how did this happen ?

[tonyts50]

ok took my head of the other day after blowing up my suzuki ts50
the piston has hit the spark plug and put a hole in the piston what could of caused this to happen ???

\/ picture \/

https://i391.photobucket.com/albums/oo360/tonymini145/Photo-0066.jpg
____________________
tony ts50 gone from off road to on road to back off road cat c write off

why am i such a prick !!!! im such a fucking soppy bollocks

[Kickstart]

Hi

Suspect it has just burnt a hole through the piston. Compression too high, ignition timing too advanced or fuel of too low an octane rating.

All the best

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[tonyts50]

[hmmmnz]

pretty much as kickstart has said.
why do you think you have no back pressure??
a 2 stroke will barely run if it has no back pressure, thats half the principal of a 2 stroke,
are you running premix?? are you running the premix too rich (making it run lean) have you rejetted to suit the bigger bore??
so many variables.....
____________________
the humans are dead
I kick arse for the lord
Wiring Diagrams BIDNIP it bitches

[tonyts50]

[mr rip]

I had the best results with mine running an 82.5 main jet with the standard carb & air box (air fillter removed), with a 49mm bore, the exhaust was derestricted by cutting the front pipe open & drilling out the restrictor plates (found near the back where the pipe starts to narrow before going out to the tail piece)

if you can get hold of one of the ally tail pieces (like dep sport or somthing of that ilk) that you can get the end cap out of, take all of the silencer wool out of it, then re stuff it so the wool is realy loose, it'll run wisper quiet but you will have to re pack it every few weeks as it gets louder as it fills up with spent oil & crap

looking at your photo, I have to agree with the others in saying it looks like a combination of poor timing & over weak mixture,
____________________
never criticise a man until you've walked a mile in his shoes, then when the muck hits the fan you'll be a mile away & you'll have his shoes

[tonyts50]

so how do i rectify this fault ?
____________________
tony ts50 gone from off road to on road to back off road cat c write off

why am i such a prick !!!! im such a fucking soppy bollocks

[tonyts50]

also thanks for your info im now going to premix but how much to how much ? say how much 2 stroke to 5liters of fuel ??
____________________
tony ts50 gone from off road to on road to back off road cat c write off

why am i such a prick !!!! im such a fucking soppy bollocks

[hmmmnz]

you have gone to a larger carb?? what size main jet is in there??

removing the baffles from the silencer doesnt remove the back pressure,
its just a silencer, all the 2 stroke magic happens in the expansion chamber.
if you do run premix, then remember to disconnect the oil pump hose and block it off,
run between 33 to 1 and 50 to 1
so between 20 to 30mls per litre
use https://www.at-speed.com/air/oil_gas_calc.html
to make it easier,
____________________
the humans are dead
I kick arse for the lord
Wiring Diagrams BIDNIP it bitches

[tonyts50]

not very big as the engine was very hard to start all the time so the main jet was put down from standerd due to ( flooding )
____________________
tony ts50 gone from off road to on road to back off road cat c write off

why am i such a prick !!!! im such a fucking soppy bollocks

[tonyts50]

also how will i block it off ?
____________________
tony ts50 gone from off road to on road to back off road cat c write off

why am i such a prick !!!! im such a fucking soppy bollocks

[Kickstart]

Hi

What compression is it running with the big bore kit?

24mm sounds like a massive carb for a 50 bored out to 80cc. The main jet should be irrelevant for starting, so switching to a smaller one shouldn't make any difference to how difficult it is to start. Main jet is only relevant at large throttle openings.

As a stock TS50 has either a 12, 15 or 16mm carb, how are you choosing a "stock" main jet to use?

All the best

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[mr rip]

I wouldn't sudgest running it pre mix, it's more hassle than it's worth
you have to carry oil bottles around with you all the time as hardly any garages stock the stuff anymore & you can't fill up without it or it'll seize up in less than a mile

your throttle slide should have a drilled mark in it & the carb should have a corresponding screw in the body that you can use to set the oil pump (the standard carb does, anyway), take the screw out & twist the throttle untill the mark in the slide reaches the top of the hole in the body, now adjust the cable, at the pump housing,so the two marks on the oil pump line up (the oil pump is behind the front sprocket)

i've bought a few of these in the past, & the previous owner has just adjusted the pump until the two marks line up, with out the throttle being in the correct position & it causes all manner of problems
____________________
never criticise a man until you've walked a mile in his shoes, then when the muck hits the fan you'll be a mile away & you'll have his shoes

[tonyts50]

so mr rip you saying that my throttle was wide open because it was every time i started the bike with out touching the trottle it just revved it self all the way to 11000rpm and it sat there
____________________
tony ts50 gone from off road to on road to back off road cat c write off

why am i such a prick !!!! im such a fucking soppy bollocks

[Kickstart]

Hi

If it revs straight to 11k it suggests either the throttle was open or there is an air leak after the carb (doesn't take much throttle to give those revs when the engine isn't under load).

What he is suggesting is the correct way to set the oil pump when using the stock carb.

However you are using a far larger carb than standard ( and I would doubt it needs anything that large - 24mm is the stock size for an MBX125, probably capable of almost twice the power of your engine). Even compared to the largest stock size used (16mm), the 24mm carb is 125% larger in area. A massive amount.

Main cause of the damage you have suffered is either too low fuel octane rating, too high compression or too advanced ignition timing. Running lean would make any of these more likely to cause a problem. I take it the timing is standard, but after playing with a big bore kit what compression ratio have you landed up with?

What main jet are you using? What do you mean by a "standard" main jet, given that the carb is nothing like standard for the engine?

