Jump to content
Sign in to follow this  

dr650 jetting and carb Q's yet again

Recommended Posts

I know there are many threads going about this topic, but was just wondering if anyone out there could give some specific detailed instructions for someone who has ordered the dj kit, is a competent (IMO) home mechanic bikewise but never opened a carb before. Just wondering what to be careful about or any helpful advice. I ordered from Jesse, so i have seen the pics on his site, got the allen screws and extended fuel screw and K&N.

Help appreciated, Derek.

BTW :ride: anyone who thinks the dr doesnt make for a good wheelie machine stock is wrong. My 2000 650 goes up in second and i can get it to fifth and sit up there all day on the highway...untill the police arrive. :thumbsup: THanks again for any help

Share this post


Link to post
Share on other sites

The BST40 is one of the easiest carbs to work on. Drain the float bowl with small screw, remove fuel hose, and take off the tank. Take the carb off the bike and remember to leave the throttle cable holder attached to the carb. Use a small open ended spanner to loosen off the choke plunger, be careful as this part is easily damaged. It makes lfe easier if you take the airbox out first (which you probably will do anyway to cut the top open?). Take a note of where all of the breather tubes, drain tubes etc go to. Take the top of the carb off and remove the slide. Check the diaphram carefully for any rips, tears etc and replace if dodgy. Remove the needle, and keep all of the washers, spacers etc. Drill the slide as per pic on Jesse's site for better throttle response (optional mod). Add the tapered DJ needle (compared to the stocker, a thing of beauty!), being very careful that you use all spacers etc as per the instruction sheet, and that the needle fits properly into slide, and is not hung up as it can do. Take the float bowl off the carb body, hopefully they'll come off O.K, but some guys have had a hell of a job getting these soft screws out. Main is the jet on the end, so real easy to get at. Put in the jet of your choice, and refit float bowl with allen head screws (wise move!). Refit the carb top, being careful to align vacuum port with correct top orientation. Remove the brass plug covering the Pilot screw by drilling it out and unscrewing the screw completely and remove. Make sure you have the washer and o-ring as well. Refit these parts to Jesse's extended screw and set to 1.5 turns out as a starting point. Remount the carb to the boots, and reconnect everything. Put the petcock onto Prime to fill the float bowl, and then around to On. Be careful not to overtighten the choke plunger. Should start straight up and go like hell! Good luck, this is a very useful mod that should make a huge difference to your bike! :thumbsup:

Share this post


Link to post
Share on other sites

Thanks for the advice adventurebob! Once my kits arrive I'll get to workin. I saw and read all the threads I could about the jets, but none seemed to actually talk about the disassembly of the carb. Thanks for the step by step directions.

Share this post


Link to post
Share on other sites

Just an added tip from adventurebob2004's good advice.

"Take a note of where all of the breather tubes, drain tubes etc go to."

Some days, I don't remember what I had for breakfast, let alone how the bike goes back together that I tore down two days ago.

I get out my digital camera before I start taking the bike apart. I consider the camera to be as important a tool as my 8# sledge hammer for fine tuning. I take pix of everything I am going to take apart. And more pix as I disassemble each subassembly.

Some places, you just can't quite see clearly with your own eyes. The camera & flash often gets in there and gives a marvelous view.

When your scratching your head or whatever, later on, and trying to figure out which end is up, you plug the camera into your trusty old PC and it jogs your memory.

Some of the more interesting pix get printed and added to the bike's file folder for future reference.

Enjoy!

Troutte aka Michael

Share this post


Link to post
Share on other sites

Thanks much, sounds like a great idea for makin sure things go back together smoothly.

Share this post


Link to post
Share on other sites

Performance may go up but fuel mileage and range go way down. I rode with another DR last Saturday and he had the jet kit installed. We were both riding at the same pace. He got 37 mpg, and I got 54 on my stock machine. His range = 125 miles, my range = 183 miles with stock 3.4 gal tanks. He would have to buy a bigger tank ($200) and carry an extra 12 pounds of fuel to get the same range I have with the stocker. The jetting kit also makes the bike much louder.

It's a possibility that maybe his bike is running too rich. Does anyone get better than 37 mpg with the jetting kit (at sea level, 90 degrees)?

Share this post


Link to post
Share on other sites

Mileage is not really a concern for me so I think it should be fine. From what I've read he may be running it too rich though, if the mileage was hit that hard. The loudness was probably due to an opened airbox rather than just the kit, although i could very well be wrong as I have yet to get mine and install it.

Share this post


Link to post
Share on other sites

My mileage went from 23 km/l to 20 km/l which is around 15% worse, but still a hell of a lot more than 37 mpg! (54 mpg). I'm jetted pretty big @ 165 main, but the extra power, torque, throttle repsonse and shear driveability of that kit and pipe absolutely transformed the DR into more like a 650 than the corked 500 that the stocker feels like to ride. I've seen enough dyno charts to know that it's worth 20% extra at the wheel - and hey that's not to be sneezed at! Enjoy, this is one seriously fun bike..... :thumbsup:

Share this post


Link to post
Share on other sites

My thanks to you guys for the advice. Got the parts in the mail this morning, put them on this afternoon and just got back from my first test ride. It is a better bike now, a bit louder due to airbox, but tastefully louder and not worth a second glance from the cops i went by. Those screws were terrible, but finally after stripping out the phillips part, trying the dremel/slot flat blade and the screws just mushing to bits, the vice grips got them loose. Adventurebob your instructions worked perfect, thanks.

Share this post


Link to post
Share on other sites

Happy to help out, glad it went without a hitch. My float bowl screws came off pretty easy, but the bike was only 6 months old, so I guess I was lucky on that score..... Now the fun starts for you as you need to find the best jet and pilot screw settings to optimise the mixture. If you are at sea level with a stock pipe + airfilter (which I think you have?) you could try DJ 155, and around 1.5 turns out as a starter. I'm also assuming that you have cut the top open on the airbox of course, not just pulled the snorkel? Mikuni jets are also worth looking at as they are available in 0.25 increments which is useful, but be aware that a 160 Mik is not the same size as a 160 DJ and that you will need to get hold of a comparison chart off the net to figure out the equivalent sizes.

Share this post


Link to post
Share on other sites

Yeah, I'm at about 76 meters, or 250 feet. Stock exhaust with cut airbox and K&N filter. Right now using the DJ 160 with 1.5 turns on the screw for starters

Share this post


Link to post
Share on other sites

I think were about the same distance above sea level and i have the air box done as per Jesse and after quite bit of experimenting I'm doing a 155MJ and 1-15/16 turns out on the screw. Runs very well at all temps. Starts great hot or cold. :thumbsup:

Good luck,

motoretro

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:

Sign in to follow this  

×