DR650SE Index Topic #10- CARBURETOR/INTAKE

[kalsop]

Originally Posted by eakins

start by cleaning it with pine sol soak (google for hondo's thread)

you might have sticky/gummed throttle cables or throttle tube.

I did the jesse mod on my previous Dr and transferred everything back to stock but the slide piston with the extra hole drilled in it. The throttle seemed to be a bit to abrupt on deceleration. The throttle is very snappy as for as the thottle body spring back is conserned, it just seems to be a little long on deceleration. this bike only had 495miles put on it from oct 08 unil now so no telling what might have a little gum still holding on in the carb. Maybe it will subside once it has some real miles put on it.

[BergDonk]

I removed the airbox snorkel and opened up the top.
After much experimenting, including initially making up my own needle from and old FCR needle I had lying about, I got a Dynojet kit from Procycle.

Much more experimenting, and this is where I'm at:
Main 145
Pilot 37.5
FS 0.875 turns
DJ needle 4th clip from bottom
drilled slide

800 m

Leaner than most, but now working well with no surging and good economy, and pretty clean roll on from a closed throttle. Still no FCR, so I'll do that next. Nevertheless its the best DR650 with BST40 I've tried to date.

More of my DR650 stuff if you follow the link in my signature.

Steve

[NordieBoy]

Originally Posted by BergDonk

Much more experimenting, and this is where I'm at:
Main 145
Pilot 37.5
FS 0.875 turns
DJ needle 4th clip from bottom
drilled slide

DJ or Mikuni main jet?

[BergDonk]

Originally Posted by NordieBoy

DJ or Mikuni main jet?

Good question, a drilled Mikuni. I have experimented with DJ vs Mikuni and Keihin previously in other bikes and although I'm aware of the supposed differences re approach and departure profiles, they all seem to work pretty much the same for me over the years. All I do is gauge them with my jet drills, and that works for me. I leaned off the main from the supplied DJ jets to my drilled 145 and its leaner, although the 'book' says it should be richer.

A stick of solder and a set of jet drills and you can have most mains to play with.

Dunno
Steve

[NordieBoy]

Originally Posted by BergDonk

Good question, a drilled Mikuni. I have experimented with DJ vs Mikuni and Keihin previously in other bikes and although I'm aware of the supposed differences re approach and departure profiles, they all seem to work pretty much the same for me over the years. All I do is gauge them with my jet drills, and that works for me. I leaned off the main from the supplied DJ jets to my drilled 145 and its leaner, although the 'book' says it should be richer.

A stick of solder and a set of jet drills and you can have most mains to play with.

Dunno
Steve

So basically close to a DJ 155?

[BergDonk]

I had a DJ 150 in it and wanted it a bit leaner. Its the smallest the kit comes with. I found an old Mikuni main in my bits and drilled it to 145 with a drill. It feels leaner than the DJ 150, and gave me what I was after.

I could have soldered up a DJ jet and drilled it out, but I already had the Mikuni jet, so I thought I'd experiment and see what happened. All seat of the pants stuff though, so who knows.

I also neglected to add that the pipe comprises a FMF Powerbomb header and Megacycle muffler and tailpipe.

Steve

[NordieBoy]

Originally Posted by BergDonk

I had a DJ 150 in it and wanted it a bit leaner. Its the smallest the kit comes with. I found an old Mikuni main in my bits and drilled it to 145 with a drill. It feels leaner than the DJ 150, and gave me what I was after.

I could have soldered up a DJ jet and drilled it out, but I already had the Mikuni jet, so I thought I'd experiment and see what happened. All seat of the pants stuff though, so who knows.

I also neglected to add that the pipe comprises a FMF Powerbomb header and Megacycle muffler and tailpipe.

Steve

The DJ 150 is the same as a Mikuni 142 I thought?

A DJ 155 would be about right with a bit of altitude and/or not much air box cutting.

I was running a larger pilot (+2) and pilot air (+1) too.

[eakins]

http://www.advrider.com/forums/showthread.php?t=658502

[BergDonk]

Originally Posted by NordieBoy

The DJ 150 is the same as a Mikuni 142 I thought?

A DJ 155 would be about right with a bit of altitude and/or not much air box cutting.

I was running a larger pilot (+2) and pilot air (+1) too.

Now that I've got the FCR humming, I've got a mate with a DR650 who has had the choke sticking open a bit as reported elsewhere. I have since been wondering whether that was a problem with my stock carb and why I kept leaning off the pilot, dealing with a rich condition. I'll probably never know, I like the FCR too much.

Steve

[TheCowboy]

Just go my Mikuni BST40SS so-called Carb overhaul kit. Anyway I am looking at the rubber-tipped needle. On other carbs I have overhauled the needle moves up and down with float action. This needle has a pin on the top that moves - it's kinda like a plunger or somthing - when the float moves up and down it just presses on the pin (plunger) and it moves down. The old float pin-needle or whatever you want to call it I removed the pin (plunger) on top does not move at all (of course this may be why it was flooding all the time. Can anyone shed any light on this? I got no instructions with the ProCycle kit.

TheCowboy

[TheCowboy]

Disregard last post - I have fuel in the crankcase - a hole new problem

[NordieBoy]

Originally Posted by Cowboy2

Disregard last post - I have fuel in the crankcase - a hole new problem

Sounds like the same problem.

[996DL]

This link originally posted by Rumlover !

www.vmaxoutlaw.com/tech/dyno-mikuni.htm

996DL

[LexTalionis]

Years ago a buddy installed a portable A/F monitor on his flatttracker ATK and was very happy with his tuning result.

The May issue of Motorcycle Consumer News has, on the back cover, a glowing write-up of the NGK Powered AFX Air-Fuel Monitor.

Dave Searle at MCN states, "Air-fuel ratios by themselves are not the final answer, but they're close, and from that baseline, additional dyno or stopwatch tuning to totally perfect the setup will require less time and money." My thought, exactly. I'm guessing the tuning arrived at using one of these devices is satisfactory for 98% of DR riders.

Reading some of the anguished emails from riders soliciting tuning help makes the $260 cost a cheap investment for mental health.

Searle states 13:1 is the optimal A/F ratio for power and cooling on the DR.

Lex

[NordieBoy]

Carb MainJet equivalents...

PHP Code:

hole     Kehein      DynoJet     Mikuni
0.0570    147.5       136        127.5
0.0580    150         138        129.4
0.0590    152.5       140        131.3
0.0600    155         142        133.1
0.0610    157.5       144        135.0
0.0620    160         146        136.9
0.0630    162.5       148        138.8
0.0640    165         150        140.6
0.0650    167.5       152        142.5
0.0660    170         154        144.4
0.0670    172.5       156        146.3
0.0680    175         158        148.1
0.0690    177.5       160        150.0
0.0700    180         162        151.9