fuel level vs. plastic floats

Need some help? Put your question up here. Many years of experience on the board to help you get up and running.

Moderators: oldjapanesebikes, H2RICK, diamondj, Suzsmokeyallan

Post Reply
User avatar
jabcb
Moto GP
Posts: 4240
Joined: Mon Dec 13, 2010 4:32 pm
Country: USA
Suzuki 2-Strokes: 69 T350 thru 75 GT750
Location: southwestern Pennsylvania

fuel level vs. plastic floats

Post by jabcb »

I’ve had good luck setting float levels on the carbs with metal floats. When I checked the fuel levels they are typical close.
But fuel level can be useful for dealing with repaired or dented floats. And for checking for a sunken float without taking the carbs apart.


But the carbs with plastic floats are more problematic. You set the float level without the float which I thought was OK.
But that leaves a question about the float: do you have the correct float?

These two are supposedly Mikuni floats the T250/GT250. They look the same but the pins are at different locations.
ImageParts_0580 by jabcb, on Flickr

Which is correct? One will give the correct fuel level when you adjust the float level. The other won’t even be close.

I use one of these to check for fuel level: https://www.z1enterprises.com/fuel-leve ... uzuki.html
BAS (Bike Acquisition Syndrome) - too many bikes but have room for more

Suzuki:
GT750 2x75
GT550 72 & 75
GT380 72
T500 69 project & 73 project
T350 69 & 71
Honda 85 CB650SC & 86 CB700SC
09 Triumph Bonneville SE
User avatar
kb75ts250
On the street
Posts: 28
Joined: Tue Aug 01, 2017 11:48 am
Country: US
Suzuki 2-Strokes: ts250m
Location: Brighton, MI USA

Re: fuel level vs. plastic floats

Post by kb75ts250 »

Wow - that's quite a catch and VERY observant of you. Obviously those floats would give different fuel levels. According to Partzilla the plastic floats for all T250 series are supposed to be P/N 13252-18620 but I also found P/N 13252-28310 and -30650 for plastic floats for other models. I wonder if in the past somebody mixed up the floats - or if there was a lot of manufacturing variability?

In any case, the most common fuel level related issue we used to see was leakage from the overflow hose. Most of the time the issue was a poor float valve seal. Even though the needle and seat visually looked ok, there would still be a slow weeping of fuel. The cure was a gentle tap on the needle using a valve stem cap with core remover like this http://boltmotorcyclehardware.com/metal ... river.html. You have to use this kind of cap because it clears the little spring loaded plunger built into the float needle. The tap coins the needle and seat and that almost always fixes the issue.
Currently - 75 TS250, 02 Kaw ZX-6R
Previously - 70 T350, 71 TS250, 72 GT380, 72 TS125, 72 TS250, 75 Yam YZ360B, 72 GT380 diy cafe racer, 80 GS750, 73 TS185, 82 GS1100
User avatar
jabcb
Moto GP
Posts: 4240
Joined: Mon Dec 13, 2010 4:32 pm
Country: USA
Suzuki 2-Strokes: 69 T350 thru 75 GT750
Location: southwestern Pennsylvania

Re: fuel level vs. plastic floats

Post by jabcb »

The level pin hole is undoubtedly molded into the plastic. The float diameter & thickness is the same, so its very easy to mix them up.
BAS (Bike Acquisition Syndrome) - too many bikes but have room for more

Suzuki:
GT750 2x75
GT550 72 & 75
GT380 72
T500 69 project & 73 project
T350 69 & 71
Honda 85 CB650SC & 86 CB700SC
09 Triumph Bonneville SE
User avatar
kb75ts250
On the street
Posts: 28
Joined: Tue Aug 01, 2017 11:48 am
Country: US
Suzuki 2-Strokes: ts250m
Location: Brighton, MI USA

Re: fuel level vs. plastic floats

Post by kb75ts250 »

I could see mixing them up happening for sure! Too bad the floats don't have part numbers molded into them. Just curious, when you pulled your carb(s) apart did you have those two different floats in it (or them)?
Currently - 75 TS250, 02 Kaw ZX-6R
Previously - 70 T350, 71 TS250, 72 GT380, 72 TS125, 72 TS250, 75 Yam YZ360B, 72 GT380 diy cafe racer, 80 GS750, 73 TS185, 82 GS1100
sportston
Expert racer
Posts: 1119
Joined: Wed Jul 10, 2013 12:04 pm
Country: England, UK
Suzuki 2-Strokes: FZ50, GP100, RG125 Gamma, GT380, Bandit 1200S

