Right Carb Leaking (Finally Threw In The Towel)

[bdholsin]

I've adjusted the float level on my right hand carb a good dozen times, if not more. I just can't get it to stop spewing fuel out of the main air passage and into my filter. I finally threw in the towel two days ago and ordered a new float, float needle and float needle seat. I actually ordered a pair of each figuring since I have the carbs off I'll do the replacement on both sides. My luck dictates that as soon as I get this problem solved for the right side the left will start acting up so I'll preemptively address it now.

No matter how many times I cleaned and adjusted it just wouldn't stop leaking. Maybe the float valve (right at the sealing tip) was damaged...who knows. Hopefully this will fix the problem and I can have the 'ol girl back on pavement soon. Parts are supposed to be here tomorrow. Carbs are sitting on my shelf and snickering at me every time I walk by. I think they know they got the better of me this time.

 

[TeeCat]

bd...

I think your purchase is a well-informed shot at the problem and should have a reasonable chance of success. I did this with my BS 38s, but ultimately they apparently had other more cryptic issues, and they now have a seat in the corner of my shop, facing the wall, ever since a single Mikuni round slide unceremoniously frog marched their refractory asses right out of the holders. (Many people love them... I had simply reached critical mass and deemed life too short to waste another second on them). I do hope you get this sorted!

TC

 

[bdholsin]

Thanks for the positive words TeeCat. I actually feel a little bit better about ordering the parts now.

If this doesn't solve the problem I think there may be a nice XS650 bon fire in the not too distant future.

 

[TeeCat]

If this doesn't solve the problem I think there may be a nice XS650 bon fire in the not too distant future.

Well, some of us would likely be more than willing to walk you through a single-carb conversion before you do anything drastic.

TC

 

[DogBunny]

I hope you ordered genuine Mikuni float valves, which are more expensive, but are readily available everywhere.

The Mikuni valves don't leak. If you compare them to knock-offs under a magnifier, the difference is like night and day. I tried knock-offs, for me they leaked, and the Mikunis were the solution.

 

[5twins]

Yes, my dealer even told me the knock-off valves are junk. He won't use them. Many aftermarket floats are junk too. MikesXS ones used to be that way, don't know if they are now. His brass ones could spring leaks in as little as a couple months and the plastic ones fit too loose on the pivot pin so they metered inconsistently.

 

[bdholsin]

I ordered from mikesxs.net...hopefully I'll get good parts. Their quality is hit and miss as I've read from other peoples experiences. Personally, I haven't had any issues with the parts I've ordered there in the past. The single SNAFU I have had was resolved immediately and to my complete satisfaction.

If it comes to a single carb conversion, which I hope it doesn't, I'll follow up with all of you right here.

Thank you, gentlemen (and any ladies who have or will pipe in).

 

[69er]

sometimes the o-ring on the needle jet goes bad and allows the gas to leak past that and the float bowl continues to fill up

(Part #48-5020 mikes)

 

[blue900]

I found the o-ring for needle seat let fuel seep by and after it sat a few hours it was slowly leaking fuel out on the ground, Nearly tore the rest of my hair out. These where new parts from mikes o-ring and seat, 5 or so years ago.
I found when chasing the problem a small amount of teflon tape in the groove where the oring goes on the outside of the seat, 2 or 3 single layer wraps. then the o-ring snugged things up and no more leak. A year or so later i had them apart for cleaning again and forgot the tape and had the same leak.
No Problems after the repair.
Genuine Mikuni for me next time.
Anyway if they leak try that.
The Needle seats need to fit in carbs snug for the o-ring to seal.

 

[xjwmx]

Yes, my dealer even told me the knock-off valves are junk. He won't use them.

I used the non-Mikuni valves (bs34) from Mike's, in part on 5twins recommendation So far so good...

 

[CDNTX650]

i also use the floats from mikes for my 34's. They were as good of a fit as the factory ones on the pivot pin. Bike runs great with no more gas pouring all over. (my brass ones were full of gas)

 

[bdholsin]

i also use the floats from mikes for my 34's. They were as good of a fit as the factory ones on the pivot pin. Bike runs great with no more gas pouring all over. (my brass ones were full of gas)

Aren't brass floats used on BS38's? My 34's have the black plastic floats. While the floats themselves seem OK, I wonder if there may be a small burr on the tang that holds the valve resulting in the leakage. Whatever the case, i'll get it figured out today when the parts arrive. I just checked the delivery status and UpS is showing "out for delivery".

 

[gggGary]

First year BS34s (1980) used brass floats the later ones switched to plastic. They interchange with each other. A leaking oring that seals the float valve body to the carb body is a common issue on BS34s on many different bikes.

 

[grepper]

I had the same problem with my bs34s. Turned out the problem was the floats from mikesXs. I resorted to buying the floats from the local Yamaha dealer, no problems after that.

bdholsin: If you deside to have a xs650 Bon fire, I have a couch you can burn instead and I'll take that xs650 off your hands. I'm in MI too...

 

[CDNTX650]

yup, mine are 80 bs34's. now with plastic floats. Me second set of bs34's are 81 and one of the pivot pins is stuck....i need to replace the float valves...so far i have used some parts from them though so it's handy having them.

 

[bdholsin]

Where you located grepper?

I wouldn't actually torch the bike...although, some days my frustration gets the better of me and the thought crosses my mind. Then I remember how much money and time I have put into it and quell the thought. I really like the bike...she's just a little tempermental from time to time.

I have replaced the float seat o-rings a couple times. Admittedly they have been off the shelf o-rings from my local Do-it-best hardware store. I'm 99.9% certain that the parts I've been using are good and the right size (or at least close enough as they are quite tight). I use a little oil to slide them into the carb body for a good seal.

 

[grepper]

>Where you located grepper?
I work in Lansing and live in Ionia (between GR and Lansing). I see your near Mt. Pleasant.. Fire Up Chips! I went to CMU.

When I was about my carbs, I made a little stand for them with some scrap wood. So I could set them up and test them before I put them on the bike.

One easy, but expensive route, would be to say F*** it and buy a new set of vm's from 650 Central or PWKs from MikesXS. You could get $50+ for the old ones on eBay. Or you could send them off to be professionally rebuilt by olfschool carbs (http://www.xs650.com/forum/showthread.php?t=5882

 

[bdholsin]

Well I'm up and running with no leaks. Parts arrived today and everything went together nicely. Seems that either my frugality or stubborness is the source of much of my frustrations. Either way its my own darn fault for fighting with the old parts. I should have just bucked up a couple months ago and bought these parts.

Grepper, yeah, I live close to CMU but I'm a graduate of MTU (go Huskies). Actually I'm a UofM fan to the core. Especially since my wife is a graduate of the UofM dental school.

Now, on to my next problem with the bike...oil leak. That'll be a whole new thread this winter.