XJ900 Starter Clutch Replacement

Well, after trying and hoping and then trying some more I had to face the fact that most likely the springs in my Seca 900 starter clutch are probably worn out and need to be replaced. In a couple weeks I am going to pull the engine and do the dirty. I have only done a top end rebuild as far as engine work so this is definitely new territory. I'm a teacher so no school during the summer and I'll have plenty of time. Yes, I plan on replacing the chain guide as well as all the other pertinent 40 year old gaskets, seals and o-rings I may disturb from it's slumber. I very much look forward to this project.

I know that it's possible that the starter clutch could very well be cracked but if it is indeed just weak springs should I still replace the whole starter clutch assembly or will just replacing the springs be fine?
Also, since I only plan on splitting the lower halves of the engine will I still be able to replace the chain guide without removing the lower crank?

 

I have done this work on my machine but l dismantled the whole engine to fit an endless cam chain so l don't know if the guide can be replaced with the crankshaft in place. You are better to replace the whole starter clutch, as they can crack and that's more time and money to do the work again. @Jetfixer changed the complete unit on his 750 but l am not sure if his old hub was cracked or he did it as a precautionary measure.

It's not difficult just a bit time consuming and more expensive since the clutch is inside the cases.

 

I wonder if Yamaha intended the starter clutch to last the life of the engine because of where it is fitted and lack of access to replace it in the engine design?

 

I lucked out on both the engines I did the guides were in good shape so I did not replace them. As I understand it the preferred way to replace the guide is to pull the head and the cylinders off and of course the lower case off. As far as the starter clutch , once the lower case half is removed it is straight forward to pulling the little bastard out. I bought a rebuild kit from the UK was a great kit came with new rollers, heavy springs and cups that are drilled to let oil through . Putting it back together only hard part is putting the shift drum to shift fork in place in lower case and making sure the chain is in the right orientation on the lower case half. I used .020 safety wire for the guide and .032 wire to keep the shift drum in place , just before seating the case half I pulled the wire out this worked fine. Make sure you have red and blue locktight and note some fasteners are peened over an inch pound torque wrench is required don't cut corners if you went this far you don't want to pull a stud or an insert get all your torque figures written out it help. I used a large wooden palate on my garage floor it worked great and did not have to worry about damaging any thing on the cases. The other thing I recommend is a large rubber mallet....DO NOT use a hammer . And buy a good set of torque bits sockets and Allen bolts to ( harbor freight) these are really best. The first engine took me awhile about a week only working a few hours a day on it , I made a mistake I rotated the crank and the cam chain tensioner was out the cam timing skipped and suspect I may have bent a valve have not looked at yet. The second engine went much faster and has been running great and no slipping when hot. Below are some photo's I recommend taking lots as you go , I see a cardboard box drew out a pattern wrote down the size of bolt as each one was removed pushed in bolt this way I did not mix up fasteners. Hope this helps cheers.

 

Another question that just popped into my head is: Is it possible to replace the chain guide

How do you know when to use Blue Loctite or Red Loctite?

 

Use Blue loctite when you want to disassemble parts later. Use red when you don't want to disassemble them well you can with heat.

https://www.loctiteproducts.com/en/know-how/build-things/threadlocker-red-or-blue-which-ones-right-for-you.html#:~:text=Loctite threadlockers are primarily designed,is a more permanent fix.

 

Wouldn't any Loctite melt due to the extreme heat of the engine?

 

No as Franz stated blue on most bolts , but red in areas that would not be taken apart , the starter clutch bolts the final drive bolts all use red locktite. Locktite is a high temp adhesive.

 

Hello everybody. So I finally tackled the starter clutch replacement job about a month ago. I'm in the process of putting the engine back together when I came across a little issue. During the initial tear down I had also taken apart the entire clutch apparatus and also removed the oil pump drive sprocket which sits behind the clutch. Now it's 3 weeks later and upon reassembly of the entire clutch system I looked at a parts diagram just to make sure I had everything, and it seems that there is a THRUST WASHER missing THAT WASN'T THERE IN THE INITIAL TEARDOWN. This thrust washer is apparently the first thing that goes on before the oil pump sprocket (see pics). At the moment I have the oil pump sprocket on the shaft and it lines up perfectly with the sprocket on the oil pump which means a washer would throw off the alignment. The pic I included is from the Haynes which covers the XJ900 from "83-'94 so I'm wondering if this is something for later model xj900's, however, when looking at a parts diagram for the '83 xj900 it definitely indicates that it's suppose to be there.The original manual does not show this washer being taken off in any of the pics or instructions so no help there. I guess it's possible that I might've lost the washer but I was extremely thorough putting every last bolt, nut, washer, and screw into plastic bags. I also never had any issues (other then a slipping starter clutch) with the bike. No shifting issues at all. So I'm a little aprehensive to move forward. Can anybody shed any light on this?

 

Update: I'm an idiot. The thrust washer is indeed there, I just never took it off. I'm just glad it didn't fall off when I was moving things around. Whew!

 

Would anybody happen to know if there's a definitive procedure to torquing down the cam caps? The manual does not specify. Is there a torquing sequence? Should I torque the two inner cam caps and work my way out to the two outers? Or vice versa? I've read things about doing it in stages and having the crank at TDC. I do know that the caps that are closest to the cam chain sprocket are really there to hold the top cover down. Also, what do the arrows on top of the cam caps mean?

 

So as I was reinstalling the engine two of these little rubber donuts fell off the engine. Would anybody happen to know where they go?