XJ 750 Starter clutch going out?

Just got a 1982 Seca, and it turns out it has a lot more problems than I had initially hoped. When I go to fire it up, about 50% of the time the starter seems to slip and disconnect...I'll push the starter button, and hear a "RRR--whizzzz" type noise. If I hold the starter down after that happens, the whizzing noise will keep going (like the starter motor is still spinning, but it's not connected to anything). What options do I have? Replacing the entire starter clutch? How expensive would that be, and would I be able to do it on my own (competent mechanic + Google, but nothing special), or will I need to take it into a shop?

 

Hi
Starter clutches are an annoying thing and that sounds exactly like your problem. Do you have the service manual (I wouldn't rely on Google as while it can be straight forward for the competent mechanic it is an involved job). Also you need to make sure you've got all the right tools (which I didn't so why I outsourced it).

First of all I would plan to replace the starter clutch unit, I have been warned off by a lot of mechanics about buying the "repair kits" you see advertised. The second is from a $ perspective you better check whether it is a split case job or not. I have a similar issue with my XJ650Turbo and I have read up the manual and its engine out, split case job.
Now some mechanics may say they have a way to do it engine in, but unless you know them well and they regularly service this type of bike I'd be cautious. I just had my Kawasaki GPz750A done and while the book said it could be done engine in, my mechanic said he'd prefer to do it engine out so he can see properly what's going on. So I removed the engine and gave it to him along with the required parts (clutch and gaskets). It still cost me $550 (AUD at an hourly rate of $88 per hour). The clutch was $100 new from the manufacturer and I bought a full gasket set for about $120 off eBay. Yes it adds up but I'm happy with the result. I would think that it will be pretty much the same for your bike, there are new ones advertised on Ebay starting about USD70.

 

STARTER CLUTCH REBUILD PARTS:

sms6) OEM and aftermarket parts to rebuild your STARTER MOTOR CLUTCH DRIVE. Yamaha used a "centrifugal clutch" type of drive system to engage and disengage the starter motor drive from the engine gear, and over time the springs, spring caps, and roller pins that provide the engagement action can fail....which is terrible, as these are a real pain to replace, and require dis-assembly of the upper and lower engine cases.

However, there are a few alternative methods that might (or might not) save you some incredible effort and allow you to "dodge a bullet" and repair your starter clutch system in an easier manner; but, the success of such methods really depends upon whether the clutch failure is due to mechanical wear or damage to the pins, caps, or springs (in which case, you MUST somehow get in there and replace those items), or, if the caps and pins are merely "seized" in the starter clutch hub due to accumulated varnish and sludge, etc.----and in such a situation, then you might be able to clean out the mess and restore the clutch to an operational condition.

Methods a) and b) below address the problem of "sludge-seized" component pieces. Method c) deals with the problem of damaged parts. Note that if any of the major components are damaged---the clutch hub, or any idle gears or sprockets---then the engine is going to have to come out and taken apart to allow access to such larger pieces.

a) Pull the starter motor.....or, even better, the alternator shaft housing.......and shoot lots of solvent (seafoam, carb or brake cleaner, etc.) directly onto and into the Starter Clutch Assembly. Then, drain all of your engine oil and refill with fresh oil. Run the engine while on the centerstand until it's warmed up, drain the oil again, and fill with fresh oil. If the starter clutch was just sticking, this method may wash away enough of the accumulated gunk and set you on your way.

b) Next, it may be necessary to actually run a solvent in with the engine oil in an attempt to loosen any engine oil sludge that has accumulated over time, and locked the starter clutch roller pins. Of course, such solvent should be run in the engine with the bike on the centerstand, and not any under load!!! Then drain and flush this solvent-and-oil mixture, refill with fresh oil-only, run on the centerstand again, and then drain and refill with fresh oil-only again......now you can ride it again. You want to make DARNED SURE that you get all of the solvent-saturated oil out of the crankcase before you put the engine under load, and risk chewing up engine bearings, etc. with solvent-thinned oil!


AND, be aware that a failing battery and/or a starter motor with a shorted winding or excessive carbon build-up on the commutator, or even burnt contacts in the starter solenoid, can reduce current to the starter motor to a point where it can't produce enough torque upon the starter clutch, and thus mimic starter clutch failure symptoms (that "bag of rocks" sound and an engine that doesn't turn over), so be sure to eliminate those as potential problems before digging into your engine!


ALSO, TAKE NOTE OF THIS EXPERIENCE FROM ANOTHER XJ-OWNER:

"If there is not enough grip between the plunger and the roller, it can skip, causing the grinding, clacking noises you hear. I have been told by a Yamaha mechanic with over 20 years experience that it is very possible for some synthetics to greatly increase the chances that this will occur......"

