Author Topic: CO screw adjustment question.  (Read 22476 times)

Offline Qwodracer

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Re: CO screw adjustment question.
« Reply #25 on: August 09, 2021, 05:51:11 PM »
Cleaned all the rubber manifold boots, Soaked them all in Rubber renue. Cleaned the TBs, cleaned the intake plastic piece.

reassembled everything.
new clamps from EME
new bosch fuel psi regulator (because i had it apart anyways)
new fuel lines
new vacuum line for the psi regulator
synced TBs, and yes now one is NOT reading higher than the others. they are synced at 6inches

then adjusted the co screw, but cannot get the rpm to raise, it just stays the same, and the more out I adjust it the rpm starts to drop when i push the start button (like 8 turns) but idle stays the same from about 4.5-8 turns

took the bike for a ride and the problem still exists (tried 7 turns and 5.5 turns), just not as bad as it was. certainly the vacuum leak was affecting it.
  • Upstate NY
  • 1992 K75

Offline Laitch

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Re: CO screw adjustment question.
« Reply #26 on: August 09, 2021, 07:11:52 PM »
If you live near an AutoZone or NAPA, you should be able to borrow an exhaust gas analyzer at no charge.
What type of fuel injectors did you use as replacements?
From where are you getting your lean-drop instructions? Try these if you haven't yet. Rebalance the throttle bodies with the CO screw 1.5 out at the beginning. Remember the CO screw setting at the highest attainable idle. If it doesn't get any higher past 1.5, 1.5 is it.
  • Along the Ridley in Vermont.
  • 1995 K75 89,000 miles

Offline rbm

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Re: CO screw adjustment question.
« Reply #27 on: August 09, 2021, 07:52:48 PM »
What type of fuel injectors did you use as replacements?
+1  That would be my question too.  What was wrong with the original injectors that prompted you to replace them? You seem to have symptoms of a rich mixture.  If you replaced the OEM injectors with 4-hole high performance Ebay ones, that might account for the overfueling and fouled plugs. 
  • Regards, Robert
Toronto, Ontario

1987 K75 - Build Blog @http://k75retro.blogspot.ca/
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Offline Qwodracer

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Re: CO screw adjustment question.
« Reply #28 on: August 10, 2021, 07:23:39 AM »
I did get 4 hole injectors from Amazon. I had a leaky o ring on one injector and that caused a mini fire and melted a good part of 1 injector. So I figured I should buy new ones. Are the 4 hole bad? I still have the stock ones, I could probably swap the caps but I don’t trust the body of the one that got melted. Or is the problem not the 4 holes, but the overall flow ?

(I put 4 hole injectors in my Volvo and bmw and Supra and never had a problem, but they were all rated the same cc as the single hole.)
  • Upstate NY
  • 1992 K75

Offline Qwodracer

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Re: CO screw adjustment question.
« Reply #29 on: August 10, 2021, 07:27:58 AM »
If you live near an AutoZone or NAPA, you should be able to borrow an exhaust gas analyzer at no charge.
What type of fuel injectors did you use as replacements?
From where are you getting your lean-drop instructions? Try these if you haven't yet. Rebalance the throttle bodies with the CO screw 1.5 out at the beginning. Remember the CO screw setting at the highest attainable idle. If it doesn't get any higher past 1.5, 1.5 is it.

Hmm at 1.5turns my idle is only 650-700rpm. I’m at about 2.25 turns to get ~1000 rpm
  • Upstate NY
  • 1992 K75

Offline Laitch

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Re: CO screw adjustment question.
« Reply #30 on: August 10, 2021, 07:42:28 AM »
Stop at the best attainable without exploring the outer galaxies then try following those instructions.
  • Along the Ridley in Vermont.
  • 1995 K75 89,000 miles

Offline The Mighty Gryphon

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Re: CO screw adjustment question.
« Reply #31 on: August 10, 2021, 11:03:32 AM »
Four hole injectors?  I'm looking for 16 hole injectors.  Can you imagine the power to the rear wheel with those suckers?!  I'd try 32 hole injectors, but I don't think the clutch and transmission could handle the power.
  • In my garage in Marilla, NY
  • '91K100RS White/Blue
Current:
'91 K100RS16V "Moby Brick Too"

Past:
'94 K75RT "Ilsa, She Wolf of the SS"
'92 K100RS16V "Moby Brick" (RIP, deceased in a vehicular assault)
'94 K75S Special Edition Dakar Yellow "Cheetos"
'89 K100RS Special Edition "Special Ed"

