Articat Teen

Alright, I have a 1988 650 in a 1992xcr 440 chassis. I rebuilt this motor due to low compression (80 across). It was .20 over so I went a size bigger, .30. I have 120 across compression. The sled came with triple htg pipes (hate them, looking for single manifold if anyone has one). Its jetted stock at 270. Sled flys for say 1000ft. Then bogs down. If you rev it up for 7 - 9 revs it will fly for another 1000ft or so. When it bogs down, it wont go past 5k. When it picks up, it runs strong at 8k almost 9k. If your screaming across a lake, it will go good if you keep it at the bar. Also it has no grunt coming outta the hole, off a dead launch, it just blah.. lol. This makes powder riding next to impossible. Every time I tear down carbs the bowls are full. Needle and seat work well as blowing in the fuel line and holding at half will stop, and released will let you blow through. Plugs are a beautiful chocolate colour. Not black, not white. so WTF! Carbureted 650 Triple with HTG triple pipes .30 over. All new fuel lines. etc. Thanks for reading any insight needed!

__________________
1990 Indy 500
1991 Indy 500 short track
1992 Indy light 340

meburdick

If that motor is cranking up to 9000, I would guess that you're fuel-starved. It sounds to me like what's happening is this:

- Idles and the fuel pump is delivering plenty of fuel to keep the bowls full
- You drive off and things are still ok
- You peg it and the motor revs up pretty high, sucking fuel down at a rate much faster than what the pump can replenish
- You let off and the pump can catch back up
- Process repeats

If this is, in fact, what is happening, there's a pretty good chance you're going to hurt your motor. When that fuel supply runs down, you're running lean (and hot). When it catches back up, you're ok again.

With the different motor in there, do you have a fuel pump capable of supplying an appropriate amount of fuel to the carbs?

__________________
2002 Edge X 500: https://plus.google.com/photos/11364...45853579342449
1998 Indy 440: https://plus.google.com/photos/11364...10516040672513

Articat Teen

That's exactly how it seems. But if it is in its "bogging" stage If I shut it down plugs are still a decent brown. When I did the motor swap I had the full 650 chassis. But tunnel was folded. So the electrical, bars, steering and fuel assembly are all off that chassis. Basically swapped everything over. Now my one concern is the fact that it is bored .30 over, running triple HTG pipes but there way louder then a triple set up seems, they seem to look homemade.. but the carbs are only running 270 jets. I believe 270 is stock in this motor. Thanks for the quick reply!

__________________
1990 Indy 500
1991 Indy 500 short track
1992 Indy light 340

Articat Teen

What you posted on Way2sick thread. "With jetting, you run into issues with a bog, rough running, cutting out, power fade, etc." That's exactly what it seems like. It bogs off the line, runs good around mid, but at top it seems to throw you back and forth after 1000ft or so. Power there one second, and not the next. After reving it a few times, it comes back for just a short amount of time. With all 3 hoses off fuel pump, it pushes tons of fuel out. But Ive also noticed that there is air bubbles that seem to return towards tank.. is this normal?

__________________
1990 Indy 500
1991 Indy 500 short track
1992 Indy light 340

meburdick

If you're running stock jets on a motor that's bored over, you should check for piston wash.

Pull the plugs and rotate the motor to bring each piston through at least a full "cycle." Look to see what the wash pattern looks like on the surface of the piston and do a Google search for some images of piston wash. You don't want to see black because that means you're running cold and/or rich. You don't want to see white and ashy everywhere because that means you're running hot and/or lean. You should see some darker areas and some lighter areas in a definite pattern. Again, a Google search for some images will help you understand what you're looking for.

Try running the sled BELOW the max RPM across a lake something. Get it up to 70 and hold it there. See what happens. If you can ride it like that for a half mile or so, do it. Then, hit the kill switch and coast it out. Pull the plugs and check them. Do this at a variety of speeds. This is referred to a plug chops.

Figure out the max speed you can run the sled at for at least a half mile without it conking out on you and do a plug chop at that speed. Then, try going up just a couple of miles an hour. At the first sputter, kill it and do a plug chop.

When you let it idle back down, it starts to reverse the indicators on the plugs. So, you have to hit the switch and coast it out in order to get the right reading.

__________________
2002 Edge X 500: https://plus.google.com/photos/11364...45853579342449
1998 Indy 440: https://plus.google.com/photos/11364...10516040672513

meburdick

Check the fuel filter and the pickup line in the tank. Air bubbles will happen, but they should be very small (from the vibrations). You could also have issues with the needles and seats in the carbs if they're not opening properly to allow all of that fuel into the carb.

Have you gutted and completely cleaned the carbs yet? Ethanol is NASTY stuff and is very hard on the lines, the seats/needles, carb bowls, and the jets. Check that pickup line carefully, too.. I've heard of the lines falling off in the tank and I've also heard of the intake screens getting dirty and restricting fuel flow.

