Carb Jets, where to get.

[AllanB]

Looking to replace the main and pilot jets in my 2 Keihin VD carbs for my 1983 Honda NV400..oh and new float chamber gaskets too.

The only stuff I can find on ebay is from the US, who sell a Sigma upgrade kit, but want to keep things standard.

And I would like to buy from Thailand. Somewhere in the Northeast would be nice, if not mail order?

Thanks IA.

[rodknock]

if you want bigger jets, just drill them out.

[AllanB]

if you want bigger jets, just drill them out.

?

[stubuzz]

Most motorbike shops have a selection of jets.

[papa al]

if you want bigger jets, just drill them out.

Yep.

For smaller jets, pean them smaller.

[AllanB]

As I said, I want standard jets.

Now being a rare bike info is difficult, the spec on the Keihin VD carb, for another bike says the main should be #110, but the one in there is a #118. This type....

The pilot in the carb is a #35.This type......

Are these pretty standard designs used for other bikes and is there a place to get them here in LOS, maybe mail order. I don't know anywhere in Khon Kaen.

The ones in there look a bit manky, probably as old as the bike.

[canthai55]

Soak in carb cleaner, and use a tip cleaner designed for an oxy acetylene torch.

Available at any tool shop who sells welding supplies.

Be gentle, as you do not want to change the diameter of the holes, or make them egg shaped.

[AllanB]

Soak in carb cleaner, and use a tip cleaner designed for an oxy acetylene torch.

Available at any tool shop who sells welding supplies.

Be gentle, as you do not want to change the diameter of the holes, or make them egg shaped.

As I have said I want new ones, the originals are very old and the bike runs a bit rough, with one cylinder rich the other lean, with both mixture screws in the same position, both carbs synchronised and both floats set at 7.5mm.

Everything else on the fuel system has been renewed and so I want to get everything up to date.

I already have jet cleaners, which actually only fit the main jet, the other pilot jet #35 being too small even for the tiny size 6.

These pictures were taken from a website, they are not mine, as I have said, mine are a bit manky..

[VocalNeal]

These pictures were taken from a website, they are not mine, as I have said, mine are a bit manky..

Allan,

Have you tried bunging the appropriate amount of fuel system cleaner in your tank? Might help clean out the gunge.

For jet cleaning use a piece of wire separated from some braided copper electrical wire. Happy to send you some braided stainless wire from which you can separate individual strands.

Of course NV400 was never sold here so...

Thought: Are both idles set correctly? That would make a difference , cylinder to cylinder.

Edited October 15, 2015 by VocalNeal

[AllanB]

These pictures were taken from a website, they are not mine, as I have said, mine are a bit manky..

Allan,

Have you tried bunging the appropriate amount of fuel system cleaner in your tank? Might help clean out the gunge.

For jet cleaning use a piece of wire separated from some braided copper electrical wire. Happy to send you some braided stainless wire from which you can separate individual strands.

Of course NV400 was never sold here so...

Thought: Are both idles set correctly? That would make a difference , cylinder to cylinder.

Finally got hold of "Jo Modify" today (I thought he had disappeared) and he fixed me up, 650 baht + 50 baht for a courier. That was for 4 jets and two gaskets.

One thing he did ask was whether I wanted a #120 for the rear cylinder which runs hotter, so should be bigger and richer, I said no as the V twin is liquid cooled. Is that right, that they should both be the same?

The butterflies are set the same, using a small round rod, acting as a feeler gauge, doesn't the linkage take care of the rest in terms of idling? If not how do you set the idles?

I like old bikes, but wish I could bolt on a fuel injection package and plug in a gizmo, I do find these Jap carbs complicated, must be a nightmare with 4 of the buggas, as on a CB400. The old SU's on my Spit were so simple to set up and no jets to block, no diaphragms to rot.

[bramds]

Who is this Jo Modify?

I need some bits and parts too for my carbed bike.

[AllanB]

Who is this Jo Modify?