So this weekend I drained the synthetic out, put some cheap 20W50 in, and rode it for a little while. Then I drained the cheap oil out and put Castrol GTX 20W50 in and the starter does not malfunction anymore, not even once! I cant believe it! I guess these bikes were not made to run synthetic---I'm sticking with conventional oil from now on."


c) If none of the above solutions work, then it might be time to do the dirty deed. If you read this thread, you'll get a good idea of what challenges you're up against.

http://xjbikes.com/forums/index.php?threads/1700

When you finally get the starter clutch assembly out of the engine and available for rebuild, we suggest that the central hub unit be inspected carefully for any damage or cracks, and replaced if needed. Here is a common problem that you need to look for (scroll down for the image of the cracked hub):

http://xjbikes.com/forums/index.php?threads/18676

There’s only one way to repair a starter clutch that’s bad without splitting the engine cases, and it ain’t pretty:

http://xjbikes.com/forums/index.php?threads/48348


By the way, if you do decide to split the engine open and perform open-heart surgery, you might as well replace the primary chain and guide while you're in there, as those are also "wear items" and will cause problems if and when they start failing!


Starter Clutch Components and Operation:

The general layout of the starter motor clutch system is as follows (it differs slightly between the various engine types, but overall, here is what is happening):

a) the starter motor gear operates upon a PRIMARY IDLER GEAR (which is supported on its own shaft)....

b) which in turn spins the another INTERMEDIATE IDLER GEAR attached to the rear side of the STARTER CLUTCH ASSEMBLY.

c) This entire "starter clutch assembly" consists of the above intermediate idler gear and a CENTRAL HUB UNIT which contains the centrifugally-operated springs, caps, and roller pins which lock the starter clutch operation to the starter motor. Failure of both the hub unit itself (it can develop hairline---or larger----cracks over time) as well as wear or seizure of the springs, caps, or roller pins accounts for 99.9% of all starter clutch problems and failures.

d) The "central hub unit" is attached via rubber ABSORBERS operating on the STARTER WHEEL to the starter clutch OUTER COVER, and this outer cover has a DRIVEN GEAR which is operated by the PRIMARY CHAIN, referred to in technical manuals as the "Hy-Vo" chain. Hy-Vo Chain is a unique type of Silent Chain. Hy-Vo stands for High Capacity, High Velocity, and Involute Tooth, and it is a registered trademark of Borg-Warner Automotive, Inc.

http://chain-guide.com/applications/1-6-3-inverted-tooth-chain.html


e) The starter clutch assembly rides upon the same shaft that drives the alternator.

f) If you are going to have the starter clutch assembly out of the engine and available for rebuild, we suggest that the central hub unit be inspected carefully for any damage or cracks, and replaced if needed. Here is a common problem that you need to look for (scroll down for the image of the cracked hub):

http://xjbikes.com/forums/index.php?threads/starter-clutch.14924/

Also take note that if the hub is not cracked, there is some good advice about re-conditioning the hub that you may wish to follow.

If the hub is secure, then always replace the springs, caps, and pins, as well as the rubber absorbers used within the starter wheel.

 

As Len alluded to, try either servicing/cleaning the starter, or putting a better one in. Ive had the same problem, and every time, it has been solved with replacing the starter. I haven't rebuilt any of them yet.....still going through my parts. when I run out of starters, I'll rebuild one......lol

Anyway, try replacing it first. You might save yourself a lot of time and hard work.

 

I might try that on my Turbo as well, quick and easy job comparatively.......

 

I just had some one else xj in with the same problem. Change the oil to a non synthetic, non detergent oil, problem no more.

 

...and they are lying.

 

Entertain yourself---

http://xjbikes.com/forums/threads/starter-clutch-issues.1700/

Dave

 

I think that was the first thread I read from start to finish on here. Very entertaining.

 

Okay, thanks for the replies, all. The bike is in a shop right now for tires and some other stuff, but there's no way that I'm gonna pay the $500 they want to replace the starter clutch themselves, so I'll give an update once I've started working on it myself. I guess my first bike will be quite a learning experience.

 

There ya go!!!!! Take it slow, read, ask a lot of questions here, listen, learn and do. You CAN do it. Just stick with it and don't give up. You'll be ok

Dave Fox

 

Here is an overview of what you will be doing. You do not need to pull the head or the cylinders to split the lower case from the upper case.

http://xjbikes.com/forums/threads/xj750-engine-removal-and-split-pictures.38545/