81 GS650 tuning help Dynojet stage 3

[Gsnoob]

Well thank you trip for a better understanding of CV carbs that explains a bit about how if im in like 1st 2nd and open up the throttle to quick why she lags for a breif sec then goes.

I think at this point my W.O.T is where my problem is like i said if i dont hit the throttle hard I can get up to 55mph and youd never tell anything was wrong its if i open it up past half to 3/4 that im getting stumble and falling flat if I hit WOT she bogs and its not feeling like the Vacum bog i can hold it and doesnt not clear and blackens the plugs.

If im understanding correct my Clip on needle has more to do with my mid then WOT I did not knwo that I thought it regulated how much fuel is put in at WOT, so I think at this point im going to go home tongiht and drop the 160mains and install the smaller 155s and see what she does cause lastnight like i say my low end and midrange felt pretty good could tell mid wasnt perfect but like you say ill perfect that after i can achive a good WOT.

Also to koolaid kid yes its the second transition to WOT that we are tlakign about.

Thanks again for all the help and if my ideas on what i need to do like switching to 155s to try and fix this pls feel free to let me know if im misunderstanding something

when you say hitting it hard do you mean very quickly opening the throttle over half way immediately? Any CV carb will fall on it's face until vacuum catches up and draws more fuel in..

these type of carbs do not have accellerator pumps so don't crank them open and think there is a problem.. I call it stabbing into the throttle.

the little washers are half steps between the needle notches -- very super fine adjustments... you are not there yet. if you don't need them leave them OUT.

ok you understand to get the idle perfect 1st.. second step is to get W.O.T.(main jet circuit) to make power but not foul the plugs.. then finally start disecting the midrange needle settings.

to get the main jet circuit correct you have to get in high gear over 6K RPM and over 3/4 open throttle ~( W-ide O -pen T- hrottle)\\

you want a main jet that pulls HARD to redline with out blackening / sooting up the plugs... this is when you should have a couple of clean plugs for a visual .choose a cylinder and guess at the other 3.
I do the testing by pulling the choke/enrichener while going down the highway.. you are looking for the choke/enrichener to kill the power not make more. W.O.T. plug chopping is not necessary for average riding - when you get a plug color lighter than greasy/sooty BLACK you are getting close and can do the micro adjustments with your washers and needle position. I love how smooth well tuned CV carbs transition from idle to midrange and gear shifting is easier - MPG goes up and the world becomes a better place

you are not going to permantly damage anything with overly rich -- lean has to go into lean misfire to do damage. lean misfire is a horrible popping cracking jumping event. shown by White Blistered plugs- and an engine that just wont go or stop with predictable pattern.

 

[koolaid_kid]

You should not have a stumble; that was the whole point of going to CV carbs. As trippivot said, you have to tune each section individually. First, you get it running fairly well. You seem to be there already. Then you tune the main; the plug chop method is crude but works after a fashion. Then the needle, which is where you spend most of your riding time. Finally the pilot jet, which can be painful but beneficial.
I just finished tuning my GPz and it has no stumble anywhere. And I would know, the stumble was the reason I sold my 78 GS750E.

 

[UncleBen]

gsnoob, if the DJ155 jets end up working and you aren't going to use the DJ160's, let me know! I am about to order a set myself and I would take them off your hands.

 

[Gsnoob]

Maybe im missusing the word stumble when im saying stumble what im talking about is the bike bogs like hell and sputters with a terrible power loss soon as i back off clears up and it only seems happens when i open up the throttle in a higher gear if this is not whatsconsidered a stumble I do apologize

You should not have a stumble; that was the whole point of going to CV carbs. As trippivot said, you have to tune each section individually. First, you get it running fairly well. You seem to be there already. Then you tune the main; the plug chop method is crude but works after a fashion. Then the needle, which is where you spend most of your riding time. Finally the pilot jet, which can be painful but beneficial.
I just finished tuning my GPz and it has no stumble anywhere. And I would know, the stumble was the reason I sold my 78 GS750E.

