14T sprocket for Monster 400

[bangkokmonster]

Hey, my Monster lugs and lurches around under 3000rpm, sometimes even at 4k it cuts out and then jumps forward. It's a bit of a pregnant dog on a track, so I was thinking of changing the front sprocket over to a 14 tooth. How do you think it will effect the lurching at low rpm? Also, it's a bit of a stupid question but, are monster sprockets the same sizes? Could I use any Ducati 14t sprocket? Or even a 620 (as it is the closest big relative)? M400 parts are difficult to come across without a long wait here so I'm looking for a quick, easy fix.

Thanks
Dec

[ducpainter]

Jeff_H @monsterparts...

Chris @ca-cycleworks...

or brad black @bikeboy.org will be the best sources for answering your questions regarding if the 620 sprocket will fit. I think it will.

I'd bet all of them could supply the parts too, and Brad is in Australia.

As far as helping with the lurching at low rpm...you bet it will.

[rata911]

Instead of decreasing one tooth at the front sprocket I'd always add some teeth at the rear sprocket. Just my opinion.
Space in the front is scarce and a 14T sprocket isn't helping a lot as the chain makes an even sharper turn due to the smaller radius.

[brad black]

same as all the other 520 sprockets, genuine used to be 44910061A i think.  afam AS52604-14, supersprox 10-736-14, don't know the jt number.  400 is just a little 600, pretty much the same otherwise from bore and stroke.

they come to aust as a grey import with 14/46 gearing.  i went back to a 15 on the front of one and it felt a bit better.  also did the cam timing on it which helped, so it may not work so well on an as delivered bike.  owner liked it better anyway.

make sure the idle mixture is not too lean - wind the screws fully in then out at least 2 turns, maybe 3.  i've found the ones i've worked on have generally been very lean on the idle mixture which really affects them down low.  generally they seem ok down low ime once that's done for what they are.

if you go 3 bigger at the back you'll most likely need a new chain.

[bangkokmonster]

Thanks for the replies, you've really helped me out. About the sprockets - am I better off going up 1,2, or 3 sizes in the rear? Which is better for the bike, down in the front (14) or up in the back?

I've had pretty bad problems with the mixture, but I was told because I didn't buy the bike with a red key the only Ducati mechanic couldn't do it (he said he wasn't able to remap/reflash the ECU) So, I can just turn a screw and adjust it? Where?! 

Cheers guys

[bangkokmonster]

Oops yea, one more thing - I bought my 2005 M400 without a red key (clearly a mistake). I have read a little bit about it and it really seems pretty retarded (thanks Ducati!), but what would I need to replace on the bike to either get a new red key or disable the 'red key system'?

Thanks tons

[ducpainter]

I wasn't aware the 400 was injected.

The best route is to send your ecu to someone and have it reflashed to eliminate the immobilizer and red key.

Do a search for ecu reflash. I'm sure there must be someone on your side of the world that does it, otherwise lots of folks have used desmoporsche or added rexxer replacement ecu's.

Otherwise you'd have to replace the ecu, gauges, and all the locks.

[bangkokmonster]

What about the fuel/air mix? How can I adjust that with a screw? Where is it?

[brad black]

sorry, the only 400s i have seen have been carbed models.

you need the diagnostic tools to do the idle mixture adjustment as it's all electronic - technoresearch vdsts is the cheapest for the single user version and something you would be well served to buy by the sounds of it.  you don't need the red key though, you only need that to code more black keys.  if it runs it will talk to the diagnostic tools.

http://www.technoresearch.com/Products/VDSTS-Motorbike/VDSTS-Motorbike  the single brand version is around $200 i believe?

you need a longer chain to go up 3 teeth at the back, so it's much cheaper to go one down at the front.