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GS1100E and Mikuni 33 smoothies

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Sooo, how's everyone's winter going?? Cabin fever here in North East Ohio so I'm doing some leg work and research on things that need to be addressed on the 83 1100E before the weather breaks. Among those things are my inconsistent idle. I've heard a ton of stories on the idle of these 33 smoothies. Consensus seems to suggest that these are a nightmare to get the idle correct. To give a bit of a back story, I got the bike frOM the original owner, he had the original CV's replaced with the 33 smoothies, around 25 years ago. the bike sat from 2007 until 2016 untouched in a garage with a tank full of 10 yr old gas. I purchased it from that point and immediately drained it, ripped the carbs off (not really knowing what they were), cleaned them with seafoam spray and gunk carb cleaner, put them back together, bench sync'd and reinstalled them. The thing runs like a raped ape anywhere past 1/4 throttle. It will not hold a consistent idle though and it has serious hesitation when taking off from idle. It always wants to idle around 2000-2500. If I turn the idle screw just a smidge, it'll drop to 1000, then 500, then 250 then die. no matter what I do to try to correct the idle, it's either waaaaay to high or it wants to die. Anyone else have this issue with the 33 smoothies??? Any tips on tuning would be plenty helpful.
 
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Did you adjust the valves? Fading idle is a sign of tight valves

You dipped the carb bodies?

Replaced the O rings and jet block gaskets?
 
I did replace all of the gaskets and o-rings when I opened them up and cleaned them. I didn't check the valves, that actually sounds like the next thing that should be on my list. My cleaning process only consisted of spraying out all of the passages and brushing/blowing the gum out. I had to free up one of the slides so that particular carb did get a bit more attention but after all of that, I put it all together with new gaskets and o-rings and proceeded on with the bench syncing.
 
Also, would the valves being out of spec cause it to idle consistently high? Like I said in the first post, it automatically wants to idle high, it only starts to drop when I mess with the idle screw. Other than that, it's revving it's balls out at 2500 rpm at any given point after warming up.
 
No, valves too tight causes a dropping idle

You carbs probably aren't clean enough.
You need to dip/boil/ultrasonic clean the bodies (pick one)

High idle is most likely a air leak
 
they do have a sticking throttle due to the amount of air flow. Hence the dual cables and strong springs. I got a Mikuni 1979-1988 vm carb Guide, if u PM me ure email ill post it to ya. Just a few pages on 29,33's and a set up guide
 
I will probably be ripping them apart again pretty soon. I have a small oil leak that needs to be addressed and a snapped clutch cable that I'll be replacing in the next few weeks so I will knock it all out at the same time.

My initial thought was the pilot circuit was probably not functioning correctly, or the pilot air screws were out of spec/sync but with the lack of vacuum, the only real way to sync them up while running is by ear or if you tap vacuum ports into the boots (really wanted to avoid that).
 
Not going to be any specifics here, unfortunately, since I didn?t build or tune this bike (which I?m now reviving), but just a word of encouragement that my VM33 carbs were the best tuned I?ve ever used, and they idled fine. Huge top end but very controllable on the street, just like the brochure says.
When I get her running again (stator) if seafoam doesn?t do the job, I may be digging into the carbs and might have more info.
 
Do yourself a favor and get those valve clearances set to proper specs and THEN drop those carb bodies and internals into some carb dip for 24 hrs. After that, make sure you clean every little orifice with small wire. It sounds like some passages might be at least partially plugged. Good luck.

edit: I now see that my reply is 3 months after you posted this. Have there been any successes to report?
 
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alke46 said:
Do yourself a favor and get those valve clearances set to proper specs and THEN drop those carb bodies and internals into some carb dip for 24 hrs. After that, make sure you clean every little orifice with small wire. It sounds like some passages might be at least partially plugged. Good luck.

edit: I now see that my reply is 3 months after you posted this. Have there been any successes to report?
Click to expand...

Excellent advice for me, too, though - I just got my VM33 carbs apart, and two of them are great, and one of them is a bit gnarly and another suspect, and the throttle shaft is frozen up. Bike has been sitting for years, it was being loaned out before sitting so I don't know its terminal state, and I have no idea what the current state of the valve clearances are yet. Lots of things to check out before firing this back up. At least these VM carbs seem easy to work on.
 
Actually despite the old thread I'm curious to see if there was a resolution to this too! Just getting my Kat ready for the road with a set of VM33's on it and I've been having a similar issue, although it's been looking to me like they are setup too rich except for the pilots which were too lean.

My focus at the moment is simply to get a reasonable idle and up to probably 1/4 throttle somewhat sorted so I can get it on the road, then tune the rest from there. I've borrowed a mates' AFR gauge and sensor which of course makes things a hell of a lot simpler!

The carbs were very clean when I got them but I've verified all the passages are clear and all the gaskets were serviceable so I haven't replaced those at this point in time. I was planning on replacing them soon though, just saving the $$ for the on road costs first.
 
They have different Throttle Slides in them aswell. Kawa and suzi. The throttle Valve is 1.5 on one and 2.0 on the other. Pic below (green highlight).

Carb Info.jpg
 
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sharpy said:
They have different Throttle Slides in them aswell. Kawa and suzi. The throttle Valve is 1.5 on one and 2.0 on the other. Pic below (green highlight).
Click to expand...

The air jet size is significant too. 1.5 slide (rich) has a 1.2 air jet (lean) to match - and vice versa for the other version.
I have struck a case of used 33's where it became apparent the wrong combo had been installed.

On another thread about 33's some time back, Ray encouraged vacuum syncing of 33's. I'll endorse this heartily.
For a racebike, bench syncing of the slides is good enough. For a road bike, use a vacuum sync.
 
Since posting that I revisited the bench sync which I only gave a cursory glance to... it's far more important than I realised! My lack of a stable idle was due to them being way out of sync, fixed that and most of my idle woes are solved. I also discovered by the use of an AFR gauge that the 17.5 pilots weren't lean at all after the bench sync, so I've gone back to them.

The carbs have the 1.5 throttle valves which I already knew meant the carbs were likely set up for a Kwak (but thanks Sharpy!), but as best I can tell the impact there is initial cracking of the throttle from what I've read, and 2.0 valves are NLA now.

The carbs are set up as tested in the garage with 0 kms so far, this is just to get it registered when I can then tune on the road:

Pilots - 17.5
Air screws - 3/4 turn out
Needle - Middle position
Mains - 122.5
Air jets - 0.6
Throttle vavles - 1.5

The jet needle and needle jet are as outlined in the Sudco screen shot Sharpy posted.

I haven't vacuum sync'd them yet but going by the tuning guide (in addition to Ray's advice now I know it), they say sync the carbs manually but use a vacuum gauge to set the pilot air screw, typically the highest vacuum point is the correct air screw setting.

Another month or so and I can get some real kms done and know how the carbs truly are...
 
The slide number is simply the height of the cutaway. If you need a 2.0 slide a 1.5 can be converted by raising the height of the cutaway.
Conversely, to convert a 2.0 to a 1.5, material is machined off the flat bottom edge of the slide.

Done a lot of this over the years. Pre internet, carb bits were hard to find in NZ so you made stuff...
 
Yep cool Greg, while I understood that referred to the cutaway I didn't think about modifying them... hopefully something I don't need to consider as that's a daunting prospect for me!
 
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