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Complete engine rebuild Suzuki GT750-B

So we started the rebuild of the three carburettors, and yes there were fuel and air channels which were totaly blocked by dirt, VERY BAD adjusted FUEL FLOATS, remember there is one way to adjust the fuel floats: IN THE RIGHT WAY, otherwise your GT750 wil run bad. Also found about three defect M4 threading, we will repair ths with helicoils.
So we started the rebuild of the three carburettors, and yes there were fuel and air channels which were totaly blocked by dirt, VERY BAD adjusted FUEL FLOATS, remember there is one way to adjust the fuel floats: IN THE RIGHT WAY, otherwise your GT750 wil run bad. Also found about three defect M4 threading, we will repair ths with helicoils.
Why is the carburettor on the top of the membran wet of fuel?
Why is the carburettor on the top of the membran wet of fuel?
Clear to see, the blue paper is wet of fuel. This in combination with bad adjusted carburettors caused that fuel ran into the cilinders.
Clear to see, the blue paper is wet of fuel. This in combination with bad adjusted carburettors caused that fuel ran into the cilinders.
Leaking petcock in the position ON, should leak anyway, because there is no vacuum.
Leaking petcock in the position ON, should leak anyway, because there is no vacuum.
Removed SRIS valve to drain the engine.
Removed SRIS valve to drain the engine.
Carburettor bank for a total rebuild. They look like nothing was done in the past on this carburettor bank before.
Carburettor bank for a total rebuild. They look like nothing was done in the past on this carburettor bank before.
Removed the carburettors, the intake rubbers are so hard we could get the carburettor bank of the cilinders, after using some heat we could remove the carburettors.
Removed the carburettors, the intake rubbers are so hard we could get the carburettor bank of the cilinders, after using some heat we could remove the carburettors.
Resmoved SRIS valve from the LEFT cilinder, where we found at least 300cc fuel oil mix coming out.
Resmoved SRIS valve from the LEFT cilinder, where we found at least 300cc fuel oil mix coming out.
SITE UPDATE 12-03-2025: Today we started to do some repaires on the GT750-B bike where we did the rebuild of it's engine. CLIENT said: Engine won't start but has run just for some short test starts. Of course we DRAINED the engine first, and yes AGAIN we see a lot of fuel oil mix seaping from the engine. This should have caused a hydraulic lock for sure.
SITE UPDATE 12-03-2025: Today we started to do some repaires on the GT750-B bike where we did the rebuild of it's engine. CLIENT said: Engine won't start but has run just for some short test starts. Of course we DRAINED the engine first, and yes AGAIN we see a lot of fuel oil mix seaping from the engine. This should have caused a hydraulic lock for sure.
Close up of the cooling pressure gauge. When the value stays on 1 bar the cooling system will be OK.
Close up of the cooling pressure gauge. When the value stays on 1 bar the cooling system will be OK.
Setting the pressure on 1 bar which have to stay 1 bar for a long period of time.
Setting the pressure on 1 bar which have to stay 1 bar for a long period of time.
Installing the cooling pressure tester for checking if there are no leakages in the system.
Installing the cooling pressure tester for checking if there are no leakages in the system.
Closing the cooling system on the GT750 for pressure test.
Closing the cooling system on the GT750 for pressure test.
Completed engine almost ready for use. Some parts are at the owner.
Completed engine almost ready for use. Some parts are at the owner.
Completed engine almost ready for use. Some parts are at the owner.
Completed engine almost ready for use. Some parts are at the owner.
Completed engine almost ready for use. Some parts are at the owner.
Completed engine almost ready for use. Some parts are at the owner.
Completed engine almost ready for use. Some parts are at the owner.
Installed barrel. Pistons on the right place? Think about Left is right and Right is Left.
Installed barrel. Pistons on the right place? Think about Left is right and Right is Left.
Before the barrel goes down definitely, the last check for the coolant o-rings between the engine and the gasket.
Before the barrel goes down definitely, the last check for the coolant o-rings between the engine and the gasket.
