Are You Sick Of You Bolts Snapping!!!!

2door said:
If you are breaking grade 5 and grade 8 fasteners you have some serious vibration issues caused by an out-of-balance, or a bent crankshaft. These little two strokes do not provide enough torque to compromise standard or upgraded hardware. Either you have improperly installed the engine or you have a crank problem. If you're using rubber or any resilient material between the engine and the bike frame that will increase your vibration and hasten the failure of fasteners. Solid mount the engine and securely attach the exhaust manifold with the proper fasteners and torque. Grade 12 fasteners should NOT be used for any application on a motorized bicycle, motorcycle or automobile. Like that man said, you might as well use fasteners made of glass. Grade 5 is sufficient and grade 8 is just a comfort factor.
Tom
Click to expand...

it kept snaping the cheap 6mm blots tapped out and replased with 5/16 grade 8 bolts no breakige now i don't have any vibration or bent crank the engine is fine !!!! cheap factory 6mm bolts!!!!!!!!!
 
Pablo said:
The funny thing is we have people call and email to ask us about our hardware kits. Here is what they say basically (or some form of this): "I won't buy your (blank) engine hardware kit because all the hardware is not grade (8,10,12 pick a number)" OR "It's not ALL stainless steel". In a way this is kinda cool because we can explain a little about threaded fasteners and how super high tensile strength is not always best or stainless is not the steel of choice for fasteners in all cases.

On special the full kit is $8.95. Considering some high grade specialized screws and such can be $4 each and above, a full kit of hardware for under $10 just doesn't seem that bad.

Eng-Hard.jpg
Click to expand...

cheap factory bolts no thanks!!!!!!!!!!
 
diceman2004 said:
i,m sorry but this sounds like a low budget science fiction movie to me
how are you snapping gr5-gr8 bolts
theories
1) your bolts are loose
2) your using stainless bolts
3) the bolts aren,t actually the grade you say
4) the holes thru the parts you are bolting together aren,t square to each other
5) aliens intercepted you engine while it was being shipped and replaced it with an indestructable titanium based alloy thet looks just like the white metal the original case was made of , just so they could watch you from space and belly laugh every time you break a bolt
Click to expand...

read the post !!!!!! it was snaping those cheap factoy 6mm bolts that aren't worth the threads the chineese put on themlaff
 
impression said:
umm, it's very hard to see what you've done here. how about a few shots starting from far away :) and from different angles :Dauflg
Click to expand...

piece of steal curled under th rear mount attached to the rear post with to c claps works very good easy to make ...
 

Attachments

  • 0917092111[1].jpg
    0917092111[1].jpg
    18.6 KB · Views: 180
Pablo said:
Dude I agree, but are you saying SBP HW kits are "cheap factory bolts"?
Click to expand...

yepper look at them they're the same crappy 6mm bolts there JUNK!!!! i up graded and made a brace under my back mount no prblems 200miles still strong!!!dnut
 

Attachments

  • 0911091526a[1].jpg
    0911091526a[1].jpg
    40.5 KB · Views: 238
This may be a little off topic but I have tried out 2-sets
of SBP engine bolts. This is the expierance I had with their
engine bolts.
1. Rear motor mount- they do bend when tightening or streatch
but I have not had one snap.
2.Frount mount- I use the SBP front universal adapter plate mount.
3. Magneto cover- I can not use because they do not fit properly on
my engine
4. Clutch Cover- They fit properly but ended up pulling hole threads
out of a couple when loosing.
5. Exhaust AND INTAKE - Good Product ... I like
6. Sprocket Cover- Good FIT
7. Engine case- I did not get them to fit properly

With this experiance, No I would not buy the complete engine bolt
kit from them but it would be nice for them to seperate and sell seperate.
 
Just an FYI, our bolts are grade 5 or better, made in the USA and lot traceable back to the manufacture per aircraft industry standards. So to say they are the same cheap Chinese hardware is simply not true.
 
Pablo said:
The funny thing is we have people call and email to ask us about our hardware kits. Here is what they say basically (or some form of this): "I won't buy your (blank) engine hardware kit because all the hardware is not grade (8,10,12 pick a number)" OR "It's not ALL stainless steel". In a way this is kinda cool because we can explain a little about threaded fasteners and how super high tensile strength is not always best or stainless is not the steel of choice for fasteners in all cases.

On special the full kit is $8.95. Considering some high grade specialized screws and such can be $4 each and above, a full kit of hardware for under $10 just doesn't seem that bad.

Eng-Hard.jpg
Click to expand...


Seems like a much needed upgrade for us po'folks......a downright acceptable price to boot !...( LOL ) .....excellent !......



