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Have a big block 200 Mugello, 25mm dellorto, MB/BGM big bore, when started runs & ticks over nicely, but left overnight it is very difficult to start in morning, recently rebuilt new seals etc. I must admit have not finally jetted in carb, but the carb was ok on a MB RT kit 195/200, 98 m/j 53 pilot 60 choke, any ideas ?

Does it start ok if you hold your hand over the carb mouth? if so it would indicate that the choke is not operating properly. I had a similar problem on a TS1 which turned out to be the cable nipple had come out of the recess in the chock lever

Also, always keep the throttle closed until it fires up, don't wring the throttle whilst kicking.

air leak?

Slack choke cable

As far as I can see the choke is working correctly, would a bigger choke jet help

Do you turn your fuel off over night?

Yes

TS1-200 wrote:As far as I can see the choke is working correctly, would a bigger choke jet help

Have you tried pulling choke on by pulling the cable by hand rather than flipping choke switch. Slight bit of slack in cable may not be lifting plunger up enough, when cold.

try a 70 choke jet.

might be worth checking the timing ? do you know the settings ?

18 deg. BTDC, the choke is lifting ok, it clears the hole, will try a 70 choke jet

Make sure you only have one type of ignition suppressor fitted. Either the plug cap or the plug itself but not both.

It should start ok with those jets.Have you any idea what the atomizer and needle are.I have a Casa 210 on a big block with a Dellorto 25mm PHBL carb and that starts from cold with 1 or 2 kicks.Mine has 98 main,47 pilot and 60 choke with an AQ268 atomizer and a D29 needle.Mine runs a Scootopia Ancillotti.It runs through an undrilled airbox with a standard filter.

Plug gap too wide?

Is the petrol old. Long shot I know, but the unleaded sold nowadays does not store well, causing difficult starting issues.

^... LIKE both of the above.

If this isn't a new kit, what was the ring gap like, too big may cause bad starting.

Looks to be sorted, there was a small amount of slack in the choke cable, as mentioned above, although the choke plunger went to the top of the hole, I have adjusted the slack out(well most of it) as I do like to make sure that the plunger seats properly when choke off, wouldn`t have thought it would have made a difference, but it has, thanks for all your suggestions

Glad you got it sorted.