Topic: F2 Hard Cold Start

[Floshenbarnical]

Back again with my woes.

My F2 refuses to kick start 50% of the time when stone cold, as in, at 8am in the morning. Facts:

- Open 4:1 exhaust
- K&N pod filters
- Did valve clearance, cam chain tension, <600 miles ago
- Running 20w50 oil, good oil pressure
- Rejetted from 35/105 to 40/120 with OEM jets
- Bike starts with 1/2 kick when warm
- Bike performs smoothly throughout the RPMs without stumble or hesitation
- Moves like a scalded dog at WOT
- Snappy throttle response, doesn't fall on its face
- Idle stays flat as a pancake and doesn't creep or move
- No inline fuel filter
- Correctly-sized fuel line runs downhill from petcock to fuel inlet without flattening out etc
- If I put the bike in 3rd and go for a jog and dump the clutch, the bike starts and stays started
- Choke operates correctly (removed pod filters to confirm)

Hoping for a prioritized list of things to check. I have the day off tomorrow so am prepared to get stuck in.

Cold start procedure:

1. Turn ON petcock and wait a minute
2. Couple of throttle twists
3. Choke on full, kick.

[TwoTired]

Your carbs have accelerator pumps.  Cold engines need extra fuel.  Choke helps with that.  Try giving the throttle a couple twists in addition to applying choke.  Might also add a bit of throttle while you kick.

Probably should have listed your cold start procedure.

[Floshenbarnical]

I updated my post.

[TwoTired]

When cold, what is your battery voltage with the key turned on?  Low voltage=poorer spark.

Had to chuckle that your posted procedure didn't include turning the key on. HA!  I think that's in the operators handbook.

Anyway, check if your choke plates ALL fully close.  And perhaps more  full throttle twists could help to get the carbs really rich for starting.

With pods and open exhaust, there isn't much extra choke from the filter/box, or back pressure to help with starting.

You made the mods so it wouldn't behave like stock, right?

[Floshenbarnical]

When cold, what is your battery voltage with the key turned on?  Low voltage=poorer spark.

Had to chuckle that your posted procedure didn't include turning the key on. HA!  I think that's in the operators handbook.

Anyway, check if your choke plates ALL fully close.  And perhaps more  full throttle twists could help to get the carbs really rich for starting.

With pods and open exhaust, there isn't much extra choke from the filter/box, or back pressure to help with starting.

You made the mods so it wouldn't behave like stock, right?

I will buy a battery voltage tester and test it. I will also check/ replace spark plugs. I will try more throttle twists - I had been worried about flooding it, but perhaps I'm worrying for no reason.

All choke plates close fully.

I just realized my carbs may need re-syncing. I was a bit naughty and took the carbs back off to adjust float height and didn't resync with vacuum gauges. So I'll do that also.

Had an expert do my ignition timing so I'm confident that's ok.

[Floshenbarnical]

Lol, freezing cold start this morning. THREE FULL twists of the throttle, full choke, ignition ON.

Started with one kick.

Can anyone advise how many turns I should set my fast idle cam to? I forgot to set it when I put the carbs on.

[denward17]

This is from the workshop manual for a K7:

1. Remove the fuel tank.
2. Pull the choke knob out fully and turn
the adjusting screw until it touches the
stopper.
3. Push the choke knob in and turn the
adjusting screw in 2·1/2 turns.
Fast idle speed: 3,0QQ ........ 4,000 rpm