carb question

[johnr]

this is my first tech question in the oilcooled world, so here goes.
i remember from the old place a thread about the little inserts for the flatslide cv carbs that went on top of the slide needle to stop it from rocking about in the slide and prematurely wearing the needle and thee emulsion tubes. ive tried searching using different terms but ive not managed to find anything relating to it. has anyone got any info on who made them? im going to fit a set of 36mm carbs to the gsxr motor in the kat i just got and thought id strip them first and see if theeyre worn, if so, i will order new ones, but reccon that fitting the little spacer/bush on top of the needle might prolong the life of the parts. any ideas?

[clivegto]

@Wescooley19 Simon Francies on face book was making some sort of kit for that if I remember rightly.

[johnr]

cheers clive, ive messaged him.

[jameskat]

[MeanBean49]

You just need to dremmel little half moon bits on the standard plastic doughnuts. Or if your careful dremel out the raised bits at the bottom of the slides

[johnr]

ok, ive just got the carbs that im going to use out of the shed and decided to give them a clean in the ultrasonic bath before rebuilding them. theres a bit of crud in there so theyre probably due a clean. now i bought these carbs for the kat with its aircooled motor and im planning to fit them to the oilcooled motor thats in there. as theyre apart and have been dry for a while, im not taking chances with the o rings and seals and plan to fit a new set. but before i order a set, can anyone give me a positive identification on them, this is the marking etched on the end body which im assuming is the identifying mark?? afaik theyre 38mm off a gsxr750.

anyone identify which model they are off so i can order the correct refurb kit for them?

Edited December 31, 2017 by johnr

[Captain Chaos]

Yes they look like 38's from a 750 L/M.

And according to my 750L supplementary manual, 17D80 is for E-02, 15, 21, 25, 34, 53 markets. Which is UK, Finland, Belgium, NL, Italy and Spain by the way.

[johnr]

cool, cheers mate. i kinda figured that, but never knew it for sure, so youve confirmed it, and i can order a refurb kit for em.  now to figure if its worth reinstating the blanked off power jet circuit or leave em like they are.

never realised it was a 17d80, the 1 is pretty invisible. so ta!

 

[Captain Chaos]

You're welcome

leave the power jet alone, it's a complete headfuck to adjust properly, and with a small change in circumstances (cooler/warmer weather for example) they are off again. It is basically designed as a half size main jet, if for example 130 is too small and 132,5 too big, the PJ circuit can compensate for that.

At least that's how I understood the explanation from the Suzuki tech dude at Nimag long ago.

[Captain Chaos]

 

Power Jet Circuit, GSXR750, as installed on air cooled gsxr750 w/ 38mm Mikuni carbs, 90-92

Power jet carbs – Mikuni’s great addition to a carb used in a high rpm application.

The power jet adjusts high rpm mixture, in the gsxr750 – from 10 to redline, in 1/3rd the step of a main jet change. Changing a main jet, in the 38mm carb, as installed on the gsxr750, adds or subtracts up to 2% CO per main jet change – when the CO% needs to be adjusted in in .2%-.4% for best power attainment.
Changing the power jet allowed much finer increments of change and, just as critically, happened to change the fuel delivery curve to what was optimum for the gsxr750 – something that would have required main air jet changes and other modifications to attain, but would still leave the main jet fuel delivery steps too coarse.

http://oldskoolsuzuki.info/archives/category/tuning/carburetor

 

[johnr]

yeah, i read that the other day, didnt realise it was about the carbs ive got.

 

[Blue]

As my 38’s are on my 1127 I’ve fitted a specific kit from factorypro 

[johnr]

mine were jetted and setup for a 1127 when i got them, on spec i fitted them to my aircooled kat 1170 and whether by fluke, good luck or planning, they were pretty much perfect in every single part of the rev range, best fuelled engine i ever rode, it just worked with no steps, holes flat spots or roughness from idle to the redline. theyve lain in a cupboard in the shed since probably 2008!

[Madb]

 the power jet circuit only works with the air box on, according to factory pro. they have a good write up about it.