Brother got SBP expansion chamber, less power now

[ivan H]

Hi Youngreasemonkey, yeah, Hi Po everything uses copper & have done 4 ages. You explained the hi silicon content of piston alloy 2 me & its effect on cutting tools. I recently added 2 ports & a cutout on the skirt 4 use with reeds. Ur definitely right, & I expect the Chinese dont use the best alloy in these things. Cheers

 

[young grease monkey]

oh yeah, it was why there are very few companies making billet pistons. cast requires very little material removal, so less tool wear. same with forged. the chinese pistons aren't actually that bad, it's the rings that are too thick so they wear the cylinder, and the cylinder plating is terrible. i want to make a nice top end kit for these in a few years when i am doing custom fab full time and have a good machine shop. i see so much potential in the hf engines too, i really want to make a water cooled head for mine. it kills me that i don't have the time right now. i just hope i can finish my hf 99 build before summer ends.

 

[dmb]

the chineeze make a very nice bicycle 2 stroke motor with correct port timing, cooling, piston. its called a dax gp 50

 

[ivan H]

the 48cc, regardless of distributer, is definitely a better balanced motor. I dont put Chinagirls down, I use 1 so,,, u get wot u pay 4, they're not a state of the art 2 stroke. Port timing & size is a very,, subjective matter, they're ported for low rpm power, not a hi rpm screamer, but they're designed to provide cheap, low fuel use bicycle assist power, which they do well enough. Cheers