Jetting carbs...

**manwithav8** · 16th September 2007, 17:15

Who has done this and what brand of jets have you used?

The bike in question is a Ducati Monster with cored cans and about to fit a K&N air filter.

The two jet kits I have heard of that are worth using are the Dynojet kit and the factory pro kit.

What is best and why?

**Paul in NZ** · 16th September 2007, 18:34

Talk to Chris (I think??) at Motormart and book a session on the dyno - cheaper and better in the long run!!

**hospitalfood** · 16th September 2007, 18:54

I went to the dyno at henderson motorcycles, all good, toby is the man to talk to when he is there. they work on dukes and he may no what size you need.
have heard dyno jet kits wear out.
the maker of the carbs will have jets in all sizes I would think.
with less back pressure in the exhaust it will run lean, also more air flow from a better air filter will make it run lean. the two combined could be dangerously lean, running lean means running hot usually, worst case burning holes in pistons ( not that uncommon ).
recommend dyno asap. before that do not thrash your bike.

**manwithav8** · 16th September 2007, 19:09

thats why I was heading to motomart eventually lol...

I have still got the original cans (not on the bike) and haven't fitted the K&N yet. I didn't think just the cored cans alone would cause any issues but do however know once ther eis more air getting in there then it is time for more fuel..

Worst case senario I can always take the cored cans off and refit the stock ones until I get some dyno time and jets...

**Paul in NZ** · 16th September 2007, 19:39

Give them a call and ask. I doubt the K&N will cause much of an issue but the guys there have done a lot of this stuff and they would be the experts I reckon... Bikes are set up pretty lean for emission stds these days but so it may benefit fron a slight upsize in jets - but a phone call does not cost much ;-)

**manwithav8** · 16th September 2007, 19:51

will give them a call tomorrow....

I still want to jet though.. I am itching to pull the carbs lol... Will wait till I have all the bits and peices needed though and will call Motomart in the mean time..

**Paul in NZ** · 16th September 2007, 20:41

Its just got dellortos? Usually pretty simple things but lots to play with - slide cut aways, needles etc etc..

**limbimtimwim** · 16th September 2007, 20:53

Save yourself some money and have a go yourself first. There are only two carbs.

I've done the factorypro route myself twice, and it's been fine. Sure, you'd get that last few % if you go to a dyno, but you may be happy with the performance of your own work.

After you are done, ride it, pull out the spark plugs and check they are about the right colour.

**manwithav8** · 17th September 2007, 17:09

Mikuni carbs, I haven't actually looked properly yet.

I have heard the factory pro kit is alot easier to install so may go with that option

I will be doing the jet kit myself and tuning... If I have problems after that I will book in some dyno time.

**Paul in NZ** · 17th September 2007, 17:43

The factory pro kit usually means not drilling the slides which is a good thing.

Check the specs of your bike real careful and make sure it's identical to a 'merkin one or else you will have a nice paperweight...

**rogson** · 17th September 2007, 18:18

Originally Posted by Paul in NZ

The factory pro kit usually means not drilling the slides which is a good thing...

Dynojet kits often recommend drilling the air-transfer hole in the slides. This speeds the response of the slide to throttle changes and hence improves the throttle response.

Factorypro kits don't recommend this but often include lighter slide springs in their kits in an effort to do the same thing.

IMO Factorypro's approach is simply a marketing ploy to differentiate their products since firstly they are Johnny-come-latelys compared with Dynojet and secondly they know some owners will be reluctant to take to their slides (which are not cheap) with a drill.

My recommendation is - if you want to improve throttle response (and who doesn't?), then drill the slides.

**manwithav8** · 17th September 2007, 20:58

I don't know about that drilling stuff lol...

I like the idea of the softer spring for now, if it isn't so good then can do the dynojet....

If the jet kits are cheaper than new slides ( ducati being expensive for oem parts) then that might be the way to go..

**Paul in NZ** · 17th September 2007, 21:37

Softer springs on V twins is not always a good idea. The increased vacuum that a bigger cylinder makes can make em sticky but at least it's easy to go back...

**Paul in NZ** · 17th September 2007, 21:38

Originally Posted by rogson

Dynojet kits often recommend drilling the air-transfer hole in the slides. This speeds the response of the slide to throttle changes and hence improves the throttle response.

Factorypro kits don't recommend this but often include lighter slide springs in their kits in an effort to do the same thing.

IMO Factorypro's approach is simply a marketing ploy to differentiate their products since firstly they are Johnny-come-latelys compared with Dynojet and secondly they know some owners will be reluctant to take to their slides (which are not cheap) with a drill.

My recommendation is - if you want to improve throttle response (and who doesn't?), then drill the slides.

Good post - thanks - learnt summat...