Author Topic: Ever heard of needles and jets going bad?  (Read 12767 times)

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Offline raymond10078

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Ever heard of needles and jets going bad?
« on: October 25, 2011, 10:24:58 AM »
Another forum user has been told (by his mechanic) that he needs four new needle jet sets.

While the bike is a "A" model, I was hoping that non-A owners could share if this seems reasonable.  My first impression was to wave the BS flag.  Bike is a 750A with about 8,000 miles.

If it turns out to be true (parts needed), I've tried to find these parts (trying to help), to no avail so far.  If somebody knows of a source for these rare "A" model parts, any leads would be appreciated.  I've advised the owner to start looking for other carb sets, too.
1978 CB750A (upgrading very, very slowly)

Past bikes - Honda: SL350, CX650C, CB900C, CB1000C, CM450A; Kawasaki: several 1972 750 H2's; Suzuki: TC90J.

Bikes I want: CX650ED, a mid-sized japanese V-twin with ABS.

Offline Gordon

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Re: Ever heard of needles and jets going bad?
« Reply #1 on: October 25, 2011, 10:30:21 AM »
It's rare for jets and needles to need replacing.  They're brass, so they don't really corrode.  The needles can become tapered in the middle due to wear from rubbing the inside of the jet, but it takes a lot more than 8,000 miles to do that. 

Offline madmtnmotors

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Re: Ever heard of needles and jets going bad?
« Reply #2 on: October 25, 2011, 10:52:56 AM »
Yeah, hard to imagine. I've been following the other thread as well and my carbs (78' 750K) are pushing 60,000 miles with the original main jet needles and seats. Runs like a top. I think he needs a new mechanic.
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Offline Bob Wessner

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Re: Ever heard of needles and jets going bad?
« Reply #3 on: October 25, 2011, 10:55:27 AM »
I agree with everyone else, seems unlikely. If nothing else, have him ask the mechanic 'specifically' what conditions he is seeing that suggests these all need replacing.
We'll all be someone else's PO some day.

Offline vames

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Re: Ever heard of needles and jets going bad?
« Reply #4 on: October 25, 2011, 11:04:59 AM »
Could it be that the mechanic's nomenclature is terribly off and he's actually referring to the float valves (which are seldom but sometimes refered to as needle valves). What symptom is he claiming that new needles/jets will fix? Is he saying that replacing them will fix how the bike is running or that it will stop fuel from leaking out the overflows? Could be the difference between whether he's simply a moron or whether he's a uncouth moron.

Offline TwoTired

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Re: Ever heard of needles and jets going bad?
« Reply #5 on: October 25, 2011, 11:21:03 AM »
Could be the difference between whether he's simply a moron or whether he's a uncouth moron.

Now that's funny..

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Offline Duke McDukiedook

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Re: Ever heard of needles and jets going bad?
« Reply #6 on: October 25, 2011, 11:44:05 AM »
Or not a moron (but wrong) and just wants to unburden your surplus of greenbacks.
Unless the needles are bent, they do not wear out all that often.
 
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Offline DavePhipps

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Re: Ever heard of needles and jets going bad?
« Reply #7 on: October 25, 2011, 11:52:38 AM »
 Lpease correct me if I'm wrong on this guys, but from what I know of other carbs, needle jets are the emulsion tubes. Those are the tubes with holes in them that are below the jets.
Wear can happen with these if the brass is very soft. It's a known issue with another bike I own.
If this is what the guy is talking about, just remove the tubes and inspect them. If the tube has an oval shape it will need replaced.
Symptom of bad emulsion tube/needle jet: If the carbs are perfectly clean and setup per factory spec with stock airclener and the bike runs rich at closed to 3/4 throttle position.
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Offline madmtnmotors

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Re: Ever heard of needles and jets going bad?
« Reply #8 on: October 25, 2011, 11:56:55 AM »
Could it be that the mechanic's nomenclature is terribly off and he's actually referring to the float valves (which are seldom but sometimes refered to as needle valves).

