low to mid range flat spot

[70sbikes]

What model are they please

VM28's (probably a bit bigger than necessary, but re-jetting isn't that difficult). You also need the "top hat" type plastic/metal insert that goes into the carburetor mouth to allow them to be mounted to the standard Morini rubbers (I bought aluminium ones from NLM, and had to cut off about 10mm so an air passage wasn't blocked). K&N filters aren't cheap either...

[barney 66]

Great Thanks for the reply and pictures, I will decide end of the Summer if it’s a keeper or not, actually fancy a 500 Strada, as well
Thanks barney

[mad muller]

I know you said you have checked the timing, if you have a stobe light ,see if the advance is working when you rev the engine , just a thought as all the carb issues have been covered , you should see the timing marks move away from each other upto 6k then full advance , you prob may have tried this .

[barney 66]

I am going to try it again Tomorrow, was busy yesterday and Today, I did also find that my fuel tap wasn’t opening properly when I came to drain the tank

Thanks barney

[barney 66]

I know you said you have checked the timing, if you have a stobe light ,see if the advance is working when you rev the engine , just a thought as all the carb issues have been covered , you should see the timing marks move away from each other upto 6k then full advance , you prob may have tried this .

Sorry never actually answered your question, yes timing spot on and advances fine, also put new plug wire on yesterday and ordered new plug caps
Thanks barney

[3potjohn]

And make sure to have both taps open. Is one the electric variety? A good flow is very important as us old chaps know.

[barney 66]

Yes one is the electric,I will hold my hand up and say I have only had the electric tap on while riding, but will do what you have suggested Tomorrow
Thanks barney

[barney 66]

Ok update on this, out again this morning following my mate 25 mile round trip (ran out of time for an appointment)
maybe very slightly better but still very much there same revs and it almost stutters if you hold it between 3-5000rpm like it’s missing, wack throttle open fast it’s fine up to red line, got back put timing light on it again and at the rpm the problem is the timing light also goes erratic, have only done this on front cylinder, seems worse when warm have put new leads on
any more ideas please ?

Thanks barney

[MickeyMoto]

Buy a Honda?

[barney 66]

I did 8 weeks ago, sold it to my mate 6 weeks ago,

If that’s how they are and it’s something I have to live with then fine, if there’s something wrong I need to put it right
Thanks barney

[George 350]

A very large contributor to this mid range flat spot is the Sport cam. It has a very large amount of overlap and a significantly late inlet valve closure point. This causes significant intake pulsation, which is why it goes so rich.
As has been said before, Strada's don't do it to any great degree as their cams are so much milder.
It is also one of the reasons why many consider the 'M' cam the best compromise on the 350's. It is sportier than the Strada but not as extreme as the Sport.
If you do decide to keep the Sport, before you decide to spend a good amount of money on Mikunis, have a look at getting an M cam instead.
Regards,
George