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Discussion Starter #1
hey guys still got my on going problem of surging,sputtering at high rpms.... it looks to be like not enough fuel is getting to the carb... one second the fuel filter(clean cone type) is full of fuel and she will run fine then it will start to sputter and i will look at the fuel filter and it will only be about half full... shouldnt the fuel filter just be full at all times... the tank has plenty of gas. and is relatively clean. is there any way the petcock could not be fully openeing... and like i said at times it will be full other times it seems to not flow into the fuel filter....
 

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hey guys still got my on going problem of surging,sputtering at high rpms.... it looks to be like not enough fuel is getting to the carb... one second the fuel filter(clean cone type) is full of fuel and she will run fine then it will start to sputter and i will look at the fuel filter and it will only be about half full... shouldnt the fuel filter just be full at all times... the tank has plenty of gas. and is relatively clean. is there any way the petcock could not be fully openeing... and like i said at times it will be full other times it seems to not flow into the fuel filter....
The screens on your petcock must be clogged or you have a kink in the hose from the petcock to the filter. I suppose your gas tank could be venting poorly but I doubt that. Cheap enough to replace that petcock and seal.


Tom
 

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My 90 degree filter is 3/4 full, I would check the screen on petcock and open the gas cap when it starts to surge stock tank or Clark?
 

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Just checked mine. 90° cone filter.

Maybe 3/8" fuel in bottom, and it hasn't been running.

I am not sure what your problem is, but this question has been asked in many different forums. Fuel filters, at least in small engine applications, are seldom, if ever, "full".

It does sound like it may be starving though. Gas tank clean?
 

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Also check your air filter.
 

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Just kinda glanced through your previous posts.

Welcome. Neat bikes, eh.

Have you taken off an cleaned this "new" carburetor?

And/or cleaned it up with any new parts?

The advice here about the new jets did mine wonders.
 

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Discussion Starter #7
Thanks for the replies.. Yes it's a stock tank... Like I said its like 1/4 full when it starts to surge, the carb sounds like it backfires a bit too, (starved for fuel?). But the some times the cone is pretty much full and it seems to ride fine... Could it be possible venting issue with the gas tank...
 

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Easy things first. I'd like to emphasize what Dryden-Tdub and zdiver1 have mentioned.

I'd remove the fuel filter and hose's and see if fuel is free flowing out the petcock. If not, drain fuel from your tank and remove your petcock and check for dirt and debris blockage.

If the petcock is free from blockage and fuel is flowing from the tank in the non-running test, then hook the tank back up using only a hose from the petcock to carburator (bypassing the fuel filter).

If you still have an issue, remove the fuel cap when it happens and see what happens.

If all this checks out, start checking the carb.
 

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Take off the tank fuel cap when it starts to sputter and see if that cures it. If the vent in the cap is plugged you may have a relative vacuum in the tank and that can stop the gravity flow of fuel to the carb. You may hear a whooshing sound as you loosen the cap from air rushing in if this is the case.
 

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I went through this with a carbureted Ford Pinto, a 1973, when I was young and unemployed and broke and had to do my own mechanical work.

After replacing the carburetor with a Holley aftermarket (on a 2000cc four!) the new carb did not have provision for the integral Motorcraft-style mesh filter. It was in-line.

It bothered me that there was always air bubbled in it. I attributed drivability problems to it. And I wondered how the air, under pressure from the force of the fuel pump, would do with the float valve in the carburetor.

Try as I might, though, I couldn't route the fuel line to get that air out. And what the carb needed was just adjustment.

I let it go.

If you've got sputtering, look to see about the vital systems. Fuel - as in, restriction - air and ignition.
 

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I have seen partially full fuel filters on a number of my bikes over the years. I have blamed many running issues on this condition, yet the final fix is always something else and the filters are generally still seen a partially full. Petcock flow is generally fine, cap venting good as well. Let us know what you find out. Gerry
 

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I have seen partially full fuel filters on a number of my bikes over the years. I have blamed many running issues on this condition, yet the final fix is always something else and the filters are generally still seen a partially full. Petcock flow is generally fine, cap venting good as well. Let us know what you find out. Gerry
Exactly Gerry. +1
 

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Discussion Starter #13
Ok we'll i took the bike on a long trip this weekend. The fuel filter stayed pretty much full. The bake ran great until I was at about 4th to 5 the gear and light on the throttle... If I kept the throttle pretty much steady it sputters... It also happens as I'm getting up to speed around 25 to 35 it will sputter until I pretty much throttle out of it....
 

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Ok we'll i took the bike on a long trip this weekend. The fuel filter stayed pretty much full. The bake ran great until I was at about 4th to 5 the gear and light on the throttle... If I kept the throttle pretty much steady it sputters... It also happens as I'm getting up to speed around 25 to 35 it will sputter until I pretty much throttle out of it....
You can solve this easy enough.

Just, for a test, take the filter out of the line and run the machine. If it does the same, it's not the filter. It's something else.

Verify free fuel flow; and then move down on the diagnostic fault tree.
 

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Guaranteed it's not the filter and these are all transparent so you can see if there's any junk in them. None of the see-through filters in any car, bike, garden tractor, golfcart, I've ever owned have been full - they all are 1/3 - 2/3 full at any one time, never totally full.

You are not running the petcock in reserve mode are you, possibly picking up junk or dirt in the bottom of the tank and clogging the screen on that intake? I'm not sure about the TW200, but some bikes have a screen on the bottom of the intake hoses to keep out big debris. Or you could have some water in the bottom of the tank and you may not see that in the filter as it goes through.
 
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