In the other thread the main jet needles and seats are called out by part number, which does indeed match the part number for the main jet needles and seats. Now whether the mechanic gave him that part number, or whether the member looked it up from the description the mechanic gave, is not clear. Of course it has been difficult to get clear and accurate information from "fuwad84" since he is having trouble holding back his frustration (THAT part I understand completely):

http://forums.sohc4.net/index.php?topic=93138.msg1087254#msg1087254
TAMTF...


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Offline DavePhipps

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Offline dave500

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Re: Ever heard of needles and jets going bad?
« Reply #10 on: October 25, 2011, 12:59:07 PM »
ive never seen worn honda kiehin needles,ive seen aluminium mikuni/suzuki ones worn flat as a matchstick on one side though.

Offline mrbreeze

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Re: Ever heard of needles and jets going bad?
« Reply #11 on: October 25, 2011, 01:27:10 PM »
Lpease correct me if I'm wrong on this guys, but from what I know of other carbs, needle jets are the emulsion tubes. Those are the tubes with holes in them that are below the jets.
Wear can happen with these if the brass is very soft. It's a known issue with another bike I own.
If this is what the guy is talking about, just remove the tubes and inspect them. If the tube has an oval shape it will need replaced.
Symptom of bad emulsion tube/needle jet: If the carbs are perfectly clean and setup per factory spec with stock airclener and the bike runs rich at closed to 3/4 throttle position.
The emulsion tubes are below the needle jet. The needle jet is pressed into the carb body. The jet needle goes through needle jet and they do indeed wear over time. I'm not sure how long it takes to kill them or what the symptoms might be when they are bad.The emulsion tubes screw into the carb body under the needle jets. The main jets screw into the bottom of the emulsion tube. This area is where the tip of the jet needle lives. A coupla years ago ...the needles & jets were still available through Honda. I cant remember exactly how much they were but I'm gonna go from memory and say $ 50-100 for 4 sets.
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Offline Gordon

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Re: Ever heard of needles and jets going bad?
« Reply #12 on: October 25, 2011, 01:29:59 PM »
When discussing wear aspects, lets keep in mind we're talking about a bike with 8,000 miles on it. 

Offline DavePhipps

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Re: Ever heard of needles and jets going bad?
« Reply #13 on: October 25, 2011, 01:39:30 PM »
Never rule out the PO factor. Especially a PO with a drill.
I'm not saying that happened but I don't rule out anything.
BTW my Mikunis on my FZR have ovaled emulsion tubes, and need replaced.
That and the factory pro website are where I'm getting my info on needle jet/emulsion tube symptoms.
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Offline Deltarider

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Re: Ever heard of needles and jets going bad?
« Reply #14 on: October 25, 2011, 01:52:52 PM »
In over 130.000 kms still no signs of wear nor on jets nor on needles. Doesn't surprise me at all as the total flow of gaz is divided over four carbs.
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Offline Duanob

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Re: Ever heard of needles and jets going bad?
« Reply #15 on: October 25, 2011, 02:04:21 PM »
Could be the other side: crud and what not on the needles from sitting for a long time. Mileage has nothing to do with it but crud can make your needles to not seat properly making the bike usually run on the rich side.

A good cleaning of the needles with 0000 steel wool will fix that right up. Of course after everything else has been cleaned.
« Last Edit: October 25, 2011, 02:07:27 PM by Duanob »
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Offline phil71

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Re: Ever heard of needles and jets going bad?
« Reply #16 on: October 25, 2011, 02:36:42 PM »
needle jet? Maybe they just meant needle and seat? I could see putting 4 new ones in on a bike that sat too long with fuel in the bowls.

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Re: Ever heard of needles and jets going bad?
« Reply #17 on: October 25, 2011, 07:08:48 PM »
I want to thank everyone who has helped out so far with this issue I'm having. So back when I bought the bike it was running super rich, with gas leaking out of the vacuum hole on top of the carb float bowl, got so bad that it actually stained the starter cover. The thing always wreaked of gas to when ever it ran and even a for a little bit after. Yanked all four spark plugs out and they're all covered in soot. Not knowing much about multiple synchronized carburetor systems vs single carb engines which I am mostly used to.

