Custom 70cc engine build

Is it worth it or stupid?

  • YES

    Votes: 11 64.7%
  • Hell no

    Votes: 2 11.8%
  • Kinda

    Votes: 2 11.8%
  • YES

    Votes: 1 5.9%
  • Nah I'll pass

    Votes: 1 5.9%

  • Total voters
    17
Thread starter #81

Z.hb71

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Sooooo I was bored and made a engine off botton bracket thing so here's what it looks like, it's alittle rough, I might plasti dip it black for the time being
15439719480267004980553448670092.jpg
Made it out of 1 of those cookie tins, it's pretty strong, not that it's Gunna get a beating.
 
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Thread starter #88

Z.hb71

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Update: so this is a real update not me making a ghetto ass part or a part arrived for the truck, this is a engine update
THIS IS NOT A DRILL lol so I'm having con rod/ crank issues (I think I told u that) because the rod size is suuuupppeerrrrrr weird, it has a 14mm pin and 10mm wide which pretty much nobody uses, and the problem with that is that there is too much play in the rod/ piston Assembly and if I go with a wider rod the crank will rub the inside of the crankcase. So my choices are buy a wider rod rod and modify the crank, buy a wider rod and modify the rod. Pretty sure modding the crank wouldn't weaken it but if u know anything about that, tell me. Modding the rod is the same story. I wanna mod the crank, the problem is trying to find sum 1 to do that for sum what cheap is a challenge. Pretty sure modding the crank won't weaken it cuz 1 dude cut half of the crank web off to lighen it and it worked fine. If you've built engines b4 (pretty sure atleast a couple of u have) tell me ur opinion on this.
 
Thread starter #90

Z.hb71

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Is say depends on how much material need to come off:unsure:
I have read that guy using dremil on crank cases to get a con rod to fit. its ballanced so would not mess with them..........what a nightmare o_O:oops::eek:
Like 2mm on each side. I plan on getting it done and ballanced and trued by a professional not me. This is what I wanna remove
FE5MPQHGSUT1Z0T.LARGE_20181129202440752.jpg
That's not crank btw. I wanna remove 2mm from each side
 
Thread starter #92

Z.hb71

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U know what I'm saying? The crank is such a b!tch!!! Was battling crank probs since I got the alx case! First trying to figure out what crank to use, buying the wrong one, con rod issues for like 2 months, Jesus I can't wait for this crank to b sorted. After that it should be easy, well that's what it seams like, but u know how that goes πŸ˜‚
U know what I'm saying? The crank is such a b!tch!!! Was battling crank probs since I got the alx case! First trying to figure out what crank to use, buying the wrong one, con rod issues for like 2 months, Jesus I can't wait for this crank to b sorted. After that it should be easy, well that's what it seams like, but u know how that goes πŸ˜‚
But can't quit, gotta keep pushing forward. Not tryna quit half way through, nah nah
 

Seandonato73

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You'll be fine to remove that off the crank. You'll need a lath to do it. And you will want to give them the rod too. I doubt -2mm is as accurate a measurement as it should be. There should be a side clearance spec for the rod to crank. If you were here in the states I could reccomend the perfect machine shop but they are a little on the pricey side.
 

Scruffy

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U know what I'm saying? The crank is such a b!tch!!! Was battling crank probs since I got the alx case! First trying to figure out what crank to use, buying the wrong one, con rod issues for like 2 months, Jesus I can't wait for this crank to b sorted. After that it should be easy, well that's what it seams like, but u know how that goes πŸ˜‚

But can't quit, gotta keep pushing forward. Not tryna quit half way through, nah nah
Now you know why the complete engines are so expensive lol. Idk if the time and problems are worth the savings of building one yourself
 
Thread starter #95

Z.hb71

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Now you know why the complete engines are so expensive lol. Idk if the time and problems are worth the savings of building one yourself
I'm not sure either but I'm half way in and no quiting now!
You'll be fine to remove that off the crank. You'll need a lath to do it. And you will want to give them the rod too. I doubt -2mm is as accurate a measurement as it should be. There should be a side clearance spec for the rod to crank. If you were here in the states I could reccomend the perfect machine shop but they are a little on the pricey side.
Yeah I'll give them the rod and Cran and case to make sure it's good. Thx ,πŸ‘ there's a couple machine shops near me
 
Thread starter #97

Z.hb71

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I might be missing something here but why not just buy the crank that fits the alx case?
well this is the crank that does fit but alx either moded the crank, modded the rod, or has a custom rod. my problem is it fits but i have wayyyyy too much play on the connecting rod/ piston assembly so i have to fit a wider rod and the only way to do that is modify the connecting rod (not a fan of that) or modify the crank. modding the crank I'm pretty sure wouldn't weaken it but probably will make it unbalanced, tho i am getting it balanced and stuff. it should be fine but i trying to make sure it wont weaken the crank. ive talked to one engine builder (forgot his name lol) he said it wont weaken the crank. that probably didnt make any sense :LOL:
 
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Thread starter #100

Z.hb71

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Just wondering, how are you getting these hp estimates? Or is this just a guesstimate?
Good question. Mostly a guesstimate, this cyl was dynoed at 17.39hp on a scooter, soooo I'm going to be running e85 which add alittle, also don't forget to remove drivetrain loss cuz rcs have wayyy less drivetrain loss than a scooter. A scooter has about a 5% drivetrain loss so add that. When I first run it, it will probably "only" make 12hp cuz I'm using a small 19mm carb, once I switch to a 25mm it will open it up alot. I'm Hoping for 20hp, seams realistic to me but I could just be delusional lol racingdia.png that's the Dyno sheet for the cylinder. Mines the red line, mk1. This Dyno sheet is for a rebranded 1. They now have a mk2 but it was out of stock.
 
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