Improving low end torque

[extremeodd]

I think I'm gonna have to cut it down anyways so it don't hit my frame. I'll probably have to cut some off the stinger too.

Is there anything special I have to do when shortening the muffler? It won't be here til later today so I haven't got a chance to check it out yet.

Not really, if your using a grinder make sure the disc is fresh otherwise you will have to cut the inner pipe separately. The only thing that was a bit of a pain is the end cap, I had to torch mine to burn the paint off after drilling out the rivets to remove it. That and the inner pipe simply slides onto the end cap manifold (engine end) but is freaking welded to the tail cap so it takes a bit of work to remove enough. My advice would be to leave the welded bit on and remove the nonwelded bit. Sounds kinda obvious but it wasn't for me until I was in too far to turn back.

To attach the endcap you can use self tapping screws but I was able to simply press fit mine, took some hammering but it aint coming off.

 

[Hello Moto!]

Not really, if your using a grinder make sure the disc is fresh otherwise you will have to cut the inner pipe separately. The only thing that was a bit of a pain is the end cap, I had to torch mine to burn the paint off after drilling out the rivets to remove it. That and the inner pipe simply slides onto the end cap manifold (engine end) but is freaking welded to the tail cap so it takes a bit of work to remove enough. My advice would be to leave the welded bit on and remove the nonwelded bit. Sounds kinda obvious but it wasn't for me until I was in too far to turn back.

To attach the endcap you can use self tapping screws but I was able to simply press fit mine, took some hammering but it aint coming off.

Yep I did exactly what you told me to avoid lol! I got it shortened down but I'm going to have to have it welded. The stinger on my pipe is the exact diameter as the mounting pipe so I've done some cutting now I just have to weld the pipe to the mount. I was going to attempt it myself but FML my welder is not working! I know a couple people who can weld it for me though.

Oh yeah check out this head I got from grubee.net. No threads for the spark plug and very bad pits in the casting on the squish band. I sent them an email about returning it.

 

[extremeodd]

Shoot, I should have mentioned that the CDH66 is the exact diameter as the muffler. A piece of heater hose works great to connect them, it is cheap and makes a fairly solid connection.

 

[Hello Moto!]

Shoot, I should have mentioned that the CDH66 is the exact diameter as the muffler. A piece of heater hose works great to connect them, it is cheap and makes a fairly solid connection.

That's a good idea. I might try that just to see how it sounds and runs before I get it welded. Thanks for the tip!

 

[extremeodd]

It's not a problem, heck just to hear how it sounds you can use ducktape. I used about 30 feet of electrical tape to attach the muffler when I first got it just to hear how it sounded. Made it about a full mile before it started drooping.

 

[Hello Moto!]

So I got it rigged up for now. JB weld lol. I know it won't last but until it falls off while goin down the road it'll have to work. I'll have it properly welded when that happens. I mean it's a damn solid connection, I just don't think it'll handle the heat.

It's not very loud at all and the performance has increased by at least double. Very noticeable low end torque increase as well as general pull all the way through. I'm impressed!

Last picture is my intake situation. It offsets to the right and hits the muffler and won't fit so I have it mounted upside down so it offsets to the left. It puts the carb at a stupid angle but I haven't noticed any issues so far. So until I find a 40mm offset intake that is designed to offset to the left I guess this will have to do. It runs better with a longer intake so I don't really wanna go back to the stock intake. I have to smash the air filter down on my dellorto knock off to get it to fit with the stock intake and I don't like it.

 

[Hello Moto!]

Yeah that lasted all of five minutes lmao! Time to get it welded.

 

[JerboaJohn]

dang,, but nice to hear you got the performance you're after. I like long intakes n header tube too for the low boost.
I bet a muffler shop can weld your pipe for $25

 

[Hello Moto!]

So I got the welder to work. Not sure what was going on with it. Got it welded! Ugly as hell but it don't leak and won't fall off after riding 5 blocks lol. Covered it with some heat wrap to mask it a bit.

All in all it turned into more of a process than I thought it would but it was worth it. I've got a pretty good torque and performance boost. When the replacement hc head gets here I hope it helps a bit more. I can't believe I received one with no threads for the spark plug lmao! Don Grube from grubee was just as surprised when I emailed him about a return. That's my luck though lol!

 

[gary55]

Not sure how much wrenching you've done in the past Moto but you can typically feel if your going too tight. The beauty of these engines is nothing is all that precise, I mean look at how rough the really cheap engines are that come from China and they still work albeit not for very long. Get the bolts to the german tightness spec "gutentight" (good and tight) and recheck after half a mile to a mile.

On a side note, not to hijack the thread, I was looking at those beautiful Fred heads and was wondering, whats the CC of a stock head?

Stock slant plug 7cc