I decided that it's best to have a shop look at them and determine whats best. I'm told they need to be rebuild and that it won't be cheap. I think about it for a little bit, put together some extra cash and pull the trigger on it. I get it back a few days later and it runs great...at first. Slowly little by little it begins to bog down. What I did notice immediately was that the fuel mileage on it was still the same, about 25 MPG. I call back about it and hear from the mechanic that it most likely needs to Needle Set and Jet (Honda part number 16012-393-014), rebuild kits I've found so far don't include these. If you look in the image I uploaded it's part number 3.

Honestly, I think it's a little fishy as well.  Right now I'm sticking with this guy because I've already paid him and he's agreed to fix this problem till it's solved, but I'm still on the hook for parts. He doesn't seem like a bad guy, his shop is very old, very well known and gets lots of business despite being in the middle of no-where so I have reason to believe that I'm not being just dicked around and I may infact have a relatively rare problem.....or not.

What do you guys think my next move should be?

Offline mrbreeze

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Re: Ever heard of needles and jets going bad?
« Reply #18 on: October 25, 2011, 08:19:10 PM »
I'm not reading back to who said it but we are NOT talking about the needle and the seat!!!!!!! I bought 4 rebuild kits 4 or 5 years ago. K&L kits from Dennis Kirk. Supposed to be a way better kit than some of the crap you buy on Ebay.... (Keyster comes to mind big time!!!)............Anyhow.....the kits were $20 each +/- .....under $100. They did include the needle/jet pair in their kit although there was much dicussion here as to the difference in needle taper on the aftermarket needles. I remember most people went with stock Honda for those parts and used the aftermarket kits mainly for gaskets, seals, float needles & seats (wut you were confused with!!!)............If ya wanna run stock carbs..............DON'T buy stuff like Keyster (you will get it IN the Keyster!!!). Don't use the supplied needles/jets from any of the kits.........go OEM........my opinion  ;)....good luck & happy trails with whatever ya use.
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Offline ofreen

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Re: Ever heard of needles and jets going bad?
« Reply #19 on: October 25, 2011, 10:01:57 PM »
8000 miles is a little soon for any significant wear on the needle jet sets.  But they do wear out after awhile.  Here is a thread I did 3 years ago on the topic -

http://forums.sohc4.net/index.php?topic=41542.0
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Offline crazypj

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Re: Ever heard of needles and jets going bad?
« Reply #20 on: October 25, 2011, 10:02:58 PM »
It's rare for jets and needles to need replacing.  They're brass, so they don't really corrode.  The needles can become tapered in the middle due to wear from rubbing the inside of the jet, but it takes a lot more than 8,000 miles to do that. 
I've seen complete carbs worn out at 12,000 miles (on Yamaha  :D)
 The needle can develop wear ridge if bike is left at idle for extended periods, the pulsing makes needle 'vibrate' against needle jet.

In over 130.000 kms still no signs of wear nor on jets nor on needles. Doesn't surprise me at all as the total flow of gaz is divided over four carbs.

 Same thing happens when bike is used for commuting and is kept at pretty constant throttle.
 I've seen Kawasaki's where tip of needle has broken off (must be a Mikuni thing?  ;D)
It isn't the flow of gas, it's the vibration of needle against needle jet

 Any half decent mechanic will show you where the wear is although you sometimes need magnifier to see 'pear' shaped needle jet hole
 How many hours has he charged?
 I wouldn't even consider doing a set of 4 for less than 4 hrs labor and have spend 9+hrs on a CB750 SOHC  set of carbs (the bike was a runner and 'looked' clean  ::))
 I probably spent at least 6~7 hrs on my Katana carbs, but they were pretty 'gummy' after standing 16months.
You really NEED to use a 10x jewelers loupe to check for corrosion inside drillings in jets and carb body, just because air blows through jet it doesn't mean it's clean (which is why it's cheaper to replace jets in a shop, less than the cost of labor)
« Last Edit: October 25, 2011, 10:17:51 PM by crazypj »
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Offline ofreen

