oldbikerehab Posted May 18, 2012 Author Share Posted May 18, 2012 Thanks for all the feedback! I finally took my top end off to check things out and bring it by the shop for an autopsy. Here's a look at why splitting the cases is in order. The pin looks spent with some bluing on the ends. The good news is it looks like I can get away with a honing and stick with the 3rd over piston, if they are actually in stock as the parts website says. I put together an order for ring set, piston, piston pin, circlips, needle bearing, all OEM for $99 + shipping. Then I cleaned the piston rod. Are the brown rings where the needle bearings end anything I need to address or just standard wear? The needle bearing came out easy, I don't see any bluing from heat and don't feel any scoring with my fingernail. Is a new piston rod in order or can I use my old one? One of the mechanics at the shop said I need to run a light premix (Maybe an oz of castor or 2stroke per tank) in my tank on top of the autolube pump when I get things back together. He also recommended I read this article by Gordon Jennings. http://www.bridgestonemotorcycle.com/documents/oilpremix6.pdf Jennings makes a pretty solid case for more oil in the mix = more horsepower and less varnish buildup after some pretty conclusive testing. Anybody here run light premix on top of the autolube? Flyday- I am/was still running the junk carb and will be trying to source out what I need to rebuild my Mikuni. Also, aside from lacking the intake ports, I've been told that there is also enough of a weight difference (Wiseco=heavier, if I remember correctly) to create a noticeable difference in performance. Main question now is, should I go for a new piston rod, or stick with my old one and save $45? Are the pretty much good as long as they aren't broken? Link to comment Share on other sites More sharing options...
Moderator Cynic Posted May 18, 2012 Moderator Share Posted May 18, 2012 The colouration on the little end and the pin wouldn't bother me much, as to adding the oil that would be a big no no from me. Its innacurate and messy, not to mention a king pain in the arse away from the farm. You also have to re jet to do that on a pump motor, as you need to allow for the oil in the fuel which is effectively leaning the mixture. If you want to add oil bang on but do it the easy way with the pump. just shim it up a bit more for more stroke, even just stick a couple of turns on the cable. Link to comment Share on other sites More sharing options...
oldbikerehab Posted May 18, 2012 Author Share Posted May 18, 2012 Thanks Cynic! Good call on the shim, that's the type of feedback I was hoping for and I'm going to add one to my order. I'd really like to be able to have the bike run the way Yamaha designed it and not mess with adding stuff to the gas tank. I don't think the Suzuki 250 mentioned in the Jennings article has an autolube, thus the premix. What's the consensus on octane in a 2 stroke? I was filling up with 87, but I'm wondering if I should be using 93 when I get it running again. Link to comment Share on other sites More sharing options...
Moderator Cynic Posted May 18, 2012 Moderator Share Posted May 18, 2012 Thanks Cynic! Good call on the shim, that's the type of feedback I was hoping for and I'm going to add one to my order. I'd really like to be able to have the bike run the way Yamaha designed it and not mess with adding stuff to the gas tank. I don't think the Suzuki 250 mentioned in the Jennings article has an autolube, thus the premix. What's the consensus on octane in a 2 stroke? I was filling up with 87, but I'm wondering if I should be using 93 when I get it running again. Thats down to the ig timing. Here in the UK switching between regular (95 ) and super (98) unleaded needs a 4 degree advance on the ignition. On that theory you need maybe 6 even 7 degree's difference to swap, if the bike was set for 93 and you ran 87 that would have done for the piston, the flapping noise? could be pre ig stalling the piston causing it to wack against the bore, these old smokers can't compensate for the change like modern fi stuff. Link to comment Share on other sites More sharing options...
oldbikerehab Posted May 18, 2012 Author Share Posted May 18, 2012 Ah yes, and then there's the timing. I didn't realize that octane and timing were so closely related. I am glad that you brought it up because one thing the owner said at the shop was that while my old gas may have played a factor, he thought that my timing was the ultimate problem and that we'll put a timing light on it later. If anything, it will be nice to know exactly what my bike is tuned for when all is said and done. Lessons learned. Link to comment Share on other sites More sharing options...
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