I need some bits and parts too for my carbed bike.

He is in Khon Kaen, south of the city centre, his main claim to fame is to build choppers, but he does repairs and can make stuff too. I have a rare bike and he made some seals for my petcock when I ruined them as a result of using gasahol. He also built me a new choke cable assembly from bits he bought in.

His phone 0899 405520, but directions:- Go past Piman Chon 2 (on your left) head up that road (round a left hand bend) for 1-2km and he is on the left. A few bikes for sale outside, including a Triumph Thruxton 900 280,000baht.

He speaks a bit of English, not much, but if you show him, draw a picture, that sort of thing.

Good luck.

[canthai55]

As I have said I want new ones, the originals are very old and the bike runs a bit rough, with one cylinder rich the other lean, with both mixture screws in the same position, both carbs synchronised and both floats set at 7.5mm.

Everything else on the fuel system has been renewed and so I want to get everything up to date.

I already have jet cleaners, which actually only fit the main jet, the other pilot jet #35 being too small even for the tiny size 6.

These pictures were taken from a website, they are not mine, as I have said, mine are a bit manky..

Jets do not wear out. Carbs do. On old ones, the hard chrome piston rides right on the aluminum body of the carb. After many miles, there is clearance between the two. If this is so, you will never get it to run crisp.

Old bikes - first thing is replace carbs with new. Can't get the same ones, get close enuf or switch to Mikuni.

Or do what the guys do who restore Vincents, etc. Bore the carb body, insert sleeve, hone to correct clearance.

Now it looks old, but it ain't. It's new.

Edited October 15, 2015 by canthai55

[papa al]

Allan,

How has the bike been running since installation of new main jets?

[AllanB]

Allan,

How has the bike been running since installation of new main jets?

I haven't refitted the carbs jet, still not happy as they are not clean inside with some sort of fine residue (non-metallic) everywhere. I can see one rubber hose that hasn't been replaced which I will try to get today, I fear it is being attacked by the ethanol in the gasahol, even though the hose looks okay.

I have the carbs off so many times, I want to get everything right, or as right as I can.

I am sure Canthai is right about the carbs wearing, though they look good inside in terms of wear and tear, the sliders are ally (a little black) along with everything else. I don't think changing them is an option as everything is packed in pretty tight and no chance of getting new ones.

Still can't account for the difference in mixture between the two cylinders and when I start the bike it fires up on only one cylinder, then eventually on both. The chokes seem to both be set okay, same depth, but will recheck them inside the carb.

This bike is as frustrating as a one legged man at an arse-kicking contest.

...so close.

[papa al]

Well,

Switch carbs front/back if cyl1 vs cyl2 starting problems persist.

Then,

If no change, not strictly a carb phenomenon.

Starting difficulty likely unrelated to main jets.

How was the bike running at hi power last time you tried?

[In the jungle]

"One thing he did ask was whether I wanted a #120 for the rear cylinder which runs hotter, so should be bigger and richer, I said no as the V twin is liquid cooled. Is that right, that they should both be the same?

The butterflies are set the same, using a small round rod, acting as a feeler gauge, doesn't the linkage take care of the rest in terms of idling? If not how do you set the idles?

I like old bikes, but wish I could bolt on a fuel injection package and plug in a gizmo, I do find these Jap carbs complicated, must be a nightmare with 4 of the buggas, as on a CB400. The old SU's on my Spit were so simple to set up and no jets to block, no diaphragms to rot.:

The stock carb setup on a VFR400 NC30, which as you probably know is a liquid cooled V four, is smaller main jets in the front carbs and larger in the rear. On my bike fronts are #115 and rears are #118.

On the VFR which has Keihin CV carbs I do setup in broadly the same way you do. The only difference being I use lockwire as opposed to a small round rod to set the butterflies. Assuming the throttle linkage is in good shape you then set the idle from one master carb. It is a process that works very well for me though on the VFR it is pretty time consuming due to difficult access and complexity.

