Dunna know Carlos, whether you'd be wasting your time, sorting out the crown, looking at those almighty scrawks down the side of that piston, or do you mean cleaning the head up inside, and replacing the piston?
-- Edited by NEV on Tuesday 14th of August 2012 05:36:27 PM
Yeah you have a 3BN which is a restricted cylinder head. The 3mb heads are alot smoother without the band you have on yours. If i were you I would try and get hold of a 3mb head and fit that but if you dont want to and want a good condition restricted one still then let me know.
-- Edited by AndyYam on Tuesday 14th of August 2012 07:49:03 PM
Yeh they are, I opened it up and they were sitting on the top of the piston. Lucky really, also none of it went into the transfer ports and down the side of the piston so the bore escaped too. Just gonna get a rebore and a top quality piston and rings from now.
Ha, what happened? I rode it with the knocking/tapping and brought shoddy parts. The knocking got worse and the engine felt like it was struggling and this was why, running with 1 and a half piston rings lol. Coupled with the other bits rattling around the top end. All good now, any idea how to smooth out the dome?
I have a couple of 3BN cylinder heads. You know they are restricted though? its the 3MB that offer higher compression. If you want a replacement 3BN i'll have a look to see if they are in good condition.
if ur gunna do the top end proply mate id get the bottom end stripped and make sure its clean, small bits will wreck a top end no point in doing if or it wont last long, my mate learned the hard way spend 150 on a replate then 100 on a new piston, gaskets, and all that **** be bothered to clean out the bottom end proply, got to the 2nd corner on the track and it locked up solid, stripped it and it looked like sum one had run it on premix sand ha
so the lesson here is...if ur gunna do it, DO IT R8 1ST TIME
Guy at yamaha said to turn the engine upside down and see what happens, If the parts are big enough they'll just fall out. Other than that he said to give the engine a few revolutions by hand and see if you hear any grinding or any resistance..
I dont fancy doing that cos even at hand speed you'll still do damage to the crank right? If the bits are big enough. So first step just drain the oil and see what comes out? I'm 99% confident that none of the bits went down the side of the piston as there wasn't any marks on the bore, the mark on the piston is exhaust side and there is a slight mark on the exhaust port so seems to me the bit that made that mark was thrown out of the exhaust right? I really hope I don't have to flush the bottom end because a) I can't afford bottom end rebuild bits and b) I'm not confident doing that, coupled with the fact I need the bike for work. :(
Guy at yamaha said to turn the engine upside down and see what happens, If the parts are big enough they'll just fall out. Other than that he said to give the engine a few revolutions by hand and see if you hear any grinding or any resistance..
I dont fancy doing that cos even at hand speed you'll still do damage to the crank right? If the bits are big enough. So first step just drain the oil and see what comes out? I'm 99% confident that none of the bits went down the side of the piston as there wasn't any marks on the bore, the mark on the piston is exhaust side and there is a slight mark on the exhaust port so seems to me the bit that made that mark was thrown out of the exhaust right? I really hope I don't have to flush the bottom end because a) I can't afford bottom end rebuild bits and b) I'm not confident doing that, coupled with the fact I need the bike for work. :(
nothing will come out when u drain the oil only oil..the crank cases and gearbox are completely sealed off on a 2 stroke mate
up to you but for the longevity of the engine id be stripping it and cleaning it out, as said b4 theres all sorts of nooks and crannies for clumps of rings to get stuk 2 under the crank and round the mains, ok to turn it by hand but soon as the motors running and the rpm rises, them little particles of iron ring wil cut thru the piston like hot knife fru butter, itwill be running on a grinding paste substance b4 long from all the bits, been here plenty time, always tricked my sen it wud be fine and lasted a day or 2 b4 it rattles its tits off
do it right 1 time and save ya sen £££ thats just my 2 peneth any way
I'm in no position to be able to strip and split the cases unfortunately :( I have no time as I work 6 days a week and I don't have the mechanical confidence to be doing that. **** my life
Dunna get too despondant Carlos, AndYam can't be too far away from you in Surrey, I'm sure he'd give you a hand if you asked nicely, petrol money, bacon butties and regular cups of tea can work wonders mate.
I've actually never done a bottom end rebuild. I've got about 3 bottom ends in my shed tha I would like to rebuild at some point. Was gonna use the photo guide That's on here somewhere. On Saturday I'm taking the bottom end out of a friends dt as he is getting it rebuilt. I think he plans to get stan Stephens to do the work but not 100% sure. As soon as he finds out a price then I can let you know how much it will costs if you like. I would offer to give it a go but without a bit of practise I wouldn't want to work on someone else's engine, jus in case I messed up.
If you're up for it, we can do a 2 man job on my bottom end? I have some know how on engines but I'm too scared to do it on my own and miss something. Whereabouts you from? I've put it all back together with a spare piston and new rings that I got but it don't start now so for now, I'm giving it up with it. Haha
shes rattley but stills runs good xD