Offline volador

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Re: CO screw adjustment question.
« Reply #32 on: August 10, 2021, 02:19:39 PM »
Four hole injectors?  I'm looking for 16 hole injectors.  Can you imagine the power to the rear wheel with those suckers?!  I'd try 32 hole injectors, but I don't think the clutch and transmission could handle the power.


stick with the OEM you can't handle the power...  :dk
  • NYC NY
  • 1991 K100RS 1993 K75S ABS
5 BOROUGHS SISYPHEAN SOCIETY  MAINTAINING THE OBSESSION

Offline volador

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Re: CO screw adjustment question.
« Reply #33 on: August 10, 2021, 02:24:22 PM »
OP maybe you buy 4-Hole injectors from same seller as this dude "So! I am furious at these 4 hole injectors"
  • NYC NY
  • 1991 K100RS 1993 K75S ABS
5 BOROUGHS SISYPHEAN SOCIETY  MAINTAINING THE OBSESSION
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Offline Qwodracer

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Re: CO screw adjustment question.
« Reply #34 on: August 10, 2021, 04:10:04 PM »
OP maybe you buy 4-Hole injectors from same seller as this dude "So! I am furious at these 4 hole injectors"

Hmm interesting topic. Mine are orange. Not like color matters 😂 150cc/min should be 150cc/minute despite how many holes it has.

Looks like I spent 70$ on the three… oh well, maybe I just need to grab one oe to replace the burnt one.

  • Upstate NY
  • 1992 K75

Offline Laitch

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Re: CO screw adjustment question.
« Reply #35 on: August 10, 2021, 08:12:06 PM »
150cc/min should be 150cc/minute despite how many holes it has.
Indisputable; however, accuracy of specifications and depth of quality control are what can drive purchase cost when one product actually delivers according to its claims and another doesn't. Maybe your replacement injectors are just dandy but those of some other purchasers have been creating fury.  :laughing4-giggles:
  • Along the Ridley in Vermont.
  • 1995 K75 89,000 miles

Offline rbm

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Re: CO screw adjustment question.
« Reply #36 on: August 10, 2021, 10:07:48 PM »
OP maybe you buy 4-Hole injectors from same seller as this dude "So! I am furious at these 4 hole injectors"
I helped this member to get his bike working again.  The symptoms it exhibited were the same as the OP's - limited revs, poor idle, bogging down when twisting the throttle.  We checked everything related to spark, fuel delivery and air.  Symptoms eventually pointed to the injectors.  We replaced all three with the OEM ones he had and instantly the problems went away.  The quality of the 4-hole injectors is suspicious and leads to different experiences by different people, but generally I don't think they deliver.  Best to stick to the OEM injectors or very goos after market ones such as from tills.de
  • Regards, Robert
Toronto, Ontario

1987 K75 - Build Blog @http://k75retro.blogspot.ca/

Offline Qwodracer

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Re: CO screw adjustment question.
« Reply #37 on: May 13, 2022, 11:05:23 AM »
Back again. Wanted to report my latest findings.

Bike essentially stopped driving in September which was fine, I just put it away for the winter. Couple weeks ago weather got nice so I started tinkering again. Mind you in September my truck lost its fuel pump (1 year old) and over this winter the gas station I use, was torn down and completely overhauled, new tanks and pumps. So no surprise  that when removed the fuel pump, the screen was completely discolored pink, collapsed inward. And I found ethanol sands in the bottom of the tank. Despite cleaning the tank last year before posting all the problems.

So after much cleaning with dawn and muriatic acid and new pump screen and fuel filters the bike finally runs amazing, and that is with my orange top 4hole 150cc injectors (I even grabbed a second set because they were 25$ now instead of 75$) lol

Thanks for all the suggestions over the years. I am starting to think the Gas station that advertised “non ethanol 91octane” had a leak or contamination all along, I’ve been using it since I moved here 5 years again and went through a total of 3 fuel pumps in my truck, and many many fuel filters. I now have a pack of coffe filters in the bike box to put over the nozzle at the gas station 😂
  • Upstate NY
  • 1992 K75

Offline Laitch

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Re: CO screw adjustment question.
« Reply #38 on: May 13, 2022, 03:15:09 PM »
Thanks for all the suggestions over the years. I am starting to think the Gas station that advertised “non ethanol 91octane” had a leak or contamination all along, I’ve been using it since I moved here 5 years again and went through a total of 3 fuel pumps in my truck, and many many fuel filters.
To be fair, the station wasn't advertising "non-contaminated gas" though, was it?  :laughing4-giggles:  Thanks for posting this cautionary tale, Qwod; it makes me wonder just how long some of this non-ethanol gas sits around waiting for Brick owners to drop in and buy three or four gallons of it.  :laughing1:
  • Along the Ridley in Vermont.
  • 1995 K75 89,000 miles