All the best

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[tonyts50]

sorry kickstart no idea what you mean by this paragraph put it bluntly in dumb lol

Main cause of the damage you have suffered is either too low fuel octane rating, too high compression or too advanced ignition timing. Running lean would make any of these more likely to cause a problem. I take it the timing is standard, but after playing with a big bore kit what compression ratio have you landed up with?
____________________
tony ts50 gone from off road to on road to back off road cat c write off

why am i such a prick !!!! im such a fucking soppy bollocks

[Blau Zedong]

"Piston hit the spark plug"

Oh Tony you lol me so much!

If someone was ever ill suited to riding around on a hugely overtuned 2T, it would be you. You've chucked bits together with no forethought on setup or even if they will work.
____________________
18:54:48 Rob Fzs: jews don't give away stuff for free

18:54:59 Rob Fzs: unless its their clothes/ hair/ golden teeth

[tonyts50]

it did all work untill it started to jam on trottle and revv by itself and the it went dead thats what wrong piston has hole in and spark plugs mullerd so i think piston hit plug sorry for my downieness i dunno about compression shit lol i just bout the kit bolted up started it rode off
____________________
tony ts50 gone from off road to on road to back off road cat c write off

why am i such a prick !!!! im such a fucking soppy bollocks

[Kickstart]

Hi

Right, trying to go back a few stages.

The fuel / air mix in the cylinder is ignited and burns. As it burns it pushes down on the piston. What you want is a steady burn, not a sudden violent explosion. If the piston is at the very top of the bore then it cannot push the piston down at all (but the momentum of the crank means that it is only like that for a short time).

The fuel / air mix can also ignite just from pressure. Of course as the fuel / air mix burns and expands it increases the pressure within the cylinder anyway, so pockets of unburnt fuel / air mix can rise in pressure enough to just explode. This is known as detonation. At best this will generate a hell of a lot of extra heat (melting holes in pistons and melting spark plugs), but can have a similar effect to hitting the top of the piston with a hammer.

The higher the compression ratio (which is the ratio of the combustion chamber to the total volume of the cylinder and combustion chamber) then the higher the pressure in the head, and so more likely that the pressure will be high enough for the fuel / air mix to ignite on its own. However the higher the compression the more power you get, so it is a balancing act.

Petrol has an octane rating, which is its resistance to detonation. It is measured as the fuels equivalence in resisting detonation to a mix of 2 control fuels, iso-octane and n-heptane. 95 octane fuel has the detonation resistance of a fuel made of 95% iso-octane and 5% n-heptane. If you use a fuel of too low an octane rating then it will be more likely that you will get detonation. There are 2 real ways that a higher octane fuel can resist detonation, either by burning more slowly (so the pressure builds more slowly, but which will cost power) or by being less prone to just exploding due to pressure.

Normally the engine generates a spark before the piston reaches the top. This is so that there is enough time for the flame to spread and start to generate a large downward force on the piston for when the con rod is at a decent angle to the crank to transfer that pressure and turn the crank. If you ignite the fuel /air mix too early then the piston will not have moved down enough by the time the pressure rises enough to cause detonation. If you ignite the fuel / air mis too late then you miss the most effective time for the pressure to push the piston down and turn the crank.

So from that I hope you can see that if you raise the compression (which you quite likely have depending on what the big bore kit ws designd for), then you are more likely to get detonation. You can counter this by using higher octane fuel (which will likely produce slightly less power due to burning more slowly) or retarding the ignition timing (again will lose you power, as the most useful part of the fuel burning will happen later than is best).

The 3 things are a balancing act, and just playing with one and hoping for the best can easily result in damage (such as the hole burnt in your piston).

Running lean will make the engine run hotter anyway, and a lean mix is far less resistant to detonation.

All the best

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[Kickstart]

Hi

To add to the above, there is also the problem of preigition. You get this when part of the combustion chamber gets hot enough to act to ignite the fuel / air mix. Such as a built up of carbon that starts to glow. This can cause the engine to carry on running even when the ignition is switched off, but also there is the possibility that it will ignite the fuel / air mix before the ignition system would, so giving much the same destructive effect as advancing the ignition timing.

All the best

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[tonyts50]

it will only do 28mph if i do that ! so no way mate but heres what im prob gunna do

70 bore kit
irridium sparkplug
jet air down all the 2 stroke oil pipes to clean out any shit
bigger jet to make fuel and oil get into the piston quicker
set carb up properly but i have no idea how to do this e.g how many turns does the idle control jet need to be turned ect ?
____________________
tony ts50 gone from off road to on road to back off road cat c write off

why am i such a prick !!!! im such a fucking soppy bollocks

[mr rip]

buy yourself a workshop manual, you'll have plenty of time to read up on all the relevant chapters on adjustments & settings cause the bike is gonna spend most of it's working life in bits by the sound of it
____________________
never criticise a man until you've walked a mile in his shoes, then when the muck hits the fan you'll be a mile away & you'll have his shoes

[Pete.]

IMO you've holed the piston through too-lean a mixture. Also remember if you've bored the 50cc barrel for a 80cc piston your barrel hasn't the fin area to cope with the extra heat developed, so any full-power blasts should not be held for continuous miles - you have to rest the engine to allow the heat to dissipate.

Your lube system is probably just fine, or you would have seized it not holed the piston. Rebuild the engine and sort the mixture, IMO.
____________________
a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[Wafer_Thin_Ham]

Bookmark this thread, come back and read it in 5 years time. Then cringe.
____________________
My Flickr

[Kickstart]