New here! 50cc build

Oh oh, another question, how are the crank bearings?? Usable for a long time or should they be replaced sooner than later??
 
It's a 090 stihl chainsaw carb, it's a tillotson hl-324a. I'll find a pic for you. So far I've havent had any bearing issues with the stock bearings, but there are better bearings out there.
 
Heres a pic of my saw carb/pumper carb
20211003_181227.jpg
 
Well I use a lot of wt668 clones among others between 12 and 16mm for gopeds and 43-49cc pocket bikes. So I am very familiar. So to be adapted, what intake is used?? My favorite part isnt the tunability as much as it doesn't matter if they are at any degree possible and will still run flawlessly.
Maybe after I modify this carb I will jump straight to , as I call, a pumper carb. Or saw carb. Lol
16mm would be the min I would go with. I think I am running a 20mm venturi and 28mm bore on my big carb, and 17.5mm venturi with a 21mm bore on my smaller carbs. 12mm go ped will work, but the engine is a dog. I've tried about 50 different pumper carbs, off weedeaters, leaf blowers, up to saws. Go ped carbs are great if it's a kid riding, not much power.


pumper, saw carb, same thing to me too. lol
carb.jpg


my carbs look, just a box, lol
 
Thanks StreetRyderz I wasnt aware the 48cc were different bolt pattern, I knew they were a 40mm bore, & figured the 66/80cc was based off of it. Thanks I learned something new. Thanks for correcting me. I try not to advise in what I dont know as I'm learning as well.
Not so much correcting you as just helping to get the info needed to those looking for it.
 
Never had a prob with them, I also try to stay under 7k. They should handle 8k all day np. I know for sure they will handle over 10k in short controlled bursts.
Karl's looks nicer, hes got reeds hes running, I'm hoping to have reeds on mine in a couple weeks. Waiting on parts. I really like the adjustability without having to take carb apart for a jet change.
 
The biggest issues I face with highly modified engines is fuel supply being able to keep up with the demand, now this is mostly my own doing in trying to get all there is from the cheap china cylinders we use porting them to 23mm equivalent dia's and cross section of the transfers while being fed by a 24mm carb.

This size porting flows alot and draws fuel like crazy when rpm's are at or above 9k with a 115 main jet and a 35-40 power jet (still playing with that) so long periods of wot sucks the bowl dry faster than the petcock can flow, so I bored it out opened the channel in the valve and even the carb body this helped but only to prolong the unwanted lack of fuel.

I tried a pumper carb and it could not keep up ether even with a secondary pump and that got to be just to much plumbing for me so went back to the 24mm power jet and the biggest petcock I could find, it helped again but still not completely eliminating the issue.

I had posted pics here when I first encountered this issue of the bored out petcock and valve body and I think of the larger one I ended up going to, I had close to doubled the flow of the stock one by boring it out and that wasn't enough for even an 18mm carb with a 90 jet in it so it makes me wonder how some people are using 21mm carbs with a stock petcock without issues or even a good pumper carb when there was no way it would keep up on it's own.

Now I do understand that many don't go to the extreme's that I do but then they are trying to achieve the same thing in a manner of speaking and it's no wonder that many will never get over 50 knowing this.
 
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