Offline frankenduck

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Re: CO screw adjustment question.
« Reply #39 on: May 13, 2022, 05:34:41 PM »
I now have a pack of coffee filters in the bike box to put over the nozzle at the gas station 😂

Won't do much. Most gas station pumps have a 10 micron filter and a coffee filter is not finer than that.
Once I had a Collie pup. Dug a hole and covered him up. Now I sit there by the hour. Waiting for a Collie-flower.
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Offline The Mighty Gryphon

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Re: CO screw adjustment question.
« Reply #40 on: May 13, 2022, 10:20:47 PM »
Actually, non-ethanol gas has a pretty long shelf life, it's the E10 stuff that goes bad in 6-7 months.  I worked for a while in a boatyard where one of my jobs was cutting up old wooden cabin cruisers that had been abandoned, sometimes for as long as 20 years. 

One of the perks was that I had to pump the old gas out of the tanks before I started cutting.  I would pump out 50 or 60 gallons of 10-15 year old unleaded gas that I pumped into barrels where I let the water settle out.  I ran my car for the entire summer on that old gas and never had a problem.
  • In my garage in Marilla, NY
  • '91K100RS White/Blue
Current:
'91 K100RS16V "Moby Brick Too"

Past:
'94 K75RT "Ilsa, She Wolf of the SS"
'92 K100RS16V "Moby Brick" (RIP, deceased in a vehicular assault)
'94 K75S Special Edition Dakar Yellow "Cheetos"
'89 K100RS Special Edition "Special Ed"

Offline Laitch

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Re: CO screw adjustment question.
« Reply #41 on: May 13, 2022, 11:25:21 PM »
I would pump out 50 or 60 gallons of 10-15 year old unleaded gas that I pumped into barrels where I let the water settle out.  I ran my car for the entire summer on that old gas and never had a problem.
So that's how boutique gasoline is made! 112350
  • Along the Ridley in Vermont.
  • 1995 K75 89,000 miles

Offline The Mighty Gryphon

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Re: CO screw adjustment question.
« Reply #42 on: May 13, 2022, 11:33:50 PM »
Sunoco '92, aged in monel, it was a very good year.
  • In my garage in Marilla, NY
  • '91K100RS White/Blue
Current:
'91 K100RS16V "Moby Brick Too"

Past:
'94 K75RT "Ilsa, She Wolf of the SS"
'92 K100RS16V "Moby Brick" (RIP, deceased in a vehicular assault)
'94 K75S Special Edition Dakar Yellow "Cheetos"
'89 K100RS Special Edition "Special Ed"

Offline frankenduck

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Re: CO screw adjustment question.
« Reply #43 on: May 14, 2022, 02:23:31 AM »
I use ethanol in my Bunsen burner.  Works great for cooking up batches of high-grade meth.
Once I had a Collie pup. Dug a hole and covered him up. Now I sit there by the hour. Waiting for a Collie-flower.
New to K bikes? Click here.
K Bike Maintenance & Mods: Click here.
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Offline Laitch

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Re: CO screw adjustment question.
« Reply #44 on: May 14, 2022, 09:30:35 AM »
I use ethanol in my Bunsen burner.  Works great for cooking up batches of high-grade meth.
You must be the star of your neighborhood's bake sales!
  • Along the Ridley in Vermont.
  • 1995 K75 89,000 miles

Offline daveson

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Re: CO screw adjustment question.
« Reply #45 on: May 14, 2022, 09:04:14 PM »
Did I hear somebody say meth?
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  • Victoria, Australia
  • Current; '85 K100RT~100,000km; four other bricks. Past; Vulcan 1500, V Star 650, KLX 250(dirt bike) TT250(dirt bike)

Offline frankenduck

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Re: CO screw adjustment question.
« Reply #46 on: May 14, 2022, 09:22:56 PM »
You must be the star of your neighborhood's bake sales!

With help from the local Hell's Angels chapter, our PTA grossed $500K last year from "bake sales." :laughing4-giggles:
Once I had a Collie pup. Dug a hole and covered him up. Now I sit there by the hour. Waiting for a Collie-flower.
New to K bikes? Click here.
K Bike Maintenance & Mods: Click here.
Buy parts here.

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