Big Bore Woes-Seizure before it even started

[GoodDerf]

So as you can guess from my title I got everything back together. I was meticulous when I put it back together to make sure the rings were in the proper alignment. I also oiled the * out of the piston and the cylinder. However on the second cranking to try and get it to start I thought the battery had died, like the first time and I had been to impatient with the battery charger (It sat for maybe 2 minutes so I was pretty impatient). So I charged the battery went to start it and the engine had seized. Since I put the big bore on the engine hasn't started, and if I had to guess at most the piston rotated maybe 50 times ( That is probably being generous). I decided to that maybe I had done bad with the pulley cover on and took it off. The starter look jamed so I went to take the gear off to see what was going on and in doing so the engine un-froze. However now the engine when hand turned will get real tight and I can hear scraping in the cylinder. I haven't forced it, being scared of what will happen.

So I have given up for the night but I see another teardown in my future, but I was wondering what you all think could have freaking happened in that cylinder to cause this.

[gatfu]

I just installed my new big bore 2 nights ago and thought I had the same problem. Your piston isn't siezed. what's happened is now the compression is very high. so high its hard to crank by hand. do to this reason you need alot more cold cranking amps from your battery to crank it over cold. and being that the spree batteries are pussies they will lose cranking amps after trying to cold start it for a couple of times. I was confused by this at first cuz my battery would read 12.6 volts, however its not the voltage that does the cranking its the amps. I too was to impatient to let a charger charge the d*** thing all night. What you need to do is just jump the battery to your car for the first start up. ( alot more cold cranking amps). once it has been started that way and warmed up your spree battery will have enough of a charge to restart a warm engine.

As far as that scraping noise you heard I heard the same thing as well when i hand cranked it. i thought my s*** was * so I tore it down twice. i found no scratches or grooves in either the piston or jug. I finally came to realize that the scraping I heard wasn't scraping, rather it was those new rings sealing nice and tight.

every thing is now running great once i figured the whole battery/high compresion thing. been running it for two days tryin to break her in and have had to jump it twice from a cold start. once warmed up i can start and stop the d*** thing all day with the spree battery. I figure once the rings are broke in i shouldn't need to jump it from a cold start anymore that or I just need to find a battery that has more amps.

[benH]

slightly off topic but out of curiosity, did you have to upjet the carb or anything for the big bore kit, or could you just tune it the way it was? im trying to see if you need anything else besides the parts that come with the kit itself.

also, slightly more on topic, can you not kick start it? or just can't get the starter and battery to start it with the button from cold?

good luck

[Wheelman-111]

Greetings:

Quoth BenH:

did you have to upjet the carb or anything for the big bore kit, or could you just tune it the way it was?

The only way to "tune" the engine for high output conditions is to remove and reinstall main jets. That idle speed mixture screw adjusts only the fuel/air ratio of the idle circuit. Do some reading here and you'll see several examples of the consequences of failing to match the main jet with the larger displacements and higher RPM of Big Bore Kits + Pipes.

Polini (and I think Malossi) bore kits come with a main jet sized for the bore kit install alone. If you swap the stock airbox for a K&N or a pod filter, the jet must be enlarged (swapped for bigger) again.

[Bear45-70]

I just installed my new big bore 2 nights ago and thought I had the same problem. Your piston isn't siezed. what's happened is now the compression is very high. so high its hard to crank by hand. do to this reason you need alot more cold cranking amps from your battery to crank it over cold. and being that the spree batteries are pussies they will lose cranking amps after trying to cold start it for a couple of times. I was confused by this at first cuz my battery would read 12.6 volts, however its not the voltage that does the cranking its the amps. I too was to impatient to let a charger charge the d*** thing all night. What you need to do is just jump the battery to your car for the first start up. ( alot more cold cranking amps). once it has been started that way and warmed up your spree battery will have enough of a charge to restart a warm engine.

As far as that scraping noise you heard I heard the same thing as well when i hand cranked it. i thought my s*** was * so I tore it down twice. i found no scratches or grooves in either the piston or jug. I finally came to realize that the scraping I heard wasn't scraping, rather it was those new rings sealing nice and tight.

every thing is now running great once i figured the whole battery/high compresion thing. been running it for two days tryin to break her in and have had to jump it twice from a cold start. once warmed up i can start and stop the d*** thing all day with the spree battery. I figure once the rings are broke in i shouldn't need to jump it from a cold start anymore that or I just need to find a battery that has more amps.

