XJ750 Engine removal and split - Pictures.

Thought I would do this so I can look back and tweak my memory for next time... and who doesn't love pictures of engines??

This is in progress and the reason for the engine split is I'm replacing the oil spray nozzle, Starter/Generator chain, starter chain guide and possibly a few other things before I get to the top end and replace the pistons and barrels.

Here is a list of steps I'm following or have done so far. It isn't complete but more of an overview.

I wanted to utilise the frame as a workbench to loosen or remove some parts which suck to try and remove when the engine is out of the frame so this is why there is a fair bit of dissassembly before I get the motor out and also why I leave the rear brake and final drive connected.

1. Get zip-lock bags and pen ready and label all bolts or bits for re-assembly.
2. Get sturdy boxes for parts and bags
3. Empty tank and remove.
4. Remove exhaust system.
5. Drop oil and remove filter and drain.
6. Remove crash guards, fairing, lower fairing frame, oil distribution block and oil cooler.
7. Remove battery and battery box.
8. Disconnect charging and pickup coil connections to motor.
9. Disconnect clutch, choke and throttle cables.
10. Remove airbox breather and drainage tubes and push airbox as far back as possible and anchor then remove carbs.
11. Remove stator and rotor with special bolt.(use rear brake in first gear to anchor).
12. Remove clutch cover and remove clutch completely (have 30mm socket handy and use the rear brake in first gear to anchor).
13. Remove gear-lever and crankcase cover. Dissasemble and pack gear selector bits then loosen torx screws in middle gear bearing plate with impact driver.
14. disconnect final drive uni-joint (using rear brake to anchor).
15. remove rear brake foot pedal and spring.
16. remove all engine mounts.
17. straddle bike(cushion between chest and frame) and lift engine out on right side (brake pedal side to avoid side stand spring pillar) onto a box or crate at the same height as the lower frame tube.
18. remove engine (oil-pump) covers.
19. remove pick-up coil assembly and disconnect neutral and oil sensors.
20. ... more coming.

 

Nicely done, cds. Thank you very much for your time & effort in posting this, as I'm sure many a member will find this extremely useful. BTW, I really like that finned alternator cover, never seen one before. I think I want one!
Good luck with your project, keep us posted.

 

Now that you have the Plant out; carefully inspect the Frame at:
• Motor Mounts
• Side Stand Mounting Welds
• Middle of Lower Tubes.

Look for STRESS Related Fractures and Swollen Pipe Cracks.

The Side Stand Frame Mounts got Weldled-on without treating the Interior of the Pipe for corrosion resistance.
The Frames have a tendency to weaken and fracture as a result.

You don't want to make a sizable expenditure of funds and labor rebuilding the Plant; only to have the project jeopardized by a deteriorated Frame that needs ample restoration or possibly even replacement.

Now's the time to do it.
It's a "Better safe than sorry" move.

 

wwj750
I think by looking at this bike , it looks to be an old police version, that's why it has the finned alternator cover, CDS can confirm if it's a 750P bike.

MN

 

That finned Generator cover is the same as on the 85-86 700 X models, and will directly bolt onto the 650/750/900 engines.

Ghost

 

Thanks Mn & Ghost-Im always looking to make my Seca one of a kind while improving function. Sorry to cds for jacking his excellent thread. I really like his technique for motor removal. Please post more picks of your progress when you can-great work!

 

Where would we be without milk crates ?

 

20. Remove spark plugs, valve cover and cams(put reluctor back on to turn crank).
21. Remove Head. (The VHT aluminium paint worked a charm on the gasket!)
22. Remove Barrels.
23. Remove Pistons.
24. Remove Upper case bolts and remove reluctor.
25. Flip motor and remove sump.
26. Remove oil pump.
27. Remove Lower case bolts and split cases. (to crack the seal it's easier to temporarily flip the engine upright again and knock the upper case upwards with a rubber mallet from the front and rear where the upper case extends further than the lower case and then flip upside down again to split the case finally.)
28. Remove generator shaft cover screws and remove oil spray nozzle, generator shaft and starter clutch(don't let the starter clutch fall apart, unless you want to service it also)
29. Pull crank out and replace starter chain.
30. Replace starter chain guide.(damn soft 6mm bolts with a BUNCH of locking gunk on them... be careful or heat up around the bolt before attempting to remove. Remove like tapping a thread, ie 1/2 a turn out and 1/4 a turn in if its tight as a bugger. I did snap the lower one and ending up retapping it from the top heading in.)
31. Prep mating surface of case with a soft dish scourer and WD40/CRC to remove old liquid gasket material.
32. Check crank shell bearings oil channels are clear from old gasket and rubbish.
33. Put crank back in.
34... more to come...

