dominicbeesley
Well-Known Member
Yes, I'd try six and work up. There's no exact figure. All depends on fuel, how good or worn the dissy is, the carb setup, air flow and any build up of muck in the cylinders.
joe27979
Well-Known Member
so I retarded ignition today and checked plugs at same time :
looks like she was running lean so I backed mixture screw out 1/4 turn.
I also changed plugs setting gap at 0.8mm:
went for a drive and the rattle had deffo gone-see vid next post.
took new plug out and was still lean so I backed out mixture screw another quarter:
looks like she was running lean so I backed mixture screw out 1/4 turn.
I also changed plugs setting gap at 0.8mm:
went for a drive and the rattle had deffo gone-see vid next post.
took new plug out and was still lean so I backed out mixture screw another quarter:
joe27979
Well-Known Member
ps I presume plug colour is lean? not normal or overheated?? some advice would be good chaps.
video of engine running before retard, plug change and mixture adjust
2.25 series 3 petrol engine running before retarding and changing plugs - YouTube
video of engine running before retard, plug change and mixture adjust
2.25 series 3 petrol engine running before retarding and changing plugs - YouTube
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dominicbeesley
Well-Known Member
The colour of the plugs is indicative of rich and lean but really only just prior to the plugs being pulled. Before gas / lambda testers plug colour was used as a check but you'd do a plug pull. That is run the engine at the conditions (rpm/load) at which you wanted to check the turn off the ignition at that point, push in the clutch and coast to a stop. A bit dangerous except on a very quiet road. Your plugs show signs of BOTH rich (black soot) and lean/hot (white soot).
The white may well be from idling prior to turning off, the carb should run lean when idling.
I'd put your carb back to the setting you found by doing the proper set up...
The white may well be from idling prior to turning off, the carb should run lean when idling.
I'd put your carb back to the setting you found by doing the proper set up...
joe27979
Well-Known Member
had a good 3 hours green laning this morning, engine was running sweet before setting off.
about 2hrs in it started to faulter/bunny hop/big down at low Rpms-I had to rev through it.
on the open road in 4th it occasionally had a fit like a bunny hop/brake being applied on and off!
grr what's going on?!!
got home and checked plugs:
I also checked valve clearances, 1and 8 were a little tight so I reset them both.
vid showing rough running when I got home, carb and coil were cool to touch.
2.25 running bad after out all morning, was running sweet before I started out. - YouTube
one thing I did try was pull spark leads-when I did I heard clicking from coil and a spark was jumping from + terminal to ht lead?!!
some nice pics to cheer me up:
about 2hrs in it started to faulter/bunny hop/big down at low Rpms-I had to rev through it.
on the open road in 4th it occasionally had a fit like a bunny hop/brake being applied on and off!
grr what's going on?!!
got home and checked plugs:
I also checked valve clearances, 1and 8 were a little tight so I reset them both.
vid showing rough running when I got home, carb and coil were cool to touch.
2.25 running bad after out all morning, was running sweet before I started out. - YouTube
one thing I did try was pull spark leads-when I did I heard clicking from coil and a spark was jumping from + terminal to ht lead?!!
some nice pics to cheer me up:
still may be an air leak, does your motor have a servo? if so does it play up after braking? if yes and yes check hoses and non return valve in servo. I have had them make a car rattle like f**k and blow smoke when back on the gas after braking coursed by knackered servo letting brake fluid in to the engine.
dominicbeesley
Well-Known Member
Could be damp or white on coil give it a good go over with wd40 and wipe off and repeat. The rubber boot on the king lead should stop the spark so I'd try replacing that too...
joe27979
Well-Known Member
I moved boot which helped a bit, I guess with ht lead removed from plug the spark was finding the next easiest path to earth..?
still stuck with why it was bogging down after a good hour or twos run.
I let it cool right down when I got home, started it and it ran ok but not sweet sweet like it was before-I hadn't touched anything so what gives?
Grit Valve
2000 4.6 Vouge
Coil breaking down when hot ?
joe27979
Well-Known Member
cheers-I had thought if that so bought the Lucas gold sport coil and still same, coil is always cool to the touch too.
can I just say a big thanks to everyone who has helped me with replys to my questions this year...really appreciate it guys
Grit Valve
2000 4.6 Vouge
I would rather have the plugs a bit more brown IMO
Rather a tad rich than lean looks weak to me
Rather a tad rich than lean looks weak to me
Grit Valve
2000 4.6 Vouge
Why don't you just buy a strobe light that's the most efficient way to set timing?
