GT750 Broken head bolts

[JSJamboree]

I think I have a line on someone with a couple of motors near me. Still trying to see what they want for one. However, tomorrow i'll be going to HF to purchase 3 more heat guns. I'll try superheating the jugs to see if that gives me anything. Also on the hunt for some more sturdy C-Clamps.

I really want to get the jugs off so I can use the drill press to drill them out. I really dont want to try to drill them out by hand, even with some sort of jig.

[Suzukidave]

There is so much mass there i dont know if heat guns would do the trick , you really need some flame .. propane torch would be good but i bet even a gas welder would be better . You really have to get it hot , i dont know if you read about it but a really good penetrating oil is a mix of ATF and Acetone 50/50 .

[JSJamboree]

There is so much mass there i dont know if heat guns would do the trick , you really need some flame .. propane torch would be good but i bet even a gas welder would be better . You really have to get it hot , i dont know if you read about it but a really good penetrating oil is a mix of ATF and Acetone 50/50 .

Ive had it setting with PB blaster for a couple of weeks. Im going to take the rig all apart, working on getting some heavier duty CClamps, maybe try to up the grade of the nuts as well. During this time, i'm also going to work on getting some Acetone to give that a try. People have told me having 4 heat guns on it will get it hot enough to sizzle, i'll give that a try (I have ATF already). I have a propane torch as well, but since its heating such a small area is dissipates to fast. The idea behind the guns is you can have one pointed at each side of the cylinders so you are heating it all around at one time. It'll still dissipate down into the crankcase, but hopefully not lose as much that way. I can torch it at the time time.. we'll just have to see. Without having a full shop, making these tools is becoming more costly and time consuming than the build itself...

[Suzukidave]

I know what you mean about the cost of all this , i remember when i went to ACE hardware to get the pusher bolts and the shorter bolts to hold the plate to the block it was like $50 and that was years ago The plate was made for me by list member SmokyAllan

[Cliff]

The problem is the bond between the rusted studs and the oxidized aluminum. You have to break the bond.
If you have the time, clean out the holes with brake clean and compressed air. Fill them with Evaporust, let it sit for a day, blow out the holes and fill again with Evaporust. Evaporust will eat the rust away from the studs. Lay a block of hardwood across the top of the block and drive it down with a 2.5 lb. or better sledge. If it doesn't work at first, blow out the holes, refill with Evaporust, and do it all again the next day.
Another way is to remove the oxidized aluminum. Be careful with this! Again, clean out the holes and pour in some Drano crystals. Fill the holes with cold water. It should start to boil. Again with the hardwood and a sledge, drive the block down against the crankcase. Better wear gloves and glasses for this!
PB Blaster, WD40 or whatever will work but you have to go down each hole with a a solid punch and a big hammer to drive on the end of the stud to make it vibrate to get the penetrating oil in there and to the bottom!
Heat works as well. Aluminum expands more and faster than steel. IF the wife is not home, and I stress IF THE WIFE IS NOT HOME, preheat the oven to 500 degrees. Put your block/cases in the oven for an hour. Take it out, fill the holes with penetrating oil (that will act like a quenching effect to break the bond) and again with the hardwood/sledge hopefully there will be some movement!
Good luck!!

[JSJamboree]

The problem is the bond between the rusted studs and the oxidized aluminum. You have to break the bond.
If you have the time, clean out the holes with brake clean and compressed air. Fill them with Evaporust, let it sit for a day, blow out the holes and fill again with Evaporust. Evaporust will eat the rust away from the studs. Lay a block of hardwood across the top of the block and drive it down with a 2.5 lb. or better sledge. If it doesn't work at first, blow out the holes, refill with Evaporust, and do it all again the next day.
Another way is to remove the oxidized aluminum. Be careful with this! Again, clean out the holes and pour in some Drano crystals. Fill the holes with cold water. It should start to boil. Again with the hardwood and a sledge, drive the block down against the crankcase. Better wear gloves and glasses for this!
PB Blaster, WD40 or whatever will work but you have to go down each hole with a a solid punch and a big hammer to drive on the end of the stud to make it vibrate to get the penetrating oil in there and to the bottom!
Heat works as well. Aluminum expands more and faster than steel. IF the wife is not home, and I stress IF THE WIFE IS NOT HOME, preheat the oven to 500 degrees. Put your block/cases in the oven for an hour. Take it out, fill the holes with penetrating oil (that will act like a quenching effect to break the bond) and again with the hardwood/sledge hopefully there will be some movement!
Good luck!!

