Well, the project is finally complete and works excellent!!!! I know a few of you guys have used a couple of different styles of pipes for these 2-strokes so I figured I would give it a shot. Check out the photos. Here are the gorey details for those of you who want to try it out:
1) Stock Pocketbike pipe and silencer. You can find them on Ebay for around $25
2) Cut off headpipe close to the weld spot where the bend begins.
3) Cut off the mount bracket and save it.
4) You will have to make your rear mount bracket first so you have a way to hold the pipe roughly in place to make the measurements for the headpipe.
5) You will have to remove a section of the headpipe to shorten it enough to make the proper new bend fit correctly. ( did that make sense??)
6) Have someone help hold the pieces in place or tack them together with a weld spot here and there. Or you can mark them so you know exactly how they will fit together when the pipe is off the engine.
7) You may have to open the mount bracket holes a bit to fit the exhaust cyclinder studs.
8) Use a wire-feed mig welder and weld the pipe pieces together after you have marked how they fit together (or tacked them).
9) Grind the welds down and paint the pipe with Fast Black Gloss.
Simple as that. Now for the good stuff:
1) Intake tube was match ported to the cyclinder. I widened the area that connects to the intake port because the intake tube is round and the intake port is rectangular. This is very bad. I ground the **** out of it to get it to match as best as possible, obviously I couldn't make a rectangle shape out of a round tube but I was able to really oval the tube to match much better than the narrow stock sized opening.
2) Match ported the exhaust port to the exhaust mount bracket. They were way off, too.
3) Reshaped the exhaust gasket to actually allow the exhaust to flow properly out of the port. I had to trim almost 2mm all the way around the inner diameter of the gasket.
4) These engines have serious air leaks where the carb is mounted to the intake tube, where the intake tube mounts to the cylinder, and where the cylinder head meets the cylinder ( due to lame closed-nuts that restrict proper tightening ), just add a small loc-washer under each nut and re-torque.
Use a good quality gasket sealer and add to the intake tube on both ends to eliminate the air leaks. This helps with erratic idling and lean running conditions.
5) Replaced lame spark plug cap and plug with an NGK cap and an NGK plug.
6) I run the chain direct, sprocket to sprocket. This is unorthodox, I know, but anything that interferes with rolling of the chain causes friction which, in turn, robs power from the wheel. However trivial this might seem, it's makes a big difference with a tiny motor like this.
7) Stock main jet with the slide needle dropped to the leanest setting ( top notch on the needle). Excellent throttle reponse throughout.
8) ATV thumb throttle instead of twist.
All this gives me a top speed of 40-45, with a 44t rear sprocket, depending on ambient air temp here in Upstate NY. Humidity makes it run slower of course. It climbs hills much better and I use it commute 30 miles to work every nice day I get. I weigh 185lbs and it pulls me with little effort compared to the stock set-up. I bet this thing would hit 50MPH with a 36t.
Don't forget to check out the photos. Hope this inspires somebody.
1) Stock Pocketbike pipe and silencer. You can find them on Ebay for around $25
2) Cut off headpipe close to the weld spot where the bend begins.
3) Cut off the mount bracket and save it.
4) You will have to make your rear mount bracket first so you have a way to hold the pipe roughly in place to make the measurements for the headpipe.
5) You will have to remove a section of the headpipe to shorten it enough to make the proper new bend fit correctly. ( did that make sense??)
6) Have someone help hold the pieces in place or tack them together with a weld spot here and there. Or you can mark them so you know exactly how they will fit together when the pipe is off the engine.
7) You may have to open the mount bracket holes a bit to fit the exhaust cyclinder studs.
8) Use a wire-feed mig welder and weld the pipe pieces together after you have marked how they fit together (or tacked them).
9) Grind the welds down and paint the pipe with Fast Black Gloss.
Simple as that. Now for the good stuff:
1) Intake tube was match ported to the cyclinder. I widened the area that connects to the intake port because the intake tube is round and the intake port is rectangular. This is very bad. I ground the **** out of it to get it to match as best as possible, obviously I couldn't make a rectangle shape out of a round tube but I was able to really oval the tube to match much better than the narrow stock sized opening.
2) Match ported the exhaust port to the exhaust mount bracket. They were way off, too.
3) Reshaped the exhaust gasket to actually allow the exhaust to flow properly out of the port. I had to trim almost 2mm all the way around the inner diameter of the gasket.
4) These engines have serious air leaks where the carb is mounted to the intake tube, where the intake tube mounts to the cylinder, and where the cylinder head meets the cylinder ( due to lame closed-nuts that restrict proper tightening ), just add a small loc-washer under each nut and re-torque.
Use a good quality gasket sealer and add to the intake tube on both ends to eliminate the air leaks. This helps with erratic idling and lean running conditions.
5) Replaced lame spark plug cap and plug with an NGK cap and an NGK plug.
6) I run the chain direct, sprocket to sprocket. This is unorthodox, I know, but anything that interferes with rolling of the chain causes friction which, in turn, robs power from the wheel. However trivial this might seem, it's makes a big difference with a tiny motor like this.
7) Stock main jet with the slide needle dropped to the leanest setting ( top notch on the needle). Excellent throttle reponse throughout.
8) ATV thumb throttle instead of twist.
All this gives me a top speed of 40-45, with a 44t rear sprocket, depending on ambient air temp here in Upstate NY. Humidity makes it run slower of course. It climbs hills much better and I use it commute 30 miles to work every nice day I get. I weigh 185lbs and it pulls me with little effort compared to the stock set-up. I bet this thing would hit 50MPH with a 36t.
Don't forget to check out the photos. Hope this inspires somebody.
he's my finshed pipe