That is exactly backward to what actually happens. A new bore and rings do not seal well until they have been "broken in". So after break-in the compression will be higher, not lower. Hence your hard to crank over theory does not work.

The noise thing is normal even for a broken in engine. Piston rings sliding up and down the cylinder wall is noisy. When you either kick start or use the electric start, there is enough noise from those operations to cover the ring/cylinder noise is why you don't hear it. More oil in the cylinder helps but will not make the noise go away.

[GoodDerf]

Well I took apart my top end and found out something is going on with the crankshaft. I figure if it was to do with the cylinder, with it off there shouldn't be any turning problems, but unfortunately there still are. Yey, I guess my engine figured I took brought everything else up to spec I might as well tear the crankcase apart to and check everything in there. I am not going to be able to ride this scooter until spring now. So seeing as I am going to be rebuilding the crankshaft anyways, are there any upgrades I can do while I am in there?

[gatfu]

I just installed my new big bore 2 nights ago and thought I had the same problem. Your piston isn't siezed. what's happened is now the compression is very high. so high its hard to crank by hand. do to this reason you need alot more cold cranking amps from your battery to crank it over cold. and being that the spree batteries are pussies they will lose cranking amps after trying to cold start it for a couple of times. I was confused by this at first cuz my battery would read 12.6 volts, however its not the voltage that does the cranking its the amps. I too was to impatient to let a charger charge the d*** thing all night. What you need to do is just jump the battery to your car for the first start up. ( alot more cold cranking amps). once it has been started that way and warmed up your spree battery will have enough of a charge to restart a warm engine.

As far as that scraping noise you heard I heard the same thing as well when i hand cranked it. i thought my s*** was * so I tore it down twice. i found no scratches or grooves in either the piston or jug. I finally came to realize that the scraping I heard wasn't scraping, rather it was those new rings sealing nice and tight.

every thing is now running great once i figured the whole battery/high compresion thing. been running it for two days tryin to break her in and have had to jump it twice from a cold start. once warmed up i can start and stop the d*** thing all day with the spree battery. I figure once the rings are broke in i shouldn't need to jump it from a cold start anymore that or I just need to find a battery that has more amps.

That is exactly backward to what actually happens. A new bore and rings do not seal well until they have been "broken in". So after break-in the compression will be higher, not lower. Hence your hard to crank over theory does not work.

The noise thing is normal even for a broken in engine. Piston rings sliding up and down the cylinder wall is noisy. When you either kick start or use the electric start, there is enough noise from those operations to cover the ring/cylinder noise is why you don't hear it. More oil in the cylinder helps but will not make the noise go away.

whether the rings are broken-in or not the fact that its harder to crank over due to the higher compresion than from before with the stock piston isn't really a theory. I could turn the old piston with hardly any effort. new piston is definitly harder to turn over do to the new higher compresion than stock. I know for a fact whether broken in or not the new piston is harder to crank over due to higher compresion and thats not a theory. in fact your the one who told me this when I posted the same problem a few days ago and I quote...."That's called higher compression, AKA new found power. First make sure your battery is fully charged. Should read about 12.6 volts when fully charged and when cranking the engine (spark plug in) no lower than 10.5 volts or the battery is bad."

[Wheelman-111]

Greetings:

Quoth GoodDerf:

Well I took apart my top end and found out something is going on with the crankshaft.

WHOA, Dude! Hold on a minute there. Don't try to dazzle us with all that Tech Talk. "Somethin's going on?" We're not all mechanical engineers on here, so please try to keep it in layman's terms.

If you mean abnormal friction of some kind, hopefully this means you just dropped a cufflink in there when you buttoned it up. Check your sleeves now... If you didn't split the cases until now, is there any reason to believe you could have applied severe side-loads or twisting forces across the crank. The two flywheels have to be precisely aligned in all three planes. However they're pretty danged tightly pressed together, and it really takes some doing to move them so much that they start to touch the cases. Impact tools and dropping-the-block-on-a-crank-end type of forces.

I'd have a really close look for whatever you can see from up top. Maybe a few passes with a magnet tied to your ol' fishing pole too. Hopefully it's something simple you can resolve in time for the end of riding season.

