Author Topic: Too rich / Too lean?  (Read 4414 times)

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Offline 1965soda

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Too rich / Too lean?
« on: September 24, 2013, 11:16:12 am »
Good morning C10 enthusiasts.  Although I am not working on a C10 the commonality between that and the bike I am working on led me to ask this question here.  I am doing some fine tuning on a 1986 900 Ninja and would appreciate some jetting guidance.  The bike in question has a re-jet kit (larger mains and a different needle) and a set of Supertrapp slip on mufflers (with extra discs). 

The bike starts and runs very well, but I have noticed at full throttle the bike does not pull as strongly as it does if I slightly close the throttle.  It appears to be making more power at 3/4 or 7/8 throttle than at wide-open.  My initial thought was the bike was running rich but the plugs look good and the end caps on the Supertrapps are not overly sooty.  Also, it seems if it were running rich the extra air provided at WOT would not cause it to loose power.  This leads me to wonder if it may be running a little lean and I should either pull a couple discs out of the Supertrapps, go up a size in main jet, raise the needle, etc. 

Before I dig into it I thought I would tap the collective wisdom here and garner any perspectives/opinions.  Thanks!
« Last Edit: September 24, 2013, 11:50:58 am by 1965soda »
Currently in garage: 2011 C14, 2007 FZ1, 2001 M900 S4, 1983 900 Seca, 2003 ZRX1200, 1982 650 Seca, 8? Husq 430
Rides of the past: 2002 ZRX1200, 1986 900 Ninja, 1999 Ducati 900ss, 2002 R6, 2005 FJR, 1998 C10, 1998 VTR1000, 1989 1100 Katana, 1983 CB1100F, 1985 900 Ninja, 1983 900 Seca, 1982 Seca turbo, 1982 CX500 turbo, 1982 750 Seca, 1983 550 Vision, 1974 CB400F, mid 70's Rupp :-)

Offline mattchewn

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Re: Too rich / Too lean?
« Reply #1 on: September 24, 2013, 11:48:34 am »
1965soda,
Definitely sounds like you are lean at the top end. What carbs are on it? I don't know that pulling the discs will make up for the lack of fuel though.
Matt
There are others on here that are sure to chime in with far more bike specific knowledge than me though. Good Luck.
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Offline Kwaksam

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Re: Too rich / Too lean?
« Reply #2 on: September 24, 2013, 12:00:08 pm »
Hi, I'm sure you don't want to hear it, but....as a long time member of gpz900r.co.uk, most 900 owners have best results with completely standard jetting/needles....its the best starting point by far, just my opinion.
When its in your blood, you never turn back....

Offline 1965soda

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Re: Too rich / Too lean?
« Reply #3 on: September 24, 2013, 12:57:57 pm »
Thanks Matt.  That is my latest thinking as well (too lean).  The neat thing about the old Supertrapps is you can add/pull discs to reduce/increase exhaust flow and in theory alter the fueling needs of the engine.  I may try and pull a couple discs from each side and see how/if it responds. 

Thanks Kwaksam.  I am really trying to avoid pulling the carbs again.  If I recall correctly on the GPZ and C10 I can pull the bowls and change the mains but beyond that I think I would need to pull the carbs.  In the GPZ and C10 I had previously, I had aftermarket exhaust and did a rejet on both.  They both ran like champs.  Took a similar approach to this resto/refresh project and although it runs great in nearly all situations....I would really like to address the WOT issue.

Any other thoughts/input would be appreciated.   
Currently in garage: 2011 C14, 2007 FZ1, 2001 M900 S4, 1983 900 Seca, 2003 ZRX1200, 1982 650 Seca, 8? Husq 430
Rides of the past: 2002 ZRX1200, 1986 900 Ninja, 1999 Ducati 900ss, 2002 R6, 2005 FJR, 1998 C10, 1998 VTR1000, 1989 1100 Katana, 1983 CB1100F, 1985 900 Ninja, 1983 900 Seca, 1982 Seca turbo, 1982 CX500 turbo, 1982 750 Seca, 1983 550 Vision, 1974 CB400F, mid 70's Rupp :-)

Offline davida

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Re: Too rich / Too lean?
« Reply #4 on: September 24, 2013, 02:43:56 pm »
You may want to check that the charging system is delivering enough juice. Old connectors get dirty and can drop enough to to reduce top end.  I have not had this problem on my Kawi, but its pretty regular on my Honda
86 Concours no longer in a box.
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Offline 1965soda

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Re: Too rich / Too lean?
« Reply #5 on: September 24, 2013, 03:42:35 pm »
Thanks Davida.  Although I won't completely rule that out....I am pretty certain this is a fueling issue as it is not isolated to high RPM.  The symptoms appear in the following scenario....

