A couple of things for DIY.ers

[AllanB]

I am sure many of you seasoned mechanics will know this but I would just like to share a couple of things I learned recently. Maybe save some others time and effort.

1. Don't use LED Lilliput bulbs in your speedo/tacho, why, because they give out light which unidirectional, i.e. all the light comes out of the end of the bulb. This means that most of the light is lost when it hits the cover plate in the gauge, whereas incandescent bulbs give out light in all directions which correctly illuminates the gauge background. My speedo and tacho are a bugga to get to, so I fitted LED's to save future replacement, now I have had to dismantle them again to fit regular bulbs.

2. I have a gravity fed fuel system and when I fitted a paper fuel filter the bike would not start without a 1/3rd..ish full tank. This is presumably because there is insufficient head to push fuel through the filter which, due to the lack of space, is lying on it's side.

So if I do run low on fuel I have to remove the filter to get to the gas station....!!!

With only a little fuel in the tank the bike wouldn't start this morning, so I put 2 litres in, no problem. Prior to that I had checked and fuel was emerging from the petcock.

If I got this wrong please free to correct me, or offer an alternative.

Edited November 4, 2015 by AllanB

[papa al]

1. The best laid schemes of mice and man gang oft aglee.

2. That's weird. Doesn't take much head to push a little petrol thru, methunk.

Nuttin' kinky?

Edited November 4, 2015 by papa al

[AllanB]

A metre head of petrol is about 1psi (= 1 small fart) and the bottom of the tank is only about 5cm, higher than the filter, so the pressure is only 0.05psi, minus system losses. So I assume the pressure loss through the filter is greater than this, I think the paper filters are designed for pump systems with a few psi head.

I was inviting others to contribute as this would have stumped me to destruction, but Jo Modify who sold me the filter told me.

[papa al]

Shitcan the filter, farang.

Otherwise, how is she running?

[AllanB]

Shitcan the filter, farang.

Otherwise, how is she running?

Best so far....absolutely everything crossed. Only 2 years, not bad eh?

[papa al]

To determine head,

measure height from top of fuel level

to bottom of fuel line where it enters carbs, irrespective of filter.

[AllanB]

To determine head,

measure height from top of fuel level

to bottom of fuel line where it enters carbs, irrespective of filter.

No, it is measured to the suspect restriction, if it can't get passed the filter what difference does it make what is below...?

[papa al]

Allan, Allan, Allan....

[AllanB]

Allan, Allan, Allan....

What what what, me little flower?

The "head" is just that top of fluid to bottom of fluid x the SG of fluid, which for petrol is about 0.7.

Conversion 2.3ft H2O= 1psi.

2.3ft divided 0.7= 3.3ft, or about 1 metre.

Sorry for mixing SI and IMP, the UK is still changing 44 years later....We'll get there, about the time I get my NV working.

[papa al]

" if it can't get passed the filter". Post 7

Seriously?

So if you unhook the line connection at the carb and open the valve, nothing will run out, if less than 1/3 full?

papa very skeptible, sir.

If gas (petrol, mate) runs out, then the total column of fluid from carb on up will = the head.

Gravity is gravity / head is head.

Skinny pipe, fat pipe, filter, doesn't matter.

Head is expressed in units of height, not PSI, but pressure will vary with the density of the fluid, be it water, petrol, mercury, air, ....

[AllanB]

" if it can't get passed the filter". Post 7

Seriously?

So if you unhook the line connection at the carb and open the valve, nothing will run out, if less than 1/3 full?

papa very skeptible, sir.

If gas (petrol, mate) runs out, then the total column of fluid from carb on up will = the head.

Gravity is gravity / head is head.

Skinny pipe, fat pipe, filter, doesn't matter.

I can't do that very easily, but the float chambers were half empty.

..and if I take the filter out, all is well.

Now that the tank is half full the bike runs...yes I was surprised.

When I first installed the filter the float chambers were full and the bike started okay, I ran it for a minute and then switched off, likewise the petcock. The following morning with the float bowls now almost empty (so my petcock works), it wouldn't start.

2 litres added to the tank.....brm brm!

0.05 psi is not a lot, but even if there is a tiny dribble getting past the filter the bike will not run for long before the chambers empty.

[papa al]

Filter and @1/2 tank bike runs.

Idle, or full load?

Original configuration hab filter?

[AllanB]

Filter and @1/2 tank bike runs.

Idle, or full load?

Original configuration hab filter?

Good point, haven't tried that in earnest, have the easy option of removing it, if needs be.

Originally the bike didn't have a paper filter, just a stick in the tank and a petcock bowl...and the petcock was vacuum operated, now manual...can't get an original, nor replace the diaphragm.

I bought this bike because I thought it was simple...then

[papa al]

Endever to persevere.

[AllanB]

No! Bugga that I'll take the damn thing off...don't suppose it will do any more than the stick filter in the tank.

Papa, now you are abandoning yourself to rhetoric.

[papa al]

https://m.youtube.com/watch?v=hRX6hSGeZs4

Rhetoric you say?

Ha!