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Discussion Starter · #1 ·
Hi All;

I recently bought a Benelli TNT 1130 cafe racer which had been standing still for more than 2 years. Bit of a basket case - although the owner did say that it was running when he put it away.


I've cleaned all the contacts and installed a new battery. When starting the bike the engine turns over very slowly....


Please see this link: https://onedrive.live.com/?id=EAF275C2B7921083!103&cid=EAF275C2B7921083 to video I made when trying starting the bike.


After googling I've come to the conlusion that it (might) be the dreaded sprag clutch?


I am right in assuming this?


Are there any Benelli guru's out there that can point me in the right direction?

Kind Regards
Frank
 

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Hi ..
Just watched your video.
I'm pretty sure that is not a sprag clutch issue.
You'd hear a dreadful mechanical noise .
To me it could very well be a fueling issue, you can hear the bike almost wanting to start .
Yes it does seem a bit slow turning over that could be anything from the battery being too low an ampage , battery cables need upgrading or the starter motor needs a service or replacing.
It could be something else but I'd look at the battery /starting circuit first.
Well done on rescuing another Benelli !!
 

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Your sprag clutch is fine as far as I can hear.
It IS trying to start.
Check the battery voltage at the solenoid while you are cranking it. I wouldn't mind betting it is less than 10V.
Double up the positive battery cables to the solenoid.
Shorten the cable from the solenoid to the starter. On my Tornado it was twice as long as it needed to be.
Add a second negative battery cable to the back of the engine. The crankcase breather box is a good point.
Get your battery tested (even if it is new). 400 Amps is ideal. 250 will struggle. Lithium batteries are best.
There is a gear set from the starter to the sprag clutch. It was replaced with a lower gearing to make it easier to crank in later 1130's. It's a pain to check but if all else fails .....
 

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Discussion Starter · #4 ·
Well;

checked all the wiring again;

cleaned and sanded the earth; checked the starterrelay/solenoid (its working)... hmmm

run 12v DIRECTLY on the startermotor - it still cranking at the same speed!!!! (see video)

So it looks like its the startermotor??? Am I correct in assuming this?

Strange - never had this before - mayby oxidation built up inside the startermotor?
 

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Discussion Starter · #6 ·
So what is the voltage at the starter side of the solenoid when you are cranking?
Im not realy sure if I measured this correctly - can you perhaps explain how to do this properly...

for instance; which side(canble) of the relay should I measure?

Kind Regards
 

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Hi Frank and welcome to the site. I had a friend with a TNT that sounded very similar whilst cranking. I doubled up the leads, swapped starters, checked relay, all the things you have done. I even retarded the ignition timing a bit more at cranking speed, as it appeared to be kicking back a bit. Eventually, all of a sudden, the sprag clutch let go completely and engine wouldn't turn at all. It was like the starter motor was turning fast enough but the sprag clutch partially slips making it appear that the engine isn't turning fast enough. Its not such a huge job to fit a new one, as long as a few precaution are taken. Nigel.
 

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.. which side(canble) of the relay should I measure?
Measure as close as you can get to the contact on the starter motor. that way you see the drop due to the battery internal resistance, the cables and the solenoid switch.
If you only see, say, 9V at the starter, work your way back, taking measurements at each junction. If you see a major increase, the problem is just downstream.

I'm still putting my money on the battery, but it could be anything, including the sprag clutch as Nigel points out. I haven't seen a sprag clutch act like that. Generally they grip or they slip, not half way between, but hey, this is Benelli. Anything is possible.
 

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Discussion Starter · #9 ·
Measure as close as you can get to the contact on the starter motor. that way you see the drop due to the battery internal resistance, the cables and the solenoid switch.
If you only see, say, 9V at the starter, work your way back, taking measurements at each junction. If you see a major increase, the problem is just downstream.

I'm still putting my money on the battery, but it could be anything, including the sprag clutch as Nigel points out. I haven't seen a sprag clutch act like that. Generally they grip or they slip, not half way between, but hey, this is Benelli. Anything is possible.
I've tried 3 different batteries - the original one, a new one (yuasa) and a lithium one - so I can safely rule out the battery.

I will measure the voltage drops all the components again - just to make sure.

BTW does anybody have experience in replacing the sprag clutch?
 

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I've tried 3 different batteries - the original one, a new one (yuasa) and a lithium one - so I can safely rule out the battery.
Not necessarily.
Did you get any of them tested?
Like I said, a 900 needs more than 200A to spin it over hot. An 1130 will need more.
If your test shows at least 300A, I would rule out the battery.
 

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Hi.
Have you taken the starter out yet to test how fast it spins away from the engine ?.
I'm almost certain it's either the cables from the battery ( if good ) or the starter itself. My starter need a new denso carbon brush set.
Please don't rule that out before you dig deeper as it only costs about £25 to change but could save you hundreds !..
 

