head and piston deposits..... and disintegrated rubber sleves on cylinder studs.

[hpras]

Hey all....

Asking the collected wisdom......  does this head look ok?  The far (#1) cylinder looks different than the rest on the exhaust side.  First time deep into an engine other than a Briggs and Scrapiron, so any info would be great.



Also, what about this piston... the deposits are kinda 'bubbly'



And this is what happened to my cylinder studs..... sigh

[RichBaker]

Looks like she was burning oil in that cylinder, probably a marginal valve seal and oil seeping thru when she was on the side stand....

Don't know about the studs.

[racerrad8]

Everything looks about normal on the head/piston is the area of carbon. The difference could also be due to carb adjustments.

The valve stem seals should be replaced while you have the head off, and I stock a better positive stem seal that will outlast the stock seals.

As far as the studs, the rubber that has deteriorated was there for decoration/protection of the stud. Take it off and paint the studs and put it back together.

Randy - RPM

[hpras]

Thanks for the info, took a look at the price of those studs, a little on the dear side.

Have run into the next 'issue'.  The cases have resisted all my (calm) efforts to split them.  Thought I'd better stop for the night before I got uncalm.  Any wisdom here?  Have managed to just crack the seal at the front left corner as there were 2 good hard point to try a pry bar with, but the rest looks too thin to get really physical with it. 

Randy, how much for the valve stem seal??

[andyb]

37 bolts.  Count em.

Bastardish one under the oil pump, for example.

Needs the 3-goofy-headed-thing behind the clutch basket out.  Need all the covers off, oil pan, etc.  Oil pickup?  Don't recall.

Once you have all the fasteners out, it'll come apart shockingly easily.  And undoubtedly spray some expensive tiny bit under the workbench on the other side of the garage.

[ribbert]

Don't worry about rubber sleeves, my expert advice when rebuilding was not to replace them. 32,000 km's later I can't argue!

[hpras]

Friggin', it was the bastardish one under the oil pump  .  My paper manual mentioned nothing about removing the oil pump, my PDF version did tho....  Cases split, crank out of the top case, ready to go to the machinist.

Neither of my manual states anything about e wear limit on the starter or cam chains, but replace them if the are worn or stretched.  How much is stretched?? Could count the clicks on the cam chain tensioner, but the starter chain??  Was about 1cm of movement up and down in the china.

[fj1250]

The rubber sleeves on the studs are just noise dampers. Cut off any that are left and don't worry about it.

MC

[SkyFive]

I wouldn't have the crankshaft or case machined if I were you. Yamaha has a number system that must be deciphered to determine which main and rod bearings you need. If you machine the crank you will lose reference and determined bearing size will be a pain in the ass, if you can at all. If your crank journals are not damaged I would clean the crank, polish the journals with Simi-Chrome and clean again.

[hpras]

The cases need to be relieved for the bigbore kit, not machined on the journals.  I've got the numbering system figured out, best thing to use is a spread sheet