Author Topic: Carb Floats  (Read 4376 times)

Brian Moffet

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Carb Floats
« on: January 04, 2012, 12:41:29 PM »
Darn, they're not sealing.  Guess I'll have to take a look.  Any advice (yes, I have been through my carbs before).  Always fun to have fuel coming out the overflow when you stop...  (Oh yes, 1983 Vision)

Brian
« Last Edit: January 04, 2012, 01:40:14 PM by Brian Moffet »

jasonm.

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Re: Carb Floats
« Reply #1 on: January 04, 2012, 02:48:31 PM »
same thing happened to me this past Spring. It helps to know which carb it is. I have an electric fuel pump which allow fuel to flow w/o engine running.
Simply have TWO hoses(one for each carb) @overflow pipes. This will show which carb it is.Then you can either replace needle and seat, like me or attempt to clean and reset floats. FYI- Parts Unlimited sells the needle& seat kits. You need only to go to a Bike shop and look thru the catalogue. Or go to the dealer...yes, they are available.Also there is an o-ring around the replacable seat that can fail...dry out. OR the floats are sinking.....ethanol will attract water and cause the floats to "go BAD"
« Last Edit: January 23, 2012, 05:33:24 PM by jasonm. »
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QBS

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Re: Carb Floats
« Reply #2 on: January 04, 2012, 04:58:29 PM »
I'm pretty sure that you know this. However, over the years I've learned to never assume anything.

If you break an '83 float pedestal you'll be so bummed that you might not be able to stand it.  btdt.  If so, JB Weld could be your new bff.  Just sayin.

Brian Moffet

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Re: Carb Floats
« Reply #3 on: January 04, 2012, 07:56:43 PM »
Yup, I'm very aware of that one....  Makes me wish I had picked up those 83 floats on ebay a while ago.

Brian

VFan

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Re: Carb Floats
« Reply #4 on: January 05, 2012, 02:23:43 PM »
This might be a good time to mention that last summer I bought a carb kit off eBay that included new seats and needles. I had all sorts of problems with the fuel level overflowing when the floats were within specs. I just realized a few weeks ago when comparing them with a couple of new OEM needle/seat sets that the needles in the kit were the wrong length (too short).

I won't be buying any more kits. I'll just replace the specific components as needed.

VFan

Re-Vision

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Re: Carb Floats
« Reply #5 on: January 05, 2012, 03:44:17 PM »
Can you tell us the brand name of the carb kit with the incorrect parts?        BDC

VFan

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Re: Carb Floats
« Reply #6 on: January 05, 2012, 08:54:34 PM »
The kit that I bought was from Keyster, but I'm guessing that I suffered from a mis-packaged kit rather than a systemic problem. Since these are old carbs regardless of who puts the kits together I suggest carefully comparing the old components to the ones in the kit.

I spent quite a bit of time fiddling with the float tab trying to get the fuel level right. Downright confusing to me at the time.

VFan

Re-Vision

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Re: Carb Floats
« Reply #7 on: January 05, 2012, 09:15:00 PM »
Reckon some good photos of the parts that should be found in kits might save some grief for future rebuilders.    BDC

QBS

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Re: Carb Floats
« Reply #8 on: January 05, 2012, 11:03:02 PM »
A visual comparison of old parts Vs. new could be revealing.

VFan

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Re: Carb Floats
« Reply #9 on: January 06, 2012, 12:59:58 AM »
Sorry to say but I threw the mismatched needle/seat sets away. The needles looked the same, just shorter when I put them next to the OEM ones. The seats had a mesh screen on them but I didn't think to compare their bore depth to the OEM ones.   

Cheers, VFan

Brian Moffet

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Re: Carb Floats
« Reply #10 on: January 06, 2012, 01:16:42 PM »
The funny thing is that the carbs over-flowed when I rode to work, and then stopped on the ride home.  I had not ridden the bike in over a month.  I have ridden it several times since and it's been working fine.  I'll probably pick up parts and take a close look when I do routine maintenance on it.  Just goes to show you, ride your bike often, they like it better :-)

Brian

Rick G

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Re: Carb Floats
« Reply #11 on: January 06, 2012, 04:02:10 PM »
One of the most overlooked items that need replacement during a MC carb rebuild is the o ring on the float seat . If it fails gas will bypass the  needle and seat , no matter what the float adjustment is.
While wrenching in OR, we had  a lot of trouble with rebuild kits , most are just crap and a waste of money. The needles and seats are not accurate, the jets are poorly marked among other problems.  I replace jets (most carbs arrive for rebuild with a wild assortment of jet sizes) with genuine Mikuni jets.I make the gaskets and needles and seats, If needed, are genuine Yamaha.
Rick G
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'82.5 Yamaha XZ550 RJ  Vision,
'90 Suzuki VX800, 1990 Suzuki DR350.
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supervision

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Re: Carb Floats
« Reply #12 on: January 06, 2012, 07:02:08 PM »
   I've never heard of any of these floats taking on gas, maybe someone has. Probably just a little trash on the needle, causing a brief period of gas leaking. My bike, got a piece of metal in the needle/seat, causing me to have to fix it while out riding! What a drag that was, I could have run out of gas if.




