GSX1100 Jet needles

[Reinhoud]

I've got carburetors from a GSX1100 on my GS1000, the needles are a bit rich, the number on the Needle is 5D59. the D doesn't look like a D, more a G in mirror..

I've got a set of GSX750 carburfuckingettors laying around, the needles from this set have the number 5C32 stamped in them.

 

I found some needle size charts on the web, but no numbers what match with the needles I have.

 

Anyone here who knows what number I should look for? I need a bit leaner needles.

 

Thanks

[Arttu]

Can't help with numbers or needle charts. But can't you just measure both needles and compare them to see what kind change the alternative one would give?

[Reinhoud]

I could, but I don't have a clue how much difference in size makes a difference in AFR.

 

 

[Gixer1460]

2 hours ago, Reinhoud said:

I could, but I don't have a clue how much difference in size makes a difference in AFR.

A needle chart won't give that sort of info as AFR is very engine dependent! It can't really say if it is leaner or richer so you are back to square one!

At least with a micrometer, you could compare needles one to another and make a judgement call or do it the old school way - start lean and stone away material till the mixture is where you want it - yes, it very labour intensive, that why tuning costs loads! And as to how much, you are measuring in the 0.025mm / 0.001" range or less, so not a lot can make a difference!

[Arttu]

5 hours ago, Reinhoud said:

I could, but I don't have a clue how much difference in size makes a difference in AFR.

As above, I think you won't find that info anywhere... By measuring them you will at least know if the change would be in the right direction or not.

[Reinhoud]

Hmmm, not as easy as I hoped for..

With the RS carburetors you just looked on a list and ordered what you need, thought this would be about the same.

[Gixer1460]

51 minutes ago, Reinhoud said:

Hmmm, not as easy as I hoped for..

With the RS carburetors you just looked on a list and ordered what you need, thought this would be about the same.

With RS carbs its different - they are meant to be swapped around for tuning - with regular carbs the OEM has done the tuning - hours/days/months in varying conditions to get the best result for that particular application . . . . they don't want you messing with them!

[Reinhoud]

9 hours ago, Gixer1460 said:

With RS carbs its different - they are meant to be swapped around for tuning - with regular carbs the OEM has done the tuning - hours/days/months in varying conditions to get the best result for that particular application . . . . they don't want you messing with them!

That's true..

[Arttu]

I'm not an expert on carb tuning but I recall that usually you can't find OEM stock needles from any public needle charts. Apparently they are custom made for manufacturers. So this means that comparing the stock needles to aftemarket ones can be slightly challenging...

Maybe you can try to measure the ones that you have now and find the closest match from published charts. After that you can use the charts to find suitable tuning options.

[Gixer1460]

Or just use Dynojet or JetPro needles and jets . . . . . . . . they exist for this very reason.

[baldrick]

speak to Allens, they might know what jets you have they have an encyclopedic knowledge

 

[Reinhoud]

The turbo stuffed up, I'm bidding on another one, slightly bigger, when the bike is on the road again I'll have a look how the carb tune is.

In the past with another turbo I didn't had the problem with a rich mixture in the middle throttle running.

 

Thanks for the tips.