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Post by rallyfinnen on Apr 6, 2009 7:12:24 GMT -5
So, another nail in my FS coffin.. Did some driving today again, and blew the piston.. Was just doing normal driving, a lot of part throttle and suddenly while idling, the engine stopped. When i pulled the stater i could feel the compression was bad, and after the engine had turned a rev or two, it stopped turning. I took it home and opened it up, and could see a part of the piston had come off. One small dent in the cylinder, on the upper edge of one of the transfer ports, but I would say it's still usable. I removed a little bit of material on the sides of the piston when the engine was new, but did not touch this area, so i think it's a fatigue problem. No signs of dirt entering the engine either, that would have cased the failure. Has anybody else seen this? Do you know what pistons will fit?
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Post by rallyfinnen on Apr 6, 2009 7:20:48 GMT -5
After some more digging i found that a part of the washers centering the con-rod & bearing in the piston was in the crank case. I think this is the real 'cause of death' not the piston.
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Post by speedyd on Apr 6, 2009 8:44:27 GMT -5
awsome carnage!
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Post by fsmt4wd on Apr 6, 2009 8:59:57 GMT -5
the zen 4 bolt head and piston fit, and replace the crank while you are at it..
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Post by rallyfinnen on Apr 6, 2009 11:20:00 GMT -5
A zen is too expensive, going that route I end up with a car that cost the same as a MCD in the first place (well at least close), and I hate to admit I made the wrong choice :-) The good news is that Ronny Melkus at Melkus kartbahn, where I bought the car, seems willing to send me the needed parts without charge! So, even if I paid a bit more for the car, it seems to be a good investment in this case :-) Engine is in pieces now, and I'm cleaning all the parts. I'm thinking that maybe i should have better washers made, not so keen on putting in the same s**t again..
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Post by fsmt4wd on Apr 6, 2009 11:30:08 GMT -5
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sickboy
Full Member
hey hook me up with another fs www.fshopups.com
Posts: 187
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Post by sickboy on Apr 6, 2009 13:11:56 GMT -5
hi rallyfinne
this happend to me to i just had a spare zen hagging around so it was a quick fix for me i no they are a bit high in prices but you could always get the cy motor or a second hand zen try that
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Post by rallyfinnen on Apr 7, 2009 2:19:59 GMT -5
Sickboy: did you have the piston blow too? do you know the reason? Maybe there is a common weak point on these engines that could be fixed so they would last a reasonable time? Too bad they can't produce a reliable engine, years ago I was running a Tech and Solo engines on track cars without any issues whatsoever, just replaced the piston ring a couple of times.
I made up my mind, if i ever replace the engine on this one, I will go for something more brutal.. like a chainsaw engine! :-) That will give me more bang for the buck compared to buying a zen! It's not so tight around the engine, so a bigger one could be fitted I think. I will definitely need the 4wd conversion in that case. I will never be competing with this one, so I don't have to worry about any engine regulations.
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Post by fsmt4wd on Apr 7, 2009 6:19:36 GMT -5
sounds interesting and im sure you are the one to pull it off...