 

[Gsnoob]

Update on my situation pulled carbs back out saterday night installed the 155s, put everythign back together didnt have time to tune the idle, so yesterday I spent some time tuning the idle idk what had happend but I had a serious issue when I first started it the left carb started pushing fuel out the airbox and the left side pistion was not getting hot I checked spark and was fine but was visually gasy so I let it sit for awhile whith that plug out screwed in the mixture screw in to about 1/2 turn and started my idle tune again with it from there idk if it was flooding that cyl or what but suddenly after dropping the screw down to abotu half turn and adjusting out from there that cyl seemed to wake up and be firing correct again and got up to temp the screws are further out now then 1/2 turn of course all cyls ended up about 1 1/2 - 2 turns, I can hear a noticable differnce in the engine with the 155s in when i give it some gas however no test ride was raining like hell lastnight so ill bring her out tongiht and see what diff the 155s really made thanks for the patience guys

 

[Gsnoob]

Im so fustrated, took it out for the test ride same crap get it up to 4th 5th gear and soon as im past half throttle bogs like hell till i let off and blackens plugs, is there a way to tune the main jet or is it simply go smaller jets till its right? I hadnt switched to pods yet could that be doing it? I opend up air intake thinking so but same thing bog black plugs? Low end mid range feel okay I can cruise 55mph soon as im in 5th and go much over that it bogs liek hell, am I missing something here I knwo the install manual called for removing float bowl tubes but i didnt see anything to remove besides a copper tube in the float bowl that went down to the base of bowl but didnt touch it? What am i doign wrong W.O.T is a no go

 

[UncleBen]

If you are tuning it now with filter box and then are going to switch to pods later you will be starting all over just about from square one. get it set up the way it will be with pods/exhaust and THEN tune it. Other wise you are wasting your time.

Could be that you will not be as rich with the pods in and not need to go to a smaller main. Other wise if it is still rich at WOT, you will have to try smaller jets.

 

[trippivot]

I don't know why there is a set of 155 in a 650cc kit.. I think you should have 105 or 110 or 115. But carb tuning is part voodoo ..

steadily reducing fuel in 10% increments is wise until you get in the range your engine requires.

155-subtract 10% = 139.5 ( or what ever is closest) ride it and do it again until you have brown plugs.

I have 137.5 mains in my 1150 CV carbs I get a slight oscillating surge at WOT -- (touch lean)

I have 145 in my rs36 on a 1500cc racing engine.

mikuni brand jets -- in my engines (but the 10% thing still holds true)

 

[Gsnoob]

I know the more air flow the leaner you get and the kit does say for use with pod filters grrr I spent 113 bucks on this kit I'd hate to have it be use less and start dropping smaller mains so I think I might overnight a set of pods cause I wanna install them anyway. My question is what do I do with the oil tube going from top of engine to air box and what assuming it some kinda oveflow tube

QUOTE=UncleBen;1506176]If you are tuning it now with filter box and then are going to switch to pods later you will be starting all over just about from square one. get it set up the way it will be with pods/exhaust and THEN tune it. Other wise you are wasting your time.

Could be that you will not be as rich with the pods in and not need to go to a smaller main. Other wise if it is still rich at WOT, you will have to try smaller jets.[/QUOTE]

 

[UncleBen]

I know the more air flow the leaner you get and the kit does say for use with pod filters grrr I spent 113 bucks on this kit I'd hate to have it be use less and start dropping smaller mains so I think I might overnight a set of pods cause I wanna install them anyway. My question is what do I do with the oil tube going from top of engine to air box and what assuming it some kinda oveflow tube

That hose is just the crank case breather. Order a small filter to plug into the end of the hose and route it out of the way. If you need to get up running with pods cheap and fast, the Emgo pods are OK. Just make sure you measure your carbs to get the right size pods.

 

[Gsnoob]

Thanks I was actually looking at the Emgo ones like 5 min ago, and they are listed as a specific fit for my bike ill measure when i get home to make sure but im assuming since says specific fit and they made me choose bike they will most likely fit. Ill see what i can find to filter the breather I think I might have something at home.

That hose is just the crank case breather. Order a small filter to plug into the end of the hose and route it out of the way. If you need to get up running with pods cheap and fast, the Emgo pods are OK. Just make sure you measure your carbs to get the right size pods.

