My chop chop

Hi im from Oz and this is my 2 stroke Schwinn in progress... I've done the usual mods including a severe dose of heavy porting.

I got bored so I polished the engine covers to a mirror finish - I reckon this looks much better than the same crappy slotted cnc covers that everybody has.... I also did a little porting and port-matching with the inlet manifold...

I've ordered a aftermarket cnc head as well as a 4 litre fuel tank that should arrive very soon... I'm gonna give the head a skim to raise the compression slightly just to give it shooting match a little more oomph... let's see what happens aye... lol

Check it out
 

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Chop-chop

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May 19, 2021
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94
I know this is not my original concept and I definitely don't plan to take credit for coming up with the idea... I remember seeing it on a friend's motorized bike many years ago and I've kept the idea on the back-burner .... until now, I'm gonna apply it to my own bike.

I'm currently in the hunt for an aluminium baseball bat or two, with the longest handle I can possibly find and I plan to adapt it to the Schwinn as an exhaust pipe. Perhaps stashing an expansion chamber of sorts in the guts of it and flare the big end out as the tip... I know it'll work because it's been done and it looks and sounds soooo chunky and beefy !! Also being aluminium means it can be polished up to a mirror finish !!
 

DAMIEN1307

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I'm currently in the hunt for an aluminium baseball bat or two, with the longest handle I can possibly find and I plan to adapt it to the Schwinn as an exhaust pipe.
That is an intriguing idea...i don't think ive ever seen that mentioned or done here as of yet...DAMIEN
 

Chop-chop

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May 19, 2021
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That is an intriguing idea...i don't think ive ever seen that mentioned or done here as of yet...DAMIEN
Yea, like I'd said - I'm not gonna rip off someone else's idea and claim it as my own because I'm a strong believer of giving credit when it's due to it's rightful 'owner'... eitherway, it's a wicked idea and it would save hours in fabrication time considering it's got pretty much the ideal profiles for the job. The most that need to be done is to have the 'manifold' end bent to the correct shape to suit the exhaust path etc....the rest is done for you lol I've been looking on Ebay and going this way, a custom exhaust system can be had for no more than $20 bucks ! Also the added bonus being aluminium it's lightweight !!
 

Chop-chop

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May 19, 2021
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94
Here's a Stihl Warbro-style chainsaw carb being adapted to a 47mm jug. The adaptor plate just arrived so I'm in the process of making up a heat insulation spacer out of a piece of nylon chopping board to go between the adaptor and the carb to prevent the heat at the cylinder from affecting the fuel/carb. I'm also waiting for the velocity stack and the air filter to arrive. All I have to do after that is to tap a vacuum pulse line from the transfer port to the carb to get the fuel moving....as well as getting the throttle cable set up properly. The advantage of running this type of carb is it has it's own high and low range fuel mixture screws allowing mixture adjustments on the fly without having to pull the damn thing apart to change the jets etc.... a very simplified process when setting up fuel delivery.
 

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Chop-chop

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This is a spare ported China-doll I'd just finished assembling because I'd been bored during this extended lock-down in Sydney over the last few weeks.
It's the second of these 'Triple forty' I'd picked up recently that's got the open-style transfer ports. It's been extensively ported including matching of the transfers all the way into the case etc. The new oct-shaped cnc head just arrived today so it's coming together nicely, I've even got a new PW80 ignition setup here for it as well. If you guys remember - I originally picked up 2x of these triple-forty engines for a bargain price off Ebay and fitted the first one onto the Schwinn chopper - which I've been running-in over the last coupla months, so I dunno what I'm gonna do with this one here.... maybe just sit it on the shelf as a chat-starter over a drink.. and/or keep it for a spare. All the hard work has been done so it's ready to be dropped into and run-in on a bike.... I may even off-load it to a lucky fella bikie...
I'm planning to place an order for a Minarelli top-end conversion (or two) from Smolik in the next coupla weeks so yea.... anyways...
 

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Chop-chop

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Ok ...I've finally gotten off my ass and replaced the 32-tooth rear cog on the rear of the Schwinn chopper with a smaller 28-tooth unit. I would have to say the 28-tooth cog would have to be the absolute smallest one could fit using the popular hub adapter, the reason being that the three mounting holes that is normally drilled on the cog to mount it to the adaptor is at It's absolute limit in terms of the locations of the holes overlap the actual teeth of the cog. This is why any cogs smaller than 28-tooth doesn't have the set of three holes for the adaptor but rather the six holes for mounting using the disc-brake rotor mounts.
Eitherway, I was lucky in my particular case as when I drilled the adaptor mounting holes onto the cog, they just cleared the teeth so it all should work once I put it all back together in the morning.... can't wait to feel the change up the top-end ! Going from 32-tooth down to a 28.... I should at the very least feel a noticeable difference....
Also, with the added bonus of disc brakes !! That's right - I'll finally be able to lose the pathetic non-existent cable brake at the rear and replace it with a caliper/ rotor setup.... can't wait until the morning !!
 

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Chop-chop

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Finally done ! 28-tooth rear cog with disc brake rotor stacked-mounted. It works so much better than the stock Schwinn brakes it came from the factory with...
It's currently only running a steel-cable driven caliper but a hydraulic caliper is in the works along with the hydraulic clutch actuator I have coming in the next round of mods.
There is so much more legs up top It's beautiful and since it's only a 20 inch rear, there is still enough bottom end to get off the mark from a stand-still with no pedalling required.... I love it !
 

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Chop-chop

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I have never seen this done anywhere and I wonder why.....but I'd just trial-fitted a generic MZ65 pipe to the Schwinn chopper and it appears to sit quite nicely with no clearance issues. I plan to remove the current straight tip and adapt the silencer / muffler and tip that I previously had on the bike to it...
I think it's going to require some heat insulating exhaust wrap to some my right leg from being cooked, but other than that, it should be a straight forward exercise.
 

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