[In the jungle]

I just checked and the VFR400 carbs are Keihin VFR VDE3AA.

[VocalNeal]

I haven't refitted the carbs jet, still not happy as they are not clean inside with some sort of fine residue (non-metallic) everywhere....

the sliders are ally (a little black) along with everything else. I don't think changing them is an option as everything is packed in pretty tight and no chance of getting new ones.

Have you read your PM's

Have you sprayed the inside of the carbs/jets with carburetor cleaner

Have you checked the cylinder compressions and valve clearances

Have you fitted new spark plugs

Will you eventually bung the appropriate amount of fuel system cleaner in the tank? (when the carbs are fitted)

Final thought. Do the carburetors have a plunger type "choke" for fuel enrichment for cold starting or do they have a conventional choke. If the former maybe the little rubber seat is worn/eroded/been attacked by the alcohol.

[AllanB]

I haven't refitted the carbs jet, still not happy as they are not clean inside with some sort of fine residue (non-metallic) everywhere....

the sliders are ally (a little black) along with everything else. I don't think changing them is an option as everything is packed in pretty tight and no chance of getting new ones.

Have you read your PM's

Have you sprayed the inside of the carbs/jets with carburetor cleaner

Have you checked the cylinder compressions and valve clearances

Have you fitted new spark plugs

Will you eventually bung the appropriate amount of fuel system cleaner in the tank? (when the carbs are fitted)

Final thought. Do the carburetors have a plunger type "choke" for fuel enrichment for cold starting or do they have a conventional choke. If the former maybe the little rubber seat is worn/eroded/been attacked by the alcohol.

Done all of the above in the past...but the point about the chokes, yes, they are the plunger (enrichment) types and........

The ones I have don't have rubber seals, but seems to rely on a plastic insert in the end of the plunger, which presses against the choke hole and I can now see what may be a problem. Jo Modify made up this twin set for me and this is where I believe the problem lies.

On the carbs, the depth from the top of the thread to the hole (seat) surface measures 25.2mm on both chokes. So the total reach of the plungers needs to be 25.2mm plus a couple of mm to allow a small amount of force from the integral spring to seat them properly.

However, with the choke closed, the plunger length on the front cylinder is 26.2 which is okay, but the plunger length for the rear is barely 24.8mm. This means that the rear cylinder choke is not closing properly.

Now before I go back and get this altered, should there always be rubber seals on these enrichment chokes?

Interesting point from INJ about the different jets, even with liquid cooling, will try that when I get the big things sorted. Your VRF has similar carbs too as the VD's are CVs (constant velocity) carbs too.

Hell I wish I had a manual for this bike, think I could get one from Japan, but written in Japanese......so NFG.

But anyway cheers for that..

[AllanB]

Okay now I must apologise to Jo Modify, blaming him from making the plungers slightly too short, the problem lies with the rest of the 32 year old choke cable, specifically the 2 into 1 junction. This part has fallen to bits relying on the tiny springs on the plungers to keep everything in place, which, or course, they can't.

Sorry Jo...

[canthai55]

Been restoring old bikes and cars my whole life. 1950's Brit, 1960's Jap, HD, Indians.

You need a source of spare parts, a shop manual, and the mechanical know-how to do the work. And a large tool collection.

Sounds like all the above is lacking here.

One thing I have learned - old is just that - old. Plastic brittle, rubber hard, junk.

What I would do to this bike if it was mine - say the carbs are 30mm. Buy a new Mikuni of about 45mm. Take new carb - which is NEW, has nitrile seals so gasahol is not a problem, you can get parts for it ... to a welding shop that does AC GTAW. Have a simple Y manifold fabricated so the one carb can feed both cylinders.

Install with new throttle cable.

Jet as per Mikuni instructions. Buy a IR non-contact temp gun to set jetting according to exhaust port temps.

Throw all the old carb junk far away.

Then do the same for the ignition system. This leaves you with NEW induction, NEW electrical, and the old air pump - meaning the pistons, cylinders, heads etc.

