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Discussion Starter · #1 ·
Well, I throw myself to the mercy of the forums for any ideas...

Background - 2015 Dragster 800 RR that ive had for about 3mo. On my original test ride it fired up great, ran great, no issues. Once I got it home (9hrs away) I started to notice that it would struggle to start from time to time - usually when it was warm (like after filling with fuel). I read all the threads I could and I think I addressed most of the topics, but it still has issues. Bike just hit 7000mi so I performed all the maintenance and replaced a few bits. Details below:

  • Oil and filter change
  • Coolant flush and fill
  • Checked all the valves and they were within specification
  • Replaced a leaking valve cover gasket with a new one. Also replaced bolt and plug gaskets. Found one of the plug holes half full of oil which subsequently went in the middle cylinder. I believe the last person to service anything reused the original gaskets as they were quite firm.
  • New NGK laser iridium plugs gapped to spec
  • New Motoloctric HICAP II 4ga starter and ground cables. All terminals and connection points cleaned first - even under the little strap that goes over the post on the relay.
  • Brand new euro 4 sprag. Mine didnt make any noise and didnt seem to be slipping, but since I was in that far why not do it. The one I took out looks to be a euro 4 (8000C4242) sprag so even though the dealer had no record of a change, someone did it. It looks in great condition and doesnt seem to slip - I guess I have a spare now.
  • New air filter
  • Professionally cleaned injectors
  • Carbon canister delete
  • Some other stuff im sure im forgetting.

Battery is a Scorpion Lithium that came with the bike. It sits on a Li-ion tender when not in use and always has 13.7+ volts. Just to be safe, I took it to Batteries plus and had them load test it. He said it put out 380A which seems to line up with the 385A claims of the mfg. Fuses are good, it runs great once started, fuel is 92 octane....

Put everything back together and it still starts hard. It seems like itll pop here and there, but even on a "fast" start, it cranks for several seconds. Sometimes itll take multiple attempts to start, and sometimes I just have to walk away and come back 15min later and try again.

In watching just about every video I can find on YouTube, it seems like mine cranks slower than others. (see videos below). The first video is of my bike after reassembly. It didnt fire here due to the dry fuel system, but it gives you plenty of time to listen to crank speed. Also note, I accidentally left the tender on in this video, so it was cranking ever so slightly faster than normal. The second and third videos are similar bikes (maybe newer and one is an RC) that seem to crank much faster.

Questions for the experts:
  • Could I possibly have a bad battery even though it load tests good?
  • Can a starter be weak and slow to crank (making it hard to hit the 950rpm mark)?
  • Is there a way to manually check RPM via the CPS or something else? If RPMs are too low to fire, I doubt I can use a plug wire style rpm tester
  • Can I be so unlucky that I got a defective brand new sprag?
  • What the hell else is there that I can check or do without just throwing money at it?

I have no dealer within 6hrs of me and I have no idea what version of SW I have. Tried to buy ECU Studio, but they are out and cant get parts to make one for me. The "hold starter and pull clutch lever in until it cranks" method did nothing for me. I had a DMM hooked up to my tender leads while cranking and it looked like it hit about 11.3 or 11.5v. Unfortunately (?) that was one of its faster starts so I didnt get much time to watch the meter update. I'll try again and see what I get. Trying to think of any other tidbits I can throw out there....

My Bike



2nd Bike



3rd Bike

 

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Could it be something else ?
My bike starts this fast(like 1 sec), after being charged, or after use. The first attemp in the morning takes like two second, and is a battery with less CCA than yours.

With the older batt, my bike cranked like yours. But I know that there are some parameters that must be completed for the ecu allow the starts and those can be different between bikes.
 

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Discussion Starter · #4 ·
My bike starts this fast(like 1 sec),
Do you still have the voltage gauge hooked up like you do in the second video? Looks like you pulled down to 10.5 with the old battery which from what I gather is pretty low. I tried mine a couple more times today and it started consistently, but still cranked slow like in your second video. I measured voltage during crank and got something like 10.8.

Has it had the mapping updates? These addressed the starting issues.
No idea what SW version it has. I know there was a new one to help the starting sequence, but i have no dealer near me so I wont be getting an ECU flash anytime soon.
 

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Do you still have the voltage gauge hooked up like you do in the second video? Looks like you pulled down to 10.5 with the old battery which from what I gather is pretty low. I tried mine a couple more times today and it started consistently, but still cranked slow like in your second video. I measured voltage during crank and got something like 10.8.
[/QUOTE]

I still have the voltimeter but disconnected it a few days after replacing the batt.
I meant, perhaps for your bike it’s to low and the ECU don’t allow you the start.
With the new batt in the first start of the day, I think it dropped to 12-11.5, but started in just a second.
Do you have a tender for your batt ?
 

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All of those 3 videos seem to crank over faster than mine (2018 euro 4 dragster).
Mine always takes 2 or 3 seconds before it catches, but it always catches and fires up.

Would seem to suggest the battery/speed at which it's cranking maybe isn't the problem.
 

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Discussion Starter · #9 ·
I havent done anything to the ECU since I have no dealer near me. I dont know what is on the bike either, but since someone changed the sprag at some point it's possible they changed SW as well.

Next time I go to the Chicago area ill drag the bike along and drop it off to have the ECU flashed.

Do I remember reading somewhere that there was a change in starters at some point? If I look up used starters from 2015 bikes they are gold in color. Newer ones are silver. Ive seen some newer (2020+) used starters from parted out bikes on ebay for around $100. Might be worth a try at some point.
 

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Discussion Starter · #11 ·
You can send the ECU to be remapped, or at least you can over here in the UK. As long as the dealer has the hardware to do it. They flash it and send it back I believe.
If anyone in the US knows of a dealer willing to do this please let me know. I asked a few and they said absolutely not, bike had to be in the shop
 

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When I said dealer I sort of meant a workshop that does tuning or has a dyno etc.
I am not sure what software they use. But I did think it can be done the dealer version of ECU studio.
These folks used to advertise it, but their website has changed since I last looked. I almost used them in the past.
They used to show a fixed price the send it to them or have done on the dyno.

Hilltop Motorcycles Ltd 01455 610721

Maybe worth asking them to see if it can be done and surely there must be someone similar in the US!
 

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If anyone in the US knows of a dealer willing to do this please let me know. I asked a few and they said absolutely not, bike had to be in the shop
Reach out to Rob’s Dyno in Gardner Ma.
www.robsdyno.com
 

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Discussion Starter · #14 ·
Well I dont know if it was just a good day or what, but I took the bike out on some errands and it started up just fine every time and it was a bunch of short stops like getting fuel, picking things up, etc. Probably 6 stops in 90min The kind of stops that would have laid me up before. Maybe luck, maybe I just had to knock the cobwebs off of it after being laid up for service?
 
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