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Here’s my first real post on this forum…
To all current and future 750 twin owners: If you have never disassembled, inspected, and repaired your starter clutch, do so NOW. I assure you, it is at least *partially* broken, and will soon cause you trouble.
If you do some simple care, it will last a very long time. Unfortunately, they have three mounting bolts that all come unscrewed from the stator rotor over time. If you catch it before too late, all you have to do it loc-tite them and re-install. If it’s too late, you face a drivetrain seizure…
On this bike, only one of the screws had backed out and ground itself against the starter sprocket until it jammed and ejected a roller and spring. This caused a seizure at about 35MPH…. kinda scary, but not deadly… However, it cracked the starter clutch housing, and caused me to push the bike a mile home…
This one, I caught it before it caught me. I took it apart just to check and found all three bolts sheared in half, ready to toss themselves out into my oil circulation….
My advice? Just remove the damned starter clutch. Leave the starter, chain, and starter sprockets though. Yes, this means you’ll be kicking it from now on…
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The alternative to permanent removal of the starter clutch is to replace the bolts with modern ones of higher tensile strength. I think someone more anally retentive than myself knows the ratings for these bolts compared to the old ones 😆
Loctite and higher tensile bolts should prevent the bolts shearing or coming out, and save some more permanent damage to bike and rider.dougyt wrote:…Loctite and higher tensile bolts should prevent the bolts shearing or coming out, and save some more permanent damage to bike and rider.I agree.
…also, I want to mention that I didn’t actually remove the whole thing on both my 750s.
On the first bike, the starter clutch assembly had actually cracked in half from the seizure strain. And, I felt that the assembly might still be needed for spacing (or something, honestly I was just afraid to leave it out), so I got another starter clutch off one of my spare 400 engines, and installed the housing on the 750 without springs, pins or rollers. I used red loctite.
On the second bike, I just left the whole assembly housing out; meaning I left out the starter clutch body, 3 bolts, pins, springs, and rollers. So the only things on the crank in that area are the starter sprocket (with chain), the spacer-washer, then the stsator rotor (with bolt).
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It does work mate ive done it to mine using a NOS starter clutch assembly i bought from over the pond 😀 . Still fires up on the button now.
💡 try using loctite 571 this is super stong stud lock kaptin did you replace your bolts with stainless steel ?
No i didnt replace mine with stainless steel. Many people are fooled into thinking stainless steel fixings are better than tensile steel. They are realy on better at corrosion resistance.
Replace your bolts with 12.9 high tensile screws. The originals were pobably 8.8 at the best.
This is excellent info.
Just what is needed in this section please keep it going.
Regards to all 😀
Stainless is not the way to go, it work hardens due to heat or stress leading to crystalline cracking, not really not what you want on a starter clutch.
To be honest I’m not sure the tensile strength of the bolts is the issue, I’d guess that if any one bolt comes lose the other two are going to fail due to the starter clutch separating from the flywheel and leveraging the other two bolts.
Loctite seems like the best bet to me, given that the threads in the flywheel have stripped on one twin I owned, it doesn’t make much difference how strong the bolts are given that the plate they screw into is only mild steel.Quote:it doesn’t make much difference how strong the bolts are given that the plate they screw into is only mild steel.I’m a Nuclear Design Engineer. The issue here is an issue of shear which is where the benefits of the higher tensile bolts comes into play. They have a better resistence to shearing. You are toataly right with regards to the st/st comments and the loctite too. I used Loctite 222 which is a mild screw thread, semi permanent ie it CAN be disassembled. That worked fine. The secret is to degrease the screws and the starter clutch body thoroughly so it can do its job properly. For this i actually used carb cleaner.
kaptainkwak wrote:…I’m a Nuclear Design Engineer. The issue here is an issue of shear which is where the benefits of the higher tensile bolts comes into play…..A noocleehar whatsit? 😉 Well, I’m a garbage man. Ok, maybe not, but I aspire to be one one day.
Anyway, just to throw gas on the fire… On my two bikes, one was an issue of loosening bolts, the other was just shear.
So you’re both right.
and i’m the prime minister lol
shhh …
don’t tell anyone ,
but i’m jacques cousteau lol
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