This is a method I haven't heard yet. I'll try giving this a try, but not the oven. She can smell PB blaster in the garage from spraying it down the holes. she would for sure smell burnt everything for days in the house.

[Coyote]

i remember when i went to ACE hardware to get the pusher bolts and the shorter bolts

Strike one! Ace has a pretty good selection but they are overly proud of it. Just yesterday I went there and bought two 6mm x 34mm bolts, Six 6mm lock washers. Was just over $7.00. All were supposed to be stainless but my magnet says no. What a rip.
A couple of weeks ago I needed a new 6mm tap. Went to ACE and the rack was empty. Normal price marked was $5.99. Went to another hardware store and bought the tap for $1.60

[JSJamboree]

Well, I bought two more motors. Figured one of them should work, which it did. The only issue was the piston rings bound up on the intake ports while I was pulling it and I ended up snapping the piston pulling it. Not a huge deal, I was planning on a full bore/rebuild anyways.





Couple of new questions:

Im having a major issue getting the nuts off the clutch shaft. Impact just spins thing, I need to get a pry bar on it. Is my only option to put it into gear, jam up the sprocket and crank on it? What are the chances that is going to break tranny gears? Any other common options? I did a bunch of searching but haven't come up with much.



My issue now is going to be running slide carbs on a later model motor. Looks like the old block had a post for the cable attachment where the later model doesn't. Is there an 'easy' fix for this? My only idea is to weld on a hunk of aluminum and make it look just like the old gen motors.

[Suzukidave]

To get the clutch nut off there are a couple of ways .. jamb a cloth between the clutch and the crank or make up a tool that you weld a handle to a old steel clutch plate . About the oil pump cable mount i just made one out of aluminum and bolted it to the engine with a hole for the cable adjuster .

[tz375]

It's quite simple to fabricate a bracket for the oil pump adjuster. No need to weld the cases.

The clutch pull shaft is also easy. Try to get a thin wrench on the inner nut and loosen the outer nut - it's a lock nut. DO NOT grab the end of the shaft with anything. That short smooth end fits inside an oil seal and it it's all torn up it leaks.

Those old cases are very early 72 model with the raised number boss and are relatively rare. I would keep trying to free them over the next few months so they are available to use when you restore it and sell it as an all original early 72. In terms of running the bike, a set of 74-76 work better.

[JSJamboree]

To get the clutch nut off there are a couple of ways .. jamb a cloth between the clutch and the crank or make up a tool that you weld a handle to a old steel clutch plate.

Wait, are you saying that you can take the side cover off without removing the two nuts on the outside? I assumed the shaft connected on the inside so I would need to take it off in order to pull the cover.

[tz375]

No.

The two nuts have to come off. The short shafts stays inside the clutch pressure plate.

I suspect that when the OP read "clutch nut" they thought you meant the one on the hub. You may need to grind a spare wrench thinner to get that inner nut.

[Suzukidave]

Thats the clutch adjustment linkage , i thought you were asking about the clutch basket . Yes.. the 2 nuts have to be removed on the outside as that center shaft connects to the clutch face . Follow TZ375's instructions

[Coyote]

When I had my Buffalo, I had an el cheapo wrench that I heated and bent to about a 45 to get at that rear nut on the adjustment. Worked fine.