Good luck!

[GoodDerf]

Yes I do mean abnormal friction and by abnormal friction I mean 'oh my god what is going on in there' and it scares me to turn it over more than has been necessary.

Yeah There is reason to believe that there as been abnormal force, remember yesterday with all the trouble I was having with the flywheel coming off? Well I did the hammer trick so I would assume that would classify as abnormal force. Along with that there was messing around of getting the engine back in, I never dropped it but there was the normal finagling of trying to get everything to line up.

[Bear45-70]

whether the rings are broken-in or not the fact that its harder to crank over due to the higher compresion than from before with the stock piston isn't really a theory. I could turn the old piston with hardly any effort. new piston is definitly harder to turn over do to the new higher compresion than stock. I know for a fact whether broken in or not the new piston is harder to crank over due to higher compresion and thats not a theory. in fact your the one who told me this when I posted the same problem a few days ago and I quote...."That's called higher compression, AKA new found power. First make sure your battery is fully charged. Should read about 12.6 volts when fully charged and when cranking the engine (spark plug in) no lower than 10.5 volts or the battery is bad."

This is obviously a personal attack and I will just say you don't know the truth and even if you did you are still probably not bright enough to recognize it. Getting one side of the story from a poor loser is real bright.

[GoodDerf]

Bear you seem to be getting gatfu and myself confused. I am the one who admitted something wrong with the rotating assembly. I am the one who started this topic and have said nothing about higher compression. Gatfu on the other hand has been the one going on about higher compression.

[Bear45-70]

Bear you seem to be getting gatfu and myself confused. I am the one who admitted something wrong with the rotating assembly. I am the one who started this topic and have said nothing about higher compression. Gatfu on the other hand has been the one going on about higher compression.

I edited the post to covey what I wanted to say. I got caught up in the technical crap and lost track of what I was really trying to say. GoodDerf, if I offended you I am sorry.

[GoodDerf]

It is all good Bear, I figured it was just a simple mistake of reading to fast. I pointed out what was going on so could pwn the newb correctly.

[gatfu]

whether the rings are broken-in or not the fact that its harder to crank over due to the higher compresion than from before with the stock piston isn't really a theory. I could turn the old piston with hardly any effort. new piston is definitly harder to turn over do to the new higher compresion than stock. I know for a fact whether broken in or not the new piston is harder to crank over due to higher compresion and thats not a theory. in fact your the one who told me this when I posted the same problem a few days ago and I quote...."That's called higher compression, AKA new found power. First make sure your battery is fully charged. Should read about 12.6 volts when fully charged and when cranking the engine (spark plug in) no lower than 10.5 volts or the battery is bad."

This is obviously a personal attack and I will just say you don't know the truth and even if you did you are still probably not bright enough to recognize it. Getting one side of the story from a poor loser is real bright.

dude i wasn't personally attacking you. I was trying to point out that the problem he was describing was the exact description of the problem i had a few days earlier and what "you" told me was the solution and it worked for me. then two days later i was trying to explain how my problem sounded like the same problem he had and that "your" solution helped me out and then you "say" its theory. meant no offense man.

[Bear45-70]

whether the rings are broken-in or not the fact that its harder to crank over due to the higher compresion than from before with the stock piston isn't really a theory. I could turn the old piston with hardly any effort. new piston is definitly harder to turn over do to the new higher compresion than stock. I know for a fact whether broken in or not the new piston is harder to crank over due to higher compresion and thats not a theory. in fact your the one who told me this when I posted the same problem a few days ago and I quote...."That's called higher compression, AKA new found power. First make sure your battery is fully charged. Should read about 12.6 volts when fully charged and when cranking the engine (spark plug in) no lower than 10.5 volts or the battery is bad."

This is obviously a personal attack and I will just say you don't know the truth and even if you did you are still probably not bright enough to recognize it. Getting one side of the story from a poor loser is real bright.

dude i wasn't personally attacking you. I was trying to point out that the problem he was describing was the exact description of the problem i had a few days earlier and what "you" told me was the solution and it worked for me. then two days later i was trying to explain how my problem sounded like the same problem he had and that "your" solution helped me out and then you "say" its theory. meant no offense man.

Sorry took it wrong. It appears I'm tad bit defensive this weekend.