1100M Carbs

[Gixerjonah]

Is it generally accepted that 38mm Mikunis are a better option than the standard 40s on the 1100M ? Im having a right mare with mine and thinking of changing em.

[Oilyspanner]

If the 40s are in good condition, they're a decent carb, if a bit harder to fine tune, but work well. Are your needle jets okay ? they have a tendency to 'oval' if you look down through them (all BST carbs) and the engine will run like sh-te. Oddly the M/Ns had a reputation for not liking the earlier K/L silencers and worked better with the 41C0 ones - just an example that perhaps the 40s are more easily upset. 

Mine work really well and I wouldn't swap them - smooth torque from tick-over and pulling strongly from 3000. They work very well with big bores.

[Gixerjonah]

Thanks oilyspanner. Think im going to stick with em & have em cleaned & refurbed. Ive been saving & working overtime for ages & am now about to have a Racefit legend made & fitted, do you think dyno time will be needed after for changes ?

[Oilyspanner]

I bought a FactoryPro jetting kit which was very good and I dialled the settings in via FP's excellent 'how to'  method

http://www.factorypro.com/tech/tech_tuning_procedures/tuning_carbtune,CV,lower_rpm_engines.html

The carbs feel so good I haven't bothered to run it on Dyno, all circuits seem to work well.

[jonny1bump]

With the 40s tiny mods to the rubber on K and N filter really makes quite bit difference. Use stock needles and emulsion tube at all cost, can fine tune slide springs. With exhaust change definitely will need dyno time.

They are immensly fiddly carb but when right are superb. DO NOT remove airbox.

The 40s for me was good for 160 hp only after this figure I changed to FCRs

[Oilyspanner]

Nice input J1B, I think the 40s are airbox sensitive. I've kept my airbox and fitted a Pipercross filter (big, free flowing filter), which flows so well I had to fit the stage 3 carb kit - works really well. Maybe if you're going to use pods 40s wouldn't be as good as smaller 38/36s .

There was a thread on here recently about 1100/750 frame differences (there isn't much on Slingshots) - I was waiting for you to say that you got on well enough with the 1100 frame on track !

Have just spotted you did see the 750/1100 frame post . . . .

Edited July 25, 2016 by Oilyspanner

[jonny1bump]

I did smile when read the post.

Stage 3 kit are needle design better then dynajet kit as they just oval the emusion tube in months design is so bad especially with the lip.

I found K and N filter just with 1mm ground out rubber, stock jets and emulsion tubes, slightly lighter slide springs, 1 degree advance with engine mods and only 1186 got me to magic 160 and was completly linear not flat spots and so user friendly.

Fcrs take some getting used to but are great.

Did you see my thread did years ago on spacers I made to told needles square to get away from plastic needle holders, that hold them at angle with premotes even more wear.

Wonder if its in volts.

Streetfighter guy I think took my design and was punting them out to sell.

[jonny1bump]

Piper cross filter that is interesting few people I know really put me off using them when I was looking for flat panel filter for the big carbon airbox I made.

[Oilyspanner]

I didn't know it was your design I used for the needle spacers John - found the drawing of the spacer on some search I did, it works really well ! The standard spacer does hold the jet needle at an angle as you say, hence the uneven wear.

I had a K n N in the airbox when I got my bike, it seemed okay, but the inlet aperture had been mucked around with, so I bought the big Pipercross filter - 3 inch inlet and a  physically big filter, loads of surface area. I had enriched the carbs for the K n N and full system, but the bike was very lean after fitting the PiperX, the std needle size was too far off (even with extraspacers and clips on the bottom notch), so I bought the FactoryPro config3 kit - it made a big difference.

[jonny1bump]

Interesting.

Yes got so fed up with replacing needles and tubes I thought re-design was in order when I came up with this idea and place it in tech / info section on old site. It was so simple I could not believe had being done before, especially as every set of carbs I pulled apart every plastic spacer had worn differently.

[jonny1bump]

Here is dimensions for spacers if anyone wants to make themselves a set.

Edited July 31, 2016 by jonny1bump