Bst38 carb confusion

[Damienga15de]

So iv gone about putting in my factory pro kit in my bst38 from the 750

Carbs measure 38mm

Jets all as per Haynes manual 

Needle is a 6DZ14 it should be a 6ZD7-3 according to the Haynes 

The needles in the kit are much shorter and thinner 

 

Has anyone any ideas? Maybe someone has been butchering before me? 

 

[Damienga15de]

Bst40ss come with a 6ZD13-3 closest I can find 

[wraith]

Oil cooled or maybe water cooled carbs both fit

[Damienga15de]

Oil cooled, came off a 750M

 

[Damienga15de]

Measurements are poor the digital calipers got wet 

 

[Dezza]

44 minutes ago, wraith said:

Oil cooled or maybe water cooled carbs both fit

WC 750 carbs do not fit an oilcooled engine, at least without inlet rubber modification, as the spacing is different. WC 750 carbs have different float bowls to the oilcooled 750 38mm carbs, which have large access plugs to enable the main jets to be changed without removing the float bowls like RS carbs. The WC 38mm carbs do not have the large access plugs.

[Gixer1460]

I'm guessing the top one is stock 38 and lower is the Factory Pro kit needle?

Query - does the Short needle fit the slide and does it stay in the emulsion tube at full lift? If it does then it may be how Factory Pro engineered the fuel flow ie. onto the Main much earlier? Ifit comes out of the tube completely @ full lift i'd not be inclined to use it as it could jam open at WOT - not good! It could actually be a 36mm needle?

[Damienga15de]

It's loose in the slide I'm not doing much more until factory pro reply it's 2.5mm diameter standards 3mm 

[wraith]

20 hours ago, Dezza said:

WC 750 carbs do not fit an oilcooled engine, at least without inlet rubber modification, as the spacing is different. WC 750 carbs have different float bowls to the oilcooled 750 38mm carbs, which have large access plugs to enable the main jets to be changed without removing the float bowls like RS carbs. The WC 38mm carbs do not have the large access plugs.

I've got wc 750 38mm carbs on my gsx1100f motor with oil cooled 750 38mm  carb rubbers snug but fit with no problems 

[Blue]

I’ve got the same with factorypro kit 

[Damienga15de]

9 minutes ago, Blue said:

I’ve got the same with factorypro kit 

Did you use the needles? Iv sent a mail asking them, they appear to be 5 series needles not 6 series 

 

[Damienga15de]

The needle jets are standard 631 0-8 

 

I wonder is the 6zd14 needle a superceded part number I can't find any reference to them anywhere 

 

 

[Blue]

I ended up using 0985h-64t2-ss needles, they’re all 56mm long. 

[Damienga15de]

4 minutes ago, Blue said:

I ended up using 0985h-64t2-ss needles, they’re all 56mm long. 

The length might not be an issue but I wouldn't be happy with the slop in the retaining clip/washer have you modified anything to suit the 2.55mm diameter 

[Blue]

I used these 

[richyrich]

I don't think the one you took out is standard , it's very cylindrical and not tapered .  I took out what I think was a dynojet kit and put back to stock , needed a new emulsion tube to work with the stock needle 

[Damienga15de]

It's definitely a mikuni has a part number and the squares symbol, part numbers almost the same as a 1127 40mm carb needle. 

[Blue]

91 on 1100 40mm has 6zd13-3 

Edited May 12, 2019 by Blue