 

[Gsnoob]

Thanks for the info Trip I actually pulled stock 110s out of it as i said to Ben im goignt o try pods and if thats a no go ill start backing down my mains yeah if your running 145s on a race bike im surprised this stg 3 had 155s and 160s lol there was even a stg7 i coulda ordered i can only amagine what that had in it. Thanks for your info if these pds dont hels ill start the 10% decrease

I don't know why there is a set of 155 in a 650cc kit.. I think you should have 105 or 110 or 115. But carb tuning is part voodoo ..

steadily reducing fuel in 10% increments is wise until you get in the range your engine requires.

155-subtract 10% = 139.5 ( or what ever is closest) ride it and do it again until you have brown plugs.

I have 137.5 mains in my 1150 CV carbs I get a slight oscillating surge at WOT -- (touch lean)

I have 145 in my rs36 on a 1500cc racing engine.

mikuni brand jets -- in my engines (but the 10% thing still holds true)

 

[koolaid_kid]

A couple of things to consider:
DynoJet main jet numbers are not the same as Mikuni numbers, which is why they are so high. I am running 170s in my GPz.
If you need filters on the cheap, get the APE oiled units. Much easier to tune and filter better, IMHO.
My DynoJet kit had the wrong jets in them also, it came with 180s and 185s. Not sure if they tune at 2000 feet below sea level or what, but I used a wideband so I know my numbers are good. It also did not come with pilot jets. I had to order some from Z1Enterprises, and I went up 2 sizes.

 

[Gsnoob]

Well i wish i woulda checked back beforer placing order I woulda checked out the APEs. However by time I looked here order was placed for the EMGOs overall including overnight shipping was only 59$ Ill prolly go with something a little better quality next spring im just trying to get her up and running for last few weeks of riding. HOpe im okay with my pilots but will adjust as needed after pods I have a local suzuki dealer that says he has hole drawer of pilots just no mains thanks for tips

A couple of things to consider:
DynoJet main jet numbers are not the same as Mikuni numbers, which is why they are so high. I am running 170s in my GPz.
If you need filters on the cheap, get the APE oiled units. Much easier to tune and filter better, IMHO.
My DynoJet kit had the wrong jets in them also, it came with 180s and 185s. Not sure if they tune at 2000 feet below sea level or what, but I used a wideband so I know my numbers are good. It also did not come with pilot jets. I had to order some from Z1Enterprises, and I went up 2 sizes.

 

[koolaid_kid]

DynoJet sells the mains for $2 each plus shipping ($7 IIRC). I got 3 sizes because it was cheaper than placing 2 orders if the first order was still not correct.

 

[Gsnoob]

Alright so update I just got my Pods and will install them tonight so much for overnight I placed order last....oh I think wed called thursday "Oh im sorry we are outa stock on those and they will ship within a day or so "lol I just cant win

 

[Gsnoob]

Alright pods installed much better all way through Rpm range i retuned my idle and took her out for test ride Sooooo much better and not turning plugs black anymore plug chops from idle to basic cruise are all pretty good lookign across all cyl.

After getting her all warmed up I did do a hard run from stop to about 70ish she holds all way though 5th at W.O.T how ever in top end of 4th I still fell tad bog but almost entirly gone and no bog at all in 1-3rd

5th does still fell fairly boggy after about 7k or about 3/4 throttle on up if I open it up from a cruise speed of about 55-60ish but still not blackening plugs anything like before they are more of a dark brown now at a plug chop at W.O.T in 5th and i can still feel the boggy hesitation but NOTHING like before the pods any suggestions before wihtout ordering a new set of mains?

 

[trippivot]

what main jet and needle setting are you using now? and where are your float bowl vents vented to?

 

[Gsnoob]

Thanks for getting back to me okay so I left needle on top notch with the little washer underit

And I'm still a tad unclear about the float bowl vent tubes those are the 2 vent lines that go from the carbs and run up under the tank correct? They are in stock locations free of kinks and pinches however my install kit said the float vent tubes MUST be removed what is your advice on this should I remove them and cap it or leave them or what?

could that be causing my 5th gear bog after 3/4 throttle ? At first I had no idea what they were talking about so I looked it up on google I was real iffy about touching them sorry if my post is little messy doing it from my phone

what main jet and needle setting are you using now? and where are your float bowl vents vented to?

 

[UncleBen]

Just take the vent hoses off and leave the T's open