Newly aquired '73 & '76 Buffalo ?

[Blokhead]

Hey,
Been lurking here for a while, and have just recently picked up a couple of GT750's. One is a blue '73 that does run, but needs some TLC to be reliable. I should know soon what kind of shape its in mechanically after I get done cleaning the carbs, setting timing, flushing fluids etc. I noticed when I drained the tranny oil that there were a few drops of anti-freeze that came out. Oil was not all murky, and mixed with AF, just a few drops worth. Should I be concerned about having to rebuild the water pump?

Second bike is a '76 that was ridden for a year, and then crashed, and parked according to the story. Unfortunately the shed had a dirt floor, and moisture did a number on the chrome. I have the original title, and the bike appears to be all original including the tires. The motor is free, and probably still good, but I can't confirm the mileage. Speedometer was broken off, so I was wondering what would be good indicators of the true mileage? I'll post some pics as soon as I get it unloaded from my van.

Thanks,
Dean

[Scorch]

Thanks for the post, Dean, look forward to seeing the pics. Congrats on your new bikes!

[Blokhead]

Her's some pics of the '76. Any ideas on the mileage?

[two-stroke-brit]

no idea how you would tell the millage but on the good side of things the paint looks great compared to the rest.
all the aluminium will be able to be polished back to shiny condition it just depends on how much time and effort you are willing to put in.
good luck and post as you go we all love pictures as it makes its way back to health.
cheers mark.

[tz375]

OK, so it ran for a year so maybe a few thousand miles. But the tires look pretty work in the centers, so maybe it's closer to 5-8k miles. Of course tires were much harder back them so it's possible it did more miles than that.

Bottom line: all we can do is to guess. But that bike isn't at all bad. The 76 I bought had been in the guy's garage since 81 when it was last on the street and the chrome wasn't much better.

[Blokhead]

OK, so it ran for a year so maybe a few thousand miles. But the tires look pretty work in the centers, so maybe it's closer to 5-8k miles. Of course tires were much harder back them so it's possible it did more miles than that.

Thanks, I was looking for an estimate based on the tires. Its just a parts bike, and I was hoping to get a good motor. I don't really believe it ran for only a year, because who could afford to let a one year old bike just sit, and rot?
I pressure tested the cooling system, and it held, so maybe even the water pump is still good.
All for the whopping sum of $250.00

[Blokhead]

Well, I got the '73 running Today, and it sounds good, and has plenty of power, but holy sheet does it pump smoke out the left pipe! The two centers put out some, and the right looks normal. I cleaned the oil tank, and refilled it before riding it. I purposely left an air bubble in the line so I could watch it, and make sure the pump was working. When running it would jump forward a 1/4" or more then slightly back, then a big jump forward every second or so. Seems like way too much oil to me especially when idling. I know when pumps get worn they tend to go rich, but this seems excessive. Is it the pump, or the check valves?

[tz375]

There's not much to wear in an oil pump and it's always full of oil, but the plungers can stick. I'd guess that it sat for years on a side stand and the left crankcase slowly filled with oil. That implies a stuck check valve, so I'd flush them with rubbing alcohol. While the pump is off top flush the lines I'd check that the rotor is moving up and down and isn't stuck in the full open position.

Then I'd drain the crankcases from the SRIS valves.

[Blokhead]

Ok, I pulled the check valves, cleaned, and Mity-vac'd everything, but really didn't get that much oil out of anywhere. Let it run for about 15 mins. and now every time I rev it up it seems to put out equal clouds of smoke from all the pipes (maybe a little more from the left still, but not like before). Kinda looks like I'm fogging the motor. Smokes way more than any Kaw. triple I've ever owned. I'll swap the pump from the '76, and see what that does.

[tz375]

So far so good. It might be a good idea to remove the exhaust system and soak it something like simple green to emulsify all that oil an flush it out.

This is a regular discussion topic here and it seems that the pipes don't get hot enough with gentle riding to brun off oil in the pipes.

Some people here favor adjusting the pump to reduce oil supply at lower throttle opening. There is not agreement on that idea but I think we all agree that good quality "smokeless " oil is a must to reduce fogging.

73 (cable) and 76(rod) pumps are slightly different devices - mainly in the crank arm. If you have the pump off, clean out the octopus and banjo bolts with rubbing alcohol, but do not use an air compressor to blow through them. Excessive pressure will spit the balls out.

With the pump off, rotate it and check that both plungers are moving but take care not to drop them or their springs.

Some info here that might be useful. http://pinkpossum.com/GT750/Oilpump.htm" onclick="window.open(this.href);return false;

[Blokhead]

Well, the '76 pump cured the smoking problem! I left a small air bubble in the line again, and it just barely moves at idle, when on full it makes big jumps like the '73 did. Way less smoke now. I took the '73 pump apart, and couldn't find anything wrong. Pistons fell out, no corrosion, everything free, in fact almost no wear that I could see. No idea why it pumps more.

That was the good news. Now for the bad, I'm getting an oily residue on top of the anti-freeze when I look down the filler neck. Transmission oil (I think) is getting in there somehow. Also, I'm not sure if I'm losing coolant. Haven't felt brave enough to drain the tranny again to check.

Where exactly should the coolant level be when the system is full?

Thanks again for the replies,
Dean

[oldjapanesebikes]

A bit of oily film in the filler neck is not unusual - I would be more concerned if you had coolant and/or oil draining from the weep hole in the rear of the water pump cover on the underside of the crankcase. If you suspect a possible head gasket leak - after re-torquing the head, you might try a bit of Bars Leak/Rad Stop in the radiator.

The level should be around the tab which you can see when looking into the filler neck.

[Blokhead]

Haven't had too much time to fool with the bike (putting a new roof on my garage in this heat ), but I figured out where the small oil leak I had is coming from.......The weep hole
Does this mean the seals in the pump itself are bad, or just the o-rings that are around the body of the pump?

[tz375]

Oil leak might just be the top O ring but more likely that it's the small oil seal inside the pump. The pump needs t come out to be refurbished or replaced with a new or known good one.