Mikuni Carb Settings

[Duccout]

Hi Dan,

I have raised the needle to the max and will give that a try in the week. When I first tried the Mikuni it was far too weak, backfiring through the bellmouth and hardly running, so Motocarb sent me the next richest needle jet and it is better, so I think that I will try the next richest needle jet to that and see what it does. The problem is in the mid-throttle range as tick-over is perfect, and I can gently open the throttle and the engine will pick up OK, but at about a quarter to third throttle it wants to die.

Colin

[Dan C]

Hi Colin,

Mea culpa, I thought you were trying to sort out a starting issue.

I'm no expert on Mikuni jet sizing and nomenclature but from a previous post you mentioned your needle jet size was 169 0-6. My needle jet is a P5 (159 series). Its what it shipped with and as it happens it works on both the 350 and the 450 so i haven't had to change it and hence haven't had to learn the difference between the different options. So I don't know how different that is to yours.

But I can suggest that the needle (6F5) and jet P5 (159 series) combination I'm using works and that it might be worth trying.

Cheers
Dan

[Duccout]

Thanks Dan, I'll look into that. I'm new to Mikuni and the system seems complicated compared to Dell'Orto, but I'll get my head around it.

Colin

[Duccout]

I've just checked and the 5F21/169 combination is for 28mm carbs and the 6F5/159 combo is for 30-32mm carbs, so I think that I'm OK with what I've got, but a richer needle jet is needed.


Colin

[Duccout]

I've just been out for a run with the needle as high as it will go and there was a definite improvement in the cold-start warm-up, so I think that the next number up needle jet will do it. Other than that the engine runs as well as it is possible to get it, and I don't think that it can be improved on that score.

[George]

Sounds like you are getting all set up for the summer Colin. Well done. I went out on the Guzzi 750 today. First start for four months. Perfect. Best tonic for cheering me up. The Ducati saga continues.

[Duccout]

Hi George,

Yes, I know that officially we should not be out, but it is only exercise (all that clutch, braking and gearchange, as well as wheeling the bike about and mental exercise too) and it is great to be out in the warm Spring sunshine. This afternoon I have started painting the outside of the house, in between bike fiddling.

What 750 Guzzi have you got George? I always liked the look of the model that I think was called a Strada, one of the first small block 750 Guzzis.

Colin.

[George]

1994 Nevada with lower handlebars and few other small changes to suit me. Nevada, Targa and Strada engine, frame same with styling changes, seat, bars, tank etc

[Dan C]

Sounds like you're nearly there then Colin. Winner.

I have to say I'm really happy with the VM 30 Mikuni on the 450. It transformed the bike from a hard to start, surging around town, erratic idling, pain in the bum, to an absolute delight for everyday riding.

A couple of weekends ago I rode it to the Taree Classic bike rally, a round trip of 900kms and it ran sweetly all the way, including an altitude change of 3,000 feet. There is a stretch of motorcycling nirvana on the Oxley highway between Walcha and Wauchope (I think it was road made especially for Ducati singles....) which the 450 just reveled in. I don't have the words to describe what a blast that ride was....!

Cheers
Dan

[Duccout]

I love it when a plan comes together!