motor blew up

[ken007]

well what can i say , it blew up, only about 300k's on it since rebuild, when i started to pull it down the spark plug on that side was loose, like it still had a few turns to go loose, im thinking that caused it, it was getting plenty of oil, and going well, wasnt getting flogged, anyway the piston has disintergrated at the bottom and the top of the conrod broke off, not sure about the crank or the case at the moment, the barrel has had it as it was on 2mm over already and the small end bearing is nothing but needles all over the place, anyway such is life, i will pull it apart to see if the crank is alright and go from there,bit of a bugger .

[L.B.]

Oh Ken I feel for you man....
Hope its not too bad,what brand piston/rings you using?
I got some good 250 barrels here if ya need em.

[JonW]

sorry to hear that Ken.

[ken007]

thanks fellas, they were mitaka piston sets, everything looks perfect on the left barrell, im sure the spark plug being loose played a roll in it, anyway nearly got the motor out ,will split it and see the crank better, thanks for the offer LB, will have to play it by ear, have a spare left barrel at 1mm oversize so might try and track down the right 1 of a similar size from the old dart,plus pistons,conrods etc etc, its not the end of the world, will get some beer later and all will be well, , ken

[DOC03]

Oh Bugger Ken, that is a bastard ! Really sorry to hear that.

[ken007]

thanks doco, well, motor out, split in half, cases are ok, nothing a dremil wont fix, crank will need looking at but hopefully only needs new conrods,bearings, will need pistons , ,right hand barrell, couple of gaskets etc,even the right hand reeds have a little damage somehow, unless they were already dented, but they were covered in little bits of alloy,,, could have been worse, happened while i was going from 1st to 2nd at about 6-7000 rpm, i can only imagine how much more damage could have been done if i was cruising at highway speed, another thing i noticed was the wood ruff key ,it looks like it did its job and nearly sheared of, once again thanks, funny thing is i was just about ready to sign off on it, take a few photos and get it registered, the beer is going down well, cheers kencheers ken

[2TInstitute]

If the rod snapped it's not from the loose plug. I would guess the small end failed first. If you had a lean seizure no way would the rod snap.
When you rebuild the crank use air cooled RD rods they have better bearing sizes in them.

[ken007]

that make sense 2TInstitute, i was continually checking the plugs and monitoring oil consumption and had the pump set for extra oil,im 100% positive it wasnt lean, i noticed on the left side the bore and piston looked brand new ,but the small end bearing had a few cracks in it and was close to failure,im wondering if the bearings were no good ,what could i have done wrong?

[ken007]

are these ok or are there better ones or are they cheaper else where,
http://www.ebay.com.au/itm/YAMAHA-RD350 ... 956wt_1163

[EPApolice]

I have those Yambits rod kits in my LC and dont have any problems, in fact all the parts were from Yambits. As I said in the other post buy direct off their site not through ebay you save the VAT

[fred99999au]

no idea about the quality of the rods, but I do know that if you buy directly from http://www.yambits.co.uk they don't charge you the ebay tax. If you are outside the UK, then I also think you miss out on the VAT as well.

http://yambits.co.uk/rd350-conrod-kit-p-1692.html looks like it and is $44.50 aussie plus delivery.

[ken007]

they look like the go, i will have to wait till i track down a right hand barrell to see what size pistons i'll need, i will go for mitaka again i think,, thanks

[2TInstitute]

Ken that's the rod alright, shout yourself a pair of these. Dunno about the Mitaka's though

http://www.fondseca.com/index.php?main_ ... cts_id=814

[ken007]

those you beaut big end bearing look like the go, is that 31 pound for just 1 side or a pair? not having much luck so far trying to track down just a right hand barrell , seems like people like to keep them in sets, which is fair enough, a complete top end from slovinia at the moment in standard bore, fairly expensive but starting to look good if it would outlast me, still no hurry, i have my trusty xj to ride.

[EPApolice]

I have a barrel 64.5 bore and looks like someone honed it not too long ago, reed and manifold still attached. I dont know its history thats the way I got it PM if your interested.