Jump to content

DR650 cold idling problems, dies on throttle wack

Recommended Posts

I put an FMF Powercore 4 pipe on my '01 650 a while back, and have only shimmed the needle with a washer to compensate. From what I understand, those pipes make the bike run leaner; the shimming made a noticeable difference at 3/4-WOT, confirming that partially.

The airbox and carb are otherwise stock.

My problem is, as the cold weather is starting (at least in the mornings), full choke is barely enough to maintain idle for the bike to warm up. It'll catch easy and stumble around really low RPMs for a minute, and sometimes it will just die. I've never had to restart it more than twice however. 

My other issue that occurred during the summer is stalling from idle when opening the throttle. For example, I was in bumper-to-bumper coasting in 1st with the clutch pulled at ~5MPH and the bike idling fine. I opened the throttle normally and starting slipping clutch to accelerate and the bike snapped to a halt and the engine died, nearly tossing me over the bars and brake-checking the person behind me. Sometimes blipping the throttle at lights out of habit will do the same thing - engine 'snaps' right off, and I can hear the starter motor clutch(?) make that kickback wind noise. 

My theory is that the pilot jet at least is far too lean - would getting a larger one fix that? Or should I just go with a new jet kit altogether to match the pipe?

Share this post


Link to post
Share on other sites

Ah, no I haven't... I remember drilling that plug out, but I never actually adjusted it :/

I'll try that today and report back, thanks!

Share this post


Link to post
Share on other sites

You need a jet kit.

You also need to cut open the air box.

The #1 restriction on a DR650 is the air box then the carb and then the muffler.  Changing just the muffler will lean your jetting even more, make it louder but not much more powerful.  Power comes when you open up the air box and fix the stock lean jetting, those changes alone will wake your bike up big time.  A muffler (or complete exhaust system) is a good choice, add a pumper carb and you'll have what feels like a brand new machine. 

If you live close to Allendale Michigan send me a PM, I'll let you take a ride on a DR that has an open air box, FCR carb and a GSXR muffler.  Be warned though, your going to be depressed at the extra power that you do not have ~ which could lead to some costly mods to your DR...  :thumbsup:

Share this post


Link to post
Share on other sites

Well, adjusting the screw didn't solve the problem, but did improve it somewhat. It seems I have to go too many turns out (>3) to get where I need it. Also, there is a really bad popping on decel which was also helped somewhat by the screw adjustment. 

Thinking about going for a bigger pilot jet at least, and eventually considering full jet kit and airbox mods as zig suggested.

Share this post


Link to post
Share on other sites

Airbox mod:  https://docs.google.com/presentation/d/1CjIod38f0Qgn5yLasoS0BI-l7C1kqYeT3SyLGhf5L5k/present#slide=id.p

Header pipe grind:  https://docs.google.com/presentation/d/13dTXBFvnh1qzg70X1VStDQJ2XHeHp9ync5-KmNQ5_KM/present#slide=id.p

If you have a lot of free time and like to read about the issues with the stock DR650 jetting it has been well documented, here's a fine example on ADVrider called "The BST-40 Bible":  http://advrider.com/index.php?threads/the-bst-40-bible.347184/

Dyno Jet's DR650 Jet Kit instructions, keep in mind that Dyno Jet uses an odd numbering system for their jets:  http://www.dynojet.com/pdf/3138.002.pdf

 

As you can see, the DR650 carb issues and fixes have been well documented.  Now it's very possible that you very well could be a lot better at carb tuning than I but after seeing what some other DR650 owners have gone through so many years ago I just decided to take advantage of their sweat and knowledge.  From there I bought a jet kit, liked it but wanted more.  As luck would have it MXrob (the brain behind the FCR conversion) at the time lived just 45 minutes away, a few emails later my bike was sitting in his driveway.  I then sat back and let him do what he has done so many times before ~ build and installed a dyno tuned FCR on my DR650.  I can honestly say that the difference from a jet kitted stock carb verses an FCR is night and day.  I did go from 50 to 55 mpg down to 45 to 50 mpg, however, the increase in torque and throttle response will make you think that your riding a big bore ~ seriously.  Even so, a stock BST with a jet kit, cut air box and an aftermarket exhaust is still a good combination.  Take advantage of what companies are offering and at the very least buy a jet kit, it really does beat trail and error.   :thumbsup:

 

Share this post


Link to post
Share on other sites

Definitely getting the jet kit now, haha! I initially found the decel popping pretty cool, until I started getting headaches hearing mini explosions behind me...

After I order new rear wheel bearings and a replacement bearing chain roller (can't stand the stock one rattling) and get those in, jet kit is up next. I'm hesitant to start messing with jetting because I've had bad luck with carburetors in general so far, but I think it'll be worth it. Thanks guys.

Share this post


Link to post
Share on other sites

I picked up a 2005 DR650 with a powercore 4 FMF exhaust and also the header was swapped for FMF after-market ( I can't remember which one exactly)  and it ran like nobody re-jeted the carb.  Sure enough it was all stock carb set up and only the snorkel was removed.  I ordered the dynotune kit and I know it comes with no pilot jet.  I was thinking of ordering the next size larger idle jet separately, incase I need to swap it.   Although it sounds like it's not always necessary, I just don't want to wait a week if I need it.   I can't figure out what the stock size is.  It has no markings.  Anyone know?  I plan on opening up the entire top of the air box and running a UNI filter in there.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:


×