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Old 16-06-2022, 08:24 PM   #1
MrsC_772
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Reluctance to restart when hot

Secundus (the newer of my 696s) has developed an irritating tendency to refuse to re-start when hot. First time was after I'd stalled at traffic lights, and it has now done it at least twice after I'd stopped to fill up with fuel.

Push the starter button and there's the kind of feeble wheeze that suggests the battery is on its last legs.

Leave it around 10 minutes, push the button again, and it will start as happily as it ever does.

Andy has probed all electrical connections with a multimeter (from battery, to starter motor). The starter has a good connection with the battery.

The battery is apparently charging ok, so we don't think it's an alternator/reg-rec gremlin.

I think the battery might be the original (the bike is 9 years old) so wonder whether it is worth replacing anyway. The bike lives plugged into the Optimate when not in use.

I therefore wonder whether something is seizing/jamming when hot, but after coooling down, whatever it is is unsticking. Could I have a dodgy starter motor?

Worth replacing the starter motor? (Andy replaced the starter motor on Primus a few years ago, and even has the special home made tool. I've even found the thread http://www.ukmonster.co.uk/monster/s...ad.php?t=56223)

Anything else worth investigating before I stock up on chocolate chips, nuts and lasagne ingredients to pay Andy for a couple of horrible oily days in the garage replacing the starter motor?
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Old 16-06-2022, 08:38 PM   #2
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Could be a starter relay, I'd check that before embarking on the starter motor.
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Old 16-06-2022, 08:40 PM   #3
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That's annoying!
I'd start by having a look at the spark plugs to be see if they're nice and clean on both pots.
Fairly cheap and very easy to replace, so a good pace to start.
Things that are effected by heat can be coils and windings. Not sure what makes the spark on those models, coils, igniters or whatever? but the crank position sensor would be a suspect and can fail when hot.
An outside contender could be plug caps or HT leads?
This is a tricky one as the fault is not actually stopping the engine but rather seems to be heat from the stopped engine migrating into something that is otherwise cooled.
( hence my thinking crank position sensor.)
Going on from that my last thoughts would be a temperature sensor? (I think you have two oil temp sensors and an ambient air temp sensor, it probably isn't the latter.)

Can you read any fault codes?
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Old 16-06-2022, 08:50 PM   #4
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Quote:
Originally Posted by MrsC_772 View Post
Secundus (the newer of my 696s) has developed an irritating tendency to refuse to re-start when hot. First time was after I'd stalled at traffic lights, and it has now done it at least twice after I'd stopped to fill up with fuel.

Push the starter button and there's the kind of feeble wheeze that suggests the battery is on its last legs.

Leave it around 10 minutes, push the button again, and it will start as happily as it ever does.

Andy has probed all electrical connections with a multimeter (from battery, to starter motor). The starter has a good connection with the battery.

The battery is apparently charging ok, so we don't think it's an alternator/reg-rec gremlin.

I think the battery might be the original (the bike is 9 years old) so wonder whether it is worth replacing anyway. The bike lives plugged into the Optimate when not in use.

I therefore wonder whether something is seizing/jamming when hot, but after coooling down, whatever it is is unsticking. Could I have a dodgy starter motor?

Worth replacing the starter motor? (Andy replaced the starter motor on Primus a few years ago, and even has the special home made tool. I've even found the thread http://www.ukmonster.co.uk/monster/s...ad.php?t=56223)

Anything else worth investigating before I stock up on chocolate chips, nuts and lasagne ingredients to pay Andy for a couple of horrible oily days in the garage replacing the starter motor?
I feel your pain. I owned a Corvette which would rarely restart without a 15 -20 min interval. Unfortunately I was living in Mexico at the time and there was no chance of fault diagnosis and therefore repair.

Its a real nightmare at the petrol station, until you get a second key to open the fuel cap!

I hope youe it sorted ASAP.
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Old 16-06-2022, 09:11 PM   #5
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Might be the starter motor bushes, but a 9yr old battery has got to be a bit suspect.
Before anything try load testing it ( https://www.liveabout.com/vehicle-ba...esting-4083840 ) if that comes out OK then look at the motor itself.
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Old 16-06-2022, 09:33 PM   #6
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I don't think it's even trying to turn the engine over, when I push the button to start and it has a hissy fit.

"Could be a starter relay, I'd check that before embarking on the starter motor." We tested this and it was fine when cold (Andy probed with multimeters to see if there was a voltage drop across the relay). If the relay was the problem, would we only notice a problem when it is hot?

"I'd start by having a look at the spark plugs to be see if they're nice and clean on both pots. Fairly cheap and very easy to replace, so a good pace to start." Bike was serviced less than shortly before the first tantrum, so I'd be amazed if the plugs were a problem, but we could inspect them.

