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Hey All,

My 2015 Monster 821 has the dreaded "won't start when hot" problem. I have termis with upmap. I read on another forum that someone who had the same problem. He disconnected his exhaust servo which left the flapper open by default. He stated that this fixed his problem.

I want to at least give this a try, I'm sick of waiting for my bike to cool down to start riding again. The question I have is where the hell is the servo located? How do I get to it? Which is easier, to disconnect the power to the servo or to the cable to flapper?

Thanks in advance.
 

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Hey All,



My 2015 Monster 821 has the dreaded "won't start when hot" problem. I have termis with upmap. I read on another forum that someone who had the same problem. He disconnected his exhaust servo which left the flapper open by default. He stated that this fixed his problem.



I want to at least give this a try, I'm sick of waiting for my bike to cool down to start riding again. The question I have is where the hell is the servo located? How do I get to it? Which is easier, to disconnect the power to the servo or to the cable to flapper?



Thanks in advance.
That'd be me....servo is on the exhaust midpipe...unscrew the guard plate...advance the flap by hand...unhook the cable...tuck it all back in nice and tidy...screw back in guard...that will disconnect the servo which did help immensely but alas I'm still troubled by a hot start if the engine climbs above 186°f ...I've since bought a colder range sparkplug ( MAR10a-j ) and intend on installing this week to see if that helps....also going to peak at the valves to see if they're gummed up again





How many miles you got on it? Do you do your own valves? Have you had a chance to look at the backs of the intake valves? What's your plug gapped to initially? How long have they been in since you noticed the problem of hot starting?

Working on a few theories ...one that the heat in the plug is effecting the spark or the gap is too big and the coils just aren't up to the task when it's super hot... I've gone from a few seconds waiting to a few minutes over the course of the last 6k miles...it's a work in progress
 

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Discussion Starter #3
chrispkny

That'd be me....servo is on the exhaust midpipe...unscrew the guard plate...advance the flap by hand...unhook the cable...tuck it all back in nice and tidy...screw back in guard...that will disconnect the servo which did help immensely but alas I'm still troubled by a hot start if the engine climbs above 186°f ...I've since bought a colder range sparkplug ( MAR10a-j ) and intend on installing this week to see if that helps....also going to peak at the valves to see if they're gummed up again



How many miles you got on it? Do you do your own valves? Have you had a chance to look at the backs of the intake valves? What's your plug gapped to initially? How long have they been in since you noticed the problem of hot starting?

Working on a few theories ...one that the heat in the plug is effecting the spark or the gap is too big and the coils just aren't up to the task when it's super hot... I've gone from a few seconds waiting to a few minutes over the course of the last 6k miles...it's a work in progress
That is your post Buhgaboo! I actually commented there too.

I have just over 10,000 miles. I do not do my own valves. From what the dealer told me they actually replaced the intake valves. Not sure of the gap on the spark plugs but they replaced those too so probably factory gap.

I'm bringing my bike back in over the winter. Since it's still under warranty Ducati is making them run through a bunch of tests when I bring it back in. Ducati does want them to check the valves.

My bike won't start until it cools down to about 150 degrees. Super annoying!

This is just a long shot but do you have an MD integrated tail light. When I first installed it on my bike it threw all sorts of errors when the bike got hot and the fan came on. They had an included module that fixed the issue that I initially didn't have installed. Again, long shot. Also, do you think it's a mechanical, upmap, electrical, or combination?

I can't believe Ducati doesn't do anything about this and doesn't have an answer. A look around the internet and it's obviously not an isolated problem. Very disappointed. My next bike may have to be a KTM! Hahaha

Thanks for your posts, they rule!
 

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That is your post Buhgaboo! I actually commented there too.



I have just over 10,000 miles. I do not do my own valves. From what the dealer told me they actually replaced the intake valves. Not sure of the gap on the spark plugs but they replaced those too so probably factory gap.



I'm bringing my bike back in over the winter. Since it's still under warranty Ducati is making them run through a bunch of tests when I bring it back in. Ducati does want them to check the valves.



