Yes, those are the soft springs....remember, they were designed to be used with the proprietary sized Dynojet needles and jets....

Caution:  IIRC the Dynojet instructions calls out for you to drill out the holes in your slides, DO NOT do this...

You already have the springs, so go ahead and try them, why not?
 You can easily change them back...(like the air bleeds)

However, Stay with the tried and true oem Mikuni needles and jets.

You are in the fine tuning stage on your carbs, try different things, it's part of the rite of passage to the kookaloo zone.

IIRC you have a stock engine (bore, cams, timing) with RPM UniPods and a stock exhaust with slip ons, correct?
If so, remember that your engine is flowing only slightly more air than stock, and not by much.
The real improvement in volumetric air flow efficiency happens when you install an aftermarket 4-1 or 4-2-1 header.
Look at the Stage 1 Dyno jet instructions....Stage 3 is not what you should use.

Have fun

Pat, so interesting.... many months back when I started my FJ journey I didn't know exactly what I would need and came across this jetkit on ebay so I purchased it but haven't used it. Are these the softer springs you mention?

I could easily swap out the springs with the carbs on the bike if these springs are worth considering.

Quote from: 86FJNJ on June 21, 2025, 03:36:43 PMIs it possible I'm not getting enough fuel at peak throttle/rpm?

Could be.... Then again, with the big mains and shimmed needles you could be getting a rich slug of fuel causing the bog.

Air bleeds are easy to get to for changing....

A bit of history: Dynojet kits for our FJ's popular in the '80's and '90's used proprietary sized jets and needles (non Mikuni) in addition the kits included a softer spring for the slides. These soft springs enhanced throttle response by allowing the slides to raise up quicker in the carbs and counteracting a mid range bog our bikes often had when rejetted with fatter jets.

Cheers

Is it possible I'm not getting enough fuel at peak throttle/rpm?

Ok chat gpt says air bleed mainly effects mid range and top end, I'll try it out but I feel like the mid range is perfect with the needles shimmed so my guess is it would lean mid range out too much

I'll try it. Is there a chance that leans out the pilot circuit? I'm already 3 turns out on fuel mixture with the 40.0 pilots

Go to 160 air bleeds...see if that makes the bog go away.

Looking for some help to fine tune my carbs.

1986 FJ1200 1TX
Unipod filters
Stock headers and collector
Cobra F1r mufflers (straight through)

40.0 pilots
155 Air Bleed
Needles shimmed

I was running 115 main jets for a couple hundred miles and have just switched to 117.5 mains. Feels like it has more power now 5k-6500rpm when doing a quick twist of throttle, bike jump a bit more. But when going WOT from 5k rpm in 4th and 5th there is a slight lag of about a second and then all of a sudden the power kicks in and bikes gets power.


Is this lag indicative of main jets being too small or too large?

Quote from: Pat Conlon on June 20, 2025, 07:36:31 PM

Quote from: FJ1200W on June 20, 2025, 01:41:11 PM

Quote from: Pat Conlon on June 09, 2022, 08:33:15 AMI am impressed with the Avon 3D radials, especially the oem sized 150/80-16 back tire, even to a point of thinking that why go to the trouble of converting the rear rim over to a 17" size, when this 16" Avon handles and wears so well?

Then I'm reminded of the vast 17" selection options and if Avon ever discontinues the 150/80-16 size, you're screwed.

Still...I'm very happy with that 150/80-16 Avon radial on my '89.

"if Avon ever discontinues the 150/80-16 size, you're screwed."

And here we sit LOL!

Alas...Unfortunately yes, that Avon was a good tire but I saw the writing on the wall......so I converted my '89 over to the 17" YZF600 back rim last year.
The 170/60-17 Michelin Road 6 is also a very good rear tire.

I'm going to have to get to work on researching that conversion, yet, still holding back hope decent tires in our now quirky size will return.....

I need to mount up these Shinko's and give them a fair shake.

7000 miles is what I was able to get out of the 3D's, and that might be a record for me.

1 & 2 are synced together, call them left bank (as you sit on the bike)
3 & 4 are synced together, call them right bank

Then via middle screw, Left bank is synced with Right bank.