Tricky jetting problem DR650e

Hi all, there appears to something really amiss with my carby/jetting that is quite annoying. The fuel cunsumption is poor - 14 klms per liter and there is soot in the exhaust, it goes OK particularly if you stomp it but surges at constant speeds. It also is terrifying when you get off then on the throttle when riding hard - a huge flat spot then hold on. I have a pipe on, the airbox top is open and extra hole drilled in the slide, idle jet 45, MJ 160. I bought the bike new and am handy enough working on them but this one has me stumped - any ideas?

Regards Ian

whats the plug look like? sounds like MJ too fat.

if the plug is black & sooty, make sure the choke is closing properly

then jet that fat-ass down. buy some new plugs & start testing

the pilot is pretty fat too, so i would adjust the mix screw to only 1 turn out to start with

As you said,,,something is amiss there,,, 160 should be fine with the pipe..

The choke is a good place to start,,,,

What does it do when you pull the choke on ? Can't get any richer right ???

Might have to take the carbi back off and see what is going on with it.....

It is using waaaayyy to much gas.....

Hi all, there appears to something really amiss with my carby/jetting that is quite annoying. The fuel cunsumption is poor - 14 klms per liter and there is soot in the exhaust, it goes OK particularly if you stomp it but surges at constant speeds. It also is terrifying when you get off then on the throttle when riding hard - a huge flat spot then hold on. I have a pipe on, the airbox top is open and extra hole drilled in the slide, idle jet 45, MJ 160. I bought the bike new and am handy enough working on them but this one has me stumped - any ideas?

Regards Ian

From what you have said, it sounds like it's running rich. I would go down a size on the main jet.

With a "pipe" and an open air box the MJ160 is actually OK. Of course, if it's a Supertrapp with only one disc maybe not. :-) The pilot is too big for sure IMO. Go back to the 42.5 and set the pilot screw for the smoothest idle. Now, how about that jet needle? With an open air box if you've tried to shim the stock needle you will always have issues. Because of the stock taper you can't match a/f ratios properly for the modified, or cover off, air box at all throttle positions. For example, if you raise the needle high enough to get the 1/2 to 3/4 throttle ratios correct it will be way too rich in the 1/4 to 3/8 positions. A DJ needle will provide the proper taper to follow the increased air flow curve correctly for the modified/cover off air box. I suggest restoring your air box to it's original luster or purchasing the DJ jetting kit. (I like the latter one best) :-)

** Just to add a qualification here: You can shim the stock needle and make the bike run very well but the modifications to the air box have to be a bit less radical than the full monty top cut, or side cover removal. There are many examples of good running machines on this forum with varying degrees of box mods and jetting!

With a "pipe"

Hmm, after going back and reading this, I noticed the "pipe"... that'll teach me to post on Friday at work...

Considering a close to seal level altitude, I would probably check the choke, the cleanliness of the Carb circuits, possibly the float/needle. If a higher altitude is involved, then it could be the main. I'm assuming it's the 160 mikuni?

I would agree with Rob that the pilot jet is to large.

Hi all, there appears to something really amiss with my carby/jetting that is quite annoying. The fuel cunsumption is poor - 14 klms per liter and there is soot in the exhaust, it goes OK particularly if you stomp it but surges at constant speeds. It also is terrifying when you get off then on the throttle when riding hard - a huge flat spot then hold on. I have a pipe on, the airbox top is open and extra hole drilled in the slide, idle jet 45, MJ 160. I bought the bike new and am handy enough working on them but this one has me stumped - any ideas?

Regards Ian

14 km / liter is right around 52 mpg (US gallon). That's not bad mileage.

14 km / liter is right around 52 mpg (US gallon). That's not bad mileage.

22km/l is 52mpg

22km/l is 52mpg

Oops....

. :)

Thanks for your comments, I also thought the set up should be pretty close with the std airbox/pipe & jet mods, also I have lowered the needle right down (with no washer) to get it leaner. I'm thinking there is something seriously amiss here. Also I did put a DJ kit in it which I borrowed off a friend, I had the airbox side off and a staright thru (E series) pipe for some track fun, it had huge bottom and mid grunt and was quite impressive - and sucked fuel. I found the airbox side panel removed upsets the carby for street use so I did the top mod and put on a less obnoxious TK pipe but the DJ kit made it worse than it is now, I'm thinking I'll try his carby (with DJ) rather than just the jets as an elimination exercise.

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