Float height? - SV650.org

02-01-07, 12:49 PM

Can someone clarify whether the 7mm height specified in both Haynes and workshop manual is correct? Reason I ask is that my carbs appeared to be set up with a height of 5mm, and when I split the spare pair which I acquired from Viney these also appeared to have 5mm float height.

Ta

Jase

NedSVS · 02-01-07, 09:04 PM

According to the instructions in my Factory pro stage 2 kit the standard height is 7mm, and when I fitted the kit this is what I found them at. Has your bike had any tuning done to it (even just a exhaust can). I ask because changing the float height from standard is a method used to trim the fueling by tuners.

NedSVS · 02-01-07, 09:10 PM

Just an afterthought: you have to be sure the weight of the float is not compressing the float needle spring at all. To do this, lay the carb on its side and tilt it slowly until it just comes into very light contact with the needle, then take the measurement (the depth gauge end of a small vernier caliper works really well for this).

03-01-07, 01:48 PM

Measured them as per manual instructions, but the float could have been depressing the float needle so I'll probably have another check in the way you suggested to make sure I've not set the level too high.

The carbs should have been set right as I don't believe they were touched before I started mucking about with them. Although, I could have knocked them or accidentally set the level a bit low when had them off.

Will have myself another go at the weekend, for now I'm on a trusty old 125. Nice.

Viney · 03-01-07, 02:04 PM

I had all manner of issues with float hight when i had my carbs jetted etc. I went by trial and error but 7mm is the hight iirc.

Those carbs you had have never been touched afaik

03-01-07, 03:04 PM

Yeah they didn't look like they'd been touched (also were a swine to open up as the screws hadn't been greased) and they seemed to be 5mm when I checked. I could have measured them wrongly, so will have another look tonight as those carbs aren't actually fitted to my bike, used them for parts so they're to hand to check nice n easily.

I'm determined to get my jetting right though, it's been an absolute nightmare to date.

04-01-07, 01:42 PM

Right, seems I cocked up with the float height measurement. Mis-interpreted the 45 degree measuring thing as it seems to be pretty poorly explained in both the Haynes and workshop manuals.

But, found the best and most accurate way of measuring the height though, which was useful. I found that if you balanced the carbs on the top cap for the slide, it gave you the angle you needed where the needle just touches the float valve. Sorted.

Just need to find some time wo whip the cabrs off that are fitted to my bike and rectify them. Have an incling that the floats may have been sticking too, so will give them a good clean with the old carb cleaner to make sure all is working well.

Least I got the cam chain tensioners done so the engine isn't rattling anymore. Just the minor

issue of the fuelling...

02-01-07, 12:49 PM	#1
Jase22 Guest Posts: n/a	Float height? Can someone clarify whether the 7mm height specified in both Haynes and workshop manual is correct? Reason I ask is that my carbs appeared to be set up with a height of 5mm, and when I split the spare pair which I acquired from Viney these also appeared to have 5mm float height. Ta Jase

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02-01-07, 09:04 PM	#2
NedSVS Member Join Date: Mar 2005 Posts: 568	According to the instructions in my Factory pro stage 2 kit the standard height is 7mm, and when I fitted the kit this is what I found them at. Has your bike had any tuning done to it (even just a exhaust can). I ask because changing the float height from standard is a method used to trim the fueling by tuners.

02-01-07, 09:10 PM	#3
NedSVS Member Join Date: Mar 2005 Posts: 568	Just an afterthought: you have to be sure the weight of the float is not compressing the float needle spring at all. To do this, lay the carb on its side and tilt it slowly until it just comes into very light contact with the needle, then take the measurement (the depth gauge end of a small vernier caliper works really well for this).

03-01-07, 01:48 PM	#4
Jase22 Guest Posts: n/a	Measured them as per manual instructions, but the float could have been depressing the float needle so I'll probably have another check in the way you suggested to make sure I've not set the level too high. The carbs should have been set right as I don't believe they were touched before I started mucking about with them. Although, I could have knocked them or accidentally set the level a bit low when had them off. Will have myself another go at the weekend, for now I'm on a trusty old 125. Nice.

03-01-07, 02:04 PM	#5
Viney Member Mega Poster Join Date: Jul 2003 Location: In the shadows to the left Posts: 7,700	I had all manner of issues with float hight when i had my carbs jetted etc. I went by trial and error but 7mm is the hight iirc. Those carbs you had have never been touched afaik

03-01-07, 03:04 PM	#6
Jase22 Guest Posts: n/a	Yeah they didn't look like they'd been touched (also were a swine to open up as the screws hadn't been greased) and they seemed to be 5mm when I checked. I could have measured them wrongly, so will have another look tonight as those carbs aren't actually fitted to my bike, used them for parts so they're to hand to check nice n easily. I'm determined to get my jetting right though, it's been an absolute nightmare to date.

04-01-07, 01:42 PM	#7
Jase22 Guest Posts: n/a	Right, seems I cocked up with the float height measurement. Mis-interpreted the 45 degree measuring thing as it seems to be pretty poorly explained in both the Haynes and workshop manuals. But, found the best and most accurate way of measuring the height though, which was useful. I found that if you balanced the carbs on the top cap for the slide, it gave you the angle you needed where the needle just touches the float valve. Sorted. Just need to find some time wo whip the cabrs off that are fitted to my bike and rectify them. Have an incling that the floats may have been sticking too, so will give them a good clean with the old carb cleaner to make sure all is working well. Least I got the cam chain tensioners done so the engine isn't rattling anymore. Just the minor issue of the fuelling...