Pocketbike Forum banner

B1-C1 hp exhaust pipe.

1565 Views 12 Replies 4 Participants Last post by  EPR
I just ordered a SS exhaust for my C1, yes, from Hong Kong, Motos.
$119.00 shipped. Looks like a copy of a $300-$400 exhaust.
Does anyone know the piston diameter of a Z1 ZPF, I'm guessing 37mm, if it 39cc, but not sure, I ordered a ZPF rep piston,ring,clips & pin, $8. Going to try to make it work on a Cag or Zenoah/Mitsu cyld.


See less See more
1 - 13 of 13 Posts
The Z1 piston is 36mm oh wait the Z1 is 50ccs so its 40mm its a bzm rep
I thought I heard someone before said it was 40mm. Going to put it in my ADA 40mm Cag 2 pcs cylinder kit, if it fits.


See less See more
Nice, thats a bad *** pipe.. Wonder if it will work on the Polini? Any chance I can get you to measure the holes on the Manifold? It doest look like my polini muffler is going to work and hits the radiator.. That Upgrade is going to be a pain.. I can already tell lol!

Sweet find!
I went there to look at a part for someone else, and when I saw that pipe, I almost wet my pants,lol. I have a stock Polini pipe I got used on ebay. I bid on it, and 2 seconds later, the guy selling bid up, I did it again, it went up so, it was ending in three days, so I waited till 10 second before it ended and bid 2 more dollars, he didn't have time to bid. I know it was him cause for 3 days not one more bid. Got it for $28, He must have been POed, I beat him at his little game. I did not want to mod the Polini pipe ruin it value,lol,lol.
The problem is my Rep engine has a bigger exh port and wider studs, so I made my own out of a Cag pipe. It has Polini on it so I know its real,lol.
Yes, I think you might make it work, but you would need to weld a flange on the end of the head piece to bolt it to you engine, cause it fits up into the casting of the C1 head w/ springs. I wanted it cause I think it will leave enough space above the carb so I can pull the choke knob up on the 19mm Dell Rep carb.
See less See more
I'm just worried about space on that GRC frame.. The radiator hits the stock muffler and I can only assume the BZM head is taller than the stock 39cc head.. Don't know how its all goona fit but the frame did come in 50cc water cooled so somehow it will happen.. I'll make it work.. I might have to sell the Other blata for the polini upgrades.. :( Seems like I need 60 different parts to make it work.. Doh!
Well, the pipe is 27" long and 17" from the back pipe mount to the front of the pipe. The head pipe has a real tight bend, and it's made for a B1 C1. When I get it in a few days, I will put it up to my bike and will see,lol.
man i wish I still had my message board with all the great c1 posts we really tore that engine down and made it bad ***. The best thing to do with the stock pipe even is to stick a long *** drill bit, the thickest you can find all the way down the back we had a problem with almost every one of them where the crappy welds were clogging them up. Also here are the crank stuffers I made for for the c1 when I had my shop.


See less See more
When I did my C1, I knew very little about squish, and since the engine filled with water and I pulled the cyld, I did some porting and glued the stock paper gasket back down. Does anyone make higher compression caps for the B1 C1s?? On my Cag 2 pcs alloy heads I have 13, 15 & 17 to 1 compression caps. If my C1 were not a 50cc ( 46cc ), I would have bought a 40cc PBU Flat Top piston kit for $64.
If I pull the cylinder again on the C1, going to leave the base gasket out and glue it down with Yamabond, that will raise the compression alittle.
On my 40cc polni rep I got an upper gasket kit from MidSouth and I use the .004" thick gasket, which left .020" or .5mm, haven't started it yet, it was use but new, you can see the cross hatch marks in the cylinder so the rings have not seated yet.
well depending on what generation you have you need to check the port timing or atleast get it somewhat right. use whatever base gasket youre going to and install it and see if your piston is at the very bottom of the exhaust port at bdc. Then from there check your squish. May have to modify the cylinder head to bring it down a little, but it should be a flat top piston stock if i remember right. I thought ada did make some diff domes??
I believe I ran the piston thru it's cycle to see if it blocked any ports, and to make sure the piston skirt did not hit the cases at BDC. Mine came from Tsun as a 50cc ( 46cc approx. ), I remember reading about people converting a 39cc to 50cc and needed to grind relief to clear the skirt. I just found out they shipped the parts yesterday.
what do you mean its a 50cc? Im just use to identifying them by mm. Does it come with a new cylinder or something? We modified some of the stock c1 pistons and get pretty good results out of them.
I believe it's bore is 39.5mm and the 39cc is 37mm. It was sold as a 50cc C1. It looks like the same cylinder hogged out to 39.5mm and plated inside. They don't sell them anymore. Can't remember if the have 50cc Cyld and parts for the 50cc engine.
1 - 13 of 13 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.