Surging

[Bodge]

Hey all - I have a 96 M900.

In the traffic when I am trundling along in the first three gears at a constant revs between say 3000 and 6000 there is a noticable surging which can be quite destablising when you are negotiating the small gaps in traffic.

Is this normal? I have just had the major 10,000k service which included balancing the carbs and the workshop is highly recommended and I have no reason to doubt their workmanship.

[spacemonkey]

I might be wrong but it sounds like classic mixture problems. Have you exhaust/filter mods without dynojetting? Also lowering the gearing makes a world of difference to smoothness, as the bike is overgreared as standard.

[M900nster]

My '96 M900 was re-called to have a carb heater kit fitted. Was yours? If not I'd suggest you get one as it makes a big difference. I thought I'd need to turn the thing off in warm weather, but I was wrong. The carb heater is needed all year round. It works by re-routing hot engine oil via heat exchangers on the carb float bowls. You therefore can't expect smooth running until the engine oil is up to temprature, so warm the engine gently for 5-10 minutes before you ride off. It isn't as smooth at low speeds as my ST4 (which, or course, has fuel injection) but the carb heaters really do make a difference. :burnout:

[Bodge]

Thanks - don't think the heater is the answer - it just doesn't get that cold here. Normally above 10C in winter. Plus it does it warm or cold.

I do have DP carbon slip ons but I was under the impression thast no adjustment was required. I talked to the Mechanics the other day and they seemed to think that a certain amount of surging was normal ducati behaviour. He also suggested a change in gearing my smooth it out in the slow traffic.

He has offered to change it for nothing so I can see if I like it.

[Meteor]

I agree with Spacemonkey - my '98 M900 had all the faults you mention, since dropping 1 tooth of the front the low speed running and pick up is miles better :) .

For this model the most poular mod appears to be either 1 tooth of the front or 2 off the back.

Hope this helps....

[Bodge]

OK I will charge on with the sprocket change and see how it goes from there...

cheers

[M900nster]

Hey Bodge,
Sorry to bang on about it, but you didn't say if your bike has carb heaters. If it hasn't, I'd suggest you try riding a M900 with them to feel the difference. (Monsters from '97 on had them as standard - Ducati wouldn't have gone to the expense if they weren't needed) By all means change the gearing if you do mostly town riding, but don't expect it to sort your sypmtoms. Sure you won't have to slip the clutch so much to get away from a standstill, and the motor will be spinning a bit faster in a given gear at a given speed, but, but.... It'll still cough when changing gear, hunt like a bitch when using small throttle openings, and try to pitch you off on wet roundabouts because of the jerky power delivery. I know it's warm where you live, but it gets hot here in the summer (30º C not unusual) and still the bike needs those heaters on. I'm not the only one to experience this, am I?

[M900nster]

Forgot to mention: They do run rough when cold, but without heaters they don't run an awful lot smoother at operating temp. Switch the heaters on, and within seconds the bike's a pleasure to ride.
(If you reply saying your bike's got heaters on.... I'd better get me coat!)

[Bodge]

To be honest I am not sure whether it has carb heaters or not... I will have a closer look.

If it doesn't I am willing to try anything to get smoother riding at low revs. If you are right I might have to owe you a beer! Although you will have to come to NZ to pick it up [fine print].

Its going in today to get a 14 tooth sprocket so I will ask them about the carb heaters at the same time.

Cheers

[A Yerbury]

my carb heaters didnt make much diff on or off, hotter plugs and pro fst did, so I got rid of them for the purpose of aesthetics. look at the carbs, braid comin up with a small line about 3 inches between the bottom of carb, the switch on mine was "on" when in line, off when perpendicular, it varies depending on manufacturer I'm told. only way to be 100% is unbolt switch housing and have an eek.

[M900nster]

Look on the r/h side of the engine for a braided s.steel hose (about half inch O/D) with a little tap which diverts engine oil (on it's way to the oil cooler) so that it goes via the carb float bowls. Hopefully, your bike had the kit fitted either at the factory, or as a re-call modification (like mine), in which case turning the tap 90 degrees should do the trick. If it missed out on the heaters, you could do worse than ask your dealer to ask Ducati NZ if they'll supply the kit for free: A good will gesture to make you a happy owner, and all that. It's in their interests (and worth a try for a second pint for me? Hic!) :)
Henry

[Bodge]

Ok - definitely no carb heaters checked when I got home last night. Doubt DucatiNZ will help as its an import.

