Flat spot 4-5000rpm

The Cagiva era Morinis
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chippit
Posts: 67
Joined: 06 Sep 2009 17:03

Flat spot 4-5000rpm

Post by chippit »

Hi, the on going saga,
The tacho turned out to be a broken pin on the angle drive, now mended thanks to NLM.
I have been trying to get the dart to go a bit better, here is a list of what I have done so far;
Main jet 112
idle jet 45 (as standard)
needle height 2 (from lowest setting)
flower pot removed (but filter housing not cut down)
emulsifier 260u
The exhaust has a 'y' piece instead of the collector box
Original silencer but with little if any of the baffle remaining
The timing is slightly advanced to get the timing mark to line up on the 350 point (not the 500)Still a little way towards 500.
The carbs are balanced using a morgan carb balancer (very useful bit of kit) and mixture set
I just can't seem to get rid of a flat spot 4-5000rpm
The engine picks up beautifully from tick over and then revs freely above 6000 rpm with rapid throttle responce.
I have tried 115 jets with needle clip in position 1 and 2, the best I managed to get it was with 115 jets with the needles set right down but still is was flat between 4-6000rpm

Any help would be very useful
Thanks again for all your advise Christine
Emmohaswheelsagain
Posts: 358
Joined: 28 Jun 2008 21:13
Location: Lincolnshire

Re: Flat spot 4-5000rpm

Post by Emmohaswheelsagain »

Hi Christine,

I can't offer you a solution only to say that I suffered the same issues when I first picked up my Strada from NLM.
It flew above 6000 rpm but was less than happy between 4000 & 5000 rpm.
For many of course this is not a problem as they only ride with the needle pushed against the red line but there are a few of us who prefer the bike to be smooth all the way through the rev range. Anyway a revisit to NLM and a good deal of tweaking achieved the result I wanted.
Keep trying and you will get there.

Regards

Paul

You could always bring your bike to track day next year, a few laps of Cadwell might just cure the problem :D
Ejvin
Posts: 3
Joined: 20 Feb 2012 17:35
Location: Denmark

Re: Flat spot 4-5000rpm

Post by Ejvin »

Hi,
I am new to this forum.
I have had my Dart for a few years, and it has this very same flat spot from the very beginning.
Have you found the cause for this flat spot?
Mine has had the same cure as Paul suggested, to improve breathing. I use 115 jets and the rest is unchanged.
I have build my own mufler, reusing the alu-cans, so keep the original look - (Not that my Dart looks anything like original - but very much like a Morini, I hope)
Anyway, regardles of using the original mufler, or my own straight through, it still has this anoying flat spot.

Any suggestions would be more than welcome.

My Dart can be viewed on Sorens website: http://morinist.dk/morini/ejvin.php

Cheers

Ejvin
chippit
Posts: 67
Joined: 06 Sep 2009 17:03

Re: Flat spot 4-5000rpm

Post by chippit »

Hi Ejvin,
I took the Dart to NLM in the end and got them to fit a new timing belt and set it up as I didn't know how many miles the old one had done.
Turned out the timing was a tooth out. It has 260u emulsifier jets and 112 mains with a cut down flower pot and it runs beatifully now, thanks Alex.
The revs tended to hang up a little so I just dropped the tick over slightly and it is spot on now.
Looking forward to the better weather.
Regards Christine
nickst4
Posts: 185
Joined: 31 Oct 2011 06:55
Location: Diss, Norfolk, UK
Location: Norfolk

Re: Flat spot 4-5000rpm

Post by nickst4 »

Hi Ejvin,

I like your Dart's paint-scheme, but question the white ovals which really don't suit the aggressive angularity of the rest of it. Superb otherwise but ditch the ovals! :D

Nick, UK
Ejvin
Posts: 3
Joined: 20 Feb 2012 17:35
Location: Denmark

Re: Flat spot 4-5000rpm

Post by Ejvin »

Thanks for your quick replyes.
My timingbelt is about 4000km old, and it is close to the 6mm limit, so I will replace it.
Checked the timing just now, and it is timed correct :)
Awaiting warmer weather, to see if the new timingbelt will cure it.

Regards Ejvin
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