Inline Filter

GoldenMotor.com

Scol

Member
Jan 10, 2014
44
0
6
Ireland
I'm just after finishing my first build of a 80cc 2 stroke and took it to work for the first times yesterday 56km.
When I was driving at about 3/4 trottle ( or maybe a bit more ) it just was not running smoothly the engine was surging a little. There is a mesh filter
that is attached to the shutoff valve that screws into the tank. I'm think
of taking that off and replacing it with an inline fuel filter.

I thinking that the engine is not able to suck enought fuel.

Your advise would be most helpful.


Shey.
 

2door

Moderator
Staff member
Sep 15, 2008
16,302
175
63
Littleton, Colorado
We always recommend using an in-line fuel filter. The little screen in the petcock will work fine as long as the tank is clean. However all kit tanks need to be cleaned and flushed before installing them. They have rust, dirt and scale that will quickly clog the in-tank screen.

You also want to be sure your fuel cap is venting properly. Many have had problems with fuel flow that were caused by a vacuum stoppage due to the tank not venting. Try riding with the fuel cap loose and see if that helps. That will tell you if the cap is venting.

Tom
 

GearNut

Active Member
Aug 19, 2009
5,104
11
38
San Diego, Kaliforgnia
Just to clarify things a bit, the engine, and more specifically, the carburetor do not suck any fuel from the fuel tank.
The only force that transfers fuel from the fuel tank to the carburetor is gravity and this force does not create a powerful flow.
If the in tank fuel valve screen, fuel valve or in line filter have any restrictions in them the volume of fuel flow will be greatly reduced.
 

jpullen

New Member
Sep 18, 2013
27
0
0
Damascus GA.
When Tom says the kit tanks are dirty that is no joke. I rinsed mine out when I got my kit then again after my first gallon and the filter was covered with debris. I checked it again after the third gallon and it was still picking up same kind of crud. If you use a plastic inline filter try to keep it from chattering against the head or frame. I had a brigs filter crack after a month of bouncing against the frame.
 

2door

Moderator
Staff member
Sep 15, 2008
16,302
175
63
Littleton, Colorado
There are several older threads that discuss ways of cleaning a new, or old tank.
There are chemicals and there is the old back-yard trick of dumping in a couple of handfuls of pea gravel, sand, BBs, shot gun pellets, lead weights, all kinds of stuff that you can shake around to dislodge the rust and scale.
The trick is to flush the tank well after cleaning and use a good in-line filter in addition to cleaning.
I leave the in-tank screen in place to keep crud out of the petcock.

Tom
 

maniac57

Old, Fat, and still faster than you
Oct 8, 2011
4,484
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memphis Tn
If you just finished it, surging and rough running is common until the motor gets a few hundred miles. Some are worse than others, but ALL need a break-in period. Don't worry about tuning it until you have a few tanks of fuel through it.
That being said, an inline filter is a must have item for any china kit, and a cleaner tank is never a bad thing.
 

16v4nrbrgr

Active Member
Mar 17, 2012
1,728
4
38
North Bay
I got rid of the tank screen filter and use a clear filter from the auto parts store for a Briggs engine, that way if it's clogged, I can see it before I seize an engine due to the float bowl not filling up. Another source of problems can be from the cap not venting properly and allowing fuel to flow into the carb due to vacuum, it's supposed to leak enough air (or fuel if tipped lol) to allow the carb to fill at all times but if the engine's a ripper you can starve a carb if its not enough, then you gotta go about venting it more or a different cap.
 

Scol

Member
Jan 10, 2014
44
0
6
Ireland
What should I do when the engine is surging ? should I slow down ? keep going ?
last night I went for a spin and it started to surge I rode it for a few miles stoped and
turned around to come home but it did not surge on the way home !!!

Is it bad for the engine if it starts to surge ? am I riding it too hard on the brake in ?

Shey,
 

2door

Moderator
Staff member
Sep 15, 2008
16,302
175
63
Littleton, Colorado
What should I do when the engine is surging ? should I slow down ? keep going ?
last night I went for a spin and it started to surge I rode it for a few miles stoped and
turned around to come home but it did not surge on the way home !!!

Is it bad for the engine if it starts to surge ? am I riding it too hard on the brake in ?

Shey,
Have you checked the things already suggested such as the rate of fuel flow or if the gas tank cap is venting? Surging, to me, sounds as if the engine is starving for fuel.
Let us know what you've checked and what you've done.

Disconnect the fuel line from the carburetor, open the petcock and see how the flow is coming from the tank. You don't need a gusher but it should run a steady stream, not dripping.

Try loosening the gas cap to see if that has any effect on the way the engine runs. I would suggest not to ride the bike hard until you've found and fixed this surging problem. It could lead to bigger issues if it is indeed a lean condition.

Tom
 

Scol

Member
Jan 10, 2014
44
0
6
Ireland
I've put on the inline fuel filter and took out the filter supplied. I took it for a quick spin
last night but it did not surge. I did open and close the cap a few times.
I'll take it for a long spin this week ( commute to work 36 Miles round trip )as it only seem to surge when it fully warm and 3/4 to full trottle.

Shey in Ireland
Thanks for all your advise so far.