Post by argo1974 on Aug 16, 2014 4:07:53 GMT -5
(First published on ADVRider, slightly updated here!)
Here comes another useful mod for the TX750.
At the weekend, I worked on upper half of my 73" TX750 engine cases to improve cylinder head oil supply and de-pressurize magnetic oil filter cavity behind ignition case.
Yamaha used aluminum plugs and steel balls clued in using aluminum putty for plugging oil passages back then. My engine had aluminum plugs and removing them by boring/dremelling was pretty easy.
At first, I removed the plugs marked red (on the actual picture, you see final state after I re-plugged them at the end of the job). I removed epoxy first and used 8mm drill since the plugs are around 8,5 to 9mm in diameter. Once these plugs have been removed, I had access to oil passages from and into magnetic oil filter cavity.
The green area is intended for drainage in case there is a leak from oil feed pump into magnetic filter cavity. It also provides oil supply to oil pump shaft.
On top of the engine case, I marked the actual plugs blue. The green lines show oil passage, which is feed with pressurized oil from yellow oil passage. Brown ring is oil outlet into magnetic oil filter cavity. If you carefully follow the oil passages, oil enters into green line from yellow line, from is then forced into magnetic oil filter cavity and enters into main oil gallery at its left end, lubricates the main bearing shelss and enters the other end of the green line to go up to cylinder head. What a cross-country tour though!
Before drilling down the green line, I entered oiled cloth into the green passage between R.H. plug and main oil gallery to prevent metal chips entering main oil gallery. I used 8mm drill first, then 10mm. Once the R.H. plug was peeled out, I re-plugged the left end of green passage with M14x1 aluminum plug covered with JB Weld.
Arrow on the left shows oil passage from magnetic oil filter cavity to main oil gallery, the right arrow, where pressurized oil enters the cavity. I plugged both with M10x1 aluminum plugs covered with JB Weld.
At the very end, I used conical aluminum plugs and JB Weld to plug the bores shown on first picture. I decided for threaded plugs in pressurized (engine oil pressure is around 3.5 bar max) passages and non-threaded for others. To keep the passages clean while boring/reaming/tapping, I used oiled rags and/or constant compressed air supply (my brother was holding the air nozzle) and flushed everything before final plugging.
Now oil flows directly from yellow passage through green passage entering cylinder head pipe and main oil gallery. Magnetic oil filter cavity does not contain pressurized oil meaning the risk of over-flooding the ignition case is very low. Since the is no need to fill the cavity after initial start-up, all crank bearings and cylinder head are supplied with pressurized oil immediately after engine starting.
Argo
Here comes another useful mod for the TX750.
At the weekend, I worked on upper half of my 73" TX750 engine cases to improve cylinder head oil supply and de-pressurize magnetic oil filter cavity behind ignition case.
Yamaha used aluminum plugs and steel balls clued in using aluminum putty for plugging oil passages back then. My engine had aluminum plugs and removing them by boring/dremelling was pretty easy.
At first, I removed the plugs marked red (on the actual picture, you see final state after I re-plugged them at the end of the job). I removed epoxy first and used 8mm drill since the plugs are around 8,5 to 9mm in diameter. Once these plugs have been removed, I had access to oil passages from and into magnetic oil filter cavity.
The green area is intended for drainage in case there is a leak from oil feed pump into magnetic filter cavity. It also provides oil supply to oil pump shaft.
On top of the engine case, I marked the actual plugs blue. The green lines show oil passage, which is feed with pressurized oil from yellow oil passage. Brown ring is oil outlet into magnetic oil filter cavity. If you carefully follow the oil passages, oil enters into green line from yellow line, from is then forced into magnetic oil filter cavity and enters into main oil gallery at its left end, lubricates the main bearing shelss and enters the other end of the green line to go up to cylinder head. What a cross-country tour though!
Before drilling down the green line, I entered oiled cloth into the green passage between R.H. plug and main oil gallery to prevent metal chips entering main oil gallery. I used 8mm drill first, then 10mm. Once the R.H. plug was peeled out, I re-plugged the left end of green passage with M14x1 aluminum plug covered with JB Weld.
Arrow on the left shows oil passage from magnetic oil filter cavity to main oil gallery, the right arrow, where pressurized oil enters the cavity. I plugged both with M10x1 aluminum plugs covered with JB Weld.
At the very end, I used conical aluminum plugs and JB Weld to plug the bores shown on first picture. I decided for threaded plugs in pressurized (engine oil pressure is around 3.5 bar max) passages and non-threaded for others. To keep the passages clean while boring/reaming/tapping, I used oiled rags and/or constant compressed air supply (my brother was holding the air nozzle) and flushed everything before final plugging.
Now oil flows directly from yellow passage through green passage entering cylinder head pipe and main oil gallery. Magnetic oil filter cavity does not contain pressurized oil meaning the risk of over-flooding the ignition case is very low. Since the is no need to fill the cavity after initial start-up, all crank bearings and cylinder head are supplied with pressurized oil immediately after engine starting.
Argo