Arrow Exhaust and Bad Running

Hi All, I wonder if someone may be able to help me? I have just bought a 2015 GRiSO and the previous owner had fitted an Arrow full system. It looks and sounds great but the bike runs really badly. It seems to be over-fueling and running very rich, I understand these bikes are very sensitive to non-standard exhausts and would welcome any advice on re-mapping options and how effective these may be?

Beetle makes very good maps. Buy from him and load it up.

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Hi ok thank you I will try them

A word of advice. Before remapping there are a few things to check. Firstly and most likely is the fact the plug caps may be damaged. They are damage prone if they are removed incorrectly and this is common.

Remove the covers from the HT leads and plug caps and start the bike whilst watching and listening for the sound of the spark snapping to earth at the rocker cover. This is usually visible at the right angle 'Elbow' on the plug cap itself and the damage is caused by people grabbing the caps and trying to twist them off which tears the rubber. They should be removed by inserting a long, thin screwdriver through the cooling tunnel in the head just above the exhaust manifold and levering them off the plug from below.

The apparent rich running will be because the mixture is not being fired in the combustion chamber to the unburnt charge is expelled into the exhaust. This causes the smell of unburnt fuel, the backfiring and the shitty running.

I'm not suggesting that remapping isn't an excellent idea but it's not a 'Magic Bullet' cure all. If the bike is running poorly it has a problem beyond mapping. The stock mapping is pretty pedestrian but while it renders performance fairly lacklustre it won't make the machine run dreadfully. Also for a map to work correctly the tune must be spot-on so first let's cure the poor running, then do a full tune-up and then re-map.

Sensible and complete answer Pete. I learned something useful from you. Thanks.

Hi, thank you Pete for letting me know that, it is very useful info. I have asked the MV Agusta dealer who sold it to the previous owner if they will service it and I will be sure to pass this info to them. It has only ever had 1 service last year which was when the Arrow system was also fitted but I guess if done incorrectly it only takes 1 time to damage the leads. To explain it was sold new / old stock, unregistered in late 2019, the guy has had it around 18 months and was fed up with the bad running so sold it. Now has only 3k kms but the issue I will have over here I think is finding someone who has any knowledge and experience with these bikes. Lets see......

Great response from Roper. When I first got my used GRiSO it was running terribly especially at low rpms. I immediately started thinking map, but a Stelvio guy reminded me to check the leads first. I just went ahead with the NGK cap swap and that cured the bad running.

When I added Mark's map later it took it to the next level in terms of smoothness, pull from low rpms, and fuel mileage, but it wouldn't have fixed those crappy caps.

You should also check to see if there are any fueling "foolers" installed, or something a little more refined like a Power Commander. If any of those devices are installed, they should be removed before one of Mark's delicious maps are uploaded.

I have an Arrow exhaust on my GRiSO with a new map. It runs and sounds awesome. Fuel mileage is not what it used to be, but it is a performance map. I have over 54,000 km and I’ve only ever done regular maintenance. This bike is a beast!