Resurfacing needle and seat?

[Nice Guy Eddie]

anyone had any luck resurfacing a float bowl needle and seat valve?

I have an old bike (Mikuni carb) that I can't seem to get a new needle and seat for... it leaks kinda bad (constant drips)... I ran some 1000 grit emery cloth in the seat, and polished up the needle some, but it still leaks... (it doesn't look very bad at all though)... it's not as bad as it was leaking, but obviously I would like for it to function properly...

It's not the float hieght, as I adjusted that, and it drips even with a finger pushing the needle in...

any ideas on resurfacing the seat.... maybe a source for really old carb parts? (it's an '82 YZ125)

 

[biglou]

Everyone mentions Sudco, but I don't have any experience with them. Sounds like a good place to start. Maybe ask in the Vintage Forum? I wonder if there are any later models that have parts that would cross over? That would be ideal. Sorry I can't help more. If I get some time, I'll search around and post if I find anything.

 

[biglou]

I found this listed as the stock carb: Mikuni Vm34ss
Sudco has Vm29ss and Vm33ss carbs listed, but they look to be four-ganged for street bike.
Here is the catalog page: http://www.sudco.com/catalog/Page 128-131.pdf

I'd definitely give them a call or search around on their site. They have a ton of info there.

 

[Ol'89r]

anyone had any luck resurfacing a float bowl needle and seat valve?

any ideas on resurfacing the seat.... maybe a source for really old carb parts? (it's an '82 YZ125)

Eddie.

I've done this to some old vintage British carbs. In some of those the seat is pressed into the casting and not removable so you can't replace it.

I made a tool using a old needle soldered to a piece of tubing and also one with a small ball bearing soldered to tubing.

Using these tools and some very fine lapping compound, you can lap the seat in similar to the way you would lap a valve. Doing this will most likely change your float level so, you should recheck that after your done.

biglou's suggestion of checking with Sudco is a good one. They carry a lot of vintage stuff.

Just my $ .02

Ol'89r

 

[Nice Guy Eddie]

thank you guys very very much... I will check with Sudco (thanks for taking the time to find me the link... super cool, just like Berretta!!!... lol)...

Thats pretty much what I was thinking 89r.... I've done similar to faucet seats more times than I would ever care to remember, only with a very fine stone... I would think that if it is good enough to hold back 40psi of water it should be able to hold back the pressure of the gas tank... but then again the needle is steel (with very little force applied) and the faucet washer is rubber (with plenty of force)

well, I have nothing to loose by trying I guess, since it leaks anyways.... I'm gonna see if I can find a Dremel stone that is similar in size/shape to the needle, and then run it in a drill nice and slow and see if I can get it to work... (or would a stone be too rough?)

any advice on shape for the stone and in turn the seat?.... I'm wondering if, like valves, you want some difference in angle between the two so the force is all in one spot... or if you want the angles as close as possible.... (just thinking out loud maybe, but any input is welcome)

 

[KiwiBird]

I've used a piece of plastic hose (even a straw) on the valve itself and put some fine compound valve lapping paste on the valve to lap the valve to the seat. A grinding stone is probably too coarse and won't match the profile of the valve.

 

[JasonWho]

I iamgine a VM34SS is not too rare. I have one on my '87 KDX200. It was the stock carb. The stock valve was a 3.3. I don't know what it is on your YZ. Care to look and compare to the Sudco parts list? Are you looking for just the valve or a whole new body? You can't get a new "just the body". I have a couple of old spares I am never going to use if you ever decide to try a used one.

jasonwhokdx at mchsi.com

Hope this helps

http://www.sudco.com/vmpart3.html

Needle Valve (Needle & Seat Assembly)
002-230 VM26/26 1.0 20 - 30mm Flange
002-231 1.5 26 and 28mm Spigot
002-189 2.0 BN38 and 44mm
002-190 2.5 VM30 Small Body
002-191 2.8


002-192 VM34/39 3.0 30 - 44mm Spigot
002-193 3.3 32 - 34mm Flange
002-194 VM28/163 1.0
002-195 1.2
002-196 1.5
002-197 1.8
002-198 2.0
002-199 2.5


002-200 VM38/11 3.5 30 - 44mm Spigot


002-233
002-895
002-896
VM28/511
(Viton Tip) 1.5
1.8
2.0 30 - 38mm Spigot
Snow OEM Applications
30 - 44mm Spigot


007-288 VM15/172 1.5 VM18-20mm

Note: All of our needles are threat-in, not press-in.

 

[Nice Guy Eddie]

I've used a piece of plastic hose (even a straw) on the valve itself and put some fine compound valve lapping paste on the valve to lap the valve to the seat. A grinding stone is probably too coarse and won't match the profile of the valve.

so you're saying, hold the needle with a piece of hose/straw... cover with compound.... insert needle into seat.... and spin by hand?

