Custom 70cc engine build

Is it worth it or stupid?

  • YES

    Votes: 21 63.6%

  • Hell no

    Votes: 2 6.1%

  • Kinda

    Votes: 4 12.1%

  • YES

    Votes: 3 9.1%

  • Nah I'll pass

    Votes: 3 9.1%
  • Total voters
    33
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Seandonato73 said:
Hey im just feking with you. I'd be running the snot out of it too if I had the time
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Lol, will be fun! Can't wait to stretch it's legs.
Question, what should I do for break in? Like last time I did break in, I did 1 idle 15min run, 2 1/4 throttle, 2 1/2 throttle, and 2 full throttle, but I don't think that was adequate as that engine lasted 6 months an lost compression. So I'm thinking 4 idle runs (15 min), 4 1/4 runs, 4 1/2, and 4 full throttle, and hold full throttle for 3 seconds on the 4 full throttle runs. What u think? Overkill? Tell me what u guys do/did?
 
So I tun my engins sloppy ritch for a tank or two avoid full throttle for 3 to 4 tanks then have at it. Been doing this for my dirt bikes, saws, and rc (including glow) engines I cant say I've ever had an issue. Best way to tell of a ring has set is to check compression for the first few tanks. You'll get to a point where it will be close to the same psi every run. The ring should be set in at this point. I really only check on stuff I've done for others so I don't have to worry about an idiot tuning the carb in, but it is effective.
 
Seandonato73 said:
So I tun my engins sloppy ritch for a tank or two avoid full throttle for 3 to 4 tanks then have at it. Been doing this for my dirt bikes, saws, and rc (including glow) engines I cant say I've ever had an issue. Best way to tell of a ring has set is to check compression for the first few tanks. You'll get to a point where it will be close to the same psi every run. The ring should be set in at this point. I really only check on stuff I've done for others so I don't have to worry about an idiot tuning the carb in, but it is effective.
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Thx
 
By Chance does anyone know what these are called?
I need these to center the wrist pin and con Rod, becuase the bearing can float to one side and if it does, the rod over hands a tiny tiny tiny bit, but I want this be down correctly. I noticed alot of RC engines have this, including my old rovan which woul most likely spin more rpm than this big ass 70cc. So I'd like to have these to minimize the chances of failureDSCF9159_zpswtde7y84.webp
 
Z.hb71 said:
By Chance does anyone know what these are called?
I need these to center the wrist pin and con Rod, becuase the bearing can float to one side and if it does, the rod over hands a tiny tiny tiny bit, but I want this be down correctly. I noticed alot of RC engines have this, including my old rovan which woul most likely spin more rpm than this big ass 70cc. So I'd like to have these to minimize the chances of failureView attachment 52247
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I believe they are called thrust washers
 
Cupton79 said:
I believe they are called thrust washers
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Thx
Ok so, these trust washers, I cannot for the life of me find anything that has a step like that, so do I really need a washer with a step? Also, I'm shimming the BEARING not the rod, I don't care if the rod walks around (which is wont), I don't want the bearing walking too much, little play is fine I hear but I have too much. So can I just use steel shim(s) with a 10mm Id (same as the pins od) and a 14mm od (same as bearings of) ? I think that should be fine, but before I put something in there that could blow apart, I want to make sure it's Gunna be fine
 
28-46 blackbone gearing has landed in my mits
15626927313042280051377200490688.webpgot a scare when this was being delivered, cuz I went out there and although the tracking said it was delivered, it wasn't there and I thought "oh poop here we go again ?", so like 2 minutes after I get inside I spot the USPS truck, so I watch him for a couple minutes, and what do u know, he rolls around and drops it at my door, so what I've learned is, they mark it delivered before they actually have delivered it.
 
Z.hb71 said:
28-46 blackbone gearing has landed in my mits
View attachment 52262got a scare when this was being delivered, cuz I went out there and although the tracking said it was delivered, it wasn't there and I thought "oh poop here we go again ?", so like 2 minutes after I get inside I spot the USPS truck, so I watch him for a couple minutes, and what do u know, he rolls around and drops it at my door, so what I've learned is, they mark it delivered before they actually have delivered it.
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well at least you have it and they did not fluff it(y)
 
dougstar said:
well at least you have it and they did not fluff it(y)
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Yep ? and what's a relief for me is that I actually measured my measurements correctly when I got the clutch carrier made, meaning the bearings for the clutch bell are in the exact right place for the clutch bell so I have a perfect gear mesh, gotta give myself a pat on the back for that one lol
 
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Ran to AutoZone and got me some spark plugs and rented a torque wrench. It's pretty cool the torque wrench rental, so you go and spend $50 on the torque wrench, and you can keep it for 90 days, if you go over 90 days it's yours but if you return it before then, then they give you the whole $50 back, so it's basically free. 15627141283684299939328386373311.webp
 
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