Use of choke when warm starting my 850 with mikuni
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The yaki
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I need to keep the choke on far longer than others recommend from cold. I just changed the pilot jet to a size bigger. I can now turn the choke off earlier but flat spot when opening throttle quickly. Whatever works seems the answer ? Many different answers for different engines ? Roy.
Mart UK
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Also a mk3, but a single 34 Amal mk2. On mine the choke is either on or off, it has no adjustment in between. Cold, I start on the choke, then straight off, it needs throttle to keep running until I get to the end of my lane (400yds). No flat spots. Then ticks over and runs well. Plugs are good.
Stevo
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My ‘74 850 with Mikuni 34 usually starts first kick on choke when cold. Hold it on the throttle 1500 - 2000 rpm, choke off after 5 - 10 secs then will idle if needs be after about half a minute though I don’t like to let it, preferring to ride off asap.
Always cold starts with choke as long as throttle is kept shut.
Always cold starts with choke as long as throttle is kept shut.
My question is when my engine is fully warmed up and I leave it standing for some minutes and then try to start it.
I have found that if I leave it longer than 15 minutes I need to use the choke to start it. Is this what others have found ?
When I use the choke to start the bike (hot or cold) I turn off the choke the moment the engine fires as it runs poorly with choke on.
Dennis
I have found that if I leave it longer than 15 minutes I need to use the choke to start it. Is this what others have found ?
When I use the choke to start the bike (hot or cold) I turn off the choke the moment the engine fires as it runs poorly with choke on.
Dennis
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That is not unusual though I would say after at least 1/2 hour or more. Could not say why.
I took the throttle adjuster screw and fitted a knurled knob which makes turning the idle up or down much easier. Before putting on the choke when hot, I would try a fast idle. When cold I always use a fast idle along with the choke. With in seconds it's possible to turn off the choke and leave it on fast idle while putting on a jacket, helmet and gloves. By that time it's ready to ride.
I took the throttle adjuster screw and fitted a knurled knob which makes turning the idle up or down much easier. Before putting on the choke when hot, I would try a fast idle. When cold I always use a fast idle along with the choke. With in seconds it's possible to turn off the choke and leave it on fast idle while putting on a jacket, helmet and gloves. By that time it's ready to ride.
robs ss
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Without wishing to be a pedant....
I don't have one of those carbs, but it is unlikely to have a"choke" but rather (like a lot of Mikunis) an "enrichment circuit".
As the name suggests, it adds more fuel to the mixture via a different jet system - but will behave differently to a choke.
Personally, I would not worry too much that it requires this circuit to be activated after 15 minutes.
Both my Suzuki Katanas (750 & 1000), which had Mikunis, needed "choke" after 15 minutes in the early 80s.
Cheers
I don't have one of those carbs, but it is unlikely to have a"choke" but rather (like a lot of Mikunis) an "enrichment circuit".
As the name suggests, it adds more fuel to the mixture via a different jet system - but will behave differently to a choke.
Personally, I would not worry too much that it requires this circuit to be activated after 15 minutes.
Both my Suzuki Katanas (750 & 1000), which had Mikunis, needed "choke" after 15 minutes in the early 80s.
Cheers
marshg246
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All IMHO:
The pilot circuit on Amal Concentric, Amal MK2, and the Mikunis similar to the Amal MK2 will all drain back to the bowl over time with the engine not running. Without tickling or the enricher, it is tough to get the pilot circuit refilled when kicking. So, needing to add fuel via the tickler or enricher after several minutes is not abnormal. However, it is easy to overdo it with a warm engine and then be flooded in which case throttle is needed to add air to clear the flood.
Basically, assuming a good ignition system and properly setup carb(s), none of them need any throttle when cold or hot. Adding throttle (less than 1/4 throttle) adds air but does adds little to no fuel - thus making a lean, hard to start mixture. This is true cold or hot.
On the other hand, an e-started will normally spin a warm engine fast enough to not need the tickler/enricher.
The pilot circuit on Amal Concentric, Amal MK2, and the Mikunis similar to the Amal MK2 will all drain back to the bowl over time with the engine not running. Without tickling or the enricher, it is tough to get the pilot circuit refilled when kicking. So, needing to add fuel via the tickler or enricher after several minutes is not abnormal. However, it is easy to overdo it with a warm engine and then be flooded in which case throttle is needed to add air to clear the flood.
Basically, assuming a good ignition system and properly setup carb(s), none of them need any throttle when cold or hot. Adding throttle (less than 1/4 throttle) adds air but does adds little to no fuel - thus making a lean, hard to start mixture. This is true cold or hot.
On the other hand, an e-started will normally spin a warm engine fast enough to not need the tickler/enricher.
Stevo
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My bad Dennis, shoulda read your post properly.
Mart UK
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15mins to 30 minutes / short riding breaks, sometimes needs the choke, but not usually. But, when it does start without choke, it needs a bit of throttle for a stable tick over, for a little while.
Personally, how i approach it is, if it starts, choke or otherwise, I wouldn't worry about it. Just be checking it's fuelling fine through different throttle openings and your plugs tell you you're not over rich or lean.
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If your jetting is correct what you are experiencing is probably what should happen. Best performance occurs when the jetting is almost lean enough to create a miss in a warm motor, when you ride the bike. I usually put the bike on rollers with the enricheners open, and without using the throttle, start the motor and let it idle until it slows slightly, then close the enricheners and give it a rev. If I get a miss, I stop and raise the needles one notch.
SteveA
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That is also the choke design on a Mikuni, it is a fuel enrichment valve, which is either on or off!
Since I have twin Mikunis on my bike, I find that closing the left (right hand busy with the throttle!) and waiting for it to settle a bit before closing the right works better than dropping them both at the same time!
Also allows me to open the left again if it isn't really warm enough!
To answer the OP, no. If it is genuinely still warm, no choke.
Mart UK
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So many variables here, our bikes will each have their own little characteristics. One or two carbs, carb settings (including float levels), fuel specs, timing variables, different ignition systems and advance curves, plugs, cylinder compression... even the weather!
If you've learned it's characteristics (which might be a bit different to the next Commando) and can consistently get it to start and it then runs well once warmed through, seems fine, I'd be happy.
If you've learned it's characteristics (which might be a bit different to the next Commando) and can consistently get it to start and it then runs well once warmed through, seems fine, I'd be happy.
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