What to remove while porting??

[Rick73]

Ah, I was confused, sorry. Is your engine another generic though?
I have a different muffler, the one that's not so easy to cut off the internal tube because there's two of them. I only opened the holes in the bottom baffle plate a bit, but then added 83cm of silicone tube to quieten it so it's probably about as restrictive as stock.

I have a 38T sprocket to try out soon so I'm hoping to break 40mph (but I'm always carrying panniers and I have a trailer to pull, too!). I have a 36T but I thought that will just be a bit much and wouldn't be able to accelerate and climb very well.
With the 42T it didn't feel like it was load that was limiting the speed but just the engine's top rpm with stock exhaust port height.. Well, that and the straight wasn't long enough so I had to brake as soon as I saw the 8--- on the tach, and still nearly crashed it haha.
I think a maximum rpm of 8000 or 8500 is probably better for the lifespan of the cheap bearings than running it up to 10000 anyway.

A 36T sprocket will keep the load on your engine nice and high so that will be good for seating (or re-seating) the rings, I believe.

generic probly it don't have a name lol. I had it for a few months so far besides twerking a few things ( as you can tell by all my threads as a newbie ) engine is great. I road it all threw the winter to get to work.
the black one I got was the second I bought and was junk from the unboxing. broken of bolt in the head chain will not fit around the crank on the engine and you can tell it was just over spray painted to the point that it's in everything, magneto , chain crank, clutch ext. . complete hack job. got my money back and was told to keep it. bought another my 3rd threw pension ( same place i got my 1st one )and I did try it out it runs good still not broken in yet and I'm throwing it on another cruiser sometime this week. ganna put a for sale sign on it. I work at a grocery store and people keep asking me if I bought or built my bruins bike the one ride now. got a few people wanting one.
the 36 tooth sprocket is great for flat land I can cruise a hill ( not real steep) at about 18-20 if I'm not at a stop climbing it. I got a 28 tooth but it will not fit my hub adapter. that one sux on hills lol.
anything I've learned from building is that cruiser brakes ain't enough. I am waiting on front and rear brakes that should be in any day now.
This site has been more helpful than one could ever imagine helped me threw alot of problem solving. thanks all who helped me out.

 

[FurryOnTheInside]

generic probly it don't have a name lol. I had it for a few months so far besides twerking a few things ( as you can tell by all my threads as a newbie ) engine is great. I road it all threw the winter to get to work.
the black one I got was the second I bought and was junk from the unboxing. broken of bolt in the head chain will not fit around the crank on the engine and you can tell it was just over spray painted to the point that it's in everything, magneto , chain crank, clutch ext. . complete hack job. got my money back and was told to keep it. bought another my 3rd threw pension ( same place i got my 1st one )and I did try it out it runs good still not broken in yet and I'm throwing it on another cruiser sometime this week. ganna put a for sale sign on it. I work at a grocery store and people keep asking me if I bought or built my bruins bike the one ride now. got a few people wanting one.
the 36 tooth sprocket is great for flat land I can cruise a hill ( not real steep) at about 18-20 if I'm not at a stop climbing it. I got a 28 tooth but it will not fit my hub adapter. that one sux on hills lol.
anything I've learned from building is that cruiser brakes ain't enough. I am waiting on front and rear brakes that should be in any day now.
This site has been more helpful than one could ever imagine helped me threw alot of problem solving. thanks all who helped me out.

40mph is bloody good for a tweaked generic! I'm inspired and can't wait to try out my 38T now.
Yes, this forum is brilliant, and it's where I learned all I know too!

 

[Rick73]

40mph is bloody good for a tweaked generic! I'm inspired and can't wait to try out my 38T now.
Yes, this forum is brilliant, and it's where I learned all I know too!

38 T will be better on the hills than my 36 T. I do got to peddle a bit from a dead stop to but I can't complain I love keeping up with traffic the looks I get lol. hand brakes are a must if your rocking a cruiser bike the cruiser brakes just ain't enough. you got to slow down way before you want to stop. there ain't nothing like skidding at 25mph and still not making the turn lol. I've learned from experience, tuck and roll after I hit a curb. I saved the bike from a hard hit and the bikes fine so for short brakes are on the way any day now.
so do you use a chain tensioner? I got rid of mine i didn't feel safe with it. I do got to ad a 1/2 link because I want to bring the back just a tad.

