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Message started by marekbuk on 10/03/15 at 11:22:27

Title: Pilot jet type
Post by marekbuk on 10/03/15 at 11:22:27

I have a non bleed pilot jet in my UK S40 - these are harder to find over here but bleed types with the holes down the body of the jet are easy to source and plentiful. Are the 2 types interchangeable? ie. Can I replace mine with a bleed type?

Title: Re: Pilot jet type
Post by DesertRat on 10/03/15 at 11:24:37

I'm fairly certain the answer is YES, but the guru's will be on this post soon enough. In the mean time, check out this recent post on jets:

http://suzukisavage.com/cgi-bin/YaBB.pl?num=1443715080

Title: Re: Pilot jet type
Post by verslagen1 on 10/03/15 at 12:02:29

I believe the answer is yes, but there's a number of accounts that the bleed type are richer.

Title: Re: Pilot jet type
Post by Dave on 10/03/15 at 17:56:47

The bleed type don't do anything different than the non-bleed types in our CV carb. On the roundslide carbs the bleed holes allow air to enter the side of the pilot jets, and the air mixes with the fuel flowing up the pilot jet. The roundslide carb has an "air screw" to adjust the mixture....while ours is a fuel screw.

You can use the bleed or non-bleed types in our carbs interchangeably, as there is no air passage built into the carb where the bleed holes can access any air.

I can supply diagrams that show the difference when I am in the office if you are interested in knowing more and seeing how they operate differently.

Title: Re: Pilot jet type
Post by marekbuk on 10/04/15 at 01:10:03

Dave

Yes please I'd like to see the diagrams.

Good news that either type will work in our carbs - cheaper and easier to source for me

Cheers

Mark

Title: Re: Pilot jet type
Post by Dave on 10/04/15 at 04:26:01

I was able to search and find the diagrams online.

Here is the CV carb. You can see in the diagram that the Pilot Jet is in a hole with nothing allowing air or fuel to get to the sides of the jet. The only flow is for the fuel to flow upward through from the float bowl - the top of the pilot jet is seated against the carb body and the bottom is sealed with the threaded portion. The fuel then mixes with air in the passages drilled into the carb body, air is coming from an air passage around the needle jet (main jet) and the air comes through the main air jet at the inlet to the carb body.
(Since the pilot jet is in a blind hole....the bleed holes don't do anything).

http://i60.tinypic.com/en721.jpg

In the Mikuni round slide carb, the idle mixture is adjusted by an air screw. The pilot jet has an air chamber on the side of the pilot jet, and when you adjust the air screw it controls how much air enters the side of the pilot jet and mixes with the fuel coming up from the float bowl. The size of the pilot jet can be changed....and to make it even more confusing some of the pilot jets have different combinations of holes in the side of the pilot jets. The diagram is a little confusing - but follow that air path from the air screw down below the diagram and below the carb....it then goes over to the right and then into the left side of the carb at the pilot jet......and that is where the air is entering the side of the pilot jet - it has an air chamber around the side of the pilot jet.

http://i57.tinypic.com/2a9sjva.jpg

And....here is a diagram that shows how the Throttle Enrichment Valve works. You can see that the fuel is provided through the pilot jet circuit, and this explains why changing the pilot jet can affect the pops and bangs during deceleration when the TEV valve functions.

http://i57.tinypic.com/fv8dbr.jpg

Title: Re: Pilot jet type
Post by marekbuk on 10/04/15 at 12:40:10

Great stuff! - I can see that there will be no difference with either jet

Interesting read too

thanks Dave

BTW just returned from a 40 mile trip around our local lanes - sun was shining, bike felt and sounded great with the Dyna silencer - what a load of fun these bikes are :)

Title: Re: Pilot jet type
Post by Kris01 on 10/04/15 at 12:51:17

Have you rejetted yet? It's a totally different engine with the right jets installed (and tuned properly)!

Title: Re: Pilot jet type
Post by marekbuk on 10/05/15 at 00:22:37

I'm waiting for a 55 pilot jet. To get best idle I had to turn out the mixture screw 3.5 turns so I ordered one size up on the pilot after reading on the forum. The backfiring at 3 turns out was constant after every rev of the throttle then only another 0.5 turn out and Bingo! - no backfires ( only occasionally now -when hot also I have done the half white spacer mod.

I'm hoping that the larger pilot jet will further reduce the backfiring as the TEV draws extra fuel through this jet on throttle off! - Thanks Dave for the diagrams and explanation :)

The bike seems to have plenty of grunt at 0.5 to full throttle so I guess the main jet is fine as is. (its a 145)

we have different jetting in the UK due, I'm told, to the different grading in our fuel

Title: Re: Pilot jet type
Post by marekbuk on 10/05/15 at 01:41:43

Paul who lives in London has a '94 bike with a factory fitted 130 main and 47.5 pilot

mine is an '05 with a factory fitted 145 main and 52.5 pilot

Anyone any idea why there should be such a difference?

Title: Re: Pilot jet type
Post by gointomexico on 06/07/16 at 20:19:35

Im not so familiar with the uk, are you at higher altitude than your friend? also, is our climate drier? I cant imagine that anyone in the uk is any drier than the other.
Perhaps your buddy likes the backfiring of his ls650?

Title: Re: Pilot jet type
Post by marekbuk on 06/09/16 at 11:21:58

The UK can be very wet and we both live at low altitude. I've learnt to live with the backfiring and quite like it when the bike is very hot and when I switch off the ignition there is a second or so before the bike gives a resounding Pop! :)