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 ?

 

Definitely not!
Oh and I bought most of these parts ages ago... so it doesn't count!

 

cds - this is an awesome pictorial. So helpful! And your comments that go along with the pics are worth - well - they're priceless when you consider the time they may save another xj'er in the future.

 

And I bet you still believe in Santa Claus ;o)

 

You can make a Jig to hold the Pistons all-level at the half-stroke to make inserting the pistons back into the cylinders less of a chore.

Here's the Idea.
The measurements differ bike to bike.

http://books.google.com/books?id=x_qLnB ... ig&f=false

 

Mirco - You know looking through the pictures has made me stop and check things that I just wouldn't have seen originally. It's amazing how the camera captures so much more than you see while you're working on it.

Wiz - I started keeping a tally and freaked myself out and stopped. I now keep an eye out for bargains or swaps and also realise that it is a passion more than a necessity. Doesn't Santa claus sell cocaine infused tonics?

Rick - Excellent info! Thanks!

 

50. Clean barrel to case gasket face on barrels and fit jug o-rings and oil dowel o-rings.
51. Check barrel to head gasket face and re-face if gouged.(check with steel ruler across face.)
52. Put rear chain guide in before putting the barrels on. (the guide will wiggle through the chain hole in the barrels, after they are on, but tightening the chain guide retainer properly is difficult with the barrels in place.)
53. lower the 2 centre pistons onto the piston holding jigs.(I made these with an extra hole that the front of the piston would sit in. good thing to stop them slipping out when dropping the piston but bad thing to get out because you have to raise the piston a lot more than without the hole to slide them back out.)
54. Align the rings properly on each piston. No ring gaps above each other or facing the ports.(follow the manual for specifics)
55. Slop oil all over the pistons and barrels then lower the barrels gently onto the two pistons. Push and squeeze the rings into the piston ring grooves to allow the barrels to edge down slowly. Work on both the pistons equally to keep the barrels level with the case face. (Can't do this with gloves on. If the ring won't push into the ring groove, because its wedged, then tap the barrels upward with one hand and squeeze it in again. Take your time and be careful as it won't require any extra downward pressure to accomplish.)
56. Align the two outer pistons and do the same. (raising the 2 centre pistons and then removing the jig and putting it under the 2 outer pistons would be ideal but it seemed a bit too hectic to mess around with the jigs and the piston heights at this point so I put the outer two pistons in with patience and a few retrys to get them straight into the bores).
57. Tap the barrels down, evenly, onto the case face and oil channel dowels and tighten the front stud nut.(keep it level front to back and watch the front stud that it heads into the case hole properly.)

 

58. Fit Head and torque.(keep an eye on those YICS o-rings when lowering the head)
59. Fit front cam chain tensioner.(Make sure it is located correctly at the bottom of the case... use a torch)
60. Fit cams, fit tensioner, setup, fit cover.

 

Very nice CDS, thanks

just a quick question, was the chain(s) starting to rattle or just a precautionary maintenance replacement ?

 

Hi OzRoad,

The starter chain was making a slapping/knocking noise at idle which annoyed the hell out of me and I thought it was going to be a lot more stretched than it was.

The cam chain I have replaced previously because of the top end rattling/clicking it was causing.

The having to take off like riding a 125cc was what prompted the piston/barrel upgrade... plus darkfibre bought a big bore kit and I got his first purchase(the barrels and pistons) at a good price!

I had a lot of fun doing this... although those oil channel head stud bolts feel too springy for my liking!

 

I like this thread and all the pictures you took (that I forgot to) when dismantling the engine.
Gotta go with the idea to re-split the cases, which I have to do as well.
It's a pain in the butt, but you gotts to do whats you gotts to dos...

 

I know what you mean.
It was no where near the chore I thought it would be to tell the truth because the gasket was very easy to get off the 2nd time around, since it probably wasn't actually cured, thankfully!

The engine is all back together and in the bike now, so it's time to get the colourtune plug and carbtune out and make this thing purr!

I still feel nervous about the way those 2 oil channel head studs feel when you torque them up... I think it must be the copper washers or something that makes it feel like they spring back when you take the pressure off and it's probably the reason i stretched the hell out of them the first time I did the head gasket and had to replace the studs on this motor. Well that and I didn't use a torque wrench that time around... just my 'i think it will take more' sense of feel.

 

Just a Final followup -
I have put just over 200Km on the motor since re-installation and I now remember what a 750cc ought to feel like to ride.

It was well worth the time and effort.

sidenote: Oh and that springy feel on the oil channel studs must be normal... cause they ain't leaking, Thankfully!

 

Pr0n!

 

Hey CDS, can I ask you how the rods felt when you torqued them up to 18,1? Mine start to stick around 7,2 already...

 

Hi Erman,
Sorry I'm not sure what you mean by rods and the 18,1 and 7,2 have got me stumped also.

I didn't separate the piston rods from the crank, if that's what you mean though.

 

That was exactly what I meant. Thanks for the reply =)

 

mmm looking good<a href="http://s1291.photobucket.com/user/c...esktop - TONYS-PC/my xj750/IMG_16781.jpg.html" target="_blank"><img src="http://i1291.photobucket.com/albums...ket Desktop - TONYS-PC/my xj750/IMG_16781.jpg" border="0" alt=" photo IMG_16781.jpg"/></a>

 

Is there any chance someone has these photos downloaded and is willing to repost them?! Would love to see what I'm getting into next weekend.

 

I see the photos just fine. Try again, maybe there was a server bug on the hosting site.


EDIT: The photo hosting site is indeed beig slow. I had to reload the first page twice to see all of the photos.

 

Do I have to remove head an cans to split the case?

 

No, do you have a service manual? What bike do you have?

 

I have an 83 xj 750 I need a crumb an fork replaced, I have both items and a manual I just wasn't sure how far I had to dig to split the case.

 

Not far, but take your time. Make a cardboard template to put all of the bolts in. One for each cover, and one for the case halves. Be sure to number the templates carefully; there are bolts for the upper case, and a set of bolts for the lower case. You will also need to pull the alternator rotor.

While it's apart replace the alternator chain guide (they fail from age-related brittleness, take care when removing the guide bolts, use heat to soften the locktite) and rebuild the starter clutch. You really only want to have to split the cases once. It is a time-consuming and tedious job.

 

Y'all are very helpful thank you! The bike have 14,000 on it any other recommend upgrades while the motor is opened, and do you know any good site for parts I've just been using eBay?

 

Just a suggestion here, try and take cds1984's order of taking things down. I am thinking specifically of the rotor. I have been wrestling with the rotor retaining bolt for a few days now because I went by the Haynes manual and removed the engine from the frame before taking the alternator cover, stator, and rotor off. I imagine it would be much easier to do in the frame and being able to use the rear brake to lock the drive shaft.

 

Click the icon in the upper right corner.

Gary H.

 

I am so glad I found this link - I'm about to pull my own engine for repair and this info is awesome.

 

I've made this a sticky post, and am locking it so info doesn't get lost.