JasonWho- I'll be getting ahold of you if I need to.... the Yamaha dealer doesnt have them... Dennis Kirk doesnt have them (or at least gave me the wrong one)... Bob's Cycle Supply doesn't have them... and I can't read Sudco's catalog without DL'ing Acrobat (virus.. wiped drive kinda deal.... I'll get it back soon)

I'll try to fix this one first, just for kicks

 

[reelrazor]

Yeah what someone else up theer said. Fine lapping compound (hey!, it only works on metal to metal needle/seat combos-do NOT do this to viton{rubber} parts).

I do it with the needle I am intending on using in that seat. Just a tiny bit of compound and a few spins(clockwise/counter) is all it takes.

Pressure test it wih your mouth, you would be amazed at how sensitive your mouth and lungs are to leakage.

 

[JasonWho]

Nice Guy Eddie, what part do you think is at fault, the body itself or the valve (rubber part)?

Sudco does carry new VM34SS carbs, but they will come with standard jetting, so you will either have to buy new jets or swap in your old ones, but that doesn't sound so great for a new carb.

Also, there are different sized valves.

Whether from me or someone else, I would try a used body first before spending $100+ on a new one. At $5, it is worth a shot, anyway.

 

[KiwiBird]

You got it - hadn't thought about if it's coated in rubber so all bets are off for lapping it in if that's the case.

 

[YZ165]

Find an indapendant motorcycle shop that gets thier hard parts from K&L Supply. They have what you seek.

 

[Nice Guy Eddie]

it doesn't have any rubber.... steel needle, brass seat.... I'm going to try to get it done tommorow... I'll let you know how it goes

 

[Ol'89r]

Yeah what someone else up theer said. Fine lapping compound (hey!, it only works on metal to metal needle/seat combos-do NOT do this to viton{rubber} parts).

I do it with the needle I am intending on using in that seat. Just a tiny bit of compound and a few spins(clockwise/counter) is all it takes.

Pressure test it wih your mouth, you would be amazed at how sensitive your mouth and lungs are to leakage.

Eddie.

Like reelrazor said, just a tiny bit of compound and a few spins. Lap it in like you would lap a valve. Spin it back and forth just a few times and check it with suction each time until you have a good seal.

 

[Nice Guy Eddie]

gotcha.... and thanks again

 

[Nice Guy Eddie]

I found this listed as the stock carb: Mikuni Vm34ss
Sudco has Vm29ss and Vm33ss carbs listed, but they look to be four-ganged for street bike.
Here is the catalog page: http://www.sudco.com/catalog/Page 128-131.pdf.

this is definately not my carb.... the carb on this bike is your standard cylinder slide found stock on most older MX bikes..

how did you determine the stock carb for my bike?

 

[JasonWho]

Hi, again. Does your carb look similar to this one? Are you saying you already bought a valve seat from Dennis Kirk? What does the old one look like? Can you see it in the second picture? You need a #3.3, according to bikebandit.com. Sorry to mention a rubber part previously. I must have had a brain lapse. I know which part you are talking about.

Thanks.

 

[Nice Guy Eddie]

my carb looks pretty similar to that... hard to say "exactly".... my needle and seatlook like the one on the left, then one in the middle and the one second from the right.... DK sold me a needle and seat that looked like this, and was threaded, but was the wrong diameter.... (would not thread in... way too small)

 

[JasonWho]

Did you get a 3.3?

 

[Nice Guy Eddie]

Geez, I really don't know... I'll run and check... hold on.... lol

 

[JasonWho]

Do you have a DK part number? I have a catalog handy, besides it being online.

 

[Nice Guy Eddie]

nah... they gave me a 2.5 ..... is there still hope DK may have one?.... I am driving past their store tommorow with that bike in my trailer

 

[JasonWho]

Drivin past their store?!? Ah heck. I am through helping you. I am jealous!

The catalog only shows a 2.5 in that style. Lemme check sudco

 

[JasonWho]

MI 002.193 VM34/39 3.3 NV $18.80

Like it said above, they only have thread in, not press in (far right photo)

I think you need to call Sudco at this point. They will surely know exactly what you need IF the lapping compound trick doesn't work.

 

[Nice Guy Eddie]

quite honestly the store sux.... you stand in a little tiny room packed with overpriced motorcycle gear (NONE of the cheap stuff is on the floor) and order over little phones in cubicles.... then wait ten minutes and you have your merchandise without shipping costs (thats the good part)... they just pull it from the warehouse behind the store...

The REALLY nice part is the scratch and dent store.... THAT'S where you find the deals (I got a Thor Scattershield for $25... and shin/knee pads for $1)... even that has gotten slim now that they have DK****.... *sigh*

I also have Bob's Cycle Supply in St Paul.... but they suck even worse.. their warehouse is somewhere else and it takes a couple days to get it even if it is in stock!!...

It seems these catalog stores are pretty good at the netsales stuff, but they sure lack in the retail market... that's okay though....they're close by and cheap.. thats what really matters