SU Carbs

twiss · Post by **twiss** » Mon Jan 19, 2015 12:17 pm

Is that your wallpaper then Anton haha

Anton · Post by **Anton** » Mon Jan 19, 2015 2:18 pm

No, but perhaps it should be!

ianedwards · Post by **ianedwards** » Fri Apr 10, 2015 7:34 pm

Evening,

I've been playing around with the Kja tonight, and was convinced it's not running right, so I thought I'd check the su carb out,

Turns out it's not set up for a 1.6 after all, like I was told.

Inside was Red spring and BDL needle - setup for a 1.3

I've got a spare so I've stripped that and found a yellow spring and a BDL needle.

So I need to get a needle,

My question is do I get a BFM or try a BBZ needle, or get both and see which is better ??

Any advice?

Cheers

twiss · Post by **twiss** » Sat Apr 11, 2015 10:19 am

Basically with changing to the 1.6 the spring will make a lot more difference than the needle.
This bigger engine is sucking in more air to fill the cylinders, and as a result it will pull the piston and the needle up more making it a lot richer than it should be.
Regarding the needle, nearly all of the commonly used needles such as the ones you have mentioned are pretty similar in profile.... they could be considered more fine tuning and an engine should run relatively well even if it was fitted with a BCZ (leanest) when it should have a BBZ (richest)

Personally I think a BDL needle is the best place to start from as it is slap bang in the middle of the common needle choices...

ianedwards · Post by **ianedwards** » Sat Apr 11, 2015 11:59 am

ok cheers for that twiss, the needles make sence looking at it like that on a graph.

yea it smelt really rich while it was running, ive got a BDL so ill stick that back in for now and see how it goes, once i get her on the road, might just have to experiment if i have any issues.

djc · Post by **djc** » Sun Apr 12, 2015 7:18 am

my SU update. As a reminder it's a Rockwatt mani conversion and a rebuilt hif44 with red spring and BDL needle. Almost straight away got it running really nicely and choke working well too. But come MOT day, emissions way over limit - so a lot rich then. I leaned it a lot and it got through - max emission 3.5g, mine was reading 1.15

But it was nasty, no power, and ropey cold running.
The thing about mixture setting I found - from max rich to max lean is about 7 turns (on mine anyway). I saw somewhere here go to max rich then out 2.5 turns. On mine this is way too rich. Burlen (SU Carbs site) goes the other way. Get the jet to max lean (where it is flush with the bridge) then go 2.5 to 3 turns towards rich. This gives a very different setting. I have found this is right - good balance of nice running and reasonably clean. So all I have to do is remember to lean it about 3/4 turn next MOT.
Absolutely ace conversion though, best thing I have done to my SJ so far (not done a lot mind). Next need to fit the refurbed T-box (ex Richard) then look at springs (Llama maybe, would like YJs but too big a job I'm thinking).

ianedwards · Post by **ianedwards** » Mon Apr 13, 2015 10:58 am

just to clarify , just to be sure

rich = screw in
lean = screw out

Post by **dan_2k_uk** » Mon Apr 13, 2015 1:21 pm

ianedwards · Post by **ianedwards** » Mon Apr 13, 2015 1:54 pm

was just making sure lol,

mines running a lot better now with a yellow spring and bdl needle, it was also missing a gasket, that might not have helped.

jodan-sj410 · Post by **jodan-sj410** » Tue May 12, 2015 8:24 pm

I cant figure out what carb mine is and how to set it up. Any insight? Cheers in advance..

Suzuki Club UK

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