compression when drag the starter.
My biggest fear is that the entire carb has gone to hell. I just really need to use extreme needle settings for it to run at all.

The engine is stock and using a Victory MT pipe.

Any help will be much appriciated.
Cheers !
 
hrmm couldnt be a number of things, did you get any vid of it running? This would make it allot easier. Either its got an air leak or your carby's playing up.

take the needle to stock setting 1.5 on low and 1.25 on high and see how it idles, if idle is nice and low air leak may not be the problem. if its still bogging on 1/3 of throttle might be worth trying a different carb.

this may take a fair bit of troubleshooting but plenty of people here to help.
 
if you have to turn the needle way out then check the filter screen under the primerball on your carb. i had ruffly the same problem before and the screen was dirty. when i cleaned it out it was like a new motor again.
 
Thanks for the replys guys. I will try to record a video later today with my digital camera.

All the filters in the carb has been cleaned so that should not be the issue.
If i try the stock settings on the engine it will start, idle pretty high (not so high that the clutch engages though) and then it will die out. Then it wont start again unless i choke it. Then it will come to life for a second, then without the choke its the same thing again, it dies after idling pretty high.

Like i said if i turn out the needles 1 turn extra from stock settings (around 1 turn extra) it will atleast run. But only on 1/3 throttle, smoking pretty heavily. But as soon as i try to throttle above that it will just not ignite, you just get that hollow bogging sound. As soon i release the throttle it goes back to idle and continues to run. If i continue to give 2/3 throttle or more it will eventually die out. So i guess its something with the high needle or something.
I did notice that there was some gas on the carb before i took down the carb yesterday, around two areas. Around the throttle arm (the side that connects to the servo) but mostly around the carb against the insulator area. I checked the gaskets and cleaned them and the areas where they are connected. Didnt notice any leaks today when going over the carb.
Also one more thing, when pressing the fuel bauble it does seem to drag alot of air and the bauble really never fills up completly. Might give a hint of something being wrong? Dunno, this is driving me nuts.
 
no worries, lets concertrate on what you do have. Just to confirm its a G260 with stock carb?

should be able to point you in the right direction after seeing the vid.
 
Yup will try to get it up here asap.

The engine is totally stock with the exception of a K&N air filter and a Victory RC tuning pipe. The pipe arrived yesterday so it was this way with the stock can to, so i figured i might as well mount it since it cant make it worse :P

Will have to wait a bit more with the vid though since i leave in the middle of the city in a populated area so i cant run it here now in the morning. I also received a gasket renovation kit yesterday for the engine so will replace them all since some of them looked worn out, will do this before filming the vid for you.

I did order a Walbro WT-813HP last week so i will hopefully be able to try that carb out this week if nothing else helps.
 
It sounds like the high end is running too rich, if you unscrew the needle all the way out is it worn at all, if when you are tuning will it run if you lean out the top end?
 
I removed both the high and low needle and they don't look worn any of em. I just finished putting the engine back together after changing all the gaskets, gonna go out and start it now, doubt the gasket renovation will help any though. Will post results.

Just tried to get it to life, started and idled pretty ok with the stock needle settings. Though it would eventually die out after 30 sec or so if i didnt throttle up a bit. Turning out the L needle 1/2 turn more resulted in a permanent idle atleast. Still same problem with the higher rpms, with stock settings it just bogs out when throttling. When the L needle was turned out that half extra it atleast managed to rev up but it was not very stable at all.
Went over all seals with WD-40 no apparent change in the idle. :/
 
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As you describe it, it sounds that it is bogging down with too much fuel. Now if that was the case as you turn in the needles (clockwise) it should increase the idle speed. Also the adjustments need to be made very very small, like a 1/12th of a turn. What happens when you turn them in just a little on the High needle
 
i think i might know what the problem is, occured to me late last night when I was doing a carby swap on some of my engines, have you had the intake off at any stage? there is a small breather hole on the intake, make sure the hole is at the bottom, next is the spacer or gasket, also make sure the hole is at bottom to match intake.

I did this once and it would idle but wouldnt rev. I think this may be your problem.
 
I checked it out and the breather hole is aligned as it should be. I had been using both a stock intake and also tried a tuning intake (its a bit longer than the stock). The stock intake has breather holes both up and down so its impossible to mount wrong. The tuning one just has one but i checked and it is at the bottom. The seals and gaskets are all properly aligned. Will be checking if it helps to lean out the high needle today.
 
MrFnisse said:
I removed both the high and low needle and they don't look worn any of em. I just finished putting the engine back together after changing all the gaskets, gonna go out and start it now, doubt the gasket renovation will help any though. Will post results.

Just tried to get it to life, started and idled pretty ok with the stock needle settings. Though it would eventually die out after 30 sec or so if i didnt throttle up a bit. Turning out the L needle 1/2 turn more resulted in a permanent idle atleast. Still same problem with the higher rpms, with stock settings it just bogs out when throttling. When the L needle was turned out that half extra it atleast managed to rev up but it was not very stable at all.
Went over all seals with WD-40 no apparent change in the idle. :/
Click to expand...

have you put the high and low screws in the wrong holes i,ve had the same problem your having and thats all it turned out to be , the 2 screws look the same but there not,
 
michaellfc95 said:
my 5b done that in the end it was the plug
Click to expand...

I have ordered two new iridium plugs so i will hopefully have them soon. Thanks for the note.

pablo said:
have you put the high and low screws in the wrong holes i,ve had the same problem your having and thats all it turned out to be , the 2 screws look the same but there not,
Click to expand...

On my carb (the stock) the L and H needle are two different sizes so they will only fit in the correct hole so that's not it.
 
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