2nd or 3rd gear....mid to high RPM.....pin the throttle....as the RPMs climb roll back off the throttle a little....fee the bike pull noticeably harder

There is no perceptible miss and the bike otherwise runs really well.  Again...I may be wrong but am still thinking the issue is the mixture is either rich or lean...just a little.

Thanks again for the responses and any other ideas or applicable experiences.
Currently in garage: 2011 C14, 2007 FZ1, 2001 M900 S4, 1983 900 Seca, 2003 ZRX1200, 1982 650 Seca, 8? Husq 430
Rides of the past: 2002 ZRX1200, 1986 900 Ninja, 1999 Ducati 900ss, 2002 R6, 2005 FJR, 1998 C10, 1998 VTR1000, 1989 1100 Katana, 1983 CB1100F, 1985 900 Ninja, 1983 900 Seca, 1982 Seca turbo, 1982 CX500 turbo, 1982 750 Seca, 1983 550 Vision, 1974 CB400F, mid 70's Rupp :-)

Offline Steve in Sunny Fla

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Re: Too rich / Too lean?
« Reply #6 on: September 24, 2013, 03:45:25 pm »
it's to lean, you need bigger mains, and go up more than just one size. Steve
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Offline MAN OF BLUES

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Re: Too rich / Too lean?
« Reply #7 on: September 24, 2013, 11:13:40 pm »
I'm running ninja supertrapps on COGZilla, I did not have to play with jetting on them with numerous disc variations (3 to 8)
I agree with Steve, bump up 2 jet sizes, seeing as you didn't tell us what are in there now.
You DO however need to pull the rack to d this, its rediculous to attempt to do it on te bike
 Also gives the opportunity to spray down, clean, and examine tghe other parts/jets that work in cncert to make the "system" work...

30 YEARS OF KAW.....Rich R. (the other one..)  COG 5977  JUSTAMEMBAHNOW
and if you are gonna call me names... it's MR. Analdweeb if you please...

Offline 1965soda

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Re: Too rich / Too lean?
« Reply #8 on: September 25, 2013, 01:30:38 am »
Thanks for the additional insight and recommendations Steve and MoB.

MoB...my son and I went through the bike and finished up doing a refresh/resto on it this past spring.  I had the carbs apart and thoroughly cleaned them and reassembled using the jet kit.  The boots are pretty stiff and I am trying to avoid pulling the carbs out again if I can avoid it. 

I have all the screws on the bowls lose, two of the bowls off and removed two mains (a center and outer).  I had installed the recommended 150 on the inner cylinders and a 147.5 on the outer.  The kit indicated if it ran lean to go up a size (or two).  I am thinking based on the kit and your recommendations....I will put a 155 on the inner cylinders and a 152.5 on the outers. 

I did not get much time to work on it tonight so I hope to get the re-sized jets in and buttoned up for test ride tomorrow.  If after reading this you have new recommendations...please circle back around.

Oh and MoB....I have 16 discs each side on the Supertrapps and they sound glorious! :-)

Thanks again for the advice and recommendations! 
Currently in garage: 2011 C14, 2007 FZ1, 2001 M900 S4, 1983 900 Seca, 2003 ZRX1200, 1982 650 Seca, 8? Husq 430
Rides of the past: 2002 ZRX1200, 1986 900 Ninja, 1999 Ducati 900ss, 2002 R6, 2005 FJR, 1998 C10, 1998 VTR1000, 1989 1100 Katana, 1983 CB1100F, 1985 900 Ninja, 1983 900 Seca, 1982 Seca turbo, 1982 CX500 turbo, 1982 750 Seca, 1983 550 Vision, 1974 CB400F, mid 70's Rupp :-)

Offline Sparkie

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Re: Too rich / Too lean?
« Reply #9 on: September 25, 2013, 04:55:55 pm »
Interesting that they recommend running richer main's on the inboard cylinders even with a watercooled motor.  I've heard of this before but only with aircooled cylinders.  Any thoughts on this from you engine guys out there. Mark
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Offline works4me

