collapse

www.dimecitycycles.com

https://www.townmoto.com/collections/vanson-leathers


www.restocycle.com

www.CITYLIMITMOTO.com

www.jadusmotorcycleparts.com

www.bisonmotorsports.com

www.speedmotoco.com

www.lostapostlejewelry.com

www.cognitomoto.com

www.sparckmoto.com

www.Moto-Madness.com

www.pistonsociety.com

www.steeltowngarage.com


Author Topic: turbocharged cb550 bobber  (Read 42143 times)

Offline DohcBikes

  • Posts: 2384
  • Fuck You.
Re: turbocharged cb550 bobber
« Reply #80 on: Jan 17, 2016, 18:35:04 »
Im understanding now that my pilot is so lean, I had to have the idle screw cranked up to the midrange to get it to "idle". It did sound fairly smooth, but just falls on its face and dies if i turn the idle screw any lower than 1500 or so.
Yep.


Need to make sure the pilot circuit including the bleed circuit is clean.

Sorry im not going back that far but what carb are you running?

Dont believe the latest internet hype. If your plugs look pig rich then they are pig rich at least at one point in the rpm range.

At that throttle position you are likely idling on the approx equivelent of a 100+ pilot. Obviously that is somewhat of a cursory guess but thatll blacken your plugs in a hurry

« Last Edit: Jan 17, 2016, 18:40:21 by DohcBikes »
burning bridges sometimes light the most productive paths

Offline DohcBikes

  • Posts: 2384
  • Fuck You.
Re: turbocharged cb550 bobber
« Reply #81 on: Jan 17, 2016, 18:43:43 »
Need to get cxman in here he's a bona fide expert in fueling more than one cylinder per carb. It seems simpler but personally i can tune multiple carbs per cylinder much easier than vice versa. My holley/460 relationship is proof of that. Can't tune that thing for nothin ;D
« Last Edit: Jan 17, 2016, 18:46:39 by DohcBikes »
burning bridges sometimes light the most productive paths

Offline mswans

  • Posts: 49
Re: turbocharged cb550 bobber
« Reply #82 on: Jan 17, 2016, 19:01:09 »
carb is a 40mm flatslide mikuni, tm40. glad I have a better idea of whats going on now.

Offline cxman

  • DTT SUPPORTER
  • *
  • Posts: 2496
Re: turbocharged cb550 bobber
« Reply #83 on: Jan 17, 2016, 21:13:44 »
is it a new tm40 pumper or

old style tm 40 no pump?

do you know your idle vacuum reading?

what slide does it have  i bet it has a 2 or 2.5 and it needs  3 maybe even a 3.5 due to the turbo or it will run to rich from vacuum draw

what needle does it have

what jet needle

do you have air correct jet installed
1978 CX650 Super Deluxe
1979 XS1100 Special
1974 xl350
1983 cx650 Custom
1973 cb750
1980 cb750
1981 cb650
1982 cb900 c
1974 kawasaki 350 bighorn
1983 GL1100 aspy full dress
1983 GL1100 Nekid
and a bunch of others

Offline mswans

  • Posts: 49
Re: turbocharged cb550 bobber
« Reply #84 on: Jan 17, 2016, 22:34:45 »
is it a new tm40 pumper or

old style tm 40 no pump?

do you know your idle vacuum reading?

what slide does it have  i bet it has a 2 or 2.5 and it needs  3 maybe even a 3.5 due to the turbo or it will run to rich from vacuum draw

what needle does it have

what jet needle

do you have air correct jet installed

Hey, thanks for chiming in

No pump on this carb.
Cheap boost gauge reads roughly 10-12, not sure how accurate that is.
Slide is a 2.0
Needle reads 9zly2-58
Not sure what needle jet I have, it is pressed in. How do I determine this?
Also, what air jet are you referring too?

Offline DohcBikes

  • Posts: 2384
  • Fuck You.
Re: turbocharged cb550 bobber
« Reply #85 on: Jan 17, 2016, 22:59:51 »
Slide is a 2.0
Ok you already have instructions from the man on that, gonna want to start looking for a 3.0 or 3.5

Needle reads 9zly2-58
Good info. Things are going to get better now because you are helping people help you. Not to patronize you in particular but other members need to have this pointed out sometimes imo.

