3.5 Sport stalling

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Tim Louth
Posts: 70
Joined: 23 Mar 2018 12:29
Location: Fareham, UK

3.5 Sport stalling

Post by Tim Louth »

I have a Morini 3.5 Sport that I have restored over the last couple of years.
I have it almost finished now and tried to take it for it's first run today.
It starts and idles really well but as soon as you let the clutch out to pull away it stalls.
On the centre stand you can run it in gear and go through all the gears and it will run with a bit of 'brake load' but as soon as you try to ride it it stalls on clutch release.
It will pull away, over a very small distance anyway, if you really rev it and release the clutch very slow.
I have re -checked the carbs and they seem okay. They had a really good clean during the build as well.
I have re-checked the ignition, bang on ANT.1.
Nothing much has been changed since I got it in the way of carbs/jets and the previous owner did use it regularly before he passed on I believe.
I don't suppose you guys have come across this before and might have any suggestions for possible causes.
Many thanks.
norbert
Posts: 750
Joined: 15 May 2007 15:15
Location: Lübeck/Germany

Re: 3.5 Sport stalling

Post by norbert »

Have you had a look at the clutch, wether there is mounted a bounded steel plate and how the grooves of the clutch center are?
Tim Louth
Posts: 70
Joined: 23 Mar 2018 12:29
Location: Fareham, UK

Re: 3.5 Sport stalling

Post by Tim Louth »

Hi,
I think the clutch is okay. Most of it was replaced anyway.
It runs okay on the stand and also with a little brake load.
mbmm350s
Posts: 666
Joined: 22 Jun 2018 10:18
Location: Reading UK
Location: Berkshire UK

Re: 3.5 Sport stalling

Post by mbmm350s »

Is it drum brake rear. Is the torque reaction rod fitted correctly.
Mark
Tim Louth
Posts: 70
Joined: 23 Mar 2018 12:29
Location: Fareham, UK

Re: 3.5 Sport stalling

Post by Tim Louth »

No, disc brake rear.

I have checked and re-checked pretty much everything so I need to give it another go out on the road as I have been told they need a bit of throttle to get moving due to engine design.
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Ming
Posts: 798
Joined: 01 Aug 2014 16:32
Location: France
Location: Central France

Re: 3.5 Sport stalling

Post by Ming »

Tim Louth wrote:... give it another go out on the road as I have been told they need a bit of throttle to get moving due to engine design.
I was about to say - I find I need to give mine a bit of throttle / clutch feathering as it stalls fairly easily. I think someone once said that they need to be ridden like a 2 stroke! :roll:
Tim Louth
Posts: 70
Joined: 23 Mar 2018 12:29
Location: Fareham, UK

Re: 3.5 Sport stalling

Post by Tim Louth »

WILL GIVE IT ANOTHER GO NEXT WEEK WHEN I AM OFF WORK.
Guilllaumeee
Posts: 2
Joined: 23 Oct 2021 18:52
Location: Paris , France

Re: 3.5 Sport stalling

Post by Guilllaumeee »

Hi everyone,

I'm sorry to update this discussion which is a bit old but I have exactly the same problem with my 350 sport (drum brake on mine).

I have revised the carburetors, replaced the clutch plates etc. nothing helps, it keeps stalling when releasing the clutch (but on the center stand no problem).

Have you found a solution since? I saw that above you mentioned a "torque reaction rod"? Where exactly is it located?

Thank you very much for your help, I've been lost for months..
morini_tom
Posts: 919
Joined: 05 May 2006 13:47
Location: Northampton

Re: 3.5 Sport stalling

Post by morini_tom »

I own this bike now and the stalling problem is sorted. To be honest after buying it I did quite a lot to it before I even attempted to ride it, but as far as I know Tim resolved the stalling issue.

I think Tim said the issue ended up being that the balance pipe between the carburettors (the one on the engine side of the carb) had a tiny split in it, which wasn't immediately obvious. Your bike being a drum sport proabbly doesnt have a balance pipe though. Still worth spraying some colstart spray or similar around the inlet menifolds at idle- any change in engine runing would signify air (and therefore the coldstart spray) being drawn in.

Other than that, Tim checked and double checked everythign and I'm not aware of anything else he found. When I bought the bike I stripped and rebuilt the carbs, finding a few issues there but mainly one of the needle jets wasn't properly seated on its fibre washer.

I also rewired quite a few bits, including completely stripping the fusebox and re-riveting many of the terminals, and replacing the ignition switch as they were making intermittent contact. This helped cure intermittent misfires I had but as I said, the stalling issue was never there.

The torque reaction rod mentioned was not relevant to Tim's (my) bike because being a disc model there isn't one, but on your bike it's the metal rod which bolts to the rear brake plate and runs I think below and to the front of the swingarm. Its there to react the torque generated when the brake is applied, which would otherwise rotate the brake plate. If it's not installed right then perhaps its allowing the brake plate to rotate and apply the back brake?

It is worth making sure that the clutch plates are releasing properly. A worn clutch basket or hub could cause the plates to bind. Check for grooves worn in the splines and replace or file them smooth. Also, uneven clutch spring pressure can cause the cluth to not lift square. Check the springs are all the same length and the cups/nuts done up to the same tightness (they dont need to be mega tight!)

Be absolutely sure you are pulling away in first! It's not unheard of to have a false neutral caused by improper gearbox or gear linkage setup that causes you to think you're pulling away from 1st when you are infact in a higher gear. next time the stall issue happens, before trying to do anything else, put the bike on the centre stand and count the gears up and down to make sure you were definitely in 1st when it happened.

And finally, when you ride with a group of morinis you will notice many seasoned morini riders do tend to give a bit more throttle when pulling away. I tend to raise the revs a bit and then modulate the revs as I feed the clutch in, almost like you might a 2 stroke. I don't even think about it when I do. They dont need mega revs to pull away but they're not 900cc V twins don't forget.
Vitesse
Posts: 218
Joined: 05 Jan 2019 13:42
Location: Barnacle
Location: Crowcombe

Re: 3.5 Sport stalling

Post by Vitesse »

morini_tom wrote: 16 Jan 2022 15:58
Be absolutely sure you are pulling away in first! It's not unheard of to have a false neutral caused by improper gearbox or gear linkage setup that causes you to think you're pulling away from 1st when you are infact in a higher gear. next time the stall issue happens, before trying to do anything else, put the bike on the centre stand and count the gears up and down to make sure you were definitely in 1st when it happened.
I had this exact problem on my Kanguro. Couldn't get it to pull away - only to find that the linkage was on upside down and I was in 2nd or 3rd!
Guilllaumeee
Posts: 2
Joined: 23 Oct 2021 18:52
Location: Paris , France

Re: 3.5 Sport stalling

Post by Guilllaumeee »

morini_tom wrote: 16 Jan 2022 15:58 And finally, when you ride with a group of morinis you will notice many seasoned morini riders do tend to give a bit more throttle when pulling away. I tend to raise the revs a bit and then modulate the revs as I feed the clutch in, almost like you might a 2 stroke. I don't even think about it when I do. They dont need mega revs to pull away but they're not 900cc V twins don't forget.
Thank you very much for your reply! After months of trouble, my Morini 350 is running very well again! :twisted:

Your message made me recheck different things and realize that :

1. Although I had replaced the clutch disks, I made a mistake when I mounted it: the smooth convex clutch disc was not placed in the right order (on my model, it is the last one to be inserted, not the 1st one)
2. I disassembled and reassembled the carburetors, I had a problem with the throttle cables, which I replaced again and re-set

Thanks again!
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