Is there a kit out there?

Part number?

[M900nster]

That's interesting Bodge,
If you've definitely not got a fuel blockage, or electrical fault (these are definitely ruled out, right?) I feel pretty sure that carb heaters will have more effect on your surging problem than lowering the overall gearing.
You've nothing to lose by asking your dealer to try asking Ducati NZ for a free carb heater kit. If you draw a blank, and such a kit is not available in NZ, there are several links to UK based Ducati spares people on this web site, and a search engine will turn up dozens of others. Shop around.
All the best
Henry

[Pedro]

Carb heaters do fak all on my 900 to make it run smoother - I wouldn't hold out too much on that theory personally, I think there may be more to it.

From memory, I had a bike many years ago that did a similar thing and I think it was carb related. It might be a combination of poor tune and/or worn carbs. Has it been tuned & balanced recently?

Ped

[Bodge]

Its just had its 10,000 km service. Shims, belts, filters, [including fuel], oil, carb balance. It did it before and it still does it.

It happens on constant low throttle - up to about 60kms. So its basically around town when you are crusing at a constant speed. It doesn't show under acceleration or at highway speeds.

[A Yerbury]

has the sprocket helped? the carb heater kit is a few lines of braided hose, some banjo bolts and a switch but as the peddler sez, they arent much cop.

[M900nster]

I agree with Pedro, that you must make sure the carbs are working as well as possible before resorting to other expensive measures. However, I have found that the carb heaters make a difference. I owned a 1999 M900 from new, which had heaters as standard, and the 1996 model I now own had them fitted on a re-call in November 1997. Ducati wouldn't have paid for that if wasn't necessary. My experience is that these bikes run rough if you leave the carb heater tap in the off position. Switch it on, and (as long as the engine oil is up to operating temprature) within a few seconds the power delivery smooths out considerably. We have to keep things in perspective though: Ducati engines have a short stroke, light flywheels and huge carbs, so they're never going to chuff along as smoothly an old single carb BSA, or Matchless. However, despite it's high state of tune, a carburetted Duke can be made to run surprisingly sweetly.
One thing you could try, to see if it is a carb icing problem, is to put a dash of Silkolene Pro FST (cold weather fuel additive) in the fuel tank. Motorcycle News says 'it works brilliantly'.
I do hope you get to the bottom of this one soon.
All the best
Henry

[Bodge]

Hey I really appreciate all your time on this one.

Just to throw a spanner in the works I was riding home last night and I had some clear road to really concentrate on what was going on between my legs :lol: . Seems the surging might not be the problem. Feels like a small irregular miss and when the motor picks it up again it creates a little surge?

I am taking it back to the shop - paid them good cash to sort it so they can problem solve it - I will pass on all the feedback from here too. They will change the sprocket at the same time.

Thanks again.

[DesmoDog]

Here's my tuppence (thats old money kids) worth. Mine does this when its been lying up and the conditions are damp. It really does surge, then dies awqay, then surges again. I've got the battery chargig at the moment because I couldn't start it at all yesterday. Everything is pointing to the carb at the moment, possible a buggered float needle or such like - At least thats what the book of lies tells me. I'm off to buy some FST and try to start it up in an hour or so. Wish me luck.

[Byron Kauffman]

I just posted this same response on another problem, it is worth a look for you too.
It could be that the vacuum fuel petcock has gone bad letting it fill the carbs. My friend with a ducati shop is always complaining about them. When I built my bike I removed it and put on a old style manual petcock. A Bimota Mantra (same driveline as a Monster) owner friend had the problem where the vacuum petcock would shut off the fuel flow whenever it felt like it. It would make the bike surge on and off as it opened and closed the fuel supply. A new petcock solved the problem.
Just a thought.

[Rockhopper]

The official price for the carb heater kit is over £200!! Nelly at Cornerspeed (www.cornerspeed.co.uk) has one set left in stock at £158 i think he said.

[DesmoDog]

Well going on what's been said here I'd save myself the wonga and go for a petcock or a check over.

[Bodge]

Just an update:

Sent the bike in to have the fuelling checked [I was sure this was it]. Turns out it was running a little on the rich side but the surging/hesitation is actually because I have flogged cush drives... A little embarrassing that I didn't notice that but it did a good job of simulatind a fuelling prob in my defence...

Next piece of bad news is that there are no cush drives in NZ - waiting on shipment from Italy.... waiting .... still waiting....