Can't get Cyl 3 above 350° & fuel in vac line

Maintenance, repair, troubleshooting, etc.
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mvk24
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Tue May 30, 2017 2:09 pm

Jimbo wrote:
Tue May 30, 2017 10:49 am
Here is a youtube video link of how to check the float height (wet test method) while the bike is running. Video was made by a XJrider member.

phpBB [video]


All you need is some clear fuel line.

Another tip: I replaced all of my fuel lines with clear fuel line so that I can visually see the fuel flow and fuel quality at a glance.
Good video! So basically put clear tubing on the float bowl drains and see if the level matches where the line is casted onto the bowl? Which direction would the float have to go up or down in accordance to the level on the hose being above or below the line? I currently have all clear hoses that's how I found the fuel in my vac line.

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radare
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Tue May 30, 2017 2:24 pm

mvk24 wrote:
Tue May 30, 2017 2:09 pm
Jimbo wrote:
Tue May 30, 2017 10:49 am
Here is a youtube video link of how to check the float height (wet test method) while the bike is running. Video was made by a XJrider member.

phpBB [video]


All you need is some clear fuel line.

Another tip: I replaced all of my fuel lines with clear fuel line so that I can visually see the fuel flow and fuel quality at a glance.
Good video! So basically put clear tubing on the float bowl drains and see if the level matches where the line is casted onto the bowl? Which direction would the float have to go up or down in accordance to the level on the hose being above or below the line? I currently have all clear hoses that's how I found the fuel in my vac line.
You want it to be 6mm below the line. Bending the float tab so the float closes earlier (higher float distance from the gasket surface to the float) will cause the level to be further below the line.

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radare
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Tue May 30, 2017 2:33 pm

BTW, the affects of float height on mixture is as follows, taken from https://www.fix.com/blog/motorcycle-car ... djustment/:
If fuel is leaking from the carb, it can potentially cause a serious problem – fire. If the fuel height is too high but the bike is running, the engine will have a tendency to display a rich running condition, which will make the throttle response slow and the engine note muffled. This condition is generally accompanied by a strong smell of unburnt fuel from the muffler. If the fuel height is too low, the engine will display a lean running condition, where the engine typically hesitates before accelerating or surges as the throttle is opened. The bike may also misfire when the throttle is closed.
I've always thought the float-height settings provided in the FSM are incorrect. 6 to 8mm (dry) or 6mm below the line (wet) seem to provide a really rich setting and at the 8mm dry setting, the floats darn-near hit the carb body. Many I've pulled apart, untouched, have been in the 13mm range. Exploring the impacts of a lower fuel level might be beneficial.

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Jimbo
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Tue May 30, 2017 6:06 pm

We are approaching this systematically. Number 3 cylinder is obviously running rich with respect to the other cylinders (colder temp and black sparkplug). First we want to eliminate the float as potentially being off. Since you have 3 other cylinders running well, it makes sense to check the wet float height against the others. They all should be the same. If #3 wet float height is higher than the others, then that is your problem. If the float height is the same as the others, then problem is elsewhere and we can move on to the next potential problem. I have seen floats that when measured dry look like they should all be the same only to find a float off because it is heavier than the others or has a poor sealing float needle allowing excess fuel to flow making that cylinder rich. The wet test is nice as it give fuel float level in real time while it is running.

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mvk24
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Tue May 30, 2017 8:30 pm

Jimbo wrote:
Tue May 30, 2017 6:06 pm
We are approaching this systematically. Number 3 cylinder is obviously running rich with respect to the other cylinders (colder temp and black sparkplug). First we want to eliminate the float as potentially being off. Since you have 3 other cylinders running well, it makes sense to check the wet float height against the others. They all should be the same. If #3 wet float height is higher than the others, then that is your problem. If the float height is the same as the others, then problem is elsewhere and we can move on to the next potential problem. I have seen floats that when measured dry look like they should all be the same only to find a float off because it is heavier than the others or has a poor sealing float needle allowing excess fuel to flow making that cylinder rich. The wet test is nice as it give fuel float level in real time while it is running.
Sounds like a good plan guys thank you. In the video he bends the line towards the body of the carb and the level seems to change. Should I have the line bent back against the body or vertically up and down parallel to the carb body? Don't wanna have a misreading on the wet method.

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mvk24
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Tue May 30, 2017 8:32 pm

radare wrote:
Tue May 30, 2017 2:33 pm
BTW, the affects of float height on mixture is as follows, taken from https://www.fix.com/blog/motorcycle-car ... djustment/:
If fuel is leaking from the carb, it can potentially cause a serious problem – fire. If the fuel height is too high but the bike is running, the engine will have a tendency to display a rich running condition, which will make the throttle response slow and the engine note muffled. This condition is generally accompanied by a strong smell of unburnt fuel from the muffler. If the fuel height is too low, the engine will display a lean running condition, where the engine typically hesitates before accelerating or surges as the throttle is opened. The bike may also misfire when the throttle is closed.
I've always thought the float-height settings provided in the FSM are incorrect. 6 to 8mm (dry) or 6mm below the line (wet) seem to provide a really rich setting and at the 8mm dry setting, the floats darn-near hit the carb body. Many I've pulled apart, untouched, have been in the 13mm range. Exploring the impacts of a lower fuel level might be beneficial.
Yea I saw the issue choosing the float height when I was trying to set them a few months ago. I think I went with 7mm but do you think I should be going for something different if I end up opening them up again? You had me measure from the float nearest the needle valve so I set all the right side floats to what I think I remember was 7mm.

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radare
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Tue May 30, 2017 9:15 pm

Sorry, I went off on a big tangent. Thanks Jimbo for reeling me back in. No, don't change your float heights. Just check them wet and see if they are all the same. Target is 6mm below the line.

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mvk24
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Wed May 31, 2017 1:18 pm

radare wrote:
Tue May 30, 2017 9:15 pm
Sorry, I went off on a big tangent. Thanks Jimbo for reeling me back in. No, don't change your float heights. Just check them wet and see if they are all the same. Target is 6mm below the line.
Hey as per the petcock leaking issue I can't find one on eBay for some reason. Did we find any other bikes that used the same petcock to broaden my search? Idr a donor thread just that the Acerbis was a match but as you suggested I rather find another OEM

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radare
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Wed May 31, 2017 1:23 pm

Search eBay or Amazon using the p/n.

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mvk24
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Wed May 31, 2017 7:53 pm

radare wrote:
Wed May 31, 2017 1:23 pm
Search eBay or Amazon using the p/n.
Any chance you have that part number off hand

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