Standard porting

[MrTwoJay]

Hi all, Hope you doing well.
I went for some fun at a MX track the weekend. The first real performance test for my blaster. I did notice my tranny oil getting used up rather quickly, and smoking a wee bit too much. So, i recon right side crank seal, right? Pulled that out, and the bush looked rather grooved. (should have done leakdown test BEFORE taking it out though...)
Have to wait until the 6th jan just to get quote/availability on seal, the bush i just polished up on the lathe with some emery cloth, and looks good, and still within spec.

Anyhow, Its been bugging me, that maby there was another leak in the crankcase-transmission. So i sealed up and pressure tested, and vacuum tested.
Result: A very small leak,(+-0.1b/min) that i could not detect with soapy water, however when putting the breather pipe in a jar of water, i noticed bubble, per second. So the next step was splitting the motor.
I might as well replace ALL seals and gaskets while its apart.
I did notice the guy that replaced the crank (previous owner), used ultra grey RTV, which i seem to think would not work so great with all fuel around there. ( I could not see exactly where it was leaking, but did notice there was virtually no sealant on most of the mating surfaces, or it was squeezed out)

Anyone with experience with different types of sealant???
Im goin to try Yamabond4... Any application tips??

Now, im curious if anyone has a standard barrel lying around to measure, as i don't know what exactly was done porting wise... there is something done, but would like to compare. Do the ports come from the factory coated in black, or silver? because mine is all black, just looks shaped by the sleeve.

This thing pulls like a monster, has a performance xhaust and runs a 310main jet.

Im actually going to make a paper template of the ports before assembling, for reference. So and dimensions would be appreciated.

LOL, i also noticed that some idiot used a cut washer in place of the flywheel key, there was a very little bit of play too (timing???)

 

[jus_me]

I'm not sure on the rest but the washer u say instead of the woodruff key should be replaced with the woodruff key and yes that's what sets your timing. You can also advance your timing a tad since your in there. It's an easy mod. Look for timing advance in the threads, i even think there is a video.

 

[Larry's Shee]

I use 3Bond (1194?) , will depend on what's available easiest in S.A. , and cost.
Stock ports will have some black paint in them, though will be hard to tell on ex.
I suggest replacing both crank seals, which other than Yammy seals they come both in set. Put some grease in and on seal surface. Also some times they can leak @ keyway on clutch side, little Yammabond/3bond works good. Chances are the RVT they used on case halve might be the source of the leak through vent hose.

 

[MrTwoJay]

Yeah, im doing ALL seals and gaskets ( hope I cand get all the parts though) while its open. Bearings look ok still, but not so easy to judge them.

I'm starting to think that the 'washer' instead of the flywheel key was a lame-ass way of advancing the timing??? Assemble, hold crank, twist flywheel, and torque bolt. A huge recipe for disaster. ..

The casing leak could possibly be from the sealant (aparantly the best ultra greay stuff) not being suitable for continuous fuel contact.
When I got it, the fuel tap was leaking and floats incorrectly set, thus leaking fuel out the overflow, someone blocked the overflow pipe to stop the dripping, and I guess the fuel went into the motor.

After checking with a degree wheel, I saw advance range up to 6 degrees

 

[MrTwoJay]

O well, did some more porting today, and a decent flow job. Seems like they just took a grinding stone and shaped the ports a bit. (Not the way im used too seeing it done) now its raised about 1.5-2mm across 75% of the top port and about 1mm to the sides.
Have taken some photos, but might upload when I am on the pc again, this sites uploading procedure is not too user friendly...