 

[FurryOnTheInside]

38 T will be better on the hills than my 36 T. I do got to peddle a bit from a dead stop to but I can't complain I love keeping up with traffic the looks I get lol. hand brakes are a must if your rocking a cruiser bike the cruiser brakes just ain't enough. you got to slow down way before you want to stop. there ain't nothing like skidding at 25mph and still not making the turn lol. I've learned from experience, tuck and roll after I hit a curb. I saved the bike from a hard hit and the bikes fine so for short brakes are on the way any day now.
so do you use a chain tensioner? I got rid of mine i didn't feel safe with it. I do got to ad a 1/2 link because I want to bring the back just a tad.

LOL yeah brakes do help. Haha. I have a 220mm (huge) disc on the front, with a Shimano Deore hydraulic brake (but I'm changing it to a Magura MT2 this weekend hopefully) and I have a Magura HS33 hydraulic rim brake on the rear which basically makes it a 620mm disc.
I do use a tensioner because my frame has vertical dropouts. It's a repurposed chain retention device meant for a dual chainring mountain bike so it has a wide pulley wheel.
I'm using a #410 BMX (1/8") chain but I have just got a 9 speed (11/128") mountain bike chain that I should be fitting soon. This will hopefully allow me to fit two or three rear sprockets and select the right one for the terrain (not gears, just manually moving the chain and repositioning the tensioner to hold the chain tight).



Back on topic, I don't think we've discussed the transfers at all so far in this thread..

More torque can be gained from improving the scavenging (and with a small rear sprocket it needs all the torque it can get), keeping the intake charge inside the cylinder while pushing all the exhaust gasses out, and not mixing the two together too much. It should also reduce the heat, the two-stroke smell and the amount of hot oil spraying out of the muffler.
We can help the fresh intake charge stay separate from the exhaust gasses by redirecting the exhaust side of the transfer ports to angle them more towards the intake side of the cylinder. This could be tricky because there's not a lot of wall thickness on the outside of the transfers, and we must not break through to the outside.
Jaguar used JB Weld to build up the port, which is safe but it reduces the cross sectional area of the port somewhat.
Street Ryderz used his rotary tool to grind back which keeps the cross sectional area for good flow, but that corner of the port is where you run the risk of breaking through.
I did a bit of both. I want to go a bit further with the grinding back, but it is difficult to reach in there. So to make it a bit easier to reach I'm planning to cut open a bit at the bottom of the transfers, where we would normally "knife" the transfer wall to improve the flow out of the crankcase. Like a scalloped/webbed effect. Some cylinders have open transfers anyway, so I see no problem with having partially open transfers.

Happy Time transfer redirect

• FurryOnTheInside
• Sep 9, 2017

EU eBay motor, gave it Jaguar's transfer redirecting mod.
This will help keep more of the fresh...

Crappy Time transfers

• FurryOnTheInside
• Aug 23, 2017

Knifed my transfers, kinda roughly. No idea if this helps at all when carb etc is stock. Can't...

 

[Carl Walichnowski]

LOL yeah brakes do help. Haha. I have a 220mm (huge) disc on the front, with a Shimano Deore hydraulic brake (but I'm changing it to a Magura MT2 this weekend hopefully) and I have a Magura HS33 hydraulic rim brake on the rear which basically makes it a 620mm disc.
I do use a tensioner because my frame has vertical dropouts. It's a repurposed chain retention device meant for a dual chainring mountain bike so it has a wide pulley wheel.
I'm using a #410 BMX (1/8") chain but I have just got a 9 speed (11/128") mountain bike chain that I should be fitting soon. This will hopefully allow me to fit two or three rear sprockets and select the right one for the terrain (not gears, just manually moving the chain and repositioning the tensioner to hold the chain tight).



Back on topic, I don't think we've discussed the transfers at all so far in this thread..

More torque can be gained from improving the scavenging (and with a small rear sprocket it needs all the torque it can get), keeping the intake charge inside the cylinder while pushing all the exhaust gasses out, and not mixing the two together too much. It should also reduce the heat, the two-stroke smell and the amount of hot oil spraying out of the muffler.
We can help the fresh intake charge stay separate from the exhaust gasses by redirecting the exhaust side of the transfer ports to angle them more towards the intake side of the cylinder. This could be tricky because there's not a lot of wall thickness on the outside of the transfers, and we must not break through to the outside.
Jaguar used JB Weld to build up the port, which is safe but it reduces the cross sectional area of the port somewhat.
Street Ryderz used his rotary tool to grind back which keeps the cross sectional area for good flow, but that corner of the port is where you run the risk of breaking through.
I did a bit of both. I want to go a bit further with the grinding back, but it is difficult to reach in there. So to make it a bit easier to reach I'm planning to cut open a bit at the bottom of the transfers, where we would normally "knife" the transfer wall to improve the flow out of the crankcase. Like a scalloped/webbed effect. Some cylinders have open transfers anyway, so I see no problem with having partially open transfers.

