1989 Kat 600 Help!

[doubledscar]

I had a previous posting and was a little unsure about everyone understood me correctly.

On my 1989 Kat the stock settings for the carbs use the #1 and #4 Carbs to have the main jets 137.5 and the #2 and #3 are 135. Why is that?

If those jets are differant should the pilot screw still be 2 turns out stock on all the carbs? Or since the jets are bigger on #1 and #4 Should those be set differantly?

Please Help! Thanks Again!

[katrider]

All I can tell you is my carbs have the same main jets in all four carbs and my pilots are all set the same (2 out, but I need to turn them in 1/4 turn...it hangs up when coming back down to idle when I 'blip' it...)

[doubledscar]

what kind of katana do you have year? size? cause according to the suzuki dealer the outter two are differant than the inner two. is there anyone else out there that can help? or has their opinion.

[The CyberPoet]

(A) yes, the turns should be the same for all of them according to the factory manual (2-3/8ths turns is recommended for the 98+ in the OEM config).

(B) The difference in sizes is for EPA pollution reasons -- the inner cylinders heat up further than the outers because of airflow across the engine at speed, resulting in slightly better atomization of the inner cylinders' fueling. To keep the engine balanced in power when running very lean (the way it ships originally), Suzuki opted to use one step-leaner jets on the center two cylinders in the USA. For most markets around the world, Suzuki uses the same sized jets all the way across, as do all the aftermarket jetkits I've seen.

Cheers
=-= The CyberPoet

[loudnlow7484]

Stock 600's have 135-137.5 mains in them?!?! Stock 750's have 102.5's right? I suppose I don't quite understand the jetting thing, cuz that doesn't seem right. I'd figure that a 750 would have bigger mains than a 600.

[md86]

Different size carbs , though . Probably has something to do with it ...

[Mojoe]

I didn't know much about carbs except the basic function of them, until recently. My V&H engine requires pretty massive carbs and will be finicky with the atmospheric pressure and all that crap, so I did a bit of studying.
Cyber is on the right point with (B) explanation, except for maybe the EPA being the reason. My bike is a Canadian model (more similar to European than US model), and I too have different jet sizes on the 2 inner carbs. It is my understanding that it is more of a performance issue than environmental issue. It boils down to air-flow and heat.

And md86 is correct.....smaller carbs, bigger jets. Smaller venturies require bigger jets to supply adequate fuel.

[wittymonkey]

for how the carb works check this :

http://auto.howstuffworks.com/framed.htm?parent=question377.htm&url=http://204.71.0.3/motoprof/moto/mcycle/carb101/carb101.html

It's a general motorcycle carb , it's only theory ... I think understanding something is usually very usefull if you are working on it.

G.

[The CyberPoet]

They may not be the stock jets... different companies use different jet numbering schemes...

Cheers
=-= The CyberPoet

[Mojoe]

I am 200% positive my jets have never been changed. The previous owner of my 92 owned it one summer then died...no mods. In gact, the carbs never came of the bike until last year.
Same with my 93.....never touched. And as dirty as the carbs were on that, I don't think they ever came off either. The manulal states the same two sizes as I have.

The 40mm carbs I just bought have 145's and 147's.

[doubledscar]

ya i took my carbs down to the dealer remember i hav an 89 kat. They said that the stock would be 137.5 outters and 135 on the inners. Weird i know. but now someone says 2 turns out is this correct. I k now someone said 2 5/8s but that was for the 98+ wha bout the 89!? Thanks