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Old 04-06-2008, 05:48 PM   #1
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Default MAJOR Engine troubles (i think...)

Hi, Guys, Ive never used a RC car Forum so i hope this is the right spot to ask this kind of question.

I was driving today and noticed my car was making a funny noise, and that it was also losing power more and more every minute i drove it. It turns out one of the problems was i was accidently running "lean". I "richened" it and after that it ran A LOT better. But i was still hearing a funny noise...

I took it into the shop and started to take the flywheel apart to see what was wrong with it. I couldnt notice any damage, but im new to this, and all i know is my flywheel is broke! it just spins freely and doesnt catch on to spin the "engines insides" Thats my 1st problem

My 2nd problem is the bearings need to be replaced in my engine and im not sure how to do that or what size. I read the instruction book and couldnt figure it out, they also didnt tell me what size bearings I need, I have some 8x16s on hand.

My 3rd problem, and what I think (but i dont know anything about RC engines) is my most serious problem, is the piston kind of gets stuck when it hits the very top of the sleeve. Is this because my engine is completely taken apart? is it because the bearing is wrecked?

Im also having a hard time taking the piston, conrod and crankshaft apart/out of the engine. I'd like to take a look and see how things work, clean it out a little bit, maybe oil it.

Thanks A LOT in advance to everyone who answers (and everyone who tries to answer)

PS; My engine is a LRP Z.28R Spec.3 Pullstart


Carl
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Old 04-06-2008, 07:09 PM   #2
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Quote:
Originally Posted by new to rc cars View Post
Hi, Guys, Ive never used a RC car Forum so i hope this is the right spot to ask this kind of question.

I was driving today and noticed my car was making a funny noise, and that it was also losing power more and more every minute i drove it. It turns out one of the problems was i was accidently running "lean". I "richened" it and after that it ran A LOT better. But i was still hearing a funny noise...

I took it into the shop and started to take the flywheel apart to see what was wrong with it. I couldnt notice any damage, but im new to this, and all i know is my flywheel is broke! it just spins freely and doesnt catch on to spin the "engines insides" Thats my 1st problem

My 2nd problem is the bearings need to be replaced in my engine and im not sure how to do that or what size. I read the instruction book and couldnt figure it out, they also didnt tell me what size bearings I need, I have some 8x16s on hand.

My 3rd problem, and what I think (but i dont know anything about RC engines) is my most serious problem, is the piston kind of gets stuck when it hits the very top of the sleeve. Is this because my engine is completely taken apart? is it because the bearing is wrecked?

Im also having a hard time taking the piston, conrod and crankshaft apart/out of the engine. I'd like to take a look and see how things work, clean it out a little bit, maybe oil it.

Thanks A LOT in advance to everyone who answers (and everyone who tries to answer)

PS; My engine is a LRP Z.28R Spec.3 Pullstart


Carl
1. It sounds to me like the fly wheel collet may have worn out due to the clutch nut not being tight enough try replacing that first

2. how old is the engine and why do you think the bearings need to be replaced. if they do 8x16s wont do it unfortunately I don't personally know much about LRP engines but at a guess I would say that the front bearing is a 7x19x6 and the rear bearing if its a 14mm crank would be a 14x25.4x6.

3 the piston should get "stuck" at the top of the sleave if pushed all the way to the top it is called pinch and it happens because the sleave is actually tappered. To get the piston and rod off the crank you need to first remove the sleave I normally do this using a proper tool but if you don't have one you can use a cable tie. remove the colling head off the engine and place the head of the cable tie into 1 of the ports while the piston is at the bottom(BDC) then carefully & slowly turn the engine over with your hand to push the sleave out. once the sleave is out the rod should come off the crank ralitively easily unless it is a new engine.

MAKE SURE YOU TAKE NOTE OF HOW EVERY THING COMES OUT AND PUT IT BACK IN THE SAME WAY

good luck

Adrian
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Old 04-06-2008, 07:23 PM   #3
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Originally Posted by RETRO RC View Post
1. It sounds to me like the fly wheel collet may have worn out due to the clutch nut not being tight enough try replacing that first

2. how old is the engine and why do you think the bearings need to be replaced. if they do 8x16s wont do it unfortunately I don't personally know much about LRP engines but at a guess I would say that the front bearing is a 7x19x6 and the rear bearing if its a 14mm crank would be a 14x25.4x6.

3 the piston should get "stuck" at the top of the sleave if pushed all the way to the top it is called pinch and it happens because the sleave is actually tappered. To get the piston and rod off the crank you need to first remove the sleave I normally do this using a proper tool but if you don't have one you can use a cable tie. remove the colling head off the engine and place the head of the cable tie into 1 of the ports while the piston is at the bottom(BDC) then carefully & slowly turn the engine over with your hand to push the sleave out. once the sleave is out the rod should come off the crank ralitively easily unless it is a new engine.