Before the barrel goes down definitely, the last check for the coolant o-rings between the engine and the gasket.
All pistons installed and checked for the right position of the circlips.
All pistons installed and checked for the right position of the circlips.
Piston installed. Check for the genuine Suzuki circlip.
Piston installed. Check for the genuine Suzuki circlip.
Piston installed. Check for the genuine Suzuki circlip.
Piston installed. Check for the genuine Suzuki circlip.
Preparing the pistons for installing.
Preparing the pistons for installing.
Cleaned cilinderhead ready for use.
Cleaned cilinderhead ready for use.
Some severe corrosion in the thermostat housing you can throw away the thermostat. Never use water as coolant.
Some severe corrosion in the thermostat housing you can throw away the thermostat. Never use water as coolant.
Cleaning the cilinderhead upper side and lower side.
Cleaning the cilinderhead upper side and lower side.
Cleaning the cilinderhead upper side and lower side.
Always clean the exhaust ports before installing the barrel.
Always clean the exhaust ports before installing the barrel.
Had to clean the barrel top and bottom.
Had to clean the barrel top and bottom.
Had to clean the barrel top and bottom.
Cleaned it.
Cleaned it.
Very dirty starter engine.
Very dirty starter engine.
Never forget the oil pump pin. Oip pump has had a bench check test.
Never forget the oil pump pin. Oip pump has had a bench check test.
Hangtest for the oil hoses for checking the check-valves. The owner used WRONG and to thick 2stroke oil so all the check-valves are defect.
Hangtest for the oil hoses for checking the check-valves. The owner used WRONG and to thick 2stroke oil so all the check-valves are defect.
Routing the cables.
Routing the cables.
Engine clutch panel closing the engine.
Engine clutch panel closing the engine.
Installing rotor, rotor blot torqued with 20NM.
Installing rotor, rotor blot torqued with 20NM.
Kickstarter spring and spring guide installed.
Kickstarter spring and spring guide installed.
Installing clutch complete, M8 bolts are torqued.
Installing clutch complete, M8 bolts are torqued.
Secured and torqued clutch nut.
Secured and torqued clutch nut.
Installing the clutch basket with the large needle bearing and the thick spacer.
Installing the clutch basket with the large needle bearing and the thick spacer.
Installing parts for the clutch, so shim and the large ring.
Installing parts for the clutch, so shim and the large ring.
New nylon reinforced waterpump gear.
New nylon reinforced waterpump gear.
Starter gears, two rings needed.
Starter gears, two rings needed.
This is the right method for torquing (45NM) the nut for the starter clutch.
This is the right method for torquing (45NM) the nut for the starter clutch.
Needle bearings for the starter clutch. Use some grease when installing. Woodruff key installed.
Needle bearings for the starter clutch. Use some grease when installing. Woodruff key installed.
Nice clean engine.
Nice clean engine.
Nice clean engine. Bolt nr 24 is now a M6 stud, because we needed more length, with a special nut.
Nice clean engine. Bolt nr 24 is now a M6 stud, because we needed more length, with a special nut.
Nice clean engine.
Nice clean engine.
Something is missing: Look at the markings.
Something is missing: Look at the markings.
Before closing the engine, all surfaces need some sealant.
Before closing the engine, all surfaces need some sealant.
Checking the "dogs" of the gears, when they are worn you get gear problems.
Checking the "dogs" of the gears, when they are worn you get gear problems.
Checking the "dogs" of the gears, when they are worn you get gear problems.
Checking the "dogs" of the gears, when they are worn you get gear problems.
Checking the "dogs" of the gears, when they are worn you get gear problems.
Checking the seals if they don't hit the turning parts of the cranckshaft.
Checking the seals if they don't hit the turning parts of the cranckshaft.
Checking the seals if they don't hit the turning parts of the cranckshaft.
Checking the seals if they don't hit the turning parts of the cranckshaft.
Oil pump gear, the ring has to be on top.
Oil pump gear, the ring has to be on top.
