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The 2-Stroke Garage => Turning Wrenches => Topic started by: AAAltered on April 22, 2024, 10:17:33 AM

Title: VM28 Float Needle
Post by: AAAltered on April 22, 2024, 10:17:33 AM
I am having fueling issues.  Bike will not start.  Petcock flow tested fine.  A tad of fuel into the plug holes and it fires right up, but doesn't keep running.
I have suspected float issues for some time, I replaced the float valve with Viton last season.
Question I have, is this the corr3ct installation and orientation for this type of valve?  My old ones didn't have any little clip on them.  Can I run without these clips?
(https://i.ibb.co/44ffK8D/IMG-2922.jpg)

(https://i.ibb.co/nQM5nQw/IMG-2923.jpg)
Title: Re: VM28 Float Needle
Post by: 1976RD400C on April 22, 2024, 11:08:35 AM
Looks like it is installed right. When I installed the vitron's in my carbs I noticed that the tab that pushes on it needed to be adjusted because the new needles stuck out of brass valve farther and caused the fuel level in the bowls to be too low (maybe I have the wrong needles?). Do you have a side view of the carb with the needles in showing that flat brass piece the floats push on and does it look level?
Title: Re: VM28 Float Needle
Post by: AAAltered on April 22, 2024, 11:16:42 AM
Carbs are now apart, in the ultrasonic, then getting a blowout.  BRB...

(https://i.ibb.co/BCvKXb9/image.jpg)
Title: Re: VM28 Float Needle
Post by: AAAltered on April 22, 2024, 11:43:23 AM
So here is the side view.

The needle sits well and closes well, I can tell by blowing gently into the gas line port.
(https://i.ibb.co/YkbpdtH/IMG-2927.jpg)

(https://i.ibb.co/48t9TKK/IMG-2926.jpg)

If I tap the carb body, the needle does fall down a few mm.  Is this normal?
(https://i.ibb.co/19BPYbt/IMG-2928.jpg)
Title: Re: VM28 Float Needle
Post by: m in sc on April 22, 2024, 01:10:14 PM
can be. it reacts differently with fluid above it. 15mm with it just touching the tip of the needle. in the 1st pic in reply above, if thats 'closed' the tangs are hanging too low. in all my experience with mikunis, the tangs typically are horizontal when the needle is just closed, not compressing the needles spring loaded tip.  :twocents:

Title: Re: VM28 Float Needle
Post by: 1976RD400C on April 22, 2024, 05:21:34 PM
Check it like this. Notice how the steel needle doesn't seem to stick out like the vitron.

(https://i.ibb.co/QdyvcsG/20240422-165724-1.jpg) (https://ibb.co/2NG36XB)
(https://i.ibb.co/sqPs56Q/20240422-171214-1.jpg) (https://ibb.co/fHSr8nt)
Title: Re: VM28 Float Needle
Post by: AAAltered on April 22, 2024, 11:09:37 PM
Thanks guys.  It did run after reassembly, but I did not have time to shake it down.  It's warming up here finally, I will get a ride in this week and see how it is.

I'll need to tear them back down to measure the float height...
Title: Re: VM28 Float Needle
Post by: m in sc on April 23, 2024, 08:01:46 AM
IF you have a spare carb bowl to sacrifice, or a bowl drain, IMHO the -best- way to verify fuel level is with a height gauge.

(https://2strokeworld.net/wp-content/uploads/general-tech/float-setting-w-tube/float-setting-r5_5-e1685146037251.jpg)

(https://2strokeworld.net/wp-content/uploads/general-tech/float-setting-w-tube/float-setting-r5_3.jpg)