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A high carb disaster? One mans story/opus magnus

Old 06-28-2011, 08:30 PM
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A high carb disaster? One mans story/opus magnus

During my absence I have not been unproductive. Right about the time that the weather changed I developed a small problem in my normally delicious bike. You can see what I am talking about below

YouTube - ‪06-22-11 Carb problems? You decide‬‏

0:00 - normal acceleration
0:54 - Acceleration, Stall, Acceleration to 0-100~ mph
3:14 - 2nd gear slip to neutral (another problem I have)
3:21 - low idle
4:42 - Slowing down in neutral with a stall
5:01 - stall while clutch-in in 1st gear

I cannot abide with having a bike that shuts off so I decided that it was time to take some things apart inspect clean and service/replace as necessary. Since I bought the bike used there are several unknowns I have been living with that have been driving me up the wall. A major one being the condition of the two carburetors; are they dirty? Are they synced, have they been jetted yet, Is anything broken in there? These are questions that kept me up at night. Since I now had a reason too I decided to make an adventure into what is often considered too complicated for the typical owner or as I see it; a mechanical challenge. You will find out in the end that like anything else mechanical it is in fact very simple when broken you have the right tools on hand.

I had some objectives for this work.
1) Inspect the carburetors and fuel system
2) Clean the inner areas. Since the bike is 11 years old now dirt and grime have accumulated on the insides.
3) Install sync ports for future carburetor syncing
4) Inspect spark plugs
5) Inspect hose condition
6) Lubricate

Yes I realized that in the videos I mislabeled some things, but rest assured it is all ok.

To start with I removed my tank with an 8mm socket for the front two bolts and 10mm for the rear.

YouTube - ‪Carb Job Part 1 Tank Off‬‏

This is an overview with the tank off. Looks a bit complicated eh? Donít worry itís really not

This is an overview of the lines that run out of my tank.
YouTube - ‪Carb Job Part 2 Hoses‬‏

This is a view of the petcock connections on the petcock.

This is the inside of my air box. She is due for her 2 month cleaning. You can see the two velocity stacks and the bypasses that feed air into the enrichment circuit.

YouTube - ‪Carb Job Part 3 Inside the air-box‬‏

This is a view in which you can see the two mini air filters. These were actually missing when I got the bike from go eco,

Without the velocity stacks you can see the 8 brass screws that hold the air box onto the carburetors. Donít forget to stuff rag into the air intakes lest you drop a screw into your valve chamber!

This is an overview without the air box. The TPS is on the other side of the rear throttle arm joint.

YouTube - ‪Carb Job Part 4 Carbs exposed‬‏

This is what she looks like without her Air box. The O rings are in excellent condition and I cleaned them and added a little bit of all purpose grease.


This is the left side between Frame and carburetors. You can see the Stock automatic CCT which I will replace later on with more reliable manual ones.

This is the right-side between frame and carburetors. I believe that is a thermostat, but I would have to look it up.

In this picture we can see the carburetor sync adjuster. On this bike the rear carburetor is adjusted to match the front carburetor.

In this view we can see my throttle pulley. I had previously adjusted this when Voodoo pointed it out as having too much play, but since I have to remove it I went ahead and cleaned lubed and readjusted it and the spring.

This is a short video on slackening and removing the throttle.

YouTube - ‪Carb Job Part 5 Throttle‬‏

This is a view of the throttle bolts and nuts.

This is a view with the upper elbow cover removed. I donít like that rust so I will replace that entire handle eventually.

This is a further info on how I removed the throttle.

YouTube - ‪Carb Job Part 5.5 Carb side throttle‬‏

This is a picture with the cable removed from the upper guide on the pulley.

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Old 06-28-2011, 08:30 PM
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Oh boy is that ugly!

That grey thing is the TPS connector.

Throttle Position sensor close up. Say cheese!

This is the hose that runs coolant to (or maybe from) the water pump line, I disconnected this to drain excess fluid. Be sure to put a pan beneath this so your dog does not drink it.

This is the boot that connects the front carburetor to the engine. You only need to loosen the top strap. It is 8mm and is the most difficult part to work in the entire process due to the angle

This is the front coolant line. Be careful while removing these as they do leak a bit of coolant.

This is the rear fuel enrichment plunger assembly. You use a 10mm open wrench on this after pulling the boot back. This particular plunger assembly will prove to be very troublesome later one.

Look Ma no carburetors! This is the view without carburetors. Again you MUST remember to put a rag in those intakes if you drop something in there while the valves are open you are in serious financial trouble.

