The little monster is officially outta commission

[ben2go]

Did the bolt break in the same spot as the original? If so, there may be a burr or sharp edge on the back of the steel frame mount. Burrs in this area can cause bolt failure. Also, the bolt not being tight in the hole can cause a shearing effect due to the engine trying to rotate in the mounts and snap it.

[prismways]

Fair points. Unless we can remove the engine from the frame, it would be difficult to fully inspect the openings for burrs. I guess we can use a round file to blindly smooth out the insides.

Originally Posted by ben2go

Did the bolt break in the same spot as the original? If so, there may be a burr or sharp edge on the back of the steel frame mount. Burrs in this area can cause bolt failure. Also, the bolt not being tight in the hole can cause a shearing effect due to the engine trying to rotate in the mounts and snap it.

[Skin Mechanic]

Originally Posted by ben2go

Did the bolt break in the same spot as the original? If so, there may be a burr or sharp edge on the back of the steel frame mount. Burrs in this area can cause bolt failure. Also, the bolt not being tight in the hole can cause a shearing effect due to the engine trying to rotate in the mounts and snap it.

The bolt broke on the right side this time, just behind the threads. The hole is about 2mm larger than the bolt, plenty of room for the engine to bounce around on the bolt and shear it off at the mounting bracket.

Originally Posted by prismways

I was able to find this bolt that is similar to the one that I have on my Vader.

https://www.mcmaster.com/#91292a525/=17v6hcr

What do you think?

I haven't considered using a socket head screw, but it should work since it has the same head diameter as the hex head. I was able to slide a 9.5mm drill bit into the bolt hole so I could up-size to a 3/16" bolt. I found a self-lubricating bearing that might solve the shearing problem:

https://www.mcmaster.com/#2868t57/=17v8lgy

[prismways]

Nice! that bearing would definitely work! did you only drill into the frame or did you drill into the engine bolt hole too?

Originally Posted by Skin Mechanic

The bolt broke on the right side this time, just behind the threads. The hole is about 2mm larger than the bolt, plenty of room for the engine to bounce around on the bolt and shear it off at the mounting bracket.



I haven't considered using a socket head screw, but it should work since it has the same head diameter as the hex head. I was able to slide a 9.5mm drill bit into the bolt hole so I could up-size to a 3/16" bolt. I found a self-lubricating bearing that might solve the shearing problem:

https://www.mcmaster.com/#2868t57/=17v8lgy

[Skin Mechanic]

Originally Posted by prismways

Nice! that bearing would definitely work! did you only drill into the frame or did you drill into the engine bolt hole too?

I didn't drill it out, I just used the bit to measure the diameter of the bolt hole since my caliper was too big to maneuver into place. I've ordered 4-3/8" o.d. bearings and 4-7/16" o.d. bearings. I'm hoping the larger ones will fit, but I may have to heat up the bolt holes with a propane torch. If I can find my grease gun I'll pack the mounts with marine grease.

[prismways]

Ok, interested to see how it all comes together. Keep us updated!

Originally Posted by Skin Mechanic

I didn't drill it out, I just used the bit to measure the diameter of the bolt hole since my caliper was too big to maneuver into place. I've ordered 4-3/8" o.d. bearings and 4-7/16" o.d. bearings. I'm hoping the larger ones will fit, but I may have to heat up the bolt holes with a propane torch. If I can find my grease gun I'll pack the mounts with marine grease.

[Skin Mechanic]

The bearings and socket head screws arrived a coula days ago. Unfortunately the threads were too long on the screws so I had to use the cad-plated bolts I had ordered previously.



Also, the 7/16" bearings were way too big, though the 3/8" bearings did fit with a little motivation.



After seating the bearings in the upper mount and sliding the bolt into place I started working on the lower mount. About an hour later I realized there was no way in hell I could install bearings in the lower mount. Someone at least as blind as me drilled the holes in the frame mount and they were off by about 2mm. I had to drive a large screwdriver into the mount with a hammer to get the replacement bolt to go in. It would be possible to install bearings in the lower mount, but the engine and frame mounts would have to be drilled out, which would create even more play should the bearings fail. I'll have to stick with my 50% solution.

[prismways]

Wait, what do you mean the threads were too long? why would that be a problem?