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hoppy
Junior Member
BlownClone
Posts: 69
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Post by hoppy on Apr 9, 2009 18:13:59 GMT -5
Sickboy: did you have the piston blow too? do you know the reason? Maybe there is a common weak point on these engines that could be fixed so they would last a reasonable time? Too bad they can't produce a reliable engine, years ago I was running a Tech and Solo engines on track cars without any issues whatsoever, just replaced the piston ring a couple of times. I made up my mind, if i ever replace the engine on this one, I will go for something more brutal.. like a chainsaw engine! :-) That will give me more bang for the buck compared to buying a zen! It's not so tight around the engine, so a bigger one could be fitted I think. I will definitely need the 4wd conversion in that case. I will never be competing with this one, so I don't have to worry about any engine regulations. my stock fs engine did the same... less than 30 mins running, still throttle governed at 1/2 throttle... then she just stopped... and ya, the top end conrod/gudgeon pin spacer broke and smashed the internals... and i have read this happening time and time again in other forums... basically... the engines are simply crap. no quality at all. i figured ok, with upgrades and a new motor will be worth almost an mcd... but what do you do.... scrap the fs and lose all purchase money? or bite the bullet and repair it as things break so at least i can enjoy it. that's what i have done. i went out and bought a zen 4 bolter, a few upgrades, and had a blast of a time! awesome feeling having all 4 wheels frying tires, 70kph+ full side drift... at the end of the day, once a few of the weak points are improved, accidents and wear are going to happen regardless of name brand or clone car... i have questioned myself too since i bought my fs, but the fact is i have it so i might as well enjoy it :-D my fs onroad is in bits at the moment... sick of the weak chassis so i'm making a new one from 5mm ally, but folding the sides up to make it more rigid coz sick of the fs chassis bending so d**ned easily lol also making my own lower control arms (sick of popping.snapping rose joints), making an ally servo plate, and also ally shock towers but bracketing them to the chassis coz too much stress on the diff boxes. most of this i do myself... cheap, and eventually she'll become very reliable... i hope lol but ya, the zen is not cheap, but honestly she's an awesome motor. cy's are widely used and much cheaper, no doubt look for a second hand one chainsaw motor?? lol i have thought of a whipper snipper/ weed wacker motor... dont go too big otherwise you'll be stripping main gears, blowing differentials.... then you'll be really pissed off! lol even my zen gc270rc is borderline too much for the drivetrain i think... sadly my work has been insanely busy, havent touched my fs in weeks, but i will... :-D
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Post by fsmt4wd on Apr 10, 2009 1:55:08 GMT -5
a stock MCD also needs work and many upgrade the gears and gear plate and center diffs to alloy/steel. all in all a stock MCD costs as much as a Hopped Up FS. for about 1500 dollars you can have a FS that can withstand a hard bashing and reliable at the same time, i have spent well over 2000 euro on me truck and could easily drop another 1000 on her...just my bank is not so easy...
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Post by rallyfinnen on Apr 10, 2009 3:05:57 GMT -5
It sucks that the engines are so bad.. seems they would just need 'that little extra' to be fairly reliable. The precision on the engine is not 'porn for engine nerds', but i think it could be fairly usable if things like this would not kill it. Maybe I should try making some washers when i put it back together.. I saw the same happen to some guy with a 'carbon fighter' (basically a black FS) too, even with the stock muffler! Hoppy: were you running it with a pipe or the stock muffler when the piston blew?
Maybe if we can all conclude on the cause for blown engines, there might be a fix for that too!
Parts for my engine are on order from China, so it will take some time before I get them.. I don't know what engine I might put in if i replace the stock, depends on what i can get and what fits.. My car is already more expensive than intended from the start, but i'm definitely not going to go to the 2000Eur range :-) Actually thinking of getting a Carbon Fighter as a spare parts car. Just 299Eur..
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Post by rallyfinnen on Apr 10, 2009 4:59:21 GMT -5
Some thoughts about the the cause for piston/washer failure.. The centering of the con-rod is up to the washers in the piston. As you see on the crank, there is nothing to center the con-rod. Looking at the piston end, there is about 1mm axial play. I'm thinking this could cause the con-rod to work as a 'whip' at some engine speeds, destroying the washer. Or it like this: On the other hand, there is also some radial play in the washers, so maybe the constant rattling can cause them to brake with time.. There is of course no guarantee that the washers are the cause for the mayhem, they could also be a symptom, cracking because the piston twists when it breaks.. The wear pattern in the cylinder indicates that things are not properly lined up, with one side in the bottom end of the cylinder more worn/polished than the other. By that I mean that the cylinder is polished next to one pair of transfers, and still has the machining pattern on the other side. Any more ideas?
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Post by rallyfinnen on Apr 11, 2009 5:02:52 GMT -5
Some more photos.. The piston skirt is running pretty close to the crank, but I'm not sure it's close enough to touch at high revs.. There will be some stretching and compressing of the con-rod, but i would guess that would be limited to maybe 0,5mm.. However, with some play in the bearings, the piston might start to touch the crank..
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Post by rallyfinnen on Apr 12, 2009 4:51:20 GMT -5
I've been doing some more digging around.. Seems the Zen 260 piston should fit the FS. A piston is not that expensive, so that might be the way to make the engine reliable.. Here is a pic of the piston with some approximate dimensions: By the way, what other failures have you seen on the FS engine? If it's all bad, there is no use in trying to fix the piston problem..
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