My bike won't start until it cools down to about 150 degrees. Super annoying!



This is just a long shot but do you have an MD integrated tail light. When I first installed it on my bike it threw all sorts of errors when the bike got hot and the fan came on. They had an included module that fixed the issue that I initially didn't have installed. Again, long shot. Also, do you think it's a mechanical, upmap, electrical, or combination?



I can't believe Ducati doesn't do anything about this and doesn't have an answer. A look around the internet and it's obviously not an isolated problem. Very disappointed. My next bike may have to be a KTM! Hahaha



Thanks for your posts, they rule!
Omg...I'm glad I'm not alone...lol...I've tried many many things...I run the motor stupid hard and am very prone to carbon buildup in the intakes...my initial assumption was that the buildup absorbs the first shot of fuel throwing off the mix...it still may hold true I haven't been in to look since I last blasted them with walnuts...which worked amazing...but not something I want to do every 3k miles...it's getting wheeled into my apartment this week for some work and plan to take a looksy at everything...please let me know what the dealer comes up with...if they changed out the intakes I might assume that was from the carbon...I have swapped brand new oem heads and valves at 26k miles and that just reset the problem for me...swapped oil ...octane...engine map... habits...still haven't narrowed it down...all this was occurring in the stock configuration...termis weren't added to later and I haven't done anything with the taillights but I know how frustrating it is checking faults when problems start overlapping...
 

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Your spark plug shows a rich fuel mixture.
Test or change the water temperature sensor located on the horizontal cylinder head. this sensor has a large effect on the fuel mixture
There are two other sensors that have a somewhat smaller effect - Air temp. and Air pressure. these can also be tested.
 

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Your spark plug shows a rich fuel mixture.

Test or change the water temperature sensor located on the horizontal cylinder head. this sensor has a large effect on the fuel mixture

There are two other sensors that have a somewhat smaller effect - Air temp. and Air pressure. these can also be tested.
I have swapped nearly every sensor associated with the engine at one point or another to no effect...temp sensors always read accurate on the dash...the richness I'm inclined to think is more altitude related? Always in the mountains upto 5k ft constantly under high loads...I was about to install a colder plug but after looking at the one in the pic I looked into a hotter one... ultimately settling on an mar9a-j platinum...which is the exact plug I use now minus the Platinum of course...I read they run hotter so it's a win win scenario.

Come to think about it...how would I know the water temp on the dash is correct or not....will swap that sensor this weekend...it has always registered on the cooler side...got it up to 179°F but that was triple digits speeds...generally runs around 165....185 if I'm doing the speed limit...220 in traffic
 

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If you are running it at high altitudes - you should check and clean the pressure sensor located in air box cover. this sensor controls the fuel mixture at high altitudes
 

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If you are running it at high altitudes - you should check and clean the pressure sensor located in air box cover. this sensor controls the fuel mixture at high altitudes
I've swapped entire airbox assemblies ( I have two complete motors) ..nothing improved...nothing got worse...
 

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The options are getting slim.

Although rare - their have been problems with the rubber intake manifolds cracking and resulting in a vacuum leak. This would result in the ECU trying to overcompensate with extra fuel.
Lol...mine cracked early on....it's been long since replaced... problem is that the airbox barely fits and if you force it too much the intake gives up...I've since sorted the technique....I'm going to leave everything as is (in terms of the map sensor)...going to install the colder range plugs just to see how they react while I'm waiting on the Platinum ones to come in.


I would love to see a video of someone on an m821 get the engine up to where the fans come on shut it off and restart it


I can't detect any power loss either...
https://youtu.be/BpeulJRQEaE
 

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I want you to do a test - while the engine is cranking over when hot ( the problem is there ) check the voltage at the battery posts and get back to me with the results
 

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I want you to do a test - while the engine is cranking over when hot ( the problem is there ) check the voltage at the battery posts and get back to me with the results
13.4 ....few month old shorai
 
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