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Having just got my 500 running, I'm interested in any advice on jetting. I haven't actually ridden the bike yet, other than up and down the cul de sac where I live, but my impression is that it's generally a bit on the rich side. The pilot jet is 52 and although I can get excellent idling, I think it is tending to bog down a bit coming off idle. I'll get a better idea when I can ride it properly - I'm hoping to go for MOT later this week. I had to replace the choke jets, which were badly corroded and the originals were 48, a size which is no longer available. I have put in 45 and they seem fine, it starts very well and runs well on fast idle for a good while before it starts to splutter. The main jet is 125 and the atomiser is 262T - of course I don't know how those are performing, but I'd be interested in anyone else's experience.

Foot pegs!! The gap between the right hand foot peg and the gear pedal is 12cm, centre to centre and it's a bit too tight to get my toe under the pedal to change up. I'd really appreciate it if someone else could check the gap on theirs. I've tried raising and lowering the footpeg and I can find a spot where an up-change is OK, but then I have to lift my foot off the peg to change down, I can't win! It's not the end of the world, but I can see myself having to make a new gear pedal.

Hi, my 500 5 speed Morini had the following jetting etc

Pilot 45
Main 125
Starter 48
Atomiser 264T
Needle X1 3rd groove
Slide 40

Along with the standard air box and exhaust it ran well and usually started first kick.

Yet most 500 6 speed engines I've serviced have had 264CE Atomisers and some had X8 Needles along with 42 or 43 Pilots.
I've also seen 264T and BC264 Atomisers in 500s.

Many thanks for the information! I am away for the weekend on the Morini 500 and learning a lot about how it goes in the process. A 45 pilot jet sounds about right to me. The 52 jets which I have are a bit too rich and I think this is causing a significant stutter coming off idle once warmed up. It's OK when cold or half warm. I never made a note of the needles, so I need to check that and I'll try to figure out the difference between the different atomisers mentioned.

Just before I left home on Friday I fitted new O-rings on the dipstick. This was because the originals had gone hard and it was very difficult to re-insert the dipstick. Well the new ones are too loose and the result is oil everywhere, what a mess. I now have the dipstick jammed in with plastic insulating tape and that seems to have cured it for the time being. I shall be going carefully through my O-ring collection for something more suitable when I get home! What a pain!

But what about the mayonnaise ? Though unless you have clear breather tubes I suppose a quick status check isn't practical whilst away.

72degrees wrote:But what about the mayonnaise ? Though unless you have clear breather tubes I suppose a quick status check isn't practical whilst away.

Well! It's a lot better. The bike has been experiencing an "Italian tune-up" continuously for the last 3 days, largely because I've been riding with my friend on his Norton Commando, which has about a 20bhp advantage, and the roads around here are just lovely.

The mayonnaise has been better every day until today I can't really say I can see any in the transparent pipes - that is the two pipes from the collector to the air cleaners and the big pipe from the crankcase to the collector. Also, the bike has been going better and better with use, apart from the one issue with hesitation coming off idle or off over-run when fully warm. I am very hopeful that smaller pilot jets will solve that - it feels like bogging down rather than a fuel starvation thing. Anyway, room for a bit of experimentation there I think. Apart from the oil being lost around the dipstick (sigh!) it hasn't used any oil and it seems to be doing about 65mpg, even with fairly "spirited" riding. For a 40 year old bike I'm pretty happy with that.

I'll try to post a more comprehensive report when I get home.

Regards to all,
Joe.