Here
When using any vacuum gauge keep in mind that they are all calibrated at sea level and read-outs in the instructions are in reference to that level. When above sea level all readings will drop one division per each 1,000 feet of altitude above sea level. Thus a reading of 20 inches of vacuum at sea level would drop to 19 inches at 1,000 feet, 18 inches at 2,000 feet, etc. All readings are taken at idle except as noted.
If your engine is barely able to sustain 2"Hg vacuum at idle, it will be hard to tune using this method, but it is still useful. In most cases if you use a quality large faced Vacuum gauge, with some experience you can effectively tune your car's fuel and timing systems. Tuning with the engine running compensates for wear in the timing gear and valve train, and therefore providing better results than with the manufacturers recommended settings.
Note: All adjustments are made with the transmission in PARK or NEUTRAL, with the exception of Idle Speed, which is set in DRIVE.
Caution: Make all adjustments from the side of the vehicle, rather than standing in front of it.
Vacuum Gage Connection
Connect the gauge to a "manifold" vacuum source, NOT "ported" vacuum, that rises as RPM increases. In most cases this will be a direct manifold source or possibly the PCV port (larger port) on the carb.
Start by first warming the engine and note the idle vacuum reading. Normal vacuum at idle should be 19-21 inches for a six cylinder, or 15-18 inches on a low compression engine. Pre-set the ignition timing so that it is close to the manufactures recommended setting, before making any carb adjustments.
Carb Adjustments
To adjust the carb, start by leaning out one of the mixture screws (turn in) until the gauge as well as the engine begins to shudder. Next bring the screw back towards rich (turn out), while watching the gauge. Stop adjusting when the gauge reaches it's highest reading. Then do the same process for the other mixture screw. After each adjustment is made, reset your idle speed.
Small adjustments are best, and in fact "optimum" carb settings on the vacuum gauge (highest reading) is usually richer than it needs to be. In other words, once the highest reading is reached, back-off (or lean) the adjustment approximately 1/4 turn in. You may have to repeat the process a few times to get optimum results, but it's worth the time and effort.
Note: With a properly jetted carburetor, turning either of the mixture screws all the way lean, should kill the engine. If not, you're too rich! This may require re-jetting, or drilling the primary butterflies to add more idle air. Many of the newer "race" carbs allow you to change Idle air bleeds to fix this.
For carbs with 4-corner mixture screws, you have to take a bit more time. You can also run the engine at a "steady-state" RPM of say, 2500 RPM to double-check your secondary mixture screw settings. Do this with temperament! It takes time to get used to what you are seeing as well as if it is actually helping. Each engine will behave differently.
Remember to rev the engine to clear the spark plugs before taking your final reading and readjust if necessary. When you blip the throttle, the needle should drop to as low as 2, pop back up to as high as 26, and quickly level off in the normal zone.
Ignition Timing
After the carb mixture is set, you can proceed with the ignition timing. Slacken the distributor clamp bolt, and with the engine still at idle, advance or retard the ignition until the highest steady vacuum reading is obtained. Then retard the timing until the vacuum gauge reading drops slightly, approximately one half to one inch. In some cases, you may need to retard the timing up to two inches to prevent pre-igniton (pinging).
Note: If you can't get the reading into the "normal" zone by adjusting the distributor then valve timing is the problem. Timing with a vacuum gauge will normally result in timing that is more advanced than what specifications call for, so you need to be alert for any pre-ignition (pinging) in the engine and adjust accordingly (retard the timing if needed).
Your engine should now be tuned to perfection.
Here
When using any vacuum gauge keep in mind that they are all calibrated at sea level and read-outs in the instructions are in reference to that level. When above sea level all readings will drop one division per each 1,000 feet of altitude above sea level. Thus a reading of 20 inches of vacuum at sea level would drop to 19 inches at 1,000 feet, 18 inches at 2,000 feet, etc. All readings are taken at idle except as noted.
If your engine is barely able to sustain 2"Hg vacuum at idle, it will be hard to tune using this method, but it is still useful. In most cases if you use a quality large faced Vacuum gauge, with some experience you can effectively tune your car's fuel and timing systems. Tuning with the engine running compensates for wear in the timing gear and valve train, and therefore providing better results than with the manufacturers recommended settings.
Note: All adjustments are made with the transmission in PARK or NEUTRAL, with the exception of Idle Speed, which is set in DRIVE.
Caution: Make all adjustments from the side of the vehicle, rather than standing in front of it.
