Compatible flat top pistons

[Will'smotobikes19]

I'm going to replace the stock crank on my motor when it comes with a 3mm stroker crank might replace the hardware too. For the 48mm sleeved cylinder, a windowed flat top piston and stroker crank it is $150 US. But will probably last twice as long as the chrome lined $30 cylinder. Plus you get a few more ccs of displacement.

 

[Philandra Chambliss]

[QUOTE="Philandra Chambliss, post: 463968, member: 27979]
In addition I'd rather snap a crank then a Jug to fail.

Much easier to replace a jug than a crank [/QUOTE]

By time a bottom end fails a cast iron Jug has already done it's duty if it's using high end bearings. The chances of blowing a high CR builds like 35% versus bone stock which is between 35-43%

If the engines cheap anyway get more for your value cast iron if it's a none chrome bore makes porting easier

There's a lot of slap job cylinders that are crap on kits, but if you buy a replacement it's higher quality then installed versions.

 

[Philandra Chambliss]

I'm going to replace the stock crank on my motor when it comes with a 3mm stroker crank might replace the hardware too. For the 48mm sleeved cylinder, a windowed flat top piston and stroker crank it is $150 US. But will probably last twice as long as the chrome lined $30 cylinder. Plus you get a few more ccs of displacement.

I'm rolling two bikes now ones a pawn shop saved CDH and or zeds it has a lot of job stuff on it had to craft a motor mount system to get the bike up to Snuff the tensioner system was a piece of crap fixed that too with my stick welder tried to fix the gas tank too but that kind of burn through LOL even if I put it on one setting it wouldn't Ark enough to get the ark started you turned out 2 to 2.5 burn straight through I call it the redneck mobile reason why it's cuz it's so so so horrible when I got it but little bit of my Ingenuity and knowing how to make these little bikes work and how to put them together and running a business building them I pretty much got this whole thing down pack FYI if anyone has a problem with the speech that's been said through Google Voice Chat tell it to my scab hand right now they got hit with a butterfly knife try to cut off a throttle grip when I sit to use my razor blade

 

[Street Ryderz]

Mzparts miami sells 48mm flat tops with the 48 mm iron sleeved cylinder I just bought it.

Yes Mz sell's them but they are 48mm not 47mm witch is the stock bore and therefore stock replacement size and all the stock replacements are domed.With the 48mm steel sleve you now need to source the rings used and the piston when replacing them,MZ doesn't list those and the use of that set up requires further crank balencing due to the added weight of that piston.

 

[Philandra Chambliss]

Yes Mz sell's them but they are 48mm not 47mm witch is the stock bore and therefore stock replacement size and all the stock replacements are domed.With the 48mm steel sleve you now need to source the rings used and the piston when replacing them,MZ doesn't list those and the use of that set up requires further crank balencing due to the added weight of that piston.

One could also counter balance the piston but one may still have to disassemble it to do a balance factor.

2 stroke stuffing of YouTube made a custom balanced crank with steel slugs on a press.

It's not hard personally I'd wait for the bearings to fail or leak split the case then find the balance factor.

If your going though all that may as well Chuck the stock crank and find a engine that has a similar sized cc and stroke from a reputable vendor such as stihl.

 

[Street Ryderz]

One could also counter balance the piston but one may still have to disassemble it to do a balance factor.

2 stroke stuffing of YouTube made a custom balanced crank with steel slugs on a press.

It's not hard personally I'd wait for the bearings to fail or leak split the case then find the balance factor.

If your going though all that may as well Chuck the stock crank and find a engine that has a similar sized cc and stroke from a reputable vendor such as stihl.

Unless you have a machine shop with lathe,mill,presses and alot of experience and even then not so easy to adapt a crank!Also a good crank could cost as much as a complete engine,if it was easy to do then every one would be doing it!

 

[Will'smotobikes19]

When I bought the 48mm jug it came with a stroker crank which I think is already balanced and there was a piston kit in the picture, wrist pin rings and piston and since its called a set I'd think it includes the piston kit too since why would you call a cylinder by itself a set. I'll just have to wait till it comes. Maybe if it didn't come with a piston I'll see if I can use a wiseco one. Pretty sure 48mm is 70 or 72cc. So not an unusual size for 2 strokes. Just looked on ebay there is several flat top 48s for sale they are for chainsaws maybe one of them could work.

 

[Stoneman]

I actually found this today

https://www.ebay.com.au/itm/262557223586

 

[Steve Best]

Usually domed pistons are preferred for power due to the smaller angles needed at the ports, stronger dome and better scavenging swirl dynamics.

Flat top pistons have a very slight theoretical surface area advantage but are mainly used for ease of manufacture.