Points Cover Screws

Monowakari

Monowakari

XS400 Enthusiast
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So i noticed after riding today that the screws holding my points-cover on rattled out during my ride.

Magically the cover was still hovering there! '78 xs400

How can I fix this? I cant find dimensions for the screws anywhere, I have the clymer manual and I cant find anything in there, and sifting through online is becoming inane.

Am I stuck until I find a wrecker or parts bike to snag them off of?
 
Last edited:
Yamaha was ce and made most of their bolt part #s decode to dimensions.
If you check here: http://www.partzilla.com/parts/sear...78/XS400E/CYLINDER+HEAD+-+CYLINDER/parts.html
You'll find part number 29 is what you need and is: 98501-05035-00
The 05035 is the important part.
The 05 indicates it's an M5 metric machine screw and the 035 indicates that it should be 35mm long.
The only thing it doesn't tell is the thread pitch but those are likely standard for the size.
In a pinch Home Depot might have one that'd work but I wouldn't recommend them for permanent usage.
Theirs are fairly cheap fasteners. One of the fastener wholesalers (Fastenal, Fastener Force) might have a stainless steel option with a better head type, or you can order online cheap on eBay.
 
I have exactly the opposite problem... my points cover screws are tiiiiiiight in there and on the verge of stripping. I've hit them with some wd40 in hopes itll seep a little and loosen them up. Otherwise - any tips?
 
An impact driver is a great tool for that situation.
The threads are pretty far away from anywhere you can apply wd40.
If you arent already, try applying the wd40 to the gap between the cover and the head near where the screws are. Some might get in there.
 
That's a fair idea. I wasn't thinking about the threads being further back. Went to buy an impact driver and the shop was out - bought a torch and tried that to no avail. I don't have a Dremel and can't cut another screw slot unfortunately. Any other left-field ideas short of a mallet and a pry bar :p?
 
In the absence of an impact driver, you could use an old ordinary screwdriver, (one that you wouldn't mind if it got damaged!) And a hammer. This isn't quite as effective as the impact driver, but I have used this method in the past, with some success. Give it a try, it will either do the job, or it might at least loosen the offending screws?

Merlin
 
MerlinDudley said:
In the absence of an impact driver, you could use an old ordinary screwdriver, (one that you wouldn't mind if it got damaged!) And a hammer. This isn't quite as effective as the impact driver, but I have used this method in the past, with some success. Give it a try, it will either do the job, or it might at least loosen the offending screws?

Merlin
Click to expand...
Sadly I've tried this as well. I've tried placing a hex-driver over the screw head and whacking it with a mallet to unseat it, doing this again with a torch, WD-40, 3-in-1, and a hammer and screwdriver. Makes me think previous owner hasn't looked under the hood in a very long time.
 
Brock, it looks to me that the last time ANYONE saw under that cover, was on the assembly line, at the Yamaha factory, by the sound of things?
Another possible way of extracting these offending screws, is to get a hold of a set of bolt/screw extractors, and drill the heads off the screws, just enough to get the cover off. Then the options are, 1, WD40, and a set of clamping pliers, to undo the screws! 2, drill a hole in the ends, of the screws (the ones that you drilled the heads off!) Then fit the screw extractor, into the hole in the end of the screw. (The extractors have a left hand thread) used in conjunction woth the ubiquitous WD40, this should get the offending screws out!

Merlin
 
MerlinDudley said:
Brock, it looks to me that the last time ANYONE saw under that cover, was on the assembly line, at the Yamaha factory, by the sound of things?
Another possible way of extracting these offending screws, is to get a hold of a set of bolt/screw extractors, and drill the heads off the screws, just enough to get the cover off. Then the options are, 1, WD40, and a set of clamping pliers, to undo the screws! 2, drill a hole in the ends, of the screws (the ones that you drilled the heads off!) Then fit the screw extractor, into the hole in the end of the screw. (The extractors have a left hand thread) used in conjunction woth the ubiquitous WD40, this should get the offending screws out!

Merlin
Click to expand...

So - are you saying it's not really necessary to get in there? I'm in the middle of troubleshooting my ol' beast and figured I should check every nook and cranny shy of taking the engine apart.
 
If it were a TCI bike I'd say probably not a likely spot to find problems but points wear out, get pitted, increase gaps, etc.
It'd be worth getting in there, checking condition, oiling the cam, setting the gaps and static timing, especially if it hasn't been open since the factory.

I'll second the drilling the head off option, if nothing else is working.
It'll expose the threads for you to apply wd40 to and expose the shank of the screw to get some pliers on.
 
I too often use WD-40 but in fact it's not very good for removing stuck screws, something like Liquid Wrench is more likely to do the job. There are instructions on the can that tell you how to best use it and following them makes a difference. Applying the liquid and then taping on the head with a hammer causes the liquid to migrate along the shaft of the screw. Several applications and lots of waiting in between may do the job. You can use a good fitting screwdriver bit and hammer with a box end wrench attached to try to turn them. If none of that works you can drill the head off as a last resort!
 
Hi Mose, I don't think that They sell that "Liquid Wrench" here in the UK?
What company market it? So that I can look it up on their website, and possibly put in an order for some?

Merlin
 
Sorry, I should have looked to see where you were from. Liquid Wrench is made by Radiator Specialties Company in Indian Trail North Carolina USA www.liquidwrench.com Probably not worth all the effort to get it. Surely someone in the UK makes a similar product. If you need the cover off soon you would probably be better off to follow HoughMade's instruction
 
Boy am I confused. You are in the UK, I got confused by all the different responses. No matter what you decide to do, as I said, surely someone in the UK makes a penetrating oil. I discovered many years ago that most chemicals work better if you read the instructions and follow them.
 
Excellent. Bought some PB blaster and it hasn't done the trick. I think the trouble is too far along the screw for the liquid to get to it. Getting my hands on an impact driver tomorrow - who'd have thought that all hardware stores within reasonable distance of me either don't stock them or are out... - and will give that a shot. Last resort is drilling.
 
Excellent, give it time to work and when you get the impact driver you will probably get them out. Be sure to use the driver carefully to getd good contact with the screws. Good Luck
 

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