Re: fuel level vs. plastic floats

Post by sportston »

kb75ts250 wrote: The cure was a gentle tap on the needle using a valve stem cap with core remover like this. The tap coins the needle and seat and that almost always fixes the issue.
What a brilliant bodge. Simple but effective, if you have a slightly oval seat. Thanks for that. I would have simply replaced the needle and seat. That is great in an ideal world, but not always practical when you need an immediate fix. Your way would be a great immediate fix.
User avatar
kb75ts250
On the street
Posts: 28
Joined: Tue Aug 01, 2017 11:48 am
Country: US
Suzuki 2-Strokes: ts250m
Location: Brighton, MI USA

Re: fuel level vs. plastic floats

Post by kb75ts250 »

sportston wrote:
kb75ts250 wrote: The cure was a gentle tap on the needle using a valve stem cap with core remover like this. The tap coins the needle and seat and that almost always fixes the issue.
What a brilliant bodge. Simple but effective, if you have a slightly oval seat. Thanks for that. I would have simply replaced the needle and seat. That is great in an ideal world, but not always practical when you need an immediate fix. Your way would be a great immediate fix.
As long as the needle and seat were visually good I used to do that whenever re-building a carb. It only took a few seconds to do and it was great insurance against having the customer come back later with a problem. Now I just need to get off my dead ass and do it with my own TS250. I noticed a little piddle under it yesterday.
Currently - 75 TS250, 02 Kaw ZX-6R
Previously - 70 T350, 71 TS250, 72 GT380, 72 TS125, 72 TS250, 75 Yam YZ360B, 72 GT380 diy cafe racer, 80 GS750, 73 TS185, 82 GS1100
User avatar
jabcb
Moto GP
Posts: 4240
Joined: Mon Dec 13, 2010 4:32 pm
Country: USA
Suzuki 2-Strokes: 69 T350 thru 75 GT750
Location: southwestern Pennsylvania

Re: fuel level vs. plastic floats

Post by jabcb »

kb75ts250 wrote:I could see mixing them up happening for sure! Too bad the floats don't have part numbers molded into them. Just curious, when you pulled your carb(s) apart did you have those two different floats in it (or them)?
One set was in my T250 when I bought it. The other set was purchased as new spares & were supposedly correct for the T250/GT250.
I don’t remember which one is correct.

If you pick up a T250/GT250 that’s a barn find, you shouldn’t assume it has the correct floats.
Prior to noticing this, it would probably have never occurred to me to check to see if the floats are correct.
BAS (Bike Acquisition Syndrome) - too many bikes but have room for more

Suzuki:
GT750 2x75
GT550 72 & 75
GT380 72
T500 69 project & 73 project
T350 69 & 71
Honda 85 CB650SC & 86 CB700SC
09 Triumph Bonneville SE
User avatar
kb75ts250
On the street
Posts: 28
Joined: Tue Aug 01, 2017 11:48 am
Country: US
Suzuki 2-Strokes: ts250m
Location: Brighton, MI USA

Re: fuel level vs. plastic floats

Post by kb75ts250 »

jabcb wrote:One set was in my T250 when I bought it. The other set was purchased as new spares & were supposedly correct for the T250/GT250. I don’t remember which one is correct.

If you pick up a T250/GT250 that’s a barn find, you shouldn’t assume it has the correct floats.
Prior to noticing this, it would probably have never occurred to me to check to see if the floats are correct.
When you work on these old bikes never assume anything is correct. Lots of previous owners tinkering, old dealer inventory could get mixed up, part numbers get interchanged, exploded views in parts manuals not the same as how the bikes were actually built, differences by country, who knows what else.

Anyhow, it would have never occurred to me either that those float pin locations might be different. You made an amazing catch there. I know I'll remember that one and I'm pretty sure you will too, and hopefully that little tidbit of knowledge will help other people in the future too.
Currently - 75 TS250, 02 Kaw ZX-6R
Previously - 70 T350, 71 TS250, 72 GT380, 72 TS125, 72 TS250, 75 Yam YZ360B, 72 GT380 diy cafe racer, 80 GS750, 73 TS185, 82 GS1100
Post Reply