tarmac tickler wrote:[not the first time its happened on this barrel,/quote]
wouldnt be the first rapido to come with a pissed up bore from new!! dont matter what crank, webs, rod, shimmed or not if the pistons being forced up n down off centre thousands of times a minute somethings gonna give,, get it checked before you re-build or your on a hiding to nothing
This is distressing to read and learn about...possibly overlapping with the Rapido 'soft liner' reports that have made it through to the rock that I live under? Spot-On advice above BTW!
Have to confess that I know little about the barrel/cylinder machining sequence post casting. Presumably the spiggot, base and head gasket surfaces are machined prior to the boring bar (never come across a pub with that name yet) and hone?. In which case it is the machinist's fault (else they would all be like that). Depending on the severity of the missalignment the barrel should be recoverable with a re-bore. BUT you will lose the 'edge' on the tuning done when going oversize
If the bore is true to the studs + spiggot, then the gasket faces need re-doing. With the longer rod crank (you need a new crank anyway) this is probbably the better option in this scenario, as you can square the barrel (quite cheaply) and optimise port timings with the packer required (MBD, Scooter Center and LTH have all got a good range of these). If still in spec piston to bore clearance wise you could poss save on new piston and re-bore costs.
Anyhow thst is what my mechanic told me down the 'Bull and Bush' 't other nite disclaimer
is it worth getting the Meceur crank split? are the webs any good on them? Also what conrod to replace with is it one of these http://www.ebay.co.uk/itm/YAMAHA-RD400- ... 3376aeb4d0 if so do I then need a 1mm packer plate,if I do where do you get them from? and finally any real life experience of who can do this please.Sorry for all the questions.