Best thing I ever did to ALL of the old junk I restored. Runs like new - because it is.

[AllanB]

Been restoring old bikes and cars my whole life. 1950's Brit, 1960's Jap, HD, Indians.

You need a source of spare parts, a shop manual, and the mechanical know-how to do the work. And a large tool collection.

Sounds like all the above is lacking here.

One thing I have learned - old is just that - old. Plastic brittle, rubber hard, junk.

What I would do to this bike if it was mine - say the carbs are 30mm. Buy a new Mikuni of about 45mm. Take new carb - which is NEW, has nitrile seals so gasahol is not a problem, you can get parts for it ... to a welding shop that does AC GTAW. Have a simple Y manifold fabricated so the one carb can feed both cylinders.

Install with new throttle cable.

Jet as per Mikuni instructions. Buy a IR non-contact temp gun to set jetting according to exhaust port temps.

Throw all the old carb junk far away.

Then do the same for the ignition system. This leaves you with NEW induction, NEW electrical, and the old air pump - meaning the pistons, cylinders, heads etc.

Best thing I ever did to ALL of the old junk I restored. Runs like new - because it is.

I hear what you say but this is not the UK/USA/Europe, I have rebuilt quite a few old cars and in the UK had a full workshop with a centre lathe, milling machine, HSS cut off saw, MIG, jacks, etc and a full tool kit, plus a new 50m2 workshop and could make almost anything.... but "TIT" and here I have some spanners, a porch and a fan.

Maybe it was a mistake to buy an old bike built only for the Jap market, but although frustrating it has been interesting and often fun getting things working. So I don't regret it, but I am never going to find a manual and the only spare parts available are those that are common to other bikes, the rest, well just do my best really.

With regards to the carbs, it will be a major mod to fit other carb/s due to the lack of space, basically a chop job, the existing carbs are really not that worn and it is quite easy to change the rubber/plastic bits. Much of my carb problems have been self inflicted, using gasahol when I couldn't find benzin on a couple of trips and then thinking I had got away with it, continued...doh!

I have had this bike over 2 years now and renewed, or fixed almost everything, short of an engine strip, some things have taken quite a while, but I have time and other things to do too.

I guess those who are bored reading my efforts to get this bike to where I want it, should avoid these threads, hopefully not everyone, as I would have been pretty stuck without the help I have received here...and I think others find it interesting. I like to read similar threads, pick up a few tips along the way too and have some answers myself.

When I finally get this SOB working I have a couple of long trips planned and have the luxury of a mate who can drive my old Toyota low bed pickup and come get me should I have a major breakdown. If that happens a lot I will sell it on and buy a new Vulcan, which the missus wants me to do now anyway. She thinks this is an old shed... but it is my shed.

As they say on Top Gear "How hard can it be?"

[AllanB]

Well had a few short runs and all seems well, though only a long run will tell.

One thing, the tappets are a bit noisy, just don't sound right, I read that for a large number of 4 cylinder Hondas CB400, CB750, etc.,they recommend:-

Valve tappet clearances: INLET 0.05 mm (0. 002 in.) EXHAUST 0.08 mm (0. 003 in.)

Sounds tight?

But then I found another guy from a Portuguese manual who quoted for the much newer VT600:-

Valve tappet clearances: INLET 0.15 mm (0. 006 in.) EXHAUST 0.2 mm (0. 008 in.)

Sounds slack?

Any idea why the huge difference...my bike is 1983 NV400 ..any suggestions, I am looking for a best guess here, or does anyone have a chart?

The adjustment is really easy I just need some figures.

Edited October 19, 2015 by AllanB

[papa al]

0.004" all.

[thaiguzzi]

As I have said I want new ones, the originals are very old and the bike runs a bit rough, with one cylinder rich the other lean, with both mixture screws in the same position, both carbs synchronised and both floats set at 7.5mm.

Everything else on the fuel system has been renewed and so I want to get everything up to date.

