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Custom 70cc engine build

Is it worth it or stupid?

  • YES

    Votes: 17 65.4%
  • Hell no

    Votes: 2 7.7%
  • Kinda

    Votes: 4 15.4%
  • YES

    Votes: 1 3.8%
  • Nah I'll pass

    Votes: 2 7.7%

  • Total voters
    26

Z.hb71

Well-Known Member
Messages
4,093
Location
Chicago, Illinois
Ok my ignition pinion came in today along with my 20mm drill bit. If ur wondering why I need that big of a drill bit, it's cuz I asked the machine shop to drill my ignition spur gear (aka the
Hall sensors mount) 2mm smaller than my bearing (thinking when I heat up the gear to install the bearing it will expand 2mm, well when I tried it, nope won't expand that much so this is to drill it out so I can fit me bearing.
IMG_20190514_162648.jpg
 

TODD

Well-Known Member
Messages
74
For something that size I would be more like .0005 - .001 inch (.0127 - .0254 mm) That is more in the range we would use. 2mm is to roughly .080 inch. Way too much interference fit. Even if you could get 2mm to work. The crush on the bearing would be so bad it would either bind or dent the balls into the races.
 

Z.hb71

Well-Known Member
Messages
4,093
Location
Chicago, Illinois
For something that size I would be more like .0005 - .001 inch (.0127 - .0254 mm) That is more in the range we would use. 2mm is to roughly .080 inch. Way too much interference fit. Even if you could get 2mm to work. The crush on the bearing would be so bad it would either bind or dent the balls into the races.
no now it will be 1mm interference not 2mm, it used to be about 2mm which wouldn't work now it will be 1mm.
 

TODD

Well-Known Member
Messages
74
Make sure you understand this to what I wrote. 1mm is .03937 inch. Still way to tight. If they are a good machine shop they should have known that is way too tight. They may just be figuring this is what the customer asked for so do it.

For something that size I would be more like .0005 - .001 inch (.0127 - .0254 mm) That is more in the range we would use. 2mm is to roughly .080 inch. Way too much interference fit. Even if you could get 2mm to work. The crush on the bearing would be so bad it would either bind or dent the balls into the races.
 

Z.hb71

Well-Known Member
Messages
4,093
Location
Chicago, Illinois
Make sure you understand this to what I wrote. 1mm is .03937 inch. Still way to tight. If they are a good machine shop they should have known that is way too tight. They may just be figuring this is what the customer asked for so do it.

For something that size I would be more like .0005 - .001 inch (.0127 - .0254 mm) That is more in the range we would use. 2mm is to roughly .080 inch. Way too much interference fit. Even if you could get 2mm to work. The crush on the bearing would be so bad it would either bind or dent the balls into the races.
i understand this, though 1mm worked perfectly fine for my clutch housing bearings.
 

Z.hb71

Well-Known Member
Messages
4,093
Location
Chicago, Illinois
Needed servo extensions for my CDI becuase the wires are too short so I found 10x 500mm ones on eBay for really cheap and here they are
IMG_20190515_111928.jpg
Still no word on the we're abouts on the oil seals 😠
Here's something I guess maybe dissapointing but I'm not dissapointed, so the last things I need are oil seals and crankcase bolts (couldn't find anything long enough locally)and spark plugs, so I cannot assemble the engine without bolts (obviously) so I won't be able to assemble the engine before we move, tomorrow, but even if I had the bolts I wouldn't have enough time today to assemble the engine because I still need to make gaskets, make a ignition pinion mount, assemble the actual engine and set timing. Also I don't have time today to run to the auto parts store to get spark plugs or anywhere to get crankcase bolts (even if they had any), so yeah, I'll be able to assmeble the engine possibly Sunday or Monday, whenever the crankcase bolts arrive to our new house and whenever I get my damn oil seals. It's a couple days delay but no big deal.
 
Last edited:

D3MON

Member
Messages
20
Needed servo extensions for my CDI becuase the wires are too short so I found 10x 500mm ones on eBay for really cheap and here they are
View attachment 51426
Still no word on the we're abouts on the oil seals 😠
Here's something I guess maybe dissapointing but I'm not dissapointed, so the last things I need are oil seals and crankcase bolts (couldn't find anything long enough locally)and spark plugs, so I cannot assemble the engine without bolts (obviously) so I won't be able to assemble the engine before we move, tomorrow, but even if I had the bolts I wouldn't have enough time today to assemble the engine because I still need to make gaskets, make a ignition pinion mount, assemble the actual engine and set timing. Also I don't have time today to run to the auto parts store to get spark plugs or anywhere to get crankcase bolts (even if they had any), so yeah, I'll be able to assmeble the engine possibly Sunday or Monday, whenever the crankcase bolts arrive to our new house and whenever I get my damn oil seals. It's a couple days delay but no big deal.
really exciting to see this thing come together!
hope you have luck with the oil seals, can only imagine the frustration with them at this point.
 

Z.hb71

Well-Known Member
Messages
4,093
Location
Chicago, Illinois
really exciting to see this thing come together!
hope you have luck with the oil seals, can only imagine the frustration with them at this point.
Yeah it's really frustrating, not as frustrating as some parts of this build but very frustrating for 2 little oil seals. The company started a search with USPS to hopefully find em. Honestly I shouldn't be surprised because USPS around here has always sucked. Once they delivered one of my things to a house down the road in there flower bed, once they just decided not to deliver at all that day, once they delivered at 8pm, they just don't know how to deliver.
 
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