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Jimyacky

Montesa 4rt repsol 2018 splutter fan problem?

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Hi, I’ve just been getting a 2018 repsol which is practically new. Rode for about 8hours absolutely perfect. Then developed a bit of a splutter , the revs drop and It’s cut out a time or two during the ‘splutter moments’ if I rev. When I’ve looked again, the fan has tried to start and flickers at the exact same time as the engine drops revs and runs very briefly below usual idle speed, before picking itself up again. I’ve swapped plug and cap to new and it’s the same. Cleaned air filter. There’s a host of others things to try that I’ve seen online but was hopeful someone here could identify the issue without me having to tamper too much. Any help would be much appreciated. ? 

bit more info - if it helps. Bike mostly runs fine, and as powerful as it should be besides the dip in revs (splutter). I stupidly ran it out of fuel a week ago( ran it fine for about 3hrs after- and no issues) wondered if this may have got some crap into the injectors? But the fan appears to be the culprit as it’s not kicking in even after 8-10mins idling- just flicks as though it’s trying to as mentioned above. Ta. 

Edited by Jimyacky

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At one point I got something stuck in my fan and it messed up both the fan blades and the fan motor.  As a result my bike did exactly the same thing you are talking about when it got warm and the fan tried to kick on.  The only fix was to replace both in the end.  I am sure the engine running issues (splutter) was caused by the issues in the fan motor but of course as I had broken blades so had to swap both.  Once I relpaced the fan motor the bike has had zero issues (no splutter) ever sense. 

 

Oh and I had to get the bike back to the car and the longer I ran it and the more the fan attempted to come on the worse it got tell it was fixed.  

 

PS.  If you haven't checked your idle is set to the correct 1800 RPM's I would do that first just in case.  

 

Good luck!  

Edited by jonnyc21
forgot something.
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Thanks for the reply and thanks for the good luck- it’s taking a bit of figuring out. . I’ve had it out again tonight. Runs spot on when cold- after 10-15mins riding the fan was kicking in and working as it should.(prior I maybe didn’t tax it enough as It’s had upgraded- larger radiator put on it. ) So after the 10-15mins radiator now working- but it’s still spluttering on and will eventually stall. It doesn’t sound like it’s idling fast enough. But I’m reluctant to alter Rickover as it’s still factory set - and has only be ridden for about 8-10 hours. It was sat, as a new bike, in a garage for year or so only being started up periodically. I wonder if that could have affected fuel pump? 

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Why has it had the oversized radiator fitted? Perhaps a thermostat problem. If the fan/thermostat doesn't work correctly, the ECU will kill the bike to help protect the engine

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3 hours ago, Jimyacky said:

Thanks for the reply and thanks for the good luck- it’s taking a bit of figuring out. . I’ve had it out again tonight. Runs spot on when cold- after 10-15mins riding the fan was kicking in and working as it should.(prior I maybe didn’t tax it enough as It’s had upgraded- larger radiator put on it. ) So after the 10-15mins radiator now working- but it’s still spluttering on and will eventually stall. It doesn’t sound like it’s idling fast enough. But I’m reluctant to alter Rickover as it’s still factory set - and has only be ridden for about 8-10 hours. It was sat, as a new bike, in a garage for year or so only being started up periodically. I wonder if that could have affected fuel pump? 

The tickover was low when I first got my 300 RR new and it was factory set.  I adjusted it strait away to eliminate the common issues that creates and haven't had an issue with it sense.  So, based on you thinking idle is low, I would expect that this will likely will correct the problem, though I can't promise that.  This is critical before attempting to troubleshoot anything else.  

Good luck.  

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Even the guy with the new 301 yesterday had to turn his up. My son has turned his up twice in the 2 weeks he has had it from new.

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I suspect that if its ticking over too slow the generator is not pushing enough out to power the fuel pump for the fuel injection and the fan so when the fan tries to run it robs power from pump and cause the stumble.

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turn tick over up  -its free to try?

Its a “an as new bike” but has bigger rad  = Hi, I’ve just been getting a 2018 repsol which is practically new. - maybe fan is hitting rad when it gets warm  - The fan motor is then trying to turn but drawing more current than it should - voltage maybe dropping  -especially with low tick over meaning the remaining electrical system are struggling for power.

Check fan can spin free when warm also

Edited by jimmyl
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What equipment do you guys use to measure the tickover speed or do you just do it by ear?

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Thank you everyone for you help and comments. Good news is the tick over was simply too low- I adjusted  up from factory set about a quarter turn - ran the bike faultless for 40mins...then the bloody thing boiled over! The fan was definitely running for first 20mins or so- maybe after but I stopped checking every two mins - to enjoy my riding?. I stepped off bike at the 40 minute mark and it began to boil as I watched - so hopefully caught it early enough as to not cause major damage?! - Any thoughts on this- dodgy thermostat? Bad earth? Bare wire somewhere? Too much power to fuel pump and not enough for fan? Electrical issue? Hummmm. 

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Well, if you just had a larger radiator put in recently (at least that is what it sounded like in your second post) you might just have a bit of air in the system from that and topping it back up might sort it out? You could also double check temp Sensor?

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Hopefully it will just be air in the system, but these things don't boil very often, even with the standard radiator. Again, why has it had the large radiator been fitted? Was the previous owner trying to cure a problem by fitting it? 

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Hi, thanks again everyone for your thoughts and comments. Just wanted to update this thread to help anyone in the future who might have similar issues. It was just the fan motor. Drew power from fuel pump which caused splutter. Increased tick over seemed to cure splutter but the fan was on its way out - and eventually packed in causing it to boil over. Partly my fault for not watching it closely enough- and being a massive child and concentrating on my grin while riding rather than checking the fan often. New fan= 80 quid or so, spot on ? 

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Good news 

you can grin even more now ??

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