I already have jet cleaners, which actually only fit the main jet, the other pilot jet #35 being too small even for the tiny size 6.

These pictures were taken from a website, they are not mine, as I have said, mine are a bit manky..

Jets do not wear out. Carbs do. On old ones, the hard chrome piston rides right on the aluminum body of the carb. After many miles, there is clearance between the two. If this is so, you will never get it to run crisp.

Old bikes - first thing is replace carbs with new. Can't get the same ones, get close enuf or switch to Mikuni.

Or do what the guys do who restore Vincents, etc. Bore the carb body, insert sleeve, hone to correct clearance.

Now it looks old, but it ain't. It's new.

Really?

Or are you talking about pilot jets. Or maybe main jets. Because the needle jet most certainly does wear out on every slide type carb ever made. Mikuni themselves recommend changing needle and needle jets every 10k miles or 15k kms. As the needle and needle jet control what the carb is doing between 1/4 and 3/4 throtttle, this setting is of utmost importance for most day to day riding.

Back to old carb renovation. Buy yourself a cheapo ultrasonic cleaner off ebay, 'bout £30 odd quid, the size of a toaster, strip carbs completely down to every individual component, let the machine do the rest. Rinse, repeat if neccessary.

[AllanB]

As I have said I want new ones, the originals are very old and the bike runs a bit rough, with one cylinder rich the other lean, with both mixture screws in the same position, both carbs synchronised and both floats set at 7.5mm.

Everything else on the fuel system has been renewed and so I want to get everything up to date.

I already have jet cleaners, which actually only fit the main jet, the other pilot jet #35 being too small even for the tiny size 6.

These pictures were taken from a website, they are not mine, as I have said, mine are a bit manky..

Jets do not wear out. Carbs do. On old ones, the hard chrome piston rides right on the aluminum body of the carb. After many miles, there is clearance between the two. If this is so, you will never get it to run crisp.

Old bikes - first thing is replace carbs with new. Can't get the same ones, get close enuf or switch to Mikuni.

Or do what the guys do who restore Vincents, etc. Bore the carb body, insert sleeve, hone to correct clearance.

Now it looks old, but it ain't. It's new.

Really?

Or are you talking about pilot jets. Or maybe main jets. Because the needle jet most certainly does wear out on every slide type carb ever made. Mikuni themselves recommend changing needle and needle jets every 10k miles or 15k kms. As the needle and needle jet control what the carb is doing between 1/4 and 3/4 throtttle, this setting is of utmost importance for most day to day riding.

Back to old carb renovation. Buy yourself a cheapo ultrasonic cleaner off ebay, 'bout £30 odd quid, the size of a toaster, strip carbs completely down to every individual component, let the machine do the rest. Rinse, repeat if neccessary.

The needles are fine, maybe they have been changed, but I am really glad I don't have Mikuni carbs, stripping down all the carbs every 15k km sounds like a nightmare bike, especially if you have a 4 pot. I guess you can write what you like on an instruction sheet or manual, you will certainly keep the spares turning over and the mechanics busy. Some of these bikes it's a major headache, luckily my carbs come out quite easily.

Damnedest thing........".In and out like a fiddler's elbow."

[canthai55]

Found these in USA. Sent email for a list of carb parts he can supply. Will bring over for you if you need.

http://www.ebay.ca/itm/NEW-K-L-KEIHIN-VB-VD-CARBURETOR-N424-26-SLOW-JET-55-18-4808-/181614061204

[canthai55]

changing needle and needle jets every 10k miles or 15k kms.

Never done it. Never needed to. And do not know anyone else who has had to.

[AllanB]

Found these in USA. Sent email for a list of carb parts he can supply. Will bring over for you if you need.

http://www.ebay.ca/itm/NEW-K-L-KEIHIN-VB-VD-CARBURETOR-N424-26-SLOW-JET-55-18-4808-/181614061204

Thanks a lot for the offer mate, but found them here already.

Trying to figure out valve clearances at the moment now.......maybe a new thread is required?