Not sure what needle jet I have, it is pressed in. How do I determine this?
Press it out. Now that we know what needle you have, once we know what needle jet you have somebody might have more input regarding what you might need for your particular setup.

Also, what air jet are you referring too?
The air jets/bleeds are part of the fuel circuits and are located at the mouth of the carb. When the engine draws vacuum, air helps push the fuel through the main and pilot jets. There will be a bleed for each. Some are replaceable and some are not. Please post a closeup of the intake side of your carb for clarification.
« Last Edit: Jan 17, 2016, 23:02:03 by DohcBikes »
burning bridges sometimes light the most productive paths

Offline cxman

  • DTT SUPPORTER
  • *
  • Posts: 2496
Re: turbocharged cb550 bobber
« Reply #86 on: Jan 17, 2016, 23:32:10 »
in th e air intake bell at the 6 oclock hole the brass you see inside it is the sir correct jet remove it for base tuning

we will add one back as a final tweak if needed

get a q-0 needle jet  and a q2

start with the q0

get a 6dh3 needle and a 6dh4 and start with the 6dh3

with it one lift up so second from the top

3.0 slide

get a 27.5 and 35 and 37.5 start fat with the 37.5 

set pilot fuel screw at 1.5 turns to start

throw a 200 main in to start

verify ignition both points and timing and advance mech

if you are running stock ignition you will need to limit max advance







« Last Edit: Jan 17, 2016, 23:33:44 by cxman »
1978 CX650 Super Deluxe
1979 XS1100 Special
1974 xl350
1983 cx650 Custom
1973 cb750
1980 cb750
1981 cb650
1982 cb900 c
1974 kawasaki 350 bighorn
1983 GL1100 aspy full dress
1983 GL1100 Nekid
and a bunch of others

Offline mswans

  • Posts: 49
Re: turbocharged cb550 bobber
« Reply #87 on: Jan 17, 2016, 23:37:48 »
Ok you already have instructions from the man on that, gonna want to start looking for a 3.0 or 3.5
Good info. Things are going to get better now because you are helping people help you. Not to patronize you in particular but other members need to have this pointed out sometimes imo.
Press it out. Now that we know what needle you have, once we know what needle jet you have somebody might have more input regarding what you might need for your particular setup.
The air jets/bleeds are part of the fuel circuits and are located at the mouth of the carb. When the engine draws vacuum, air helps push the fuel through the main and pilot jets. There will be a bleed for each. Some are replaceable and some are not. Please post a closeup of the intake side of your carb for clarification.

Im searching all over, and not finding a source for slides for this carburetor. is the 3.0 a dimension? Could I have a 2.0 slide modified? I do have a spare. I have a few machinist friends that do work for beer if needed.

I was not seeing any removable air jets or bleeds. I have pressed the needle jet out, and did not see any markings. I will take a closer look at this tomorrow. I will also get more detailed pics of everything on this carb. 

Offline DohcBikes

  • Posts: 2384
  • Fuck You.
Re: turbocharged cb550 bobber
« Reply #88 on: Jan 17, 2016, 23:43:38 »
The 3.0 is the size and shape of the cutaway.

Somebody else can answer the machining ? but im thinking not worth it at all plus the slides are coated. Find a 3.0

Do everything cxman just said.
burning bridges sometimes light the most productive paths

Offline cxman

  • DTT SUPPORTER
  • *
  • Posts: 2496
Re: turbocharged cb550 bobber
« Reply #89 on: Jan 17, 2016, 23:59:48 »
show a picture of the carb and the jets before you order anything

if its a knock off carb i am going to have to bow out

they dont react the same as the mikuni

also i am going to have to make a call in the morning the

 tm40 that you have looks like it only has one slide to be had now

as it phased out and been replaced by the new pumper

pm me at lunch time and i will let you knwo what i find out and if i can find a diff slide or plan

1978 CX650 Super Deluxe
1979 XS1100 Special
1974 xl350
1983 cx650 Custom
1973 cb750
1980 cb750
1981 cb650
1982 cb900 c
1974 kawasaki 350 bighorn
1983 GL1100 aspy full dress
1983 GL1100 Nekid
and a bunch of others