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Dynojet & mixture screws once again...

  • Thread starter Thread starter Pulukka
  • Start date Start date
P

Pulukka

Guest
I bought Dynojet stage 3 kit for my gsx 1100 (year 1980). I have individual filters, 4-1 exhaust and 1166 -wiseco kit installed on my bike.

I have already changed the needles and drilled the slide holes. The problem is those damn mixture screws on the engine side of the carbs. In the Dynojet installing instructions is stands that you should turn these screws open 2,5 turns from lightly seated. In my opinion they dont open more than 1,75 turns and after that they get stuck. I dont want to destroy the threads so what am I supposed to to now?

Furthermore, the previous owner has almost spoiled the screw heads so its quite difficult to turn those screws around. What to do;
Should I unscrew them as much as possible and leave them be or what? Please help!
 
If I remember correctly there are o-rings and springs under those screws. The o-rings are probably destroyed, especially if the carbs have ever been soaked in cleaning tanks.
 
Buy some PB Plaster penetrating oil and spray them in the holes and let it sit for a day. Work the screw back and forth with a good tight fitting screwdriver. DO NOT force the issue. If the screw stops coming out bring it back in and work it back out. If progress ends with this style spray some more PB and let it sit some more. If you get impatient and strip the heads good luck. I did this once and ended up replacing that carb on the rack. Get new o-rings here http://www.cycleorings.com/
If you haven't dipped your carbs in Berrymans or rebuilt your carbs check this out http://www.thegsresources.com/gs_carbrebuild.htm
Check out my bio. We have similar setups. How do you have your Dynojet set up?
 
chef1366 said:
Buy some PB Plaster penetrating oil and spray them in the holes and let it sit for a day. Work the screw back and forth with a good tight fitting screwdriver. DO NOT force the issue. If the screw stops coming out bring it back in and work it back out. If progress ends with this style spray some more PB and let it sit some more. If you get impatient and strip the heads good luck.

How do you have your Dynojet set up?
Click to expand...

I suppose these O -rings are the main issue removing those mixture screws... Thanks for the tips!

Maybe I should first reinstall those carbs back and do a test drive with those mixture screws fully opened (1.75 turns) and the think again how to proceed? I think those screws can be reached without removin those carbs again?

I just installed (1 hour ago) those DJ main jets (bigger 138s) and cleaned the carb float bowls; not much crap was found. I checked that the pilot jets are originals (45). Now I just have to manufacture a pilot jet plug because one the originals was almost melted. Tomorrow I have to go to a local "rubberstore" to find a temporary substitute for that. It takes at least 2 weeks to get those original suzuki parts here in eastern Finland and Summer is almost knockin on the damn door!

I think that I have to tune those carbs and after that buy a new set of float bowl gaskets and to remove those mixture screws and replace those supposedly destroyed o-rings... Is it possible to find those mixture screws themselves as a spare part? The heads of those are quite badly stripped by previous owner moron.

Earlier this day I installed the needles (circlip on third groove from the top and the DJ washer above it) and bored those slide holes with the included drill bit. No problems there, only one destroyed thread out of 16 :)

BTW Those DJ instuction really do suck. I?m really terrified to even think about that first start after all this hassle. I?m pretty sure my bike runs like ****.
 
Just got an email from http://www.motorcyclecarbs.com/ about the Mikuni mixture screws:

"They are set at the factory. Then they the threads that are exposed are
filled with a glue. This glue hardens and fills the threads so they can not
be removed"

Can this be true; how am I supposed the unscrew those mixture screws for 2,5 turns when those exposed threads are fille with glue? Has anyone heard of this? One of those screws opens only 1,25 rounds and the best one opens 2,25 rounds. Why there is so much difference between those screws?

What am I gonna do now.... help, please..?
 
When I rebuilt the carbs on my 1100, I had one stubborn mixture screw that was combletely stripped. Fortunately I was able to remove it with a screw extractor without having to drill. I decided to replace it, but was only able to source the part from a dealership. It was roughly $40 (US), and only came with the screw and spring (I believe there is also a flat washer and the O-ring). Fortunately a memeber here (Thanks again Jethro!) was able to supply me with the replacement for free.

As for what I used to remove the other, not-so-stripped screws, was a decent screwdriver that fit very snugly in the screw's slot.

Brad bt
 
My setup;
47.5 pilot jets
138 Dyno mains
Needle one notch up from bottom.
170 pilot air jets.
 
this is getting very interesting...

I was searching for help on this mixture screw issue and visited local, very experienced bike mechanic who had a set of used Dellorto/Malossi PHBE 34 BD (direct feed, dont know the actual english term) carbs taken straight from gsx 1100 efe. He said that I can lend them for a few days for that I can "try them on" instead of those "crappy" original mikunis with dynojet kit.

He also said that those carbs were installed on a 1,45 liter suzuki gsx (new ones) and worked perfectly; now they were useless because the owner installed a fuel injection kit on his bike. He said that when you have vacuum type carbs (gsx originals) its very hard to get all the mixture fully adjusted when using pod filters. That carb kit costs 200 euros (268 usd); ready to be plugged in. Thats quite cheap compared to finnish rates (95 octane fuel costs 1,34 euros =1.8 usd per liter).