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Re: Too rich / Too lean?
« Reply #10 on: September 25, 2013, 05:18:50 pm »
It's also interesting that rolling off from WOT results in
increased acceleration which everyone thinks is from
too lean jetting.
On both of my bikes this is occurring because of too little air
at WOT.
One one bike it occurs when the air filter is dirty and needs replacing.
On the other it's because to intake is partially blocked with a piece of foam. (Wink )

Offline MAN OF BLUES

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Re: Too rich / Too lean?
« Reply #11 on: September 25, 2013, 05:23:23 pm »
UH,
I glanced right past those jet sizes initially.... whose jets are you using?????

those aren't Keihin sizes that would remotely be close....
normal is from 120 to 135 available.... and 135 is RICH

you got some Dynajets there??? wait, dyna numbers are lower than Keihin's for equivalent sizes....

this IS why I say you can't effectively do carb work without removing them.... also, trying to fish things like the emulsion tube and needle guides.. and other jets
« Last Edit: September 25, 2013, 05:29:16 pm by MAN OF BLUES »

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and if you are gonna call me names... it's MR. Analdweeb if you please...

Offline 1965soda

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Re: Too rich / Too lean?
« Reply #12 on: September 25, 2013, 05:46:28 pm »
OK....sensing some indecision....which is good because I will not get back to this until I am home tonight. :-)

The kit came from a local shop and I think the package said Factory 5 or something like that.  The ones I have in there now have a noticeably larger opening (the outside shape and size is the same) than what came out (I believe there were 135's in there to start with).  Because they were noticeable larger than the OEM jets it led me to wonder if it may be running rich....but it seems the additional air flow at full throttle should not result in it pulling less.  There is no popping or missing at any throttle position just less pull at WOT.  Again...hoping a jet size change (up or down) will take care of it.   

MoB....recognize what you are saying....but the carbs were gone through when they were off the bike earlier this year and I am hopeful to avoid pulling them again (for fear of cracking one or more boots).  Not that it was easy...but pulling the bowls and removing the main jet with the carbs on the bike was pretty painless....hoping I can get it where it runs strong at full throttle with the jet swap.

Hope the above helps and allows for a recommendation to move up or down in jet sizes.

Thanks again!

Update....I just remembered the company that made the jet kit: 6 Sigma Racing (or something like that). 

Thanks again for any further recommendations!
« Last Edit: September 25, 2013, 06:37:26 pm by 1965soda »
Currently in garage: 2011 C14, 2007 FZ1, 2001 M900 S4, 1983 900 Seca, 2003 ZRX1200, 1982 650 Seca, 8? Husq 430
Rides of the past: 2002 ZRX1200, 1986 900 Ninja, 1999 Ducati 900ss, 2002 R6, 2005 FJR, 1998 C10, 1998 VTR1000, 1989 1100 Katana, 1983 CB1100F, 1985 900 Ninja, 1983 900 Seca, 1982 Seca turbo, 1982 CX500 turbo, 1982 750 Seca, 1983 550 Vision, 1974 CB400F, mid 70's Rupp :-)

Offline MAN OF BLUES

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Re: Too rich / Too lean?
« Reply #13 on: September 25, 2013, 07:14:32 pm »
At this point I highly suggest you get in touch with  6 Sigma...

they put together kits with alternating parts, drilling mods, and all sorts of stuff we simply cannot "see" here and now.

I am sure if the "kit was done" correctly, it would provide some performance, but not knowing what kit "stage" contents were installed, or modded we are totally blind here.
Sorry for that, we might have been able to steer you if it was a Dyna Kit as they really don't change all that much stuff, but I cannot even get a jist on their website of what 6S supplies per kit stage..

30 YEARS OF KAW.....Rich R. (the other one..)  COG 5977  JUSTAMEMBAHNOW
and if you are gonna call me names... it's MR. Analdweeb if you please...

Offline 1965soda

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Re: Too rich / Too lean?
« Reply #14 on: September 26, 2013, 12:51:03 am »
Thanks again everyone for the input and sorry....I know I was asking for some speculation based on limited info so I understood that going in.

Well the two-up rejet did not solve the problem.  There is now a distinct cut out at two points in the rpm band as the bike accelerates.  Also smells rich.  So I will pull the bowls again and go down a size from where I was before.  I am also wondering....

Is there a chance that raising the needle would help?  If I went back to the sizes I had in before and at the same time raised the needle a clip (or a spacer washer) if that may solve the full throttle softness I was originally experiencing?