Now it is time to drain. These are my carburetors in a pan. Unfortunately I did not snap a picture of the drain screws since gas vapor and flashes probably are not a good combination.

This is an overview of the removal.

YouTube - ‪Carb Job part 6‬‏

Inside the carburetors

After removing the three partially stripped screws on the diaphragm cover we can see that spring is here! Holy Allah; these springs a pain in the *** to reinstall.

Boing! This is a close up view of the top of the vacuum piston. The diaphragm looks great and is very supple. This is great news of course because each vacuum piston costs 109$

This is a serious needle at the end of the vacuum piston. Though I suppose it has to be for the biggest set of carburetors Honda has ever put on a bike (48mm).

This is what would normally be a venture chamber. You can see the butterfly valve below. That small ring is where the needle pokes in and out of.

This is where a vacuum piston lives.

I threaded one of the diaphragm cap screws in and wiggled this assembly side to side until it came out of the vacuum piston/diaphragm. The springs and washers are all perfect.

Chemtool; I used to usually run sea foam, but one day got this because of the price. It proved its power to me when it literally melted the 1 OZ plastic cup I used to measure sea foam on contact. This solution only removed a small amount of particles with the front carburetor but changed consistency and got murky when I put in the rear emulsion tubes and componentsí.

This is my forward set of floats. They are in perfect condition as is the plunger.

This is what happens when you run chemtool and sea foam through your carburetors every few tanks. The condition of the float chamber was nearly immaculate.

Plunger spring and clearance check out.

If you do not use chemtool/seafoam regularly this is why you should. In this view emulsion tubes and components are removed.

This is a butterfly valve. I think these are pretty.

This is an open butterfly valve as seen from below. I cleaned up the carbon deposit ring around and on the valve. In this view you can also see the enrichment ports and the pilot port.

Well I think I found a part of my problem? What does this say to yall?

Maybe this is my problem? What does this say to yaíll?

After reassembling the carburetors I began the process of reinstalling them. This is where I ran into problems. I had hand tightened this fuel enrichment plunger guide nut and did not like the way it was positioned. So when I touched my open end wrench to the PLASTIC freaking guide nut it snapped leaving the threads on the inside. The plunger could not be removed because it was larger than the threaded section. I decided to call it a night and do some research after this.

Oh Snap!

I forgot to take pics of the fact that I removed the heat shield and cleaned everything. The hoses and the piston heads and even the coolant reservoir. I also cleaned the grime off the outside of the carburetors and re-lubed and cleaned all springs and joints.

This is a diagram of the broken part

This is an overview of the carburetor sync mod that I made earlier in the process.
YouTube - ‪Carb sync Mod Part 6.5‬‏

The next day I picked (haha!) up where I left off. I removed the carburetors and removed the broken part as seen in the video.

YouTube - ‪Retrieving the broken SE nut from a firestorm carburetor‬‏

This is my temporary fix for the broken SE guide nut. I super glued it back together! And it works! This is of course a temporary fix. I ordered a brass guide nut from a Polaris ATV that replaces the plastic SE nut. The brass part cost 11$ apiece from Polaris and the plastic nut comes in a 36$ assembly per carburetor! Next week I will be syncing my carburetors and replacing my plugs and the SE nut.

Here we have a dramatic recreation of my first boot of the bike after the carburetor job.

YouTube - ‪A dramatic recreation of the first start after my home made carb job Part 8‬‏

And here we have the first ride. I rode her gingerly because of fear of explosion and as I realized once I got on; low tire pressure.

YouTube - ‪First ride after carb job part 9‬‏

The bike sounds fantastic and after the cleaning I found that her idle was now set too high. She is faster to warm up and snappier on the throttle response.

Any questions comments or concerns should go below.

Thank you for watching!
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Old 06-29-2011, 06:25 AM
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Great photos! Do you have a part no. for the Polaris nut?
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Old 06-29-2011, 08:14 AM
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I ordered # 7 on this parts fische.
Hopefully it is the right one.

Xtreme Powersports' 2002 Polaris ATV SCRAMBLER 400 4X4 (A02BG38CA) Parts List
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Old 06-29-2011, 09:18 AM
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Good God I thought I took a lot of pictures.

You will find that after a good sync and pilot screw adjustment, your idle will be higher than if those two are not adjusted properly and needs to be turned down, so good job man.
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Old 06-29-2011, 09:37 AM
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8541Hawk will become famous soon enough
Didn't you already post this thread?
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