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Hi all!!

I have a problem with my morini (...as usual... )

the engine does not revs up...
the engine is very fast, sounds good, have good start when cold/hot,and kilometers per luter of gas are more or less always the same...

but tryng to rev the engine over 6.000rmp is impossible...
the engine simply won't go over... looks like some sort of rev limiter...
the rpm simply stop to increase when reached 6.000
neutral or gear engaged (driving on street) makes no difference...

the alternator impedance measures around 220ohm, it is in good condition
swapped the coils and pick-up with brand new one from deltaprogetti (170 euros)
swapped three different magnet
cleaned carburettors two times and all jets and carb holes with diluent and compressed air but nothing...

timing is good

basically everything works pretty good! but i can't rev over 6.000rpm


what happened?
what to look
what to look again?
guys help me, i love my 501 and i hate to drive it in those condition

many many thanks in advance from italy

Hi elektrobank,

I had a similar problem with my dart once. The problem was caused by some missing parts from inside the airbox- I had replaced the airfilter and had not put the 'flower pot' back over the filter. The bike ran exactly as you described.

If your 501 is the late type it will have a similar airbox. This is quite restrictive, you can remove parts but of course you then need to re-jet. If you have recently had the airbox apart I'd take it apart again and make sure everything is in the right place

morini_tom wrote:Hi elektrobank,

I had a similar problem with my dart once. The problem was caused by some missing parts from inside the airbox- I had replaced the airfilter and had not put the 'flower pot' back over the filter. The bike ran exactly as you described.

If your 501 is the late type it will have a similar airbox. This is quite restrictive, you can remove parts but of course you then need to re-jet. If you have recently had the airbox apart I'd take it apart again and make sure everything is in the right place

Hi Tom!
thank you for the tips, i'll take a look and let you know
many thanks
Gianluca

Solved a small part in the airbox was missed!
found it and fixed everything, the bike runs very well

today i'll upgrade to PHBH30
any info on jets to use inside this carb?

the bike has sito exhaust (less restricted than original)
and gasflowed heads...

any suggestion?

Thanks
Gianluca

Gianluca,

Brilliant, glad that's solved it!

I have phbh 30s on my 501 dart. I have removed the rear half of the airbox and use a foam filter on the stub which used to be up inside the airfilter. I have a vacuum fuel pump off a ducati monster and the engine has a 2+2 cam. The exhaust Is custom but loosely based on the excalibur primary lengths. If you'd like to know my jetting I can dig out the details

morini_tom wrote:Gianluca,

Brilliant, glad that's solved it!

I have phbh 30s on my 501 dart. I have removed the rear half of the airbox and use a foam filter on the stub which used to be up inside the airfilter. I have a vacuum fuel pump off a ducati monster and the engine has a 2+2 cam. The exhaust Is custom but loosely based on the excalibur primary lengths. If you'd like to know my jetting I can dig out the details

this will be really interesting, also some pics will be interesting (if possible )

i have some freeflow exhaust from Sito, gasflowed heads,some work on valve seat, custom cam timing (not easy to traslate in english) and the engine is fresh, new bearings all around, new piston ring and so on...

today i started some work on carbs but at the moment i'm really TOO rich
the engine revs up only w-out the filter... and the front cilynder is usually leaner than the rear one, probably due to the air filter housing...
but i areally need smaller jets (the ones under the atomizer) i have only 102 and 110, really too big...

anyway, let me know your set up i'm really interested

Hi Gianluca,

Okay here are the carb settings on my 501 dart:

PHBH30, open airbox with ITG foam filter.
vacuum fuel pump.
Main jet: 122.
Pilot jet: 40.
Slide: 40.
Needle: X1, circlip in 2nd groove from top.
Atomizer: 262T.
Needle jet: 150.
Choke jet: 50.

I hope that gives you a good starting point.

Photos... no problem. Probably best to send me your email address and let me know what photos you want and I'll take some for you.

Tom