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Re: Ever heard of needles and jets going bad?
« Reply #21 on: October 25, 2011, 10:13:07 PM »
I've seen complete carbs worn out at 12,000 miles (on Yamaha)
 

True enough.  I've seen carbs where the slides rattle in their bores like peas in a gourd.  Fortunately, the Keihins on the 750s are a lot more durable. 
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Offline somesuch

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Re: Ever heard of needles and jets going bad?
« Reply #22 on: October 25, 2011, 11:03:38 PM »
ive never seen worn honda kiehin needles,ive seen aluminium mikuni/suzuki ones worn flat as a matchstick on one side though.

Exact same experience here.

Offline david 750f

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Re: Ever heard of needles and jets going bad?
« Reply #23 on: October 26, 2011, 12:06:49 AM »
I have definitely seen worn needles on a CB750. Needles can rattle around, there not held in place like a main or slow jet..
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Offline Gordon

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Re: Ever heard of needles and jets going bad?
« Reply #24 on: October 26, 2011, 04:52:23 AM »
Nobody is saying the needle won't wear.  My point is that any significant or even measurable wear is extremely unlikely after only 8,000 miles.  The bike is barely even broken in at that point. 

Offline Duanob

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Re: Ever heard of needles and jets going bad?
« Reply #25 on: October 26, 2011, 08:08:35 AM »
I want to thank everyone who has helped out so far with this issue I'm having. So back when I bought the bike it was running super rich, with gas leaking out of the vacuum hole on top of the carb float bowl, got so bad that it actually stained the starter cover. The thing always wreaked of gas to when ever it ran and even a for a little bit after. Yanked all four spark plugs out and they're all covered in soot. Not knowing much about multiple synchronized carburetor systems vs single carb engines which I am mostly used to.

I decided that it's best to have a shop look at them and determine whats best. I'm told they need to be rebuild and that it won't be cheap. I think about it for a little bit, put together some extra cash and pull the trigger on it. I get it back a few days later and it runs great...at first. Slowly little by little it begins to bog down. What I did notice immediately was that the fuel mileage on it was still the same, about 25 MPG. I call back about it and hear from the mechanic that it most likely needs to Needle Set and Jet (Honda part number 16012-393-014), rebuild kits I've found so far don't include these. If you look in the image I uploaded it's part number 3.

Honestly, I think it's a little fishy as well.  Right now I'm sticking with this guy because I've already paid him and he's agreed to fix this problem till it's solved, but I'm still on the hook for parts. He doesn't seem like a bad guy, his shop is very old, very well known and gets lots of business despite being in the middle of no-where so I have reason to believe that I'm not being just dicked around and I may infact have a relatively rare problem.....or not.

What do you guys think my next move should be?

I'm sticking with dirt and crud on the needles from sitting in gas. Went through the same exact thing on my bike. Cleaned the carbs three times before I cleaned the needles and it fixed my running rich problems right up. The crud is usually micro and hard to see with a naked eyue, especially when your site is bad like mine. But it's enough to hold the needle open more than the it's supposed to be allowing extra gas to constantly flow through the needles/jet when it's not supposed to, like at idle.

ALSO: make sure the old guy didn't mess with the stock position of the needle clip.
"Just because you flush a boatload of money down the toilet, doesn't make the toilet worth more",  My Stepfather the Unknown Poet

1974 CB360T
1976 CB550K2 Resurrected
1976 CB550F2 Barn Find
1979 CX500 VG "HONDA-GUZZI"
2007 Moto Guzzi Breva 750ie
2015 BMW F700GS
Another 1976 CB550K Cafe?

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Offline harisuluv

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Re: Ever heard of needles and jets going bad?
« Reply #26 on: October 26, 2011, 04:23:56 PM »
A lot of people who rebuild carbs have their own idea about what "cleaning" is.  Usually this means just dunking the whole assembly in a can of carb cleaner and then watching american idol.  Then they call you to pick up your "cleaned" carbs aka "PAY ME NOW!"

