New here! 50cc build

[DieselTech]

"D" shaped.

Ok that's what I was thinking, I need to square & radius my upper corners more defined. When that time comes to porting a cylinder.

 

[Atvrunner2]

I get to do alot of pb engines and go ped engines here and I can tell you that pb guy's are very stubborn and many just can't be helped LOL, I had an issue with one of the pocket bike groups admins for telling a guy to raise his transfers after he had raised the exhaust port and shrunk the blow down which dropped the power band to low and left the engine falling off way too soon. The admin started trying to tell me that was bad advise and that these engine's (cag) could never make enough power to power wheelie or go over 50 and well that is just simply not true! With the transfers widening the base doesn't really do anything since the highest velocity and volume is just after open when most of the port is still closed and to get any aid from the pipe the timing and blow down has to be correct or alot of the fresh charge is lost into the pipe.
The exh port timing if you want power in the higher rpm ranges has to be cut/raised, widened and radiused in the upper corners with a flat center section if you want the pipe to hit hard!
I've had this cag engine pocket dirt bike since 09 and it has been used to teach my kids and now my grand kids how to ride, I had my youngest son on this bike when he was 6 y/o flying through hydro fields and on single track area's at 40+ and when it needed a new cylinder about 4-5 years ago now I did a bit of correcting on it as I felt it could use a bit more for when I messed around with it like this, https://video-yyz1-1.xx.fbcdn.net/v/t42.1790-2/18080931_1380579515342641_5228060975554363392_n.mp4?_nc_cat=111&ccb=1-5&_nc_sid=985c63&efg=eyJybHIiOjU4MSwicmxhIjo2MzksInZlbmNvZGVfdGFnIjoic3ZlX3NkIn0=&_nc_ohc=3IIq3pgYG3sAX9sFYLH&_nc_oc=AQn-YR-7n8IFnEIXZRI8QoraF8f_2Z9Aw5VXapNKrgDa-yznSLAOWzb0EnaRTQsgDr5_DTxKiIvlbTU04bxkWwO5&rl=581&vabr=323&_nc_ht=video-yyz1-1.xx&edm=ADWe-ecEAAAA&oh=8570e52b57ef9de68415c4de6c6f8e0f&oe=61B1CEBD

Some are very stubborn. I am all about learning. I definitely don't know it all. And even though CAG engines and CG are 2 strokes, not every 2 stroke is the same and will respond differently to different modifications. There are the obvious basics. I do want to push this little motor harder after some initial runs and breakin.
Thank you

 

[DAMIEN1307]

https://video-yyz1-1.xx.fbcdn.net/v/t42.1790-2/18080931_1380579515342641_5228060975554363392_n.mp4?_nc_cat=111&ccb=1-5&_nc_sid=985c63&efg=eyJybHIiOjU4MSwicmxhIjo2MzksInZlbmNvZGVfdGFnIjoic3ZlX3NkIn0=&_nc_ohc=3IIq3pgYG3sAX9sFYLH&_nc_oc=AQn-YR-7n8IFnEIXZRI8QoraF8f_2Z9Aw5VXapNKrgDa-yznSLAOWzb0EnaRTQsgDr5_DTxKiIvlbTU04bxkWwO5&rl=581&vabr=323&_nc_ht=video-yyz1-1.xx&edm=ADWe-ecEAAAA&oh=8570e52b57ef9de68415c4de6c6f8e0f&oe=61B1CEBD

This URL signature is expired so cannot see what is posted with this...DAMIEN

 

[Street Ryderz]

This URL signature is expired so cannot see what is posted with this...DAMIEN

That's weird because that video is all ready on this site a few years back now.

 

[Street Ryderz]

Well I'll try again !

 

[Atvrunner2]

So, what would be your first mods to the smaller CG engine??

 

[Greg58]

Not really a mod but should be done, flush out the bottom end to remove any debris or metal left in it from the factory. Clean up any slag left in the ports. After that I like to get the kit on the bike and see how well it runs. Don't forget to check/add grease to the gears on the clutch side and grease the bucking bar too.

 

[Greg58]

What I recommend is stretching a old tee shirt over a bucket and securing it, I then add fuel mix to the crankcase and slosh it around, next pour that onto the tee shirt and see what comes out. I've found small bits and pieces of metal, others have found a lot more.

 

[Street Ryderz]

So, what would be your first mods to the smaller CG engine??

The first things I do is swap out the bearings and make them slip fit the shafts so that disassembly later is easy and also seat them sq in the case half's.
Then I balance and true the crank, match the transfer feeds in the case to the cylinder and deck the cylinder so piston crown comes flush to the deck.
Port timing and sizing along with correcting the transfers exhaust side and roof angles, swap out the little end bearing and shim it's end play, check and find rings with suitable fitted gap (many are too big) set squish then leak down and comp check and run it.

 

[DieselTech]

The first things I do is swap out the bearings and make them slip fit the shafts so that disassembly later is easy and also seat them sq in the case half's.
Then I balance and true the crank, match the transfer feeds in the case to the cylinder and deck the cylinder so piston crown comes flush to the deck.
Port timing and sizing along with correcting the transfers exhaust side and roof angles, swap out the little end bearing and shim it's end play, check and find rings with suitable fitted gap (many are too big) set squish then leak down and comp check and run it.

I'm glad to hear you make your bearings slip fit, if you do it, it must be OK. I watched your balance factor video & when I put my engine 2gether. I made it where my bearings were slip fit so I would not fight the bearings & the case halves when assembling. I didnt check crankshaft end play thou, I better do that.