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VFan

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Re: Carb Floats
« Reply #13 on: January 06, 2012, 08:12:28 PM »
One of the most overlooked items that need replacement during a MC carb rebuild is the o ring on the float seat . If it fails gas will bypass the  needle and seat , no matter what the float adjustment is.
While wrenching in OR, we had  a lot of trouble with rebuild kits , most are just crap and a waste of money. The needles and seats are not accurate, the jets are poorly marked among other problems.  I replace jets (most carbs arrive for rebuild with a wild assortment of jet sizes) with genuine Mikuni jets.I make the gaskets and needles and seats, If needed, are genuine Yamaha.

I believe that I am coming around to this same position. I noticed a while back that Rick had made these kind of comments before so this last time when I took my carb apart I compared the kit parts with OEM parts, including the needle/seat. Aside from my needle problems, there is a visible difference in the appearance of the holes, surfaces, and markings of the jets. The accelerator pump did look the same.

In the future, I think I might just examine each component individually and replace only what needs to be replaced rather than just automatically swap in a whole new kit. And when I do replace a component my current thinking is to use genuine parts.

VFan

 
« Last Edit: January 07, 2012, 05:00:25 PM by VFan »

Brian Moffet

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Re: Carb Floats
« Reply #14 on: January 07, 2012, 12:09:21 PM »

In the future, I think I might just examine each component individually and replace only what needs to be replaced rather than just automatically swap in a whole new kit. And when I do replace a component my current thinking is to use genuine parts.


That is what I did when I did my rebuild.  I examined what I had and what I got in the rebuild kits.  I didn't need to replace a lot of the stuff, and I did replace some I probably didn't need to.  But I didn't do a blind replacement.  I think that is probably the best approach.  (besides, I think I was able to send what I didn't use off to someone who needed it, which is always a perk)

Brian

Cdnlouie

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Re: Carb Floats
« Reply #15 on: January 08, 2012, 07:16:06 PM »
VFan don't think the Accelerator pump diaphragm is like the stock, it is not. I have not checked the 83's yet but the 82's have a shorter plunger rod requiring an adjustment of the pump rod.  The pump rod needs to be shortened to contact the plunger sooner otherwise you will get a bog with too much delay.

I don't have an exact measurement for the rod (I need to remember to do that) with the new Keyster diaphragms but I adjust them so that they have the earliest spray initiation, without hitting the throttle venturi plate. This seems to work pretty well so far.

VFan

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Re: Carb Floats
« Reply #16 on: January 13, 2012, 11:43:00 PM »
Wow. Thanks for the heads up and tip. In that the OEM pump is no longer available, at least in the U.S., it makes this tip more essential. Even before it was discontinued, the accel pump was way too much money anyway

jasonm.

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Re: Carb Floats
« Reply #17 on: January 23, 2012, 05:37:55 PM »
The kit that I bought was from Keyster, but I'm guessing that I suffered from a mis-packaged kit rather than a systemic problem. Since these are old carbs regardless of who puts the kits together I suggest carefully comparing the old components to the ones in the kit.

I spent quite a bit of time fiddling with the float tab trying to get the fuel level right. Downright confusing to me at the time.

VFan
I also had 3 kits from Keyster. I swapped out 2 needle/seat assys. One started leaking at the needle/seat shortly after replacement. For all I know...I may have gotten wrong needles. But it's been fine since that ONE was swapped out. So I used up all three... >:(
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jasonm.

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Re: Carb Floats
« Reply #18 on: January 23, 2012, 05:47:08 PM »
VFan don't think the Accelerator pump diaphragm is like the stock, it is not. I have not checked the 83's yet but the 82's have a shorter plunger rod requiring an adjustment of the pump rod.  The pump rod needs to be shortened to contact the plunger sooner otherwise you will get a bog with too much delay.

I don't have an exact measurement for the rod (I need to remember to do that) with the new Keyster diaphragms but I adjust them so that they have the earliest spray initiation, without hitting the throttle venturi plate. This seems to work pretty well so far.
there is a factory spec. bulletin of 60mm from the "bend of the rod" to the "Lever plate",  that has the spring on the other side.. But I am sure you can throw that spec. out with the Keyster kit.
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Cdnlouie

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Re: Carb Floats
« Reply #19 on: January 24, 2012, 10:46:22 AM »
You're absolutely right Jason, I usually use the 60mm measurement with the stock diaphram but the Keyster kit necessitates shortening it, or the delay will cause a serious stumble.

I should post this separately sometime but you can start with the 60mm (assuming everything else is perfect  ::) on your carbs) and adjust the rod on the bike after a few test runs. I think I did about 7 turns (shortening the rod) and it worked really well after that. You can pull the rod out of the throttle actuator and while holding the shaft from turning rotate the bent end a full revolution each time.  I started with four turns, then went to two turns and finally one more (for good measure and stopped).

The other way is to adjust it on the bench with the plunger making contact as soon as throttle plate begins to move (gaining maximum stroke and as early as possible timing of the fuel spray), that seemed to work okay on a set I did for Tiger although I did not get to field test it.

This accelerator pump adjustment is a critical part for having a really nice set of working carbs. I found that even my original diaphram that was set at the 60mm lenght was delayed and caused a slight hesitation when the throttle was turned on. This is my experience for the 82's only, but when they are dialed in they are really, really, great  8).