MAKE SURE YOU TAKE NOTE OF HOW EVERY THING COMES OUT AND PUT IT BACK IN THE SAME WAY

good luck

Adrian
1.the clutch nut is tight, I know because it WAS coming loose a few times, so this last time (a week ago) I sealed it down with Blue Loctite! you could be right though, I definately need a new flywheel.

2. the engine is about 4 months old, ive ran about 1.5 gallons through it. I dont know if they NEED to be replaced, but I think its about time, itll make tings run smoother, maybe. And when I look inside the engine from the back (i have the Pullstart off) i can see the beads of the bearing... isint there supposed to be some shield there? I wish the instruction manual would tell me the dimensions. I will search online later when I have more time.

3. I dont think this "stuck" im taking about is a pinch, although i hope it is. It almost seems to get "jammed" up there, maybe im wrong, but it doesnt feel like a "pinch stuck" it feels more like a "somethings bent inside my engine or something" stuck. I hope im wrong....

Very very good advice with the zip tie, I would have NEVER figured that one for myself. I'll try that later tonight, let you know how it works.

thanks a lot for all the help Adrian

Carl
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Old 04-06-2008, 07:25 PM   #4
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Oh yeah, maybe i should mention this about my flywheel.

When I took it off, the inside and the bearing in there was covered in tiny gold shavings (IM RICH!!!). Something in the flywheel definately got powderized.... i dont know what a new flywheel looks like so I cant tell exactly whats wrong. Ill get pics later tonight, or tomorrow.
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Old 04-06-2008, 09:51 PM   #5
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Those gold shavings are most likely the collet, the tappered peice that slides on over the crankshaft and the flywheel seats on to.
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Old 04-06-2008, 09:56 PM   #6
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also the bearing's do look like that on the inside belive me if they came apart inside u would have no motor left.
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Old 04-06-2008, 10:18 PM   #7
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Make sure BEFORE you pull the back plate off that the piston is at the top. I have seen several piston skirts broke because the piston was at the bottom when the back plate was removed.
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Old 04-07-2008, 02:58 PM   #8
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Those gold shavings are most likely the collet, the tappered peice that slides on over the crankshaft and the flywheel seats on to.
ok, guess ill order a new flywheel. thanks for the info.

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Make sure BEFORE you pull the back plate off that the piston is at the top. I have seen several piston skirts broke because the piston was at the bottom when the back plate was removed.
Too late...I dont understand how that would break something. As far as I can tell, theres no damage. I hope youre wrong.. (no offense)

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also the bearing's do look like that on the inside belive me if they came apart inside u would have no motor left.
OK, i was just a bit worried, Im new to this



Few More questions.

How come the top of my piston is brown? and how come when I took my motor apart, there was about 5ml of an oily substance in it? Im going to assume that it is unburnt fuel? so if I "leaned" my engine out a little bit would that stop it? and i also had about 15ml of the same oily stuff leaf outta my exhaust... whats with that?

thanks for the help guys.
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Old 04-07-2008, 04:53 PM   #9
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Loctite-ing the clutchnut does not mean everything is tight. If you had that problem before and now this time, plus the collet getting chewed up.. Sounds like you need a shim behind the collet so everything actually tightens up and pinches onto the collet.

You will get oil coming out the pipe and left in the engine. That is just oil left over from the combustion process. Same with the colored top of the piston. You can polish it off the top of the piston, but leave the sides and the sleeve alone. The unburnt fuel and buildup on the piston is different with different fuels. Some even turn the engine insides different colors. No big deal. Also if you run rich you get more. But it doesn't hurt anything and rich is good.
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Old 04-07-2008, 06:26 PM   #10
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If you notice on the inside of the back plate there is a milled out section for the piston skirt to clear. Leaving the piston down can break the skirt off because it sits in that groove.
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Old 04-10-2008, 03:31 PM   #11
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ok, a few more questions guys!!

What size of flywheel do I need, I ordered one of these (http://www.carolinasrc.com/webstore/...?idproduct=181) I hope it fits but I am not sure..

How come when I tighten my backplate real tight, it doesnt let me engine spin? I've tried putting Green Slime in it and it still seems to be jamming up, i have to leave my backplate kind of loose, whats with that?

How come my muffler doesnt quite make an air-tight seal at the back of my engine, the "gromit" seems to be too thin, and it leaks a black oil all over my pullstart.

Thanks in advance.
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Old 04-11-2008, 03:28 PM   #12
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Hey guys, I just worked on my car and its having some serious problems, the piston is very very very hard to get to the top of the sleeve, when i put the backplate on, it makes it almost impossible to spin, but nothings wrecked or bent. What is the problem there?
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Old 04-12-2008, 05:18 AM   #13
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How come no one is answering me?
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Old 04-13-2008, 05:45 AM   #14
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Whats going on.... did I do something wrong?
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Old 04-13-2008, 04:11 PM   #15
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the piston not fitting threw the top of the sleeve is normal because they run a tappered bore to make compression seeing as they dont use rings

did its spin freely befor u put the backing plate on

also chech that u have every thing the right way in and that u havnt got the backing plate on the wrong way
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