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It sounds like it’s spinning fast enough to start?
I’d check you haven’t fouled the plugs from flooding it. Doesn’t even sound like firing.
I have read on here that if your battery dies and the Voltage is low enough.... it can throw the sensor settings out and need to be reset with an ECU tune.
I just bought a CR the other day and going through the same thing.
After cleaning the plugs up it starts straight away but then over fuels and dies in minutes.
From then on it just cranks over like yours.
 

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Discussion Starter · #14 ·
Ok its been a while - life, ducati 748 (now crashed - another project shortly) and Covid got in the way. Summer is coming and still not starting...

Took the startermotor out and had it checked - its fine - and the advice was to get a new starter solenoid. Bought a version from yamaha which should work apparently (remember to switch the cables!!!)

Also bought the exact start kit for the cafe racer - not installed yet.

And now faced with elecktrickery - so - simple question: is there a (short) cable running from the alternator to the startermotor?

I have simply forgotten (alzheimer + korsakov) ...
 

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simple question: is there a (short) cable running from the alternator to the startermotor?
Simple answer: No

Longer answer:
The heavy cable from the alternator goes direct to the battery, definitely NOT the starter motor.

There are 3 big heavy cables to carry the starter motor cranking current.
1. From the battery positive terminal to the starter relay (The alternator cable can connect to the starter relay end or elsewhere on this cable. Perhaps that's where your confusion arises)
2. From the starter relay to the starter motor
3. An earth return (or ground or negative or 0V, whatever you prefer to call it) cable from somewhere on the engine or frame of the bike to the battery negative terminal.

The starter motor itself gets its earth connection via the body of the motor, through the bike's engine castings, to the frame and then back to the battery via a heavy earth cable.
I don't know where the battery earth (negative) cable attaches on your bike (I can't even remember where it attaches on mine), but it's very important that it makes a good earth connection. If it's on the frame, scrape off any paint or corrosion so you have clean shiny metal before bolting it on. A dodgy earth connection could indeed be the source of all your starting problems.

An important thing to remember is that you should disconnect the negative cable from the battery while you're fiddling around with the positive side. If you don't, the chances are pretty good that you'll be zapping sparks off things with your spanner when bolting up the positive cables. The negative connection to the battery is the last step in the process after everything else is done. Even then, just touch it briefly on the battery terminal to make sure it doesn't create sparks. If no sparks, bolt it on firmly and test the starter system. If the negative cable sparks on the negative battery terminal, then you've got a short circuit somewhere in the bike's wiring.

Given that you don't know how a starter motor is connected, I sense that your knowledge of things electrical is somewhat rudimentary. In your case it might be wise to get someone who knows about electrical stuff to come and have a look at your bike. You might be missing something that someone more knowledgeable will pick up. I'm not trying to be insulting or derogatory. It's just that a bit of mentoring from someone with knowledge and experience can accelerate your own learning and avoid any expensive stuff-ups. If you inadvertently create a short circuit with big heavy starter motor cable, things can go bad very quickly.

Good luck,
Cam
 

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Discussion Starter · #16 ·
Hi Cam;

Thanks for your explanation - its becoming clearer. I havent installed the battery yet so I am still (relatively) safe!

//I'm not trying to be insulting or derogatory. - no offense taken - I know my limits! I will have somebody come and have a look!
 

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Discussion Starter · #17 ·
Hi Cam;

Thanks for your explanation - its becoming clearer. I havent installed the battery yet so I am still (relatively) safe!

//I'm not trying to be insulting or derogatory. - no offense taken - I know my limits! I will have somebody come and have a look!
BTW: Im watching this:
 

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Discussion Starter · #18 ·
Well I had a pro and come and have a look - he cleaned the cables from the batt to the starter/solenoid and the startermotor is spinning up nicely now.

BUT no start - some pops and bangs - it looks as though it wants to start. No fuel? Injectors buggered? Green lights in display indicator flashing - why??? What about spraying some starting fluid into the airbox?
 

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Well I had a pro and come and have a look - he cleaned the cables from the batt to the starter/solenoid and the startermotor is spinning up nicely now.

BUT no start - some pops and bangs - it looks as though it wants to start. No fuel? Injectors buggered? Green lights in display indicator flashing - why??? What about spraying some starting fluid into the airbox?
My R160, which hadn't been running for some time was poping and banging, so I fitted a new set of spark plugs. Now starts fine. Nigel.
 

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Discussion Starter · #20 ·
The saga continues .... I had a look at the stepper motor - its is simply not moving at all when the ignition is switched on. Just stays in the "closed" position; cleaned and stripped the rotor etc. Still no movement at all. I suppose this means a new stepper motor??? - is there another reason why the motor wont move?
 
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