 

Rick - This is the frame that i painted in POR15 after re-welding the side-stand back on a few years back. I'll give it a good look over though.

Wwj750 - It sure is a XJ750P stator and rotor assembly.
XJ750P - Hitachi 22N-10 (14V 26A at 5000RPM)
XJ650G/750RH/900RK - Hitachi LD119-08 (14V 19A at 5000RPM)

 

Invaluable pics thanks for this!

 

Glad to know you already took care of the frame.

Some folks never expect that there is a problem until they return to the Bike and find it leaning way over, ... or dumped!

Great pix.
I hope all goes well and you wind-up with a fresh, new engine.

 

We were wondering how many miles or KM's this bike has on it. The main chain would indicate over 50 K miles. At least the chain guides have not started to break up yet.
MN

 

It doesn't have the original odometer on it but I'm thinking around the 50K mark also.
The guide and oil spray nozzle looked very serviceable still, compared to the other motors I've looked at.
I suspect that it has had some lower end work done previously as I've spoken to a mechanic who used to service these exact bikes here at a dealership and it was a fairly common practice for the police bikes to get the starter clutches swapped out and replaced with new ones.
Pure conjecture but interesting nonetheless!

 

34. Apply sealant to upper case (2-3mm away from shell bearings and not near the oil o-ring for the oil channel)
35. Join cases making sure the 2nd shift fork ends up in the correct spot.
36. Check the crank oil seal and crank oil plug to make sure they are aligned if they aren't genuine and don't have the locator ridges built-in.(this I neglected to do and didn't notice till after torquing all the bolts down on both sides. So... if it leaks, I'll be splitting it again!)
36. Torque the lower case bolts in proper sequence.
37. Flip and Torque the upper case bolts in proper sequence.
38. Clean the gasket from the case face for the barrels.
39. more to come...

 

After sleeping on it... I've decided to split the cases again and redo that oil seal.
Grrrr...
Cleaning those damn gasket surfaces is really the thing that sucks but what the hell! I'd kick myself if I have to pull the motor just to change this damn seal again.
If you want any specific pics of something inside the motor just say... my camera has oil and gunk all over it already!

 

I just gone through that engine in out and then in out again last week, in between i found the that my bike had the starter clutch out of the 900 installed and that the starter clutch bearing wasn't the best....Oh well it's back together again, next into the frame...then onto carb set up. Winter is the best time for all this work.

 

Very helpful thread - many thanks cds! I think you made the right decision to re-split the cases. I have made that same judgment error and had to split an engine AFTER I had it all back together.

 

rmunro - and aint it cold! holy cow! I'm not heading outside to work on it tonight thats for sure... Did that bearing die from lack of oil you think? blocked oil spray nozzle or something?

mirco - I woke up at 4am and starting thinking about that damn seal and that was a good sign that I was going to have problems I think. Still I feel your pain... I've had a few false starts with a couple of things and whilst these engines seem almost bullet proof you just can't help but worry when your sitting on the freeway that something isn't quite right.

 

39. Fit oil pump.
40. Fit sump.
41. Fit middle driven gear, bearing plates and half moon plug.
42. Fit final drive gear.
43. Fit gear change assembly.
44. Fit timing coil sensor plate, coils, reluctor and cover.(will tighten reluctor when back in frame).
45. Connect neutral switch and oil level sensor.
46. Fit crank case cover and timing coil wire retaining plate.
47. fit stator and cover (to align wires. will remove and fit rotor when back in frame)
48. Fit starter motor.
49. Fit new pistons. (put rags in holes, first, to catch the gudgeon pin clips when i drop them. Re-check clips are all in properly.)
50... more to come.

 

cds, are you keeping a record of the spend ?