Don't forget the plug in the kickstarter shaft and the primairy gear shaft (behind the blank plate).
Don't forget the plug in the kickstarter shaft and the primairy gear shaft (behind the blank plate).
Checking some important points before closing the engine.
Checking some important points before closing the engine.
Installed the gear shafts and the rebuild cranckshaft.
Installed the gear shafts and the rebuild cranckshaft.
Installed the gear shafts and the rebuild cranckshaft. CLOSE-UP of the cranckshaft.
Installed the gear shafts and the rebuild cranckshaft. CLOSE-UP of the cranckshaft.
Installed the gear shafts and the rebuild cranckshaft.
Installed the gear shafts and the rebuild cranckshaft.
Closed waterpump housing, always use the gasket and on both sides some sealant.
Closed waterpump housing, always use the gasket and on both sides some sealant.
Installed waterpump and impeller.
Installed waterpump and impeller.
Installed waterpump.
Installed waterpump.
Cleaned housing of the waterpump.
Cleaned housing of the waterpump.
Cleaned housing of the waterpump.
After installing the gear shift needle bearing we install the gear shifter. Dont forget the large ring.
After installing the gear shift needle bearing we install the gear shifter. Dont forget the large ring.
Checking all threads in the upper and lower casing of the engine.
Checking all threads in the upper and lower casing of the engine.
Cleaning the engine and housing of the waterpump. We clean this Thouroughly because otherwise you will certainly get coolant or oil leakage.
Cleaning the engine and housing of the waterpump. We clean this Thouroughly because otherwise you will certainly get coolant or oil leakage.
Rebuild waterpump.
Rebuild waterpump.
Rebuild waterpump.
Rebuilding the waterpump, YES the waterpump shaft looks bad but the surfaces for the seal and the small o-ring are very much OK.
Rebuilding the waterpump, YES the waterpump shaft looks bad but the surfaces for the seal and the small o-ring are very much OK.
This is the reason why we had to go deeper, a large peace of aluminium is broken off by the bad repair.
This is the reason why we had to go deeper, a large peace of aluminium is broken off by the bad repair.
The installed threaded bushing. So this lower engine case is repaired and the engine is usable again.
The installed threaded bushing. So this lower engine case is repaired and the engine is usable again.
Made a new threaded bushing with M8, when this was installed in the M8 hole we cut M6 thread in this bushing. The thread depth is about 20mm!
Made a new threaded bushing with M8, when this was installed in the M8 hole we cut M6 thread in this bushing. The thread depth is about 20mm!
After cleaning the hole new M8 thread is cut. We have to go deeper than normal because on top there is not enough material for a new bolt or stud M6.
After cleaning the hole new M8 thread is cut. We have to go deeper than normal because on top there is not enough material for a new bolt or stud M6.
So we had a large hole where we couldn't fit a M6 bolt anymore. So the question: How to repair?
So we had a large hole where we couldn't fit a M6 bolt anymore. So the question: How to repair?
Pulled out the last piece of the threaded bushing.
Pulled out the last piece of the threaded bushing.
A former, but very bad repair of the M6x110mm bolt nr 24. A threaded bushing was glued in the bolt hole. Not effective the threaded bushing was pulled out.
A former, but very bad repair of the M6x110mm bolt nr 24. A threaded bushing was glued in the bolt hole. Not effective the threaded bushing was pulled out.
After drilling a hole in the broken M8 bolt we noticed that this broken bolt part was moving, so we could remove it.
After drilling a hole in the broken M8 bolt we noticed that this broken bolt part was moving, so we could remove it.
After cleaning the engine first thing to do is some repairs: Removing a broken M8 bolt. Just broken removing wasn't difficult.
After cleaning the engine first thing to do is some repairs: Removing a broken M8 bolt. Just broken removing wasn't difficult.
OKTOBER 2023: COMPLETE SUZUKI GT750-B ENGINE REBUILD.
OKTOBER 2023: COMPLETE SUZUKI GT750-B ENGINE REBUILD.

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