DH

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Re: Ever heard of needles and jets going bad?
« Reply #27 on: October 26, 2011, 05:56:48 PM »
I had a set wear enough to cause an off idle stumble/rich condition under light throttle accel/decel. New sets from Honda cured it. It caused black plugs over time before fixed.
I tried them as a last resort. I'm wondering if this problem was
less of a concern back when the bikes were new and used leaded gas, the lead in the gas acting as a lubricant.
I was told that this issue was a little more common on the 750
than on the 500/550,  by a honda tech. But only after a good amount of miles on the bike, or with poor air filtration.

fuwad84

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Re: Ever heard of needles and jets going bad?
« Reply #28 on: October 26, 2011, 10:00:21 PM »
So I'm checking out google, ebay and various out of state dealerships. So far no luck, would you guys know of any place where I'd be able to find such items? Here's another question, if I just had one of those little muther-fer's couldn't I get a machine shop to replicate the other 3 and then some?

Offline GoatBaSS

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Re: Ever heard of needles and jets going bad?
« Reply #29 on: October 27, 2011, 06:19:59 AM »
Unless I am missing something, Parts N More has rebuild kits.
Leethal # 3046?
1972 CB750K/900CC Red Headed Dunstall, 1975CB750FSS Gone BNF: 1974CB500T, 1976CB750K X 2

Offline Duanob

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Re: Ever heard of needles and jets going bad?
« Reply #30 on: October 27, 2011, 08:19:43 AM »
So I'm checking out google, ebay and various out of state dealerships. So far no luck, would you guys know of any place where I'd be able to find such items? Here's another question, if I just had one of those little muther-fer's couldn't I get a machine shop to replicate the other 3 and then some?

If you insist on new then there are some on EBAY:

http://www.ebay.com/itm/1974-1976-cb550-cb550k-carburetor-CARB-REPAIR-KITS-/390352243115?hash=item5ae2ce89ab&item=390352243115&pt=Motorcycles_Parts_Accessories&vxp=mtr

First thing you should do is research how to take apart and clean them your self. get the proper tools for cleaning and make sure every orifice is cleaned thoroughly. ID the proper jet sizes and needle clip position when you're in there. Get a sync gauge of some kind. Then we can help you out alng the way. If you insist on taking the bike to someone else, we can't really help you with that.
"Just because you flush a boatload of money down the toilet, doesn't make the toilet worth more",  My Stepfather the Unknown Poet

1974 CB360T
1976 CB550K2 Resurrected
1976 CB550F2 Barn Find
1979 CX500 VG "HONDA-GUZZI"
2007 Moto Guzzi Breva 750ie
2015 BMW F700GS
Another 1976 CB550K Cafe?

  __o
_- \_<,
(*) /' (*)

fuwad84

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Re: Ever heard of needles and jets going bad?
« Reply #31 on: October 27, 2011, 12:26:36 PM »
To clarify once again I'm looking for a needle jet set, which is the needle, needle holder(jet?) and clip. Something similar would be like this over here http://www.ebay.com/itm/CB750F1-75-76-CB750-K5-NEEDLE-JET-SETS-4-/350399377199?pt=AU_Motorcycle_Parts_Accessories&hash=item51956e2f2f  But I need it for a 1977 CB750A, its part number 16012-393-014, can't find it anywhere. I've spoken to a machinist who said he may be able to replicate them, but I'd have to make sure they were made out of the correct metal...and I'm not sure if there was a further process the pieces went through.

Offline phil71

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Re: Ever heard of needles and jets going bad?
« Reply #32 on: October 27, 2011, 12:52:45 PM »
you're going to save a lot of $ if you just find a used rack and pillage it.

Offline ofreen

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Re: Ever heard of needles and jets going bad?
« Reply #33 on: October 27, 2011, 12:53:41 PM »
I've spoken to a machinist who said he may be able to replicate them, but I'd have to make sure they were made out of the correct metal...and I'm not sure if there was a further process the pieces went through.

