Mikuni Fuel Height

Phil C · Post by **Phil C** » Mon Aug 03, 2009 8:12 am

I have seen a photo of a mikuni Vm32 connected with a clear plastic pipe and the fuel level in the clear pipe is the same as the fuel height in the float bowl height . The photo did not show where the platic pipe was connected but I assume that it was the breather tube at the botton of the float bowl. How does this work since the breather is connected to a vertical brass tube inside the bowl the end of which is above the fuel level in the float bowl?

Phil C

Suzukidave · Post by **Suzukidave** » Mon Aug 03, 2009 8:30 am

I dont think it is the breather but a special drain bolt made up so a tube can be attached .

Phil C · Post by **Phil C** » Mon Aug 03, 2009 9:03 am

Ok - that makes sense

Thanks Dave

rngdng · Post by **rngdng** » Mon Aug 03, 2009 6:42 pm

I made a level gauge like that. I removed the overflow tube, and drilled the hole for a larger tube, and epoxied it in.

Lane

Coyote · Post by **Coyote** » Mon Aug 03, 2009 7:51 pm

I have seen that method of testing the fuel level externally, but I never did figure out what is used for a reference point. I mean OK, the fuel is this high in the tube. What is this really telling me? What is the reference point??
Never have worried about it much. Just spend the time to get them (the float height) correct on the bench.
That brings me to my next point. I finally had to go to THREE over pilots on my 550 to get it to idle down correctly. It runs great now, but somehow I feel like I robbed Peter to pay Paul.
Could a low float level cause the lazy return to idle that I have been fighting??

The little springy thingies in the float needles are relatively taught. I mean on the bench, they do not sag at all from the weight of the float. The needles and seats are from a Keyster kit. But then I think logically ---- if they did sag a little and I bent the float tabs to compensate, I would essentially be lowering the fuel level. I don't know whether to shite or go blind, but am beginning to feel like this whole mess I have been fighting has to do with fuel height.
On the other hand, it runs great now. Maybe I should just ride and forget it. But 3 over pilots? I mean jeeeez! That's right ----- 3 over (32.5's), genuine Mikuni parts.
Oh, and the oil pump problems I had are history. This new (to the bike) oil pump is working great. It quickly disposed of the green oil in the lines with the red oil in the tank with the expected air bubbles in between the 2 colors. It's all red now so I I know this one is doing its job.
Sorry ---- didn't mean to steal a thread.

jaybob · Post by **jaybob** » Mon Aug 03, 2009 8:10 pm

Something is still goofy Chris. I went back to the stock 25 pilots on mine to get the air screws to respond and to get the idle clean. my floats are set at 25.75mm.

tz375 · Post by **tz375** » Tue Aug 04, 2009 8:43 am

Setting float height is vital to get the right fuel level - and that's what you are trying to set.

When I have a problem that I suspect is related to floats and I already checked them the conventional way, I use a float bowl with tube attached to see where the fuel level really is.

Sometimes floats just don't float the way that you expect them to and checking the fuel level is the only way to go.

If you have a spare float bowl to modify, it's a good idea to see what is going on. That way you will know what the fuel level really is. If it's all OK then stop worrying and enjoy the ride. Summer is headed the wrong way so it's time to get out and enjoy what's left of it.

Post by **oldjapanesebikes** » Tue Aug 04, 2009 9:18 am

rngdng wrote:I made a level gauge like that. I removed the overflow tube, and drilled the hole for a larger tube, and epoxied it in.
Lane

tz375 wrote: If you have a spare float bowl to modify, it's a good idea to see what is going on. That way you will know what the fuel level really is.

Good tip - I'll have to try that - thanks !

rngdng · Post by **rngdng** » Tue Aug 04, 2009 7:01 pm

The fuel level is the main issue. If the level is above the bowl gasket; it's probably not quite correct, and will run rich. It should be a little below the gasket, (from what I've gleaned from various web-sites.).

Lane