That "guru" also mentioned those malossi carbs allow something like 5 times more air to be passed into the cylinder than original mikunis. Those carbs have only one slide per carb and thats it, no membranes or thousands of other moving parts (damn mixture screws!!!!!!!). I cant find much info of those carbs on internet; someone here in gsresources had a thread of 30 mm ones but thats about it. I think these are a bit of racing carbs which suits me fine; the faster the bike moves the better. Does anyone here have any experiences of those dellorto/malossi phbe 34 bd:s?

That guy also said that it was a mistake to drill those slide holes on my original carbs and that I should get all of those mixture screws opened and cleaned before reinstalling those back. I think its almost impossible to do that. Do I want to struggle with those stupid screws for three more days and have a risk destroying the whole set?

I got one mixture screw out of those mikunis and it took 4 hours. I had to use dremel to cut the carb body itself to gain access to the mixture screw threads and use vice grips to remove the screw itself. Not much was left of it. Damn it was stuck hard! Changing to dellortos/malossi carbs sounds tempting...

What would you do - any opinions?
 
I believe those mixture screws in the front are for idle only. So if you back them out 1.75 turns and the idle seems okay to you, you are done.
 
With his mods and the 45 pilot jet it won't be enough. Go up to a 47.5 and it might be.
 
Those dellortos/malossis sucked. The mixture was all wrong and the bike surged and sputtered. On full throttle they seemed to work quite fine and when I revved on neutral the bike seemed to scream like hell. Motor reacted on throttle bit faster than with mikunis but maybe its not worth the trouble hetting them correctly adjusted. It could be that those malossis are bit better when correctly tuned but I made a desicion to forget them and to concentrate on those mikunis. I returned them to the owner - I hope I wont regret this 8-[

After that I installed those good old mikunis back and the ride was definately better than before dynojet. On full throttle the bike is faster than hell and I can offer full throttle on fifth gear after 2000 rpm. Amazing feeling! The only glitch is that when I pull the throttle just a bit (for example driving steady 60-80 km/hour) or trying to maintain steady speed on 2000-3000 rpm:s the motor seems to surge and sputter (dont know the correct term, sorry). When I add just a little bit more throttle there is a horse kick in my a** and the bike accelerates perfectly. I cant say for sure that is there a lean spot but I have to get it corrected somehow...

Could it be that my needles are a notch or two too low. Other thing I thought was that I have to get one notch bigger pilot jets as chef1366 said (47,5).

what do you gurus think?
 
chef1366 said:
My setup;
47.5 pilot jets
138 Dyno mains
Needle one notch up from bottom.
170 pilot air jets.
Click to expand...

"Needle one notch up from bottom"; does that mean that the needle is at the second lowest position it can get or the circlip is on second lowest notch so that the needle is at the second highest position it can get? :oops:

I mean: higher = moving the needle upper & getting richer mixture; At least thats what I?m gonna try next, now the needle circlip on my bike is at the third groove from top and I think I?ll try to move them to the fifth groove from the top (then there is only one notch left and it is set at "needle one notch from the bottom", am I right)?
 
Pulukka said:
"Needle one notch up from bottom"; does that mean that the needle is at the second lowest position it can get or the circlip is on second lowest notch so that the needle is at the second highest position it can get? :oops:

I mean: higher = moving the needle upper & getting richer mixture; At least thats what I?m gonna try next, now the needle circlip on my bike is at the third groove from top and I think I?ll try to move them to the fifth groove from the top (then there is only one notch left and it is set at "needle one notch from the bottom", am I right)?
Click to expand...
That's right...........
 
chef1366 said:
That's right...........
Click to expand...

Great; I?ll have try that this weekend!

BTW, does anyone have a recommedation from where to get those 47.5 size pilot jets easily to Finland (prefarably from Europe with paypal)? Local Suzuki dealer didn?t have a clue of any Pilot jets and they will try to find out are those available as originals from suzuki. So I suppose it?s gonna take 189 weeks to get an asnswer from them... Screw them...

Is there an othor manufacturer who makes those jets intstead of Suzuki/Mikuni? Can someone tell a part number for 47.5 size pilot jets for those cv mikunis or at least what type of pilot jets those are? I just have a 45 sized jet in my hands so it?s quite difficult to try to ask for a new bigger one via internet with it...
 
Chef has you pointed in the right direction regarding jet needle and pilot jet adjustments.
All re-jetted 1100's I've been involved with had the DJ jet needles set at either the 4th or 5th position from the top...the majority at the 5th position. Test at 1/3 throttle position and get plug reads.
Drilling out the vacuum orifice to the diaphragm/piston chamber improves throttle response and is generally needed when re-jetting for your mods.
As for the stuck mixture screws, it sounds like removing them is going to cause further problems. If the o-rings inside were subject to carb cleaners, they are probably hardened/damaged and adjusting attempts may be useless. However, you can always try adjusting and see what happens.
The CV carb mixture screws should be adjusted using the highest rpm method, not by following a pre-supposed jet kit suggestion. If you're lucky, the adjustment range your semi-stuck screws are capable of may be enough to allow you to set them by the highest rpm method. With the larger 47.5 pilot jets recommended, you may find that somewhere around 1 1/2 turns out will work? Worth a try. If not, then you'll have to repair the screw adjustment problem to expect the pilot circuit to operate correctly.
Be sure the carbs are vacuum synched before getting plug/performance reads.
 
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