Bigger exhaust worth it ?

[ricky_191]

Hi all , I'm looking to get some more power out of my pit bike. I have re jetted the carbie,new air filter , ngk spark plug, port matched and cleaned out intake manifold, and a re packed muffler and got a new sprocket set up yet to be tested to get more top end power and use the more of the gears.

I was thinking of getting a new exhaust made up and using the stock muffler because both of my exhaust are rusty.

So is it worth it to get a bigger exhaust made up or will it loose power ? I have seen the big bore kits but I might be able to get one made a lot cheaper.

Also any thing else to free up some power ? Thanks

 

[motovert24]

Depends on what exhaust system you go with.
My stock Lxr exhaust is good for bottom and top power and my procircuit took off bottom end and gave it more mid-top power range.
I put my motovert exhaust system on my pitpro (48mm tip, 32mm end at the end of the pipe.
Pitpro has one of them crappy like 10mm billet end mufflers was way better with the motovert exhaust and sounded heaps better.

My procircuit of my Lxr works well with my TB184ho was great kinda like a 2 stroke. With just a tb v2 head as a ported 160ho it had 0 bottom end power had to keep the revs up. With the 160ho stock it took off a fair bit of power so i kept switching exhausts.

A race head is the best thing to do then big bore kit then say a pro circuit or fmf etc. in my opinion

 

[motovert24]

Depends on what exhaust system you go with.
My stock Lxr exhaust is good for bottom and top power and my procircuit took off bottom end and gave it more mid-top power range.
I put my motovert exhaust system on my pitpro (48mm tip, 32mm end at the end of the pipe.
Pitpro has one of them crappy like 10mm billet end mufflers was way better with the motovert exhaust and sounded heaps better.

My procircuit of my Lxr works well with my TB184ho was great kinda like a 2 stroke. With just a tb v2 head as a ported 160ho it had 0 bottom end power had to keep the revs up. With the 160ho stock it took off a fair bit of power so i kept switching exhausts.

A race head is the best thing to do then big bore kit then say a pro circuit or fmf etc. in my opinion

 

[my67xr]

does the header pipes' engine end look restricted ?
a die grinder with a carbide burr can be used to open it up a bit, sometimes the weld inside the pipe restricts flow.


otherwise i'd be looking at fitting a performance camshaft and H/D springs, and a ported head too.

 

[ricky_191]

I haven't had a look in the exhaust. Mine is pretty rusty so I might need to get a replacement, Should I get a stock one , Get one made thats a little bigger or get a performance one ?

I don't want to go fully out on mods but if I have to replace the exhaust. I want to get something that will make it go a bit better if possible.

 

[my67xr]

here is a basic generic type big bore pipe/muffler




the big bore pipes have close on the same 32mm o/d as the flange that slips inside the head on a standard pipe.
they are still stepped down a bit for the flange mounting plate, but they open back up just after it and run the bigger diameter to the muffler.
some of them step up again just before the muffler to 38mm od, so you'd need a new muffler to suit
or buy a complete new system.


a lot of the newer 125 bikes now come with the rear stepped up pipe, using 38mm i/d mufflers, something like this.
i have basically the same on my Atomik Fuse and performs well compared to the smaller/standard pipe.

Exhaust Pipe Muffler CRF50 CRF 70 PIT PRO Trail Dirt PIT Bike Thumpstar | eBay


you will need to check out what style exhaust you need before you order one too, CRF type mounting or KLX, the bends in the pipe are also different.

 

[ricky_191]

I'm thinking of getting the same diameter pipe that slips into the head and bending it to make a new pipe.. All one size. The pipe shouldn't be much and it's only a few bends to make. Thoughts ?

 

[my67xr]

you'll need some good fabricating skill to DIY,

the 180 degree bend will be the hardest to do without the pipe crimping/folding in on itself.
even with a blowtorch, i cant get my 12 Tonne pipe bender to make anything that tight.
i haven't played around with filling it with dry sand though? could help it not to collapse ?

using a one piece pipe without the step in it, the head end of the pipe will still need a flange plate to bolt it up to the head
but you could fit and weld a slightly larger pipe over the new piping and weld it on, then the flange plate can press against that to hold it in tight.

otherwise if you have a fixed/welded flange plate, the exhaust will eventually crack and break though with any movement of the exhaust or muffler.

 

[ricky_191]

I won't be doing the work. lol I know this really good guy that did my cars cat back and he did a great job and it wasn't that much.

You could maybe get a 180 bend made up all ready and then weld it to a pipe. I might take it in and see what he can do.

There is one on ebay for $80 and that's not really too much. It does come with a muffler to but is it really worth the 80$ ??? I want to see some increase for my money.

lol i'm starting to learn more about bikes. I know with cars , when you make the exhaust too big you can loose too much restriction and loose power. I'm guessing this is the same deal. Also most of the time you need a reflash or carbie work to adjust fueling to take advantage of the free flowing exhaust..

This would be easy on a pit bike and I could run a lot more fuel with the new jets. A good air filter has helped with flow and taking the crap out of the intake manifold and port matching it , has helped it a bit.

I'm just looking for the cheapest option (because budget build) with the best upgrade.