"Things that are effected by heat can be coils and windings. Not sure what makes the spark on those models, coils, igniters or whatever? but the crank position sensor would be a suspect and can fail when hot." We will investigate the sensor. Wouldn't there be a problem when the engine was running if the crank position sensor was playing up, rather than run fine when it is going, but refuse to start?

"An outside contender could be plug caps or HT leads?" We can take a closer look at the plug caps and HT leads, but again, wouldn't this be more likely to provoke misfire when running? Engine is running normally enough when it gets going.

"This is a tricky one as the fault is not actually stopping the engine but rather seems to be heat from the stopped engine migrating into something that is otherwise cooled.( hence my thinking crank position sensor.)"

Going on from that my last thoughts would be a temperature sensor? (I think you have two oil temp sensors and an ambient air temp sensor, it probably isn't the latter.) How accessible are the oil temperature sensors? (Just wondering how much dismantling we'd need to do to probe these).

"Can you read any fault codes?" We don't have a DDS code reader unfortunately, and I don't recall any error codes flashing up on the clocks.
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Old 16-06-2022, 09:37 PM   #7
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Old 16-06-2022, 10:24 PM   #8
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Was about to chip in with my comments but Rob posted my thread instead.

I am pretty sure my problem was iridium plugs and the gap on them, in the end I went back to plain old non iridium ones and I think they worked out of the box.
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Old 16-06-2022, 10:28 PM   #9
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Mmm! going back to the plugs, They are going to be pretty much all that was changed in the pre-tantrum service that would effect starting.
New plugs doesn't mean good plugs necessarily. I've recently bought a few plugs for a new rebuild and I'm now on the 3rd pair in the first 300 miles having found that they fail alarmingly quickly. The gaps always need checking from new as they are quite random out of the box. Granted I had other issues with the ignition system as well as the plugs but they did manifest a hot starting problem, with cool plugs seeming to make a better spark.
Are they the correct grade NGK plugs?

My Motobatt on the Monster is still going strong into it's tenth year but it's worth doing a voltage drop test by putting a meter across the terminals and seeing what the voltage goes down to when cranking.
Strange though as it's usually under more duress when starting cold?
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Old 16-06-2022, 10:38 PM   #10
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Quote:
Originally Posted by MrsC_772 View Post
"Can you read any fault codes?" We don't have a DDS code reader unfortunately, and I don't recall any error codes flashing up on the clocks.
If you push the left side rocker switch forward after turning on the ignition, then it will display any recorded error codes (although I'd expect to see the yellow CEL illuminated too if there are any stored codes).

These are the codes that can be displayed on the dash.




Just out of interest, how many miles ago were the valves checked?

It does sound a bit 'fuelly' to me, which might point the finger at anything that might affect the mixture. Consider the air and engine temperature sensors, the MAP sensor and the lambda sensor (you've only got one I think?). Next time you have the problem you could try disconnecting the lambda sensor to see if that makes a difference. (It will probably throw up an error code.)

This should help you locate all the sensors (it's a 796, but the sensors should be the same).





Rob has a good memory! I was also going to suggest the warm TPS reset that he posted a link to. See also here

http://www.ukmonster.co.uk/monster/s...ad.php?t=55198

You could also try a set of iridium plugs for their fatter spark but do make sure they are set to 0.9 - 1.0 mm, not the standard 0.7 - 0.8.
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Old 16-06-2022, 10:47 PM   #11
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Exact same symptoms plagued my evo. Even asked high quality dealer for suggestions. Problem solved by new battery. Previous Motobatt was only two years old and seemed ok.. but it wasn't!
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Old 17-06-2022, 06:28 AM   #12
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My EVO had the same problem.
Fitted a new Battery and all is well.
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Old 20-07-2022, 08:46 PM   #13
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Might be the starter motor bushes,
Have a gold star

I was convinced from the symptoms that it was the starter motor at fault. We tried restarting the bike after a decent run, and although the starter tried to turn it over, it was clearly struggling. I'd believe things like a bad spark plug or sensor if the engine turned over but didn't catch, but in this case although the motor would turn a bit, it couldn't make it past peak compression.

I'd already checked the voltage at the starter on a previous occasion, and that was fine - no issues with the contactor or grounding.

With all that in mind, I changed the starter at the weekend, and today we refilled the oil and tried it.

I'm pleased to report that it started first time with a cheery whirr, which apparently isn't something this particular bike has ever done until now. I'm confident it's fixed (not to mention, somewhat relieved that there wasn't a loud bang and an oily puddle, given that I'm not one of the world's natural mechanics).

I also found the root cause of the starting problem. Once the old motor was out, I took it apart and found one of the four brushes cracked and split. Looks as though it may have been like that since new given the wear pattern, and I'm surprised it ever worked.

Higher temperature = greater resistance = greater losses in the starter, which explains why it didn't have the torque to turn over the engine when hot with a failed brush.

Thanks to everyone for your suggestions, fingers crossed it stays fixed.
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