Thanks,
Salty.shft.
 
Charged-Reacter said:
This may be a little off topic but I have tried out 2-sets
of SBP engine bolts. This is the expierance I had with their
engine bolts.
1. Rear motor mount- they do bend when tightening or streatch
but I have not had one snap.
2.Frount mount- I use the SBP front universal adapter plate mount.
3. Magneto cover- I can not use because they do not fit properly on
my engine
4. Clutch Cover- They fit properly but ended up pulling hole threads
out of a couple when loosing.
5. Exhaust AND INTAKE - Good Product ... I like
6. Sprocket Cover- Good FIT
7. Engine case- I did not get them to fit properly

With this experiance, No I would not buy the complete engine bolt
kit from them but it would be nice for them to seperate and sell seperate.
Click to expand...
me niether!!!!!.duh.
 
it seems that torque and constant vibration is causing these bolts to shear for myself and others, instead of these bandaid fixes wouldn't just balancing the crank work best >?
 
Easy there Kla63! your local bolt company has all them bolts on the shelf any size and length and grade you want! dont be a hater!!!!
 
Question re: Rubber used in mounting causing bolts to break


How is this a cause of engine vib? Just curious as i am currently building my first mb, and I intend to use a thin strip of bicycle innertube @ bracket mount points on the frame.

When done correctly, this should further reduce vibration, shouldn't it? (it does with motorcycles)
 
There are two schools of thought on this and both have their merits. You can attempt to isolate your engine from the frame by using rubber. The effect is that it can reduce the vibration transferred to the frame and the rider will feel less vibration. The problem with this is that it actually allows the engine to vibrate more because it is not solidly mounted. This vibration can lead to fastener failure because the engine is now allowed to vibrate which can weaken the fastener. The other school of thought is mount the engine solid. True the rider may feel more vibration but the engine itself does not move and will not fatigue the fastener from the vibration. Both have been done with success. My preference is to mount the engine solid. The best solution is to reduce the engine vibration by balancing it. Then we wouldn't be talking about fasteners at all.
 
Ghost0 said:
There are two schools of thought on this and both have their merits. You can attempt to isolate your engine from the frame by using rubber. The effect is that it can reduce the vibration transferred to the frame and the rider will feel less vibration. The problem with this is that it actually allows the engine to vibrate more because it is not solidly mounted. This vibration can lead to fastener failure because the engine is now allowed to vibrate which can weaken the fastener. The other school of thought is mount the engine solid. True the rider may feel more vibration but the engine itself does not move and will not fatigue the fastener from the vibration. Both have been done with success. My preference is to mount the engine solid. The best solution is to reduce the engine vibration by balancing it. Then we wouldn't be talking about fasteners at all.
Click to expand...

i see what you're saying. Personally, I ride a 654cc single cylinder motorcycle everyday to work, so nothing these little engine do towards "vibration experienced by the operator" is a concern for me


The real reason i wanted to use the rubber was to preserve the condition of the frame so that when the engine vibrates, it doesnt start wearing grooves in the frame.

I fully understand what you mean by when the engine is isolated from the frame via rubber, it is free to "shake amongst itself", whereas if it was hardmounted, the vib would transfer its energy and distribute it through the frame, lessening stress on the mounts


In order to avoid both situatioins (non-transfered vibration and frame wear ) - what are the opinions on coating the bracket edges (i intend to use muffler brackets ) with a dense bead of silicone?
 
I was the fastener guy for a major industrial supplier, I think the cheap chinese, korean ect bolts are your issue, a grade 5 fastener is more than grade enough for this application.
My Engine has a rubber bushing between the frame mounts and I have had zero issues this past 5 years with any vibration or loosening due to this bushing. Maintenance being the key word here. They do shake, rattle and clang, so every once in a while I go through my "Hardley Davidson" with a couple of wrenches and a screwdriver and give things a tweak.
 
Getting into balancing the crank on a glorified weed eater engine just seems like a little overkill, I have yet to run my "Hardley Davidson" at full throttle, I'm 215 llbs (in the shower)
and can easily get 40 kph out of her, which, for the application is more than enough. I'm still having an issue or two with the #41 chain I put on her, I have to stay on top of the clutch adjustment more than usual, so I think I'm going to order up some #415 and be done with it. Re-engineering anything has its merits, but also its costs.
 
All of these problems can be solved if you just don't over torque the bolts in the first place.
I never use rubber mounts on my builds, I don't over torque the bolts, & I never have any problems with the stock bolts stripping or breaking! (it's really that simple!) ;)
 
You must log in or register to reply here.
Back
Top