__________________
2002 Edge X 500: https://plus.google.com/photos/11364...45853579342449
1998 Indy 440: https://plus.google.com/photos/11364...10516040672513

Articat Teen

Ok will forsure go through it all this week thoroughly. Pistions are tan but do resemble some black crusty stuff

__________________
1990 Indy 500
1991 Indy 500 short track
1992 Indy light 340

meburdick

A little bit of it on there in places is ok. The only way you should be 100% tan is if you run it wide open all the time and have the jetting on it "perfect" in the cold weather. Remember that you need bigger jets when the temp drops. So, perfect now could mean lean in the cold.

__________________
2002 Edge X 500: https://plus.google.com/photos/11364...45853579342449
1998 Indy 440: https://plus.google.com/photos/11364...10516040672513

joshkidner

with triple pipes you need larger than stock jets. look up what those pipes suggest you use for jets in that engine. that explains not enough fuel. rpms could hit 9k with triple pipes, but shouldnt go 1rpm over.

__________________
1987 chasis with 1985 597cc under the hood. Xtra-10, fox shocks, and a whole lotta speed!

xflyer53

Just curious, this was an engine swap, you replaced all the fuel lines. What did you use for an impulse line? If it is a soft line it may be collapsing. This would prevent proper fuel flow when you need it most.

__________________

'92 Indy 650
'95 Indy XLT 600, plastic skis, skid plate, cobra windshield, XTRA 10, full Fox package, 1" riser

Articat Teen

If by impulse line you mean the one in the tank, pick up, I never touched. The vacuum line from motor to fuel pump I used black hose. Not soft fuel line

__________________
1990 Indy 500
1991 Indy 500 short track
1992 Indy light 340

xflyer53

Ya, the impulse line is the vacuum line from the crank case to the fuel pump.

__________________

'92 Indy 650
'95 Indy XLT 600, plastic skis, skid plate, cobra windshield, XTRA 10, full Fox package, 1" riser

xflyer53

Thinking more about this, you could check the needle & seats make sure they are the correct size. I believe they should be 1.5. A 260 main is stock for for that motor. So you are slightly rich there, but having the pipes that may be about right. The other thing to check is the bowl floats. If they are hanging up, they may not allow enough fuel to keep the bowls full and you are running them dry. Letting off allows them to fill back up till you pin it again. As Burdick stated, you would never see that on pulling the plugs because your lean condition corrected itself before you shut it down.

__________________

'92 Indy 650
'95 Indy XLT 600, plastic skis, skid plate, cobra windshield, XTRA 10, full Fox package, 1" riser

Articat Teen

For the needle and seats being 1.5, how do I find this out? I will be tearing the carbs right down tomorrow, letting them soak etc. Will pull the needle and seat etc. Like the main jets, do the pilot jets also have a number? People were saying go from 45 to 40 on those.. Just trial and error I guess.

__________________
1990 Indy 500
1991 Indy 500 short track
1992 Indy light 340

meburdick

It's stamped on the needle / jet.

__________________
2002 Edge X 500: https://plus.google.com/photos/11364...45853579342449
1998 Indy 440: https://plus.google.com/photos/11364...10516040672513

Articat Teen

Also one thing I did notice, on most mikuni carburetors I've done on the needle in the slide, There was plastic o rings sorta that were on top and bottom of the little c clip.. This one has just the c clip, is this right?

__________________
1990 Indy 500
1991 Indy 500 short track
1992 Indy light 340

xflyer53

Numbers are stamped on them. Stock jets for that motor are:

Pilot: 50
Main: 260
Air screw: 1 turn out
Needle Jet: P8 (247)
Seat: 1.5

Remember the pipes require a little more fuel. If you can get the pipe manufacturers jetting suggestions that would be ideal. If not it is a bit of trial and error. Just use caution on down jetting!

__________________

'92 Indy 650
'95 Indy XLT 600, plastic skis, skid plate, cobra windshield, XTRA 10, full Fox package, 1" riser

Articat Teen

These pipes are terrible looking, and sounding. I want to say they are homemade 100%. I wish I could find a stock exhaust y pipe and run a single till I atleast set this motor up. If I knew how to post photos on this I Would show a picture

__________________
1990 Indy 500
1991 Indy 500 short track
1992 Indy light 340

xflyer53

Just a c clip is stock. Yours is stock on the 3rd notch. Lowering the notch will richen the mixture.

__________________

'92 Indy 650
'95 Indy XLT 600, plastic skis, skid plate, cobra windshield, XTRA 10, full Fox package, 1" riser

xflyer53

Here's your answer:

Polaris 1991 Polaris Indy RXL SKS 650 Exhaust Can Muffler EK | eBay

Polaris Indy RXL 650 Triple Snowmobile Exhaust Y Pipe | eBay

__________________

'92 Indy 650
'95 Indy XLT 600, plastic skis, skid plate, cobra windshield, XTRA 10, full Fox package, 1" riser