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Discussion Starter · #1 ·
I looked back 5 pages and only found one reference to this. The three factory screws are not strong enough and shear off in the starter. My friend wants to replace the factory screws with stainless steel for more strength. I'm worried they won't be strong enough and I'll just have sheared off stainless screw heads running through the motor and oil ports.

Has anyone tried stainless?

Is there a stronger screw anyone has used?
 

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I'm guessing here, but are you talking about the 3 screws in the back of the alternator rotor that hold the starter clutch on the rotor? If so, the only reason I've ever seen for them to break off is when the starter clutch gets old and starts to slip and then people don't fix it but rather keep hammering away with it slipping, trying to use it when it's in need of service, and then the screws eventually get loose and wobble in the holes until they break... but a more clear description of the bike and part involved, and a few pictures as well, would help if I'm making an incorrect assumption. Not sure what 5 pages you're referring to either. Oh, and don't worry... I've never seen any screw heads make it into oil galleries
 

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And here is the proof of what I was describing - starter clutch slippage that is let go far too long while continuing to use the starter and the additional, and more expensive to repair, damage that results. Look closely at the pictures to see the excess wear on the screw holes in the rotor and locating pin from not servicing the starter clutch in a timely manner, which made the eventual repair more difficult and more expensive

http://www.hondatwins.net/forums/57-electrical-discussion/74001-bad-starter-motor.html#post625281
 

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Another thing that can cause them to break is trying to start the engine with the timing off and it backfiring against the starter.
TOOLS
 

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Discussion Starter · #7 ·
The screws are 6mm. My understanding is the slack in the chain creates snap absorbed by these three screws. There's an article on it online where three 450's are studied for this and none made it past 5k miles without shearing them off (One bike was trashed by the metal.). Mine makes for number four. The article goes into a machine shop solution but my mechanic friend said, "Why bother? Just use stainless screws."

Sounded too simple to me and I'm spending some serious money on mine and do not want the problem. Will try and find the article again to post it. Have heard mention of aircraft screws but found none.
 

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Were the starter clutches and alternator rotors on the 450s in the article in good condition prior to the screws breaking off in the first place, so as to isolate the weakness to just simply the screws? At this stage of their lives, a lot has happened over the 40+ years and unless the 450s in question were low mileage and in good working order before the screws broke off, then there are plenty of other factors to take into account - like, how long did someone let go the obvious symptoms of starter clutch slippage and other noises related to it before actually trying to repair the problem and only then realizing the screws were broken off? If the clutch was slipping and making the usual grinding noises for a while, then it adds to the physical impact of the eventual engagement that finally turns the engine and would cause more movement and loosening of the screws in the rotor. Loose housing screws in the back of the rotor from repeated slipping and banging into engagement (when other parts like caps, springs and rollers need to be replaced but are not) are why they wobble out the threaded holes and eventually break off to begin with, not general use while in serviceable condition. Between the 450s I've owned, ridden and worked on over that time, the only ones I've ever seen break those screws were ones in dire need of repair but were long left unattended until something broke so badly that it HAD to be taken care of... not exactly concrete evidence of a poor design or weakness, but rather of an owner's poor understanding of the design and its maintenance and repair needs, done by those less knowledgeable and/or mechanically inclined or just plain lazy over the years of use. And BTW, a total of 4 out of the tens of thousands of 450s sold and surviving this long with undoubtedly average maintenance (at best) is a pretty small percentage to use as an example. If you're so concerned with the potential for repeated failures in the future, just remove the parts, put a plug in the hole for the starter motor and use the convenience and reliability of your foot instead
 

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Discussion Starter · #10 ·
Not sure if this is the specific article you referred to...
Fix and Repair the Honda 450 Twin Electric Starter
That's it!

Opinions?

I got lucky. I assumed mine were sheared off by the starter spinning free but it was actually another problem. Still, I'm not using the electric starter for fear of the potential damage if they shear.

But, back to my original question, is a stronger screw available?
 
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