Suzuki 2 Strokes

pgb123 wrote: I was wondering why the inline filter might be necessary because the petcock actually has two filters, one in the fuel bowl and one on the inlet tube.

Fuel filters in the fuel tap do not always filter the smaller crud out of the fuel. They are only usually strainers, not filters. A decent fuel filter will not impede the flow of fuel enough to give you any trouble, just don't get one that is too small. Also replace it periodically so that it does not get clogged. Trust me on this, I have seen many carbs with dirt inside despite having a "filter" in the tap or fuel pump (and that includes a Suzuki GT250 that I am working on for a friend currently. Lots of particulate matter in the carbs despite strainer in fuel tap).
My previous career was engine tuning and diagnostic technician, so I've come across many, many dirty carbs with clogged jets that could have been prevented.

My petcock is still leaking! It only leaks when the engine is running. It appears to be leaking from where it attaches to the tank. I pulled it off and sanded down the area on the tank where it seats. It has a new o-ring. I made sure it was tightened back up. Still leaks. Again, only when the engine is running. Any thoughts?

depending upon what type of fuel tap you have it could be down to different causes. Please could you post a pic or two of your fuel tap?

sportston wrote:depending upon what type of fuel tap you have it could be down to different causes. Please could you post a pic or two of your fuel tap?

This is not my actual tap because I’m not with the bike right now, but it’s the same tap.

You say it has a new o-ring. Do you mean a new oval rubber seal? Did you use new washers on the bolts? You know they should be special washers with a rubber seal (dowty washer) on right?

sportston wrote:You say it has a new o-ring. Do you mean a new oval rubber seal? Did you use new washers on the bolts? You know they should be special washers with a rubber seal on right?

Yes, the new oval rubber seal. And yes, I used new washers with the rubber seal. When I first removed the petcock, the po had two of those oval seals installed, one on top of the other, so clearly he was having the same issue. I actually replaced the petcock body, so the issue is not with that part. I assume that since it only leaks when the engine is running that this means the vacuum seal is functioning. In any event, the leaks is clearly coming from the seal between the tap and the tank.

Well that is good. Has the tank any rust or paint on the sealing area?

sportston wrote:Well that is good. Has the tank any rust or paint on the sealing area?

yeah, its got a bit of paint, which is why I sanded it down. I didn't sand very aggressively. Perhaps, I try I little harder.

I am having trouble with reconciling the fact that you say it is leaking between the tap and the tank and that it only leaks when running.
As it only leaks when running I would usually suspect the diaphragm. But I am perplexed. How could the engine running possibly change the conditions of the seal at the top of the tap?
Something doesn't add up here.
You have three surfaces sandwiched together; metal-rubber-metal.
The engine should have no effect upon them, in theory.
The only possible way I can imagine the engine would do so is if bolts were loose and the movement or vibration of the engine was moving the loose tap enough to make it leak. I find that highly improbable.

I would suggest that you remove the fuel tap and closely inspect it and the rubber seal. Is the new seal damaged or perished due to being old stock? Is the inside of the groove it sits in on the fuel tap dirty, damaged or badly molded? Are the dowty washers failing to seal due to the fuel tap housing being painted or corroded, or the bolts being damaged or corroded? Did you assemble with a drop of oil? If not, has one of the dowty washers had the rubber torn?
When it comes to sealing surfaces everything needs to be fairly level and flat; has anything warped with age or over-tightened bolts by previous owner?
The simplest reason is often a cause. Dirt. Is there any chance that flakes of rust or paint or grit got between two of these surfaces, preventing a good seal?

pgb123 wrote:yeah, its got a bit of paint, which is why I sanded it down. I didn't sand very aggressively. Perhaps, I try I little harder.

Especially on an older bike paint can sometimes have tiny cracks in it or can delaminate from the metal, which would have the potential to cause a leak. So maybe we are looking in the right direction.

get some commercial grade nitrile rubber sheet about 1mm thick and make your own tap gaskets. just remember to punch the holes out before you cut the outline. i've made and used these for ages now, including the taps with the spacer, which needs 2 gaskets, without a problem. oh yes, i always put a couple of winds of ptfe tape around the threads on the 2 fixing bolts - just for good measure
cheers, dd.

dollydog wrote:get some commercial grade nitrile rubber sheet about 1mm thick and make your own tap gaskets. just remember to punch the holes out before you cut the outline. i've made and used these for ages now, including the taps with the spacer, which needs 2 gaskets, without a problem. oh yes, i always put a couple of winds of ptfe tape around the threads on the 2 fixing bolts - just for good measure
cheers, dd.

Thanks for the tip! Have you used the nitrile sheet to make the vacuum gasket? Sounds like a great idea. Will recheck everything this weekend and report back.

yes mate, i've used the very thin nitrile sheet - 0.3mm - to make the diaphragms. dead cheap and easy enough to do. but AGAIN, make sure you punch the holes out first. this stuff is easy to rip
cheers, dd.