GRiSO 8v problem, one cylinder (randomly?) cuts out

Will give that a try. I was told to lubricate the solenoid, so sprayed a fair amount of ACF-50 (its an anti corrosion lubricant) in it 2 months back when I took the starter apart. Come to think of it, the click-no start issue has actually become worse since then. What would be the best way to clean the solenoid, spraying it with brake cleaner?

The yuasa battery is new so I assume its good, though that is of course no guarantee. I did fill it myself, following the correct protocol of letting it rest before charging etc.

Sigh. Lubricating a solenoid is a disaster waiting to happen. Oh look, it happened.

Whoever told you to do that is a moron.


Never, ever lubricate a solenoid. Remove the starter, dismantle the solenoid and clean thoroughly. Scrape any loose paint or detritus off and assemble dry.


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Like Beetle says, clean it real good, leave it dry. Others who are not from the industry often recommend lubrication of solenoids. Unfortunately, that act out of ignorance and then propagate to other victims - this does no good at all.

Solenoids with lubricant applied "attract" shit and debris, turning it into grease - guess what happens to the solenoid action when you stop it moving freely? Yes, you blow a fuse because it does not move as quickly as it is designed. Hence you problem, Timothy.

Pure alcohol is good...

Right, I'm not 100% certain its the (only) issue as the 15amp starter fuse has been blowing for a year now, well before I lubricated the solenoid. But to be safe I'll remove and clean the solenoid. Thanks.

I would be realy relactand installing a (any) fuse bigger sized that the one originaly designed. The wire size determines the fuse size. Same aplies to the fuses used on buildings etc...

Note, the 15A automotive fuse (littlefuse ATOF series blade fuses datasheet) can withstand 16.5A for at least an hour(!!), 20.25A for up to 10minutes, 30A for up to 5sec, 52.5A for up to 0.5sec - I bet the solenoid wire is undersized for that current (or the fuse is already oversized for the wire).

The undersized wire (and any bad contact), creates voltage drop, so the solenoid gets lower voltage, thus draws more current, that creates even more voltage drop, and so on, untill the fuse is blown.

I do remember, occuruner posted here in gheto, a note he found from Guzzi, telling to unplug and isolated the solenoid wire, from both the solenoid and relay, and route and connect a new wire, that should have cross section 2,5mm^2

avgpetro wrote:

I would be realy relactand installing a (any) fuse bigger sized that the one originaly designed. The wire size determines the fuse size. Same aplies to the fuses used on buildings etc...

Note, the 15A automotive fuse (littlefuse ATOF series blade fuses datasheet) can withstand 16.5A for at least an hour(!!), 20.25A for up to 10minutes, 30A for up to 5sec, 52.5A for up to 0.5sec - I bet the solenoid wire is undersized for that current (or the fuse is already oversized for the wire).

The undersized wire (and any bad contact), creates voltage drop, so the solenoid gets lower voltage, thus draws more current, that creates even more voltage drop, and so on, untill the fuse is blown.

I do remember, occuruner posted here in gheto, a note he found from Guzzi, telling to unplug and isolated the solenoid wire, from both the solenoid and relay, and route and connect a new wire, that should have cross section 2,5mm^2

Yes its a little scary putting higher amp fuses in. And I'd be extremely reluctant to put any fuses higher than 30amp in for sure. However I noticed most electric components in the bike and specifically the starter relay is rated to 30amps. So as long as the fuse stays below that it should be fine unless the wires are very thin.

About the wire to feed the solenoid, I read the same thing. However in my case I believe this is already done by the previous owner in an attempt to fix the starter issue. I believe in my case the solenoid being either sticky or simply failing for some other reason is the problem.

I will attempt to dismantle and clean it, but I already saw that this is quite difficult and requires removing/reapplying some soldering etc. so I'm also looking into a potential replacement in case I won't be able to get it to function again. Thankfully they aren not very expensive. However I have no idea which solenoid would be appropriate for the Bosch startermotor in the GRiSO.
For example would this one do? [You must be registered and logged in to see this link.]

Have a chat with [You must be registered and logged in to see this link.]. He posted a strip-down of his starter here: [You must be registered and logged in to see this link.]

I will attempt to dismantle and clean it, but I already saw that this is quite difficult and requires removing/reapplying some soldering etc. so I'm also looking into a potential replacement in case I won't be able to get it to function again. Thankfully they aren not very expensive. However I have no idea which solenoid would be appropriate for the Bosch startermotor in the GRiSO.
For example would this one do? [You must be registered and logged in to see this link.]

First of all let me say I am no expert on this but I can tell you what seems to have worked for me,

To dismantle the starter and solenoid for cleaning and greasing you don't need to unsolder anything. If you strip the starter and clean and grease the gears and mechanism of the starter first.Then clean up the plunger and body on the  solenoid with some steel wool or wet and dry soaked with WD40 to remove any burrs, then completely dry it off with some tissue before reassembling is all that is needed.

But this only solved the problem for a while and as others here have pointed out you need to increase the fuse from a 15amp to a 20amp fuse (I know it goes against all reasoning but works) as it helps compensate for any split second lag in the solenoid action. I have a 20 amp fuse in the direct feed from the battery to starter relay (well documented startus intruptius fix) and it hasn't blown in a year.
Just take some pictures as you strip the motor and you should have no problem reassembling, good luck

Okey, currently in the process of cleaning it. Solenoid plunger is now clean, moving on to the starter motor itself. Should I lubricate the gears of the starter motor or are they supposed to be dry? If so, what lubricant should I use, ball-bearing grease? WD-40/ACF-50? Oil?

I also noticed the big gear inside of the GRiSO which the starter motor engages is quite rusty, and moving it takes both of my hands and a fair bit of effort. Its also completely dry. Should I grease that gear as well as I can or is it supposed to give so much resistance?

First clean all gears and mechanism and then grease with some good quality grease. I used waterproof grease that is used on bearings etc.

The big gear that you speak off is the flywheel and if you put grease on this, it can get on the clutch and cause it to slip. You can get away with putting a very small coating of molybdenum grease on the starter gear (a tiny bit painted on) and flywheel but it is probably safer to leave it dry.

And yes, the flywheel is supposed to have this resistance.

Clear, thanks!

No, do not put any grease on the starter pinion or ring gear.

Alright, I'm calling it a cautious win. After reinstalling it gave one 'click' on the second attempt to start it, so I took it out again. Tested the solenoid by connecting it directly to the battery & the frame. It engaged perfectly every time. Then I tested the starter and it too worked perfectly.
Reconnected it, and after starting it 10+ times it started 100%. Then I replaced the 25amp fuse with the intended 15amp fuse, started it another 10 times or so and it still started 100% of the time and without blowing the fuse.

So I'm hoping the one 'click' was a flux due to misalignment of the gears or something, at least it doesn't seem to be related to the starter motor. But the bike no longer blowing 15 amp fuses (it used to blow one almost every start attempt) is a good step in the right direction.

If the click-no start does return, what would be the next logical step to check now that the solenoid and starter motor itself are clearly functioning well? I did purchase a new starter relay but I haven't installed it yet. Could a worn or sticky relay result in an occasional click-no start? Or a broken cable that occasionally comes loose enough to cause the click?