Thanks again for the continued dialog!
Currently in garage: 2011 C14, 2007 FZ1, 2001 M900 S4, 1983 900 Seca, 2003 ZRX1200, 1982 650 Seca, 8? Husq 430
Rides of the past: 2002 ZRX1200, 1986 900 Ninja, 1999 Ducati 900ss, 2002 R6, 2005 FJR, 1998 C10, 1998 VTR1000, 1989 1100 Katana, 1983 CB1100F, 1985 900 Ninja, 1983 900 Seca, 1982 Seca turbo, 1982 CX500 turbo, 1982 750 Seca, 1983 550 Vision, 1974 CB400F, mid 70's Rupp :-)

Offline Capo

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Re: Too rich / Too lean?
« Reply #15 on: September 26, 2013, 02:27:44 am »
You mentioned a fear of "cracking your boots". Are you 100% certain that all boots are in tip top shape currently??
James in Tampa. Currently being enjoyed are...04 C10,  86 C10 "Cooper" , 04 Honda vt750 "Christine" . The  only previously owned needing mention would be 74 gt750, I cant believe how many of us had a "water buffalo" !!!

Offline 1965soda

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Re: Too rich / Too lean?
« Reply #16 on: September 26, 2013, 11:21:02 am »
Good question Capo and although I cannot say they are 100%....there is no indication of a crack or leak (visual inspection and spray down test).  From what I understand....the condition I am experiencing is not indicative of a air leak...but I have been wrong many times before and would gladly welcome any further input, discussion or suggestions on this topic. 

I went back through the instructions that came with the jet kit.  I did the initial install with the 'mildest' settings they provided (smallest mains from the kit, enlarged vent hole in slider, lowest setting of the needle).  After the reassembly I also adjusted the fuel mixture screws and synced the carbs.  In that state the bike starts easily, runs very well, and pulls strongly except at wide-open (where it pulls less hard than at say 7/8 throttle opening).  Going up to the largest jets from the kit resulted in the bike starting and running well but a clear stumble at wide-open in the upper RPM band and a very rich smell. 

Thinking of going back to the smaller jets from the kit and maybe raising the needle with a spacer.  Any concerns or recommendations would be appreciated.

Thanks again!
Currently in garage: 2011 C14, 2007 FZ1, 2001 M900 S4, 1983 900 Seca, 2003 ZRX1200, 1982 650 Seca, 8? Husq 430
Rides of the past: 2002 ZRX1200, 1986 900 Ninja, 1999 Ducati 900ss, 2002 R6, 2005 FJR, 1998 C10, 1998 VTR1000, 1989 1100 Katana, 1983 CB1100F, 1985 900 Ninja, 1983 900 Seca, 1982 Seca turbo, 1982 CX500 turbo, 1982 750 Seca, 1983 550 Vision, 1974 CB400F, mid 70's Rupp :-)

Offline 1965soda

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Re: Too rich / Too lean?
« Reply #17 on: November 10, 2013, 06:17:57 pm »
I know it has been a while since i posted and thought I should provide an update in case it may help others.  After trying all the jet options in the kit and raising/lowering the needle I put the oem jets back in and took some discs out the supertrap mufflers.  The bike ran noticeably better and it appears the bike was running overly rich with the jets supplied in the kit. 

Contacted 6Sigma and asked to return the kit, reached out to a Kawi contact and he sourced two sets of Kawasaki racing jets (138's and 140's) for the 900 Ninja.  So I pulled the bowls again, installed 4 of the 140's, adjusted the mixture screws, put the carb sticks on, and buttoned it up and reinstalled the additional muffler discs.  Runs cleanly and strong to redline.  My son and I did a 3rd gear roll-on with the 900 and my C14.  The 900 pulls ahead from 30mph and holds it for awhile until I assume the c14 can get its additional weight moving.  Fun to have the 900 running like it should. :-)

Thanks and I hope the follow-up post helps.
Currently in garage: 2011 C14, 2007 FZ1, 2001 M900 S4, 1983 900 Seca, 2003 ZRX1200, 1982 650 Seca, 8? Husq 430
Rides of the past: 2002 ZRX1200, 1986 900 Ninja, 1999 Ducati 900ss, 2002 R6, 2005 FJR, 1998 C10, 1998 VTR1000, 1989 1100 Katana, 1983 CB1100F, 1985 900 Ninja, 1983 900 Seca, 1982 Seca turbo, 1982 CX500 turbo, 1982 750 Seca, 1983 550 Vision, 1974 CB400F, mid 70's Rupp :-)