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Oil pump filter element for 250 Crusaders

At last they're back again! Replacement oil pump filter element - 250 Crusader and 350 unit construction Bullet

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Mikarb float height measurement

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Mikarb float height measurement
Started at 03:00pm on the 10th October, 2017 by stinkwheel
stinkwheel Subject: Mikarb float height measurement
I'm a tad confused. In our hosts technical notes it states float height should be measured from the body of the carb but then shows a picture of it apparently being measured from the lip round the carb body.

Which is it? Should I measure from the lip (blue line) or the recess the gasket sits in (red line)? There is a roughly 3mm difference, which is a lot.

Posted: 03:00pm 10th October, 2017
Alan R Subject: Mikarb float height measurement
Hi Matey !!--------- I think the clue is in their instructions}--- Quote..."and with the float chamber gasket removed measure from the carb body surface to the top of the float, as shown below. The standard measurement is between 24-26mm"

So remove the gasket then measure from your RED least that's how I set mine..
Posted: 07:30pm 10th October, 2017
stinkwheel Subject: Mikarb float height measurement
Thanks. It was the "As shown below" bit that was confusing me because it shows it being measured from the top of the lip, effectively contradicting the written instructions.

I have it a bit on the low side then because I did it like the picture. Hopefully this will fix the high rev spluttering.

Posted: 11:15pm 10th October, 2017
Leon Novello Subject: Mikarb float height measurement
It should not matter; you have 3mm of leeway, the carburetor is not that sensitive to 2 mm up or down.
Posted: 07:05am 11th October, 2017
Presto Subject: Mikarb float height measurement
Leon is right - the tolerance is sufficient to allow for the discrepancy. But the recommended method is to measure to the lip on which a straight edge would rest if placed on the joint surface. In other words as per the illustration in the notes. But although some care needs to be taken, the measurement is not absolutely critical to the last mm in this application.
Posted: 08:41am 11th October, 2017
Presto Subject: Mikarb float height measurement
PS - the illustration in the technical note (on this site and reproduced above) corresponds with the illustration in the Mikuni tuning guide - i.e. float level measurement is the distance from the bottom of the float assembly to the bottom of the carburetor body (what becomes the top surface of the carburetor body when it is inverted) with no reference being made to the recessed surface on which the gasket is placed.
Posted: 08:51am 11th October, 2017
Alan R Subject: Mikarb float height measurement
Hi Guys------ yes, those instructions can seem to be a bit contradictory at first, can't they.........I've just had a look at my spare carb. to refresh my memory and it seems we're all}-- remove the gasket, place the steel ruler's edge on your RED line ( Which is a good broad surface compared to the thin lip ) but take the reading starting from the BLUE line ( the lip )...As mentioned it's not that critical and bending the Brass tag is a matter of guesswork at best.....I have an old 6" steel ruler that I've pre-marked those two settings on in the form of little nicks on the ruler edge...So it's become a form of "Go"..."No-go" gauge if you like.....Saves straining the old eyes, that's for sure

...Whilst you have the carb. apart why not inspect the float needle tip for ridges ( or fit a viton tipped one ), roll the main needle on a flat surface to check for straightness, the slide for wear or "Rattle" in it's bore and all jets for damage---especially the slow running one..
Posted: 10:02am 11th October, 2017
Presto Subject: Mikarb float height measurement
PPS [!] - to me the tech note seems as clear as daylight. the reason the gasket is removed is that it is possible that it may obtrude above the carb body surface. but simply measure as the tech note explains and all will be well. :-)
Posted: 10:26am 11th October, 2017
Alan R Subject: Mikarb float height measurement
"Many are the roads that lead to Rome"
Posted: 10:33am 11th October, 2017
stinkwheel Subject: Mikarb float height measurement
Aye, already replaced the needle valve because it was leaking. Going to throw a new main jet in there too. Needle itslef looks pretty ship-shape.

I'm actually wondering if my high rev stutter is points chatter, despite it feeling like fuel starvation. I solved the first misfire by replacing the 1950's condenser that had been fitted by the previous owner (probably not happy playing with 12v). When I look, the "spring" on the points is also way longer than on my other bullet suggesting this is also wrong and perhaps can't stay shut properly at higher rev speeds.

This is what was fitted. It's an indian stator plate but I think the points and condenser are off an old brit model. Condenser was definately duff in any case.:

Posted: 10:34am 11th October, 2017

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