I posted several times about carb flooding problems asking for help. I replaced needles, set float heights, checked fuel pressure, etc. but nothing helped. I suspected the needle seats but could not find anyone that had ever replaced any. yamaha made it difficult to replace them so I avoided it until there wasn't anything else to try. I am happy to report that I was able to replace them and it fixed the problem. the bike runs great. No flooding. It wasn't easy but it was worth it.
needle seat replacement
- Thread starter bob1956
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- needle replacement seat
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Thevmaxrider
Well-Known Member
Don't you have to remove the bowl cover and they come out with the jet block?
Jim, the needle valve comes out but not the actual seat. You need to drill out that brass plug on the top of the carb I believe.
Vmaxattacks
Well-Known Member
They are a brass insert with an "O" ring seal. You have to tug on them with a bit of leverage. You can also un-stake the brass plugs on the top and push them out with a small gauge pin or drill bit that fits in the hole where the needle goes and use a small c clamp and socket big enough to clear the diameter of the plug then you can press out the seeat through the top where the plug is. They are snug but they do come out :biglaugh:
First you have to remove the plugs on the tops of the carbs that are over the seats. I drilled and tapped 1/4 20 holes in the tops of the plugs on a vertical milling machine. Then I used a slide hammer to remove them. Next you press or drive the seats out the top of the carb carefully to avoid damage. Clean the hole well. Gun cleaning tools, scotch brite,sand paper, acetone.I bought my seats from yamaha. One fit properly and 3 were too loose. I loctited the loose ones in with 648 loctite which is fuel and temperature resistant. The seats come with screens snapped on the tops. Carefully remove them before pressing the seats in place. I made a tool on a lathe to fit on the outside of the seat for pressing. The tool has a hole in the end of it that clears the wire part of the screen so you can press it back on top of the seat after it is installed. I also bought the replacement plugs from yamaha that seal the hole in the carb. They were too small to press properly so I had to make new ones on a lathe. These plugs have an o ring on them that you need to replace. Be sure you use a fuel resistant o ring. Work quickly with the 648 loctite. It sets up quickly.
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Thevmaxrider
Well-Known Member
Ahhhh, now I know. With the EFI I don't worry about those things anymore, just synching and tuning....... frequently LOL.
doesn't sound like something a shadetree mechanic would be able to do then?
XBoxMax
Well-Known Member
This is way over my head but it's very interesting...
95spfldmax
Well-Known Member
If the next person that attempts the seat replacement posts some pics and details, i'd like to see this thread saved in the carb section as a sticky.
I was just in my carbs and my needles are shot. I was wondering how to go about changing the seats.
I was just in my carbs and my needles are shot. I was wondering how to go about changing the seats.
hubeerjw
Well-Known Member
I just got done rebuilding a set of suzuki carbs, these needles don't have the rubber tip, but are 100% metal. The seat is brass. With the Vmax, the needles are a little more forgiving and can make a tighter seal (assuming the rubber tip is still soft). I ended up putting a q-tip in a drill and soaking it in carb cleaner then taking the seat and "drilling"/cleaning the seat with the spinning q-tip. I did this until it was clean and the q-tip wasn't getting dirty any more. The seat on the Vmax should hardly ever need replacing (unless it is pitted/corroded). Maybe you can spin a carb cleaner-soaked q-tip in the seat and clean the seat up (and I believe you said you already have new needles) so you should be good to go.... hopefully
Jeff
Jeff
DLS951
Active Member
Yep, they can be changed.
Drill 1/8" hole all the way thru plug.
use a screw that will tap itself thru plug, run it till it comes out the other side of needle seat. (i used a 1 1/2 long screw)
Put screw/plug/seat into a vice.
Get a open end wrench to act as a block.
Teeth of the vice are squeezing the tip of the screew.
The other teeth of the vice are squeezing open end of the wrench over the top of the screw/plug/seat .
and the screw/plug/seat come OUT THE TOP OF THE CARB,
NOT
out the bowl side.
You'll need a new valve/seat and plug.
Drill 1/8" hole all the way thru plug.
use a screw that will tap itself thru plug, run it till it comes out the other side of needle seat. (i used a 1 1/2 long screw)
Put screw/plug/seat into a vice.
Get a open end wrench to act as a block.
Teeth of the vice are squeezing the tip of the screew.
The other teeth of the vice are squeezing open end of the wrench over the top of the screw/plug/seat .
and the screw/plug/seat come OUT THE TOP OF THE CARB,
NOT
out the bowl side.
You'll need a new valve/seat and plug.
You will also need the little filter screen cap that pops on the top of the needle seat if you use this method.
I prefer to drill, tap w/1/4X20 and remove the plug, then press out the seat with a 'C' clamp. Fill the tapped hole in the plug and all parts are re-useable.
texmax
Well-Known Member
Hey Danny. When you drill the plug are you going all the way through or just enough to get a screw to grab? How thick is the plug?
sdt354
Well-Known Member
The o-ring on the seat looks like it should be changed with a rebuild. When carbs sit and dry out or sure.
Steve-o
Steve-o
texmax
Well-Known Member
I'm thinking thats what happened with mine. Got busy with work and stuff and carbs sat on the bench for about a month. Gonna fill the bowls a little later to see if the fuel hydrated the o-rings enough to get them to seal. Kinda strange though, I've heard of bikes sitting around for years and not have this problem. Think I only saw one other post where they were leaking.
The plugs are a bit less than 1/4" thick (.240" ?) and I drill all the way through just to get as many threads as possible....it's soft aluminum so the more threads the better.
Be sure to tape your drill bit cause the screen bonnet isn't too far below the plug.
texmax
Well-Known Member
Thanks Danny. Looks like i was right for once. Refilled the bowls and no leak. Guess the o-rings swelled back up and made a good seal. Glad I didn't go drilling on them. My backfiring through the carb also went away after warm up. Hell, maybe i oughta go buy a lotto ticket.
Good deal....that's the best outcome! :clapping:
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