That sucks about the lower mount. Could you cut the bearing and just use it partially in the frame and not in the enginge? Just a thought.

Let's hope this works out for awhile.

Originally Posted by Skin Mechanic

The bearings and socket head screws arrived a coula days ago. Unfortunately the threads were too long on the screws so I had to use the cad-plated bolts I had ordered previously.

Also, the 7/16" bearings were way too big, though the 3/8" bearings did fit with a little motivation.


After seating the bearings in the upper mount and sliding the bolt into place I started working on the lower mount. About an hour later I realized there was no way in hell I could install bearings in the lower mount. Someone at least as blind as me drilled the holes in the frame mount and they were off by about 2mm. I had to drive a large screwdriver into the mount with a hammer to get the replacement bolt to go in. It would be possible to install bearings in the lower mount, but the engine and frame mounts would have to be drilled out, which would create even more play should the bearings fail. I'll have to stick with my 50% solution.

[Skin Mechanic]

Originally Posted by prismways

Wait, what do you mean the threads were too long? why would that be a problem?

That sucks about the lower mount. Could you cut the bearing and just use it partially in the frame and not in the enginge? Just a thought.

Let's hope this works out for awhile.

Let me rephrase that; The unthreaded part of the screw was too short and the threads didn't clear the edge of the frame mount. I thought about splitting the bearings, but they're too brittle. I broke 2 of them trying to seat them in the motor mount. I'll just have to get in the habit of inspecting the bolts when I do chain maintenance.

[prismways]

ok. that makes sense. Let's hope your bolts hold out. thanks for clarifying.

Originally Posted by Skin Mechanic

Let me rephrase that; The unthreaded part of the screw was too short and the threads didn't clear the edge of the frame mount. I thought about splitting the bearings, but they're too brittle. I broke 2 of them trying to seat them in the motor mount. I'll just have to get in the habit of inspecting the bolts when I do chain maintenance.

[PhildoScaggins]

So I hit 500 miles on my vader yesterday. I left to go buy brake parts for my 9-2x today and heard a rattling. My lower bolt finally had given in. I think that it probably lasted so long because I had done such light riding while doing the soft break in. Kept it at less than 5k with oil changes every 100mi for a total of 500mi. That said I hit 60mph on my way home the other day with nothing other than a sprocket change (16t). Now that I've passed my road test and the soft break in is done its time for the carb and exhaust upgrades!

[Skin Mechanic]

I've put about 230 miles on mine since the last bolt replacement and the new bolts seem to be holding up. I noticed some vibration on the way home from work, but it was slack in the chain. I'll have about 1000 miles on the bike before the weekend is over.

[prismways]

I am at about 400 miles. It seems to be running well and so far the bolts look intact. I noticed my stock bolts are hex head. I will try to post a picture of them.

Originally Posted by Skin Mechanic

I've put about 230 miles on mine since the last bolt replacement and the new bolts seem to be holding up. I noticed some vibration on the way home from work, but it was slack in the chain. I'll have about 1000 miles on the bike before the weekend is over.

[Skin Mechanic]

The bike is officially outta warranty with about 1200 actual miles on the engine. I did an oil change at 1000 indicated miles and inspected the engine mount bolts and they are holding up well. I road it about 80 miles yesterday and the engine is performing better now that it's past the break in phase. I was able to get the bike up to an actual 63mph on the 4 mile stretch of level road leading into town. I'm still thinking about dropping in the Pitster Pro 150cc engine, but that'll have to wait til winter. I'm having way too much fun riding it to take it outta service for an engine swap.

[prismways]

Good to hear. Would definitely be interested to see how an engine swap is done. Wonder if we can change the gearing some how and get a fifth gear out of this thing? If Lifan can do it for their KP Mini...

Originally Posted by Skin Mechanic

The bike is officially outta warranty with about 1200 actual miles on the engine. I did an oil change at 1000 indicated miles and inspected the engine mount bolts and they are holding up well. I road it about 80 miles yesterday and the engine is performing better now that it's past the break in phase. I was able to get the bike up to an actual 63mph on the 4 mile stretch of level road leading into town. I'm still thinking about dropping in the Pitster Pro 150cc engine, but that'll have to wait til winter. I'm having way too much fun riding it to take it outta service for an engine swap.