2 STROKE WORLD .net

The 2-Stroke Garage => Turning Wrenches => Topic started by: kramdua on October 16, 2023, 07:44:02 AM

Title: intermittent fuel leak
Post by: kramdua on October 16, 2023, 07:44:02 AM
i've been chasing this leak out of the overflow hoses out the bottom of the float bowls on rd350b.
i have replaced the needle and seats, set float tangs to 15mm, inspected the floats for cracks or damage. yesterday it was raining so i pulled the carbs again. checked the float height again and 15mm. made sure the needle and seats had no debris. inspected the float shafts in bowls. found nothing. started looking at the floats again and found the sleeves in the floats were loose where you could remove them. picture attached. Has anyone else run into this?
thanks,
Title: Re: intermittent fuel leak
Post by: m in sc on October 16, 2023, 07:49:21 AM
yes ive seen this before.
Title: Re: intermittent fuel leak
Post by: kramdua on October 17, 2023, 09:28:29 AM
you know when you are retired at 60 you have the extra time you need to use.
i was reading up on how to tell if the float is bad and you are not going by the appearance.
i read that the floats absorb fuel and weigh more. i have one float that looks good. it weighs 2 grams. two floats weigh 3 grams and lastly the 4th float weighs 4 grams. heavier weights don't float as well.
anyone agree or disagree?
thanks,
Title: Re: intermittent fuel leak
Post by: IR8D8R on October 17, 2023, 03:53:28 PM
Kramdua,
If you have the metal tipped fuel inlet needles, try the Mikuni needle and seat set with Viton tips. If you have the rubber tips already they may have hardened. Common issue. Sometimes polishing up the metal needles and seat will fix this if there's a residue or oxidation making them hang. I think the knockoff carb kits have the metal tipped needles. Most suppliers have the option for Viton.
https://www.economycycle.com/shop/yamaha-rd250350400r5ds6ds7-parts/fuel-and-airintake/carburetor-rebuild-kits-parts-related/carburetor-parts-carburetor-rebuild-kits-parts-related/float-valve-assembies/mikuni-viton-tip-needle-valve-assembly-for-rd250350400r5ds7-all-vm24-30mm-carb/.
 My carbs were pissing every other time I stopped and forgot to shut the petcock. Embarassing...

IR8D8R
 
Title: Re: intermittent fuel leak
Post by: m in sc on October 17, 2023, 04:45:37 PM
fwiw they are available new from multiple sources.

https://www.economycycle.com/shop/yamaha-rd250350400r5ds6ds7-parts/fuel-and-airintake/carburetor-rebuild-kits-parts-related/carburetor-parts-carburetor-rebuild-kits-parts-related/carburetor-floats/rd350250r5ds7-carburetor-floats/

https://www.summitracing.com/parts/mku-vm28-164

etc

Title: Re: intermittent fuel leak
Post by: kramdua on October 18, 2023, 07:49:19 AM
you are correct the tips are metal. i appreciate the info and it saves me from taking the carbs off another time.
Title: Re: intermittent fuel leak
Post by: lowandslow on October 18, 2023, 08:24:10 AM
I may have a similar problem with the left carb. However when I tap the bowl it fixes itself? Is mine acting up because of this issue?

Also can someone tell me if the fuel lines are the same size for the petcock and the balance pipe the connection between 2 sides of tank(1/4")?
Title: Re: intermittent fuel leak
Post by: Karl squire on October 18, 2023, 09:36:03 AM
This only fixes the symtom, not the problem, however, I just turn the gas off on my petcock, if I dont' I'll have a few drops of gas under my bike, my problem is, I think, the gas line not having a snug enough fit over the nipple on the carb, I dont have clips for them anyway it may help or maybe you are already doing this. good luck buddy.
Title: Re: intermittent fuel leak
Post by: kramdua on October 18, 2023, 12:39:55 PM
thank you.
time will tell.
Title: Re: intermittent fuel leak
Post by: m in sc on October 18, 2023, 01:07:05 PM
viton tipped needles are of course better, but the failed float itself needs to be addressed 1st.

Title: Re: intermittent fuel leak
Post by: SoCal250 on October 18, 2023, 01:08:05 PM
Quote from: lowandslow on October 18, 2023, 08:24:10 AMAlso can someone tell me if the fuel lines are the same size for the petcock and the balance pipe the connection between 2 sides of tank(1/4")?
Yes, the hose is the same for the petcock to carb fuel lines and for carb cross-over pipe.

Title: Re: intermittent fuel leak
Post by: kramdua on October 18, 2023, 01:48:42 PM
i am doing the whole repair in one shot.
thanks,