Besides that, he'd have to get the taper right, something the aftermarket can't seem to do.
Greg
'75 CB750F

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Offline mrbreeze

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Re: Ever heard of needles and jets going bad?
« Reply #34 on: October 27, 2011, 09:15:55 PM »
Like I said earlier.............They were still available from Honda a coupla years ago...........has that changed??? Also......these were the earlier ones (75 750 K).
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fuwad84

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Re: Ever heard of needles and jets going bad?
« Reply #35 on: October 28, 2011, 12:23:26 AM »
I have checked many dealerships and honda shops, they all tell me that the part is discontinued and that they have no stock of them.

Offline phil71

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Re: Ever heard of needles and jets going bad?
« Reply #36 on: October 28, 2011, 12:37:49 AM »
just get used ones man, what's the big deal? Hiring machinists? That's insane. You could buy a whole running bike for what that'll cost.

Offline dave500

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Re: Ever heard of needles and jets going bad?
« Reply #37 on: October 28, 2011, 02:31:52 AM »
anyone tried using ordinary manual gearbox ones,it might be a bit like auto and manual cars of old with carbs,they often have different jetting but the carbs seem to able to be swapped and they still run ok?an auto will like a richer slow speed circuit.

Offline d9canada

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Re: Ever heard of needles and jets going bad?
« Reply #38 on: October 29, 2011, 10:50:50 AM »
Whoa, full stop.. Man, you don't even know if the carbs need anything but a clean-up and bench sync.  Here's a good guide.

http://www.salocal.com/sohc/tech/carb/carb.htm

Click on any one of the small pictures to expand into the guide and from there you can go next previous etc.  It is a very good guide.  Usually for bikes that have sat for extended periods of time, the float bowl area will look really bad but still be OK with careful work.  I use Pine Sol to soak metal stuff overnight, NO plastics or rubber.  Rinse thoroughly with fresh water and dry with compressed air.

I built a simple plywood box with salvaged plexiglass top, you could also use glass (I will assume you know to be careful), cut two 4 inch holes for my arms, one 2 in hole in one end for air and feed hoses.  I bought a cheapo "siphon sand blast gun" on sale $18 (hey wait, I posted a thread on this..) anyway I use baking soda instead of sand.  Baking soda will clean crud but not cut into critical surfaces.  I've cleaned very nasty stuff to spotless very quickly.  It's great for small brass parts like pilot jets with the tiny little tips you can easily break using a wire "toothbrush".  Soda brings it all to a great burnished finish.  If you use soda, give the parts a quick dunk again in Pine Sol maybe 10 min, thorough fresh water rinse and dry as before.

Usually you will only need Orings and a float bowl gasket which usually is just an Oring held with just a trace of gasket glue suitable for fuel.  When I say trace, imagine a Marine drill instructor yelling in your ear.. use  a toothpick and put a trace of glue where the Oring needs to be and stick it in place. 

Quit getting scared and thinking about ordering anything.  Get it apart and have a look, which is probably the thing your mechanic did not do.

Follow the guide.  Don't worry about your inexperience.  I had never done 4 carb systems before and I followed a similar guide for CB900C carbs - I have so far turned two bikes which sat 7 and 9 years respectively into kittens that pur. At the end of the guide is the process normally called bench sync, where you get the carbs all synchronized mechanically.  Do that very carefully and your bike will run well.  A dynamic sync may make some improvement, but do make sure your valves are all spot on first or the dynamic sync is useless.

While you have the tank off, flush it and install a small inline filter (best ones are at lawnmower shops).  The filter has an arrow, make sure it goes with the direction of flow.  Tank, filter, carbs, and you will be fine.
 
You got that mister?? Hu-rah!!   8)
« Last Edit: October 29, 2011, 10:53:09 AM by d9canada »
Brian

CB350F to CB900C
GL500
GL1000
CBX
02 Sportster 883
64 Suzuki M15D Sovereign 50cc