They all say they're working 'em. But nothing yet. HPD, Rick Ritter, Hot Seat, are all saying 2 months... Based on Scrambler pipes, the Sportsman needs more bends to get back to the muffler. A larger headpipe is called for. At least 1&3/4" diameter.
Stock is 1&1/2". Cheap, effective, automotive mufflers are in the plan for most. Trouble is, the stock muffler is 5" in diameter, and there is little choice in this size. 6" mufflers are plentiful in many sizes, as short as 12" long.
Gutting the stock muffler and installing parts from a new automotive muffler is an interesting idea, but you wouldn't have the stocker to go back to. Same for the headpipe. Parts like flanges could be easily harvested from the stock headpipe, and combined with curved sections of 1&7/8" tubing with straight sections of 1&3/4"makes a nice smooth flow, albeit with a lot of welds. About 12 pieces to make the pipe + muffler. But there's no turning back, if it didn't work you'd just have to buy the aftermarket pipe anyway. I figure I can make it myself for under $50 and about a day in the shop. Of course the second one for the EXP would be easier, and now the savings are up to about $400. Since the aftermarket pipes aren't out yet....Bite the Bullet and do it? Yes, I have a MIG welder and have been welding for 30+years. My only reservation is destroying the stock exhaust in the process. Without the flanges etc. building a good exhaust from scratch is a lot harder.

 

man it sounds like if someone is going to make our HO's really run its going to be you.i will watch your progress carefully and will be doing some of the stuff to mine. keep us informed of any changes that your making and if it works or not. my email i ehaney@midsouth.rr.com if you want to contact me.

 

HAY WERE DID YOU GET THE PUMPER CARB?AND HOW MUCH?.
I DID A POST TO FIND IF ANYBODY KNEW OF SUCH A THING. AND KNOWBODY GOT BACK TO ME. NOW I SEE YOU GOT JUST WHAT I WAS LOOKING FOR!.

 

In the back of Dirt Wheels Mag is an ad for Carb
Parts Warehouse. On the internet in a Mikuni search I found a number of sites, Pro-Flo, Sudco.
IT is unanimously agreed that the 42mm TMX Mikuni is for 2-strokes only, as there is no accelerator pump. The Mikuni BST used on the latest thumpers is not available as an aftermarket carb. But these guys all have the TM Mikuni Flatside Pumper for large displacement 4-strokes. It ain't cheap.
$329. It should be here tomorrow.
I swear I'm like a dog with a rag with this thing but I want what I thought I was going to get with the H.O. and that is more power. I just did a couple of test runs, messin' with the airbox again. I've put a larger tailpipe on the stock muffler and opened it up inside a little in the process, so I thought I'd try the airbox experiments again.
With the lid off, it kinda runs. With the horn off, which must be twice the opening, it ran up to 62 with a white plug, lean that is, so it is getting and using more air than with the horn. An oversized horn would be better, quieter than no horn. And it looks like we're getting more air/fuel through the engine. I don't have any other jets to experiment with, it has a 152.5 in it. With the TM carb, the airbox becomes a mute point. Since it is not a constant velocity carb it doesn't need vacuum to operate and the airbox can be opened up as much as you want, eliminating that variable. That stock horn is really small, I can't believe it's on the H.O. but it does quiet things down, which I like. When I go up in the mountains it runs rich, I may try taking the horn off to see if it leans things out.

 

fourlix,

Does the pumper carb have a vacumn port for the fuel pump?

 

Ive only got a basic understanding of the VM carb, but I don't see how opening up the air box is any different than with w flat slide.

I understand the TM will flow more air etc. but the same air box mods would just translate into larger jets. I don't see how the VM would NEED air box restriction??? You should be able to run the VM in the identical conditions as a TM no?

Just jet up what you have and open up the inlet to the box!

 

I got a couple of jets from the dealer today. Stock was 152.5. He gave me a 155 and a 160 to try. I want to run the 155 for a while and then check the plug. It does have more go power. When I read the plug and i it is the right coffee with cream color, then I am going to pull the lid on the airbox. I have removed the outerware, so I will just have to test for a while. Then spring and summer will come and I will have to re-jet for that and then a happy medium between the two...

Weetoots

 

Muffler shops dont make the nice open bends that the custom and factory shops do. Muffler shops squeeze the pipe as they make their bends. So to get an even flow, with equal size cross-section of say 1& 3/4 inch, I will use straight sections of 1&3/4 " but the turns will be cut from 2" pipe
squeezed and bent to 90 degrees about 1& 3/4 " diameter. It's a lot of joints, but matched carefully can be done quite well. I once built an expansion chamber for a 250 Yamaha with a headpipe with 9 pieces of straight pipe. The cool benders are called mandrel benders. Some fill the pipe with packed sand and wax, others with frozen soapy water. I got a bud at the local welding/muffler shop, he told me you can't do these techniques with regular muffler shop benders or it will break their dies. At $1,400 a set he won't even let me try!!
The constant velocity carburators, need a vacuum or "pull" in order for the diaphram to open, which is why a Polaris needs the airbox lid. Too many holes and the carb doesn't get enought vacuum to work, no matter what the jets.
A TM is a straight mechanical slide carb and needs no vacuum on the air filter side of the carb to work. Besides positive throttle response, there is no built in restriction as there is with a "Constant Velocity" carb. That means horsepower potential.
I think the airbox horn can be enlarged by cutting it along the seam, kind of like filleting
a fish, then making it bigger by pop riveting and gluing a piece of plastic or something along the edges to double it's size. Some tricky bandsaw work, pop rivets and silicone to keep it flexible or??? any ideas??? Anybody know how to weld plastic? I hear it can be done.

 

What? we got fuel pumps on these things??

 

Yeah i know how to plastic weld did it in school before i went to work at polaris. U use a hot air torch and a filler rod. Which depends on the type of plastic u are welding it is kinda like tig welding with no bright light.It kinda takes lots of practice to look good, but can be done. Check with a local autobody shop they should have the tools and the rods. I was thinking of using a piece of square tubing from eves trough the platic stuff heating it up or boiling it in water then forming it to make a big snorkel. Hell even better look at a 99 mag 500 snokel it may be what you are looking for.