81 GS650 tuning help Dynojet stage 3

[Gsnoob]

Okay idle seems to be smooth, No im not letting it get that hot I unfortunatly do not have a big fan i adjusted my idle by adjusting lettign cool the adjusting some more however righ tnow its all of about 60 degrees up here in MN at the moment so it stayed pretty cool this morngin when i was messing around with it had no trouble laying hand on engine, I Realize now that main jet and idle are two diff circuts however when starting all this i did not hence my post of changing my jets bigger cause it wouldnt idle lol if that doesnt scream NOOB idk what does. I will go home tonight after work and switch back to 155s rather then the 160s I felt a most deffinate improvment after moving the clip up a notch what notch would you recommed i start on after going back to the 155s? Thanks

ok I re read thru this thread. and I want to help.

when installing a jet kit you start with getting a excellent idle FIRST- ok?

I need to know you are not tuning it until the engine is too hot to touch the fins -- get a fan blowing over your engine OR take it for a ride with tools in a pouch. I've whipped off the tank and carbs in a parking lot and made changes many -o- time. (hint) Dont get gasoline on your grips they melt

changing the main jet has nothing to do with getting your bike to idle properly..

put in the smaller main jets again and see what it does.

you may go straight to the top groove but if you are blackening the plugs it's going to be the worse as the throttle is opened widely for highway riding

In my experience- having a smaller main jet and the needle lifted as high as it goes is better than having of a big main jet and the needle in the leanest position.

[trippivot]

keep them where they are at. You might get lucky

Take it for a few mile ride, the engine really has to be over 150 degrees for your jetting adjustments to react correctly. Ambient temps 60 F and colder you might consider a 1 step hotter spark plug. This does not change the jetting but heat energy from the inner engine parts affects fuel atmoization. We are shooting for good running in all conditions you ride in

not enough heat and the engine will want you to dump gas into it.




but I bet you are getting some confidence and repetition makes adjusting just a little easier.

[UncleBen]

Well update i didnt have time to switch the needle until lastngiht took out this morning and its better now before on 3rd notch I couldnt hit it hard in 1st at all or or it would stumble and run like **** till i let off now i can hit ti in 1st - 3rd but top ens of 3rd stumbles i can seem to cruise but if i hit it stumbles and has power loss a high rpm plug chop still looks to me like rich they are still fairly black so what do i do at this poitn is it okay to raise that clip all way up to 1st notch? Or have i developed some other issue note that bike ran fine before kit was just way to lean cause of exhaust

You can raise it up to the top notch, but you can also try going a half notch first by leaving the clip in the second notch and then putting a 0.5mm washer right above the e-clip before the plastic ring. If that doesn't do it and you are still rich, remove the washer and then go up to the top clip.

[Gsnoob]

See this is why i love this site learn something new all the time i had no idea that temp will affect how much fuel she puts to it I did not have time to change clips lastnight so im glad i read your post before changing again, I will try and go for a tad longer jont before pulling clips again. At this point can i damage my engine if from this rich condition if i take it for a mile or so?

keep them where they are at. You might get lucky

Take it for a few mile ride, the engine really has to be over 150 degrees for your jetting adjustments to react correctly. Ambient temps 60 F and colder you might consider a 1 step hotter spark plug. This does not change the jetting but heat energy from the inner engine parts affects fuel atmoization. We are shooting for good running in all conditions you ride in

not enough heat and the engine will want you to dump gas into it.




but I bet you are getting some confidence and repetition makes adjusting just a little easier.

[Gsnoob]

Okay good to know that i can go half notches like that i think at some point someone recommended even leaving the washer out all together Im gonna take bike out again tonight and try getting her up to temp like trippivot recommended if still a stumble and rich ill try a half then a full if still no go ill drop back to the 155s that also came with kit.

You can raise it up to the top notch, but you can also try going a half notch first by leaving the clip in the second notch and then putting a 0.5mm washer right above the e-clip before the plastic ring. If that doesn't do it and you are still rich, remove the washer and then go up to the top clip.

[Gsnoob]

and yes trippivot my confidence in this is most deff improving lol, I now dont feel quite like im going blow it up everytime i change something.

[koolaid_kid]

You won't hurt the engine by running it rich, it is the lean condition that will burn a hole in the top of your piston.

[Gsnoob]

Okay so as of tongiht its sooo close i can feel it tried washer, stumble black pugs, move to first notch no stumble unless i hit it hard and bring past 7k then stumbles but still feels like wants to try and go and i can actually cruise at 55 with out any realy noticable problems pop here and there, but now its to late to be running it up and down the road without ****ing someone off so ill pick it up again after work tomorrow, Im thinking maybe just try pulling washer and trying one more run at 1st notch without washer before pulling mains and dropping the 155s in. Questions being can it be run wihtout the little metal washer or is thta not recommended second if I have to drop the 155s tomorrow night what notch shoudl i start on? I was thinking the very 1st on bottom seeing im so close but not sure thats why im turnign to the pros thanks

[koolaid_kid]

Let's make sure we are tracking the same transition periods; you have two. The first is from the pilot jet to the needle. The second is from the needle to the main jet. Are we discussing the second? It would help to clarify.
thx.

[trippivot]

idle-main-needle in that order

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.

[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