Pork Chop
XS400 Junkie
You could put a cable tie thru the hole on the left piston - that wouldn't come off.
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CRUNCH TIME: Motor re-assembly has begun!!!!
- Thread starter Greasey Fingers
- Start date
Yeah I should have done that
What would you do if you were in my situation now, and didnt know which one came from what side
measure the gaps with the pistons in the bores and choose the ideal set-up as per specs.
Pork Chop
XS400 Junkie
sounds like good advice. All I know is that piston rings are sharp and make quick work of careless knuckles.
Drewpy to the rescue again, your a legend mate thanks again for bailing me out 
It is good advice, the logical aproach is always best. And thats also good to know as well the rings having sharp edges, ill be careful when handle them!
Just one question Drew, how do i measure the gap with the piston in the bore. are there special feeler guages that will fit in there like that?
It is good advice, the logical aproach is always best. And thats also good to know as well the rings having sharp edges, ill be careful when handle them!Just one question Drew, how do i measure the gap with the piston in the bore. are there special feeler guages that will fit in there like that?
As you have a 50:50 chance, I would just use what you have and get the clearances equal to each bore. I.E. if one's got a really big gap and the other tight, swap 'em over.
normally you use special micrometers for internal bores and external mics for pistons.
hope you didn't mix up the rings?
normally you use special micrometers for internal bores and external mics for pistons.
hope you didn't mix up the rings?
No the rings are still on the pistons! My brother has a micrometer but its probably a normal one not especially for this job?
just use the feelers as I mentioned above
Good news you blokes! I got some NOS pistons and rings! Sorry not much progress here latly on the rebuild, ive been waiting on these parts. So now its going to be a full top end rebuild not just a freshen up. Over here in oz these are EXTREMELY rare in standard size, but in oversize are more or less non existant. Shall look into organising a rebore and proceed with rebuild, will post any progress as it happens. Oh yeah thanks heaps drew for helping me out with the part numbers, you helped make this happen mate
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no probs, make sure you get a decent machinist to do the re-bore and make sure he/she has experience and insurance. heard heaps of folks have had probs with an over zealous line borer. don't forget a decent cross hatch hone too.
also make sure you give the pistons with the barrel and they are marked for each cylinder
also make sure you give the pistons with the barrel and they are marked for each cylinder
Good call, ill make a few enquiries before booking it in to someone. Im pretty sure the vapour guy i used will be in the know.
Pork Chop
XS400 Junkie
Hey Greasey, did you remove the rocker arms for vapour blasting?
Have you had the barrels machined for the new pistons?
Have you had the barrels machined for the new pistons?
Hi pork chop, nah I didnt remove the rocker arms for vapour blasting. The guy would have said if they needed removing, hes doing bike motors all the time and rides himself. And YES the barrels are rebored and came up trumps
Had some pitting inside one of the sleeves possibly from water sitting in it at some stage, so they were a little worried it wouldnt clean right up. But ended up they came up beautiful, they even commented on how good they came up so yeah i was pretty happy. Put the pistons in the bores to see how they fit and theyre PERFECT! Was going to put the top end back together this weekend but got tied up
Anyway heres some piccys of barrelsAttachments
weird having the Yamaha logo stamped on the valve head. that would create a hot spot and cause pre-detonation!
looks like something got in the bore too, as I can see a little indent on the inlet valve.
looks the dogs though
looks like something got in the bore too, as I can see a little indent on the inlet valve.
looks the dogs though
Pork Chop
XS400 Junkie
weird having the Yamaha logo stamped on the valve head. that would create a hot spot and cause pre-detonation!
looks like something got in the bore too, as I can see a little indent on the inlet valve.
looks the dogs though
Mine have got the logo too. Might be an Aussie thing.?
Maybe you can file your logo's off pork chop if you gonna take em out. I probably would have if i thought of the hot spot thing, i dont really wanna take em all out again now...
Pork Chop
XS400 Junkie
Wouldn't filing the valve heads cause possible weaknesses in the valve?
yeah good call...
no, not the raised part.
