Pilot Jet

[Johnwhatsisname]

Hi All,
I am busy stripping and cleaning my carbs. The "Pilot Jet" as shown in the attached pic is solidly blocked. The Jet is shown as No. 17
Firstly, I am not sure if this should be blocked I.e. a blanking jet or is it in fact blocked.
I tried inserting some soft aluminium wire into it with no luck.
I am reluctant to probe/try too hard if it in fact supposed to be blocked.
The reason I ask is that I have a spare set of carbs so I though I would check one of those and also found it to be blocked.
If its supposed to be open any suggestions on clearing??

 

[Fire-medic]

Yes, use a steel wire, if the aluminum won't poke through it. However, it's a very-small hole, so it may take a bit of rotating the wire to break through the obstruction. I have a pin vise, it looks like a mechanical pencil, with a thin single strand of stainless steel wire, about 1-1/2" for this express purpose. When you're done, you should be able to see light through it when held-to a light source in the background.

In my 27 years of VMax ownership, it seems to be the pilot jets on the left side which become obstructed first, possibly-because of the sidestand.

The bike will-not operate at idle properly if one or more are plugged. When you operate higher in the rev range, the other jet circuits come into play, and the bike will run normally. Drop back to idle, though, and the cylinder(s) with obstructed pilot jets stop firing, the temperature of those exhaust pipes will noticeably-drop. It doesn't take much to obstruct your pilot jets, because of their small size. Any rust in the tank will soon fine a home in the pilot jets, plugging them and there-goes your idle quality.

I included a pic to help in bench-setting your float level, see the circle casting mark in the body of the carburetor, and the float body, just-above it.

Here's a pic of the pilot jet, w/a single strand of stainless steel wire through the hole. Another, hole open/clear.

 

[Johnwhatsisname]

Got it.Thank you.
I used some thin fishing trace wire

 

[02GF74]

yes, I had to do this. it is a tiny hole - I used a fine needle that had to be filed down to be thin enough to poke through the hole.

Once through, I used a single strand of copper wire from multi strand cable to clean it; a set of wire cutters was used to make dents so it acts like a file. On one of the jects it took a while prodding from both sides to break through; the copper wire is soft so as not to enlarge the hole and the jet is clear once the wire comes out clean.

 

[desert_max]

I always soak them overnight in solvent. Then they uually clean out easily.

 

[Fire-medic]

I use an ultrasonic cleaner, and that usually does it, but I've had ones which needed the stainless steel strand of wire to remove the plug of debris. Make-sure you blow it out thoroughly, to remove any clinging to the orifice material.

 

[Johnwhatsisname]

I’ve now done all of them and was surprised to find that three were blocked. I guess there is a strong reason to drain the carbs if the bike is to stand for any length of time.
Another thing..and in don’t want to start a new thread for every issue. I have found that most of the screws are very difficult to remove. It’s seems like there is a build up in the threads between the mild steel screw and aluminum carb body. Almost an electrolytic reaction taking place. After lockdown I am going to replace the screws with stainless steel with an 8mm hex head
in the meantime can anyone recommend an anti-seize? It’s a real pain Undoing these screws. I am currently trying Castrol DWF.

 

[Fire-medic]

Permatex

Aren't you using a hand impact driver and a ball peen hammer? Go easy on the impact because too much force could crack a carb body. Make sure you have a well-fitting Philips style tip because these are JIS standard, a Phillips is not exactly what fits them but once they come out, as you said you can replace them with Allen head cap screws.

You are going to be very happy when you find out how well the bike runs once you sync the carbs after having cleaned the pilot Jets.

 

[[email protected]]

I always soak them overnight in solvent. Then they uually clean out easily.

Same here. Drop it in and leave it sit awhile. Cleans up much easier after a soak.

 

[Johnwhatsisname]

Permatex? I assume you mean the silicon based gasket maker? That sounds like a plan. I guess it seals the threads and stops the oxidation build up. I found some Permatex Copper in the cupboard so will try that. I wasn’t planning on repeatedly removing the carbs but judging by the number of posts here under “Carbs” I am making preparation.
I was worried about using an impact driver so opted for welding a lever to the offending screws. I know it sounds a bit agricultural but if you wrap up the carb in wet cloth it works really well. I have attached some pics.
I think it’s a combination of heat and added leverage.

 

[Johnwhatsisname]

Sorry, in answer to DesertMax. I didn’t have appropriate cleaner/solvent. What do you use?
I opted for the welding method as have done this before on an outboard motor where the oxidation is crazy and will make you the same

 

[Fire-medic]

Permatex also makes a product for anti-seize application. It's that, to-which I was referring. A little goes a long-way, and it's easy to get it over everything if you aren't careful. It's hard to-remove, should you be sloppy.

Actually, a hand impact driver without being 'hit' with a hammer, will often allow you some additional leverage, because of its 'fat' handle. Having a well-fitting screw insert is half the battle. If someone has already 'bodged' the X, I either use a Dremel cut-off disc to make the slot for a blade-type screwdriver or the impact driver, or I use a 10" Vise-Grip straight-jaw plier. I've never been defeated.

 

[desert_max]

Sorry, in answer to DesertMax. I didn’t have appropriate cleaner/solvent. What do you use?

Whatever's handy. Any volatile carburetor cleaner will work - or even brake cleaner. But, due to the volatility, it's necessary to seal the container or it'll evaporate away overnight.

 

[Johnwhatsisname]

Lockdown has its upside. It forces me to look through all the stuff. Look what I found..!

 

[desert_max]

Advantages indeed. I saw an article about about a severe condom shortage. Wonder why...

 

[Johnwhatsisname]

Using a 5 fingered nitrile glove just isn’t the same...
Anyway, I am glad to announce that the carbs are back in the bike.
I set the float levels using the dry method and a vernier, they’re fairly accurate.
I also setup the sync manually after I had placed the carbs on a flat surface and fixed their location relative to each other.
I used a bright light through the Venturi and got the butterflies reasonably accurate. This needs to be finalised with the proper tools.
Started the bike and immediately it sounds much better and firing on 4 cylinders instead of 2 as before.
I think tomorrow I will risk a ride to the shops. thanks for all the input guys.

 

[desert_max]

Great work. I would just offer that while the method you describe of shining a light through to estimate the butterflies’ bench synchronization is rough at best.

As you have observed, you’ll get close, but I have always been surprised at just how much more instrument guided fine-tuning was needed after the bench sync.

 

[Johnwhatsisname]

I had a really enjoyable ride this morning. What a difference!
I know the carbs still need to be sync’d. That Vboost is great. From about 7k rpm it just pulls. Almost brutal actually - Wonderful!
I’m sure there are other issues but at least I can ride it now and find out what they are.