Happy Time transfer redirect

• FurryOnTheInside
• Sep 9, 2017

EU eBay motor, gave it Jaguar's transfer redirecting mod.
This will help keep more of the fresh...

Crappy Time transfers

• FurryOnTheInside
• Aug 23, 2017

Knifed my transfers, kinda roughly. No idea if this helps at all when carb etc is stock. Can't...

So what are using to do the porting? Are you using a rotary tool with a flex shaft?

 

[FurryOnTheInside]

So what are using to do the porting? Are you using a rotary tool with a flex shaft?

Yeah. I had one without a flex shaft and I did manage to get it done, but I used it a lot on the build and wore out the motor so I have got myself a new one and it has the flex shaft whatsit. I am using the very cheap tungsten carbide burrs sets from ebay/ China that are frustratingly just a little bit shorter than would be ideal. That's why I came up with the plan to scallop the bottom of the transfers to get a bit more reach.

 

[Street Ryderz]

So what are using to do the porting? Are you using a rotary tool with a flex shaft?

Rotary tool with flex shaft,just the rotary tool,Air pencil die drinder,anything you can get in there LOL.

 

[Rick73]

Rotary tool with flex shaft,just the rotary tool,Air pencil die drinder,anything you can get in there LOL.View attachment 82030

I got a cheapo rotor tool from Wal-Mart lol broke it so I plan on using my drill with the rotor bits.

 

[FurryOnTheInside]

I got a cheapo rotor tool from Wal-Mart lol broke it so I plan on using my drill with the rotor bits.

It won't have the necessary rpm, I think. If it's anything like mine anyway, the fastest speed on the drill isn't even close to the slowest speed on the rotary tool. Sorry.

 

[Rick73]

LOL yeah brakes do help. Haha. I have a 220mm (huge) disc on the front, with a Shimano Deore hydraulic brake (but I'm changing it to a Magura MT2 this weekend hopefully) and I have a Magura HS33 hydraulic rim brake on the rear which basically makes it a 620mm disc.
I do use a tensioner because my frame has vertical dropouts. It's a repurposed chain retention device meant for a dual chainring mountain bike so it has a wide pulley wheel.
I'm using a #410 BMX (1/8") chain but I have just got a 9 speed (11/128") mountain bike chain that I should be fitting soon. This will hopefully allow me to fit two or three rear sprockets and select the right one for the terrain (not gears, just manually moving the chain and repositioning the tensioner to hold the chain tight).



Back on topic, I don't think we've discussed the transfers at all so far in this thread..

More torque can be gained from improving the scavenging (and with a small rear sprocket it needs all the torque it can get), keeping the intake charge inside the cylinder while pushing all the exhaust gasses out, and not mixing the two together too much. It should also reduce the heat, the two-stroke smell and the amount of hot oil spraying out of the muffler.
We can help the fresh intake charge stay separate from the exhaust gasses by redirecting the exhaust side of the transfer ports to angle them more towards the intake side of the cylinder. This could be tricky because there's not a lot of wall thickness on the outside of the transfers, and we must not break through to the outside.
Jaguar used JB Weld to build up the port, which is safe but it reduces the cross sectional area of the port somewhat.
Street Ryderz used his rotary tool to grind back which keeps the cross sectional area for good flow, but that corner of the port is where you run the risk of breaking through.
I did a bit of both. I want to go a bit further with the grinding back, but it is difficult to reach in there. So to make it a bit easier to reach I'm planning to cut open a bit at the bottom of the transfers, where we would normally "knife" the transfer wall to improve the flow out of the crankcase. Like a scalloped/webbed effect. Some cylinders have open transfers anyway, so I see no problem with having partially open transfers.

Happy Time transfer redirect

• FurryOnTheInside
• Sep 9, 2017

EU eBay motor, gave it Jaguar's transfer redirecting mod.
This will help keep more of the fresh...

Crappy Time transfers

• FurryOnTheInside
• Aug 23, 2017

Knifed my transfers, kinda roughly. No idea if this helps at all when carb etc is stock. Can't...

so you would cut the piston not only on the intake but also the exhaust side?