1976 GT500a Carb problem

keepemsmokin · Posted: Sat May 14, 2011 12:00 pm Post subject:

Removed Stator assembly today and re-done leak down test on the seal and crankcase joint, Leak shown up in the crankcase joint to left side of shaft, so looks like its a full engine strip down, also evident is some kind of filler that has been previously used to seal leak, photos attached are not brilliant.
Alan

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Bikegeezer · Posted: Sun May 15, 2011 8:37 am Post subject:

This is a shame. Your engine has been hacked. #1, I see the cylinder base gasket has red silicone used as a sealant - clear indication of a hack job. That gray crap at the case joint is Three Bond sealant. That's what's supposed to be used on the case mating surface, but the amount oozing out there indicates there's some kind of damage on the surface the PO was trying to fill with the sealer. It didn't work. The surface around the bearing OD also appears to be damaged around the 8 o'clock position, and there appears to be a gap from that point up to the case joint. Actually, the bearing appears to not be seated between the 6 and 9 o'clock areas, and that may be what's causing the case to not join tightly at the forward edge. It's possible the idiot who took the engine apart tried to split the cases by wedging some metal tool in there and prying.

I'm afraid your best option is a complete strip down and careful inspection of the case. It doesn't appear there's any leakage at the seals or O rings, but that may be just because the case leakage is so large. Once you get that corrected, weakness at the seals might show up.

There's also something fishy about that crankcase, especially the Magic Marker timing mark on the wrong place and the lack of a timing notch where it should be. Does the engine serial # match the frame number? I'm thinking not.

Stu

keepemsmokin · Posted: Sun May 15, 2011 11:40 am Post subject:

Stu- I have made a start on stripping the engine, oil drained off and both heads removed, the red sealant was found to be to the joint edge of the mating face's only, examination of faces look to be good at this point

I have checked the what looks to be like a gap at the bearing between 6 and 9 o'clock with feeler gauge .002" smallest I have which does not enter, as you said when cases are split will reveal this more.

Timing mark was damaged by PO drilling screw out to remove timing plate, the magic marker was down to me only to identify position's for re-assembly.

Frame No T500-96987 Engine No T500-97138.

I will give the area of concern a good cleaning and load a more detailed photo of this as soon as possible.
Alan

Bikegeezer · Posted: Sun May 15, 2011 4:30 pm Post subject:

Okay, good. Keep going. FYI, that's not the original engine case. It's newer than the rest of the bike. No big deal, except maybe for collector appeal. My original case isn't in my bike, either.

Stu