Vacuum Gage Connection
Connect the gauge to a "manifold" vacuum source, NOT "ported" vacuum, that rises as RPM increases. In most cases this will be a direct manifold source or possibly the PCV port (larger port) on the carb.
Start by first warming the engine and note the idle vacuum reading. Normal vacuum at idle should be 19-21 inches for a six cylinder, or 15-18 inches on a low compression engine. Pre-set the ignition timing so that it is close to the manufactures recommended setting, before making any carb adjustments.
Carb Adjustments
To adjust the carb, start by leaning out one of the mixture screws (turn in) until the gauge as well as the engine begins to shudder. Next bring the screw back towards rich (turn out), while watching the gauge. Stop adjusting when the gauge reaches it's highest reading. Then do the same process for the other mixture screw. After each adjustment is made, reset your idle speed.
Small adjustments are best, and in fact "optimum" carb settings on the vacuum gauge (highest reading) is usually richer than it needs to be. In other words, once the highest reading is reached, back-off (or lean) the adjustment approximately 1/4 turn in. You may have to repeat the process a few times to get optimum results, but it's worth the time and effort.
Note: With a properly jetted carburetor, turning either of the mixture screws all the way lean, should kill the engine. If not, you're too rich! This may require re-jetting, or drilling the primary butterflies to add more idle air. Many of the newer "race" carbs allow you to change Idle air bleeds to fix this.
For carbs with 4-corner mixture screws, you have to take a bit more time. You can also run the engine at a "steady-state" RPM of say, 2500 RPM to double-check your secondary mixture screw settings. Do this with temperament! It takes time to get used to what you are seeing as well as if it is actually helping. Each engine will behave differently.
Remember to rev the engine to clear the spark plugs before taking your final reading and readjust if necessary. When you blip the throttle, the needle should drop to as low as 2, pop back up to as high as 26, and quickly level off in the normal zone.
Ignition Timing
After the carb mixture is set, you can proceed with the ignition timing. Slacken the distributor clamp bolt, and with the engine still at idle, advance or retard the ignition until the highest steady vacuum reading is obtained. Then retard the timing until the vacuum gauge reading drops slightly, approximately one half to one inch. In some cases, you may need to retard the timing up to two inches to prevent pre-igniton (pinging).
Note: If you can't get the reading into the "normal" zone by adjusting the distributor then valve timing is the problem. Timing with a vacuum gauge will normally result in timing that is more advanced than what specifications call for, so you need to be alert for any pre-ignition (pinging) in the engine and adjust accordingly (retard the timing if needed).
Your engine should now be tuned to perfection.
Last edited:
joe27979
Well-Known Member
many thanks for the procedure!
I already have a timing strobe and tacho but continue to have issues so thought I would just try the vacuum route too to see if it threw up any more ideas.
I removed carb base adaptor today and reseated it all without the old hyloma snot the PO had smeared on
as soon as I started it on choke I checked for vacuum leaks around blocks, the entire rear if the carb (mixture screw side) was ice cold to the touch!!
is this the carb icing phenomena ? it's a nice 8degrees outside and she's been inside garage all night!!
I already have a timing strobe and tacho but continue to have issues so thought I would just try the vacuum route too to see if it threw up any more ideas.
I removed carb base adaptor today and reseated it all without the old hyloma snot the PO had smeared on
as soon as I started it on choke I checked for vacuum leaks around blocks, the entire rear if the carb (mixture screw side) was ice cold to the touch!!
is this the carb icing phenomena ? it's a nice 8degrees outside and she's been inside garage all night!!
May well be icing issues you have. My Yamaha 600 diversion was out today and suffered icing until the oil was warm and then a solenoid valve opens to let warm oil through inlet fanimold. I have ridden the bike for 20 years and 128000+ miles so have got to know the icing symptoms. Old air cooled V dubs used to turn the manifolds white with ice.
dominicbeesley
Well-Known Member
It will be cold at first then will not cold and not too hot to touch when engine is up to temp. The spacer thing regulates how much the engine warms the carb. I'd say that is a red herring.
Check for air leaks when hot. I'd put back the timing and carb adjustments to how you set it with the strobe and leave alone, though I would check that the choke is not sticking and that it is snapping fully open. Then I'd try HT leads and coil.
Check for air leaks when hot. I'd put back the timing and carb adjustments to how you set it with the strobe and leave alone, though I would check that the choke is not sticking and that it is snapping fully open. Then I'd try HT leads and coil.
dominicbeesley
Well-Known Member
It's always worth double / triple checking new stuff. New stuff is far more likely to go wrong than something that has been working for a few years....
