Suzuki DR650 Mikuni carburetor re-jetting using Six Sigma Jet Kit
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- Опубліковано 5 жов 2024
- This is a short video of rejetting the Mikuni carburetor on my DR650 with a Six Sigma jet kit that I got on eBay. They include personalized instructions that were fairly easy to follow and several jet sizes for different progressive stages and altitudes. This video shows settings recommended for Houston w/airbox mod, stock muffler, and mild performance increase (small hole drilled in slide, but did not clip the spring.
EDIT: You can also call you local dealership and ask them what settings they would use. They usually sell the jets and you can pick up the spacers at Lowe's. I do recommend the extended fuel mixture screw from ProCycle. - Авто та транспорт
3:25 you missed a O-ring at the vacuum hole for gauges...
At 2:20, you can see the detail, but from the non-pointy end it should go clip,shim washers, nylon spacer. The nylon spacer will fit snug on the needle, so it is used to sandwich the loose shim washers against the metal clip and hold everything in place.
great video. and that brass jet in the float assembly is for the enrichment circuit, people still call it choke. that is the one coming from plastic float assembly, routed via outside brass pipe and coming in front of throttle flap from above
The simple answer is yes. I have read that any time you change the airflow, you need to adjust the gas flow. From the factory, the bike comes fairly lean, so most will add a bigger pilot jet, main jet, shim the needle, and turn the air/fuel mixture screw out a bit even without making the other mods. The kit I purchased had recommendations for the different stages for airbox mod, aftermarket exhaust. They even included settings for a high altitude trip I am planning through Utah this summer.
It was quick. Like a week or so. I think they have them already built. I would imagine that they just customize the instructions based on how you ride and what mod stage you are looking at. While in Utah, I did have to re-jet and I didn't have my jets with me, so I went to the local Suzuki shop and they sold me a main jet for $3.50. So, if you know what you are looking for, you could build your own kit.
i bought the procycle kit wich came with really deatailed intructions and a template for the airbox mod, new stainless replacement hex screw for the bowl and lid, needle, sppacer, an 3 jets. i like it alot
Even made me understand clearly and I bought nothing about carburettors.. Thanks man.. You must have great passion for what you do
Thanks for the comment. Glad I could help out. 😄
Good catch Peter. I took the thing apart several times in making this video. The next time I have my tank off I will have to check to see if it is really missing or if I found it and added it back after shooting this.
At 11:37 you are missing the small rubber O-ring that goes in that round port (exhaust ports as u call it) to the left of the screw hole on the top carburetor diaphragm screw hole. (Near the base of your pointer finger)
What that kit doesn't give u a new needle or main jet.... THAT'S THE WHOLE POINT of a jet ket lol
Johnny Turbo yes, I realized that when I found the tiny oring after putting it all back together but before putting it back on the bike. All good though. Thanks!
@@jaetheo 😁👍
Yeah, I did this change knowing that the bike comes from the factory with very lean settings. I also bought the bike in Utah and brought it to Houston so there was a big change in altitude. I bought the kit on eBay for under $40 so they must have raised the price. There are plenty of posts out on forums about different settings, I just wanted to be sure of the procedure and have all the parts on hand.
Great Video, Thanks for the effort and commentary.
Those Phillips heads are not standard Phillips head screws, they are called JIS( Japanese industry standard ) and are actually different to normal Phillips head screws, that’s why you will notice that they get damaged when you use a normal Phillips head screwdriver, that’s why in the pro cycle jet kit they supply you with 4 stainless steel Allen key screws to replace them, pro cycle is definitely a top notch performance kit, they also supply 3 main jets, a 145, 150, 155. Along with a tapered needle which is great, In Australia we are paying at the moment $119 for the pro cycle kit, we’ll worth it and is a kit that will give your bike a lot more go. Basically it’s a high performance kit. Hope your sigma kit goes well for you.
No, I have not fine tuned it, though I usually make a minor change when I go to Utah. I swap in a smaller main jet to compensate for the altitude. It seems to run smooth and has plenty of power without bogging down, so I have not felt the need to fine tune it. Someday I will get around to doing it though.
Thanks for posting this video...I just bought the 6 sigma kit for my kz400.
There was a slight increase in power, but the main changes were the popping on deceleration went away and the quicker throttle response. Thanks for watching!
just what i was looking for six sigma i love you
when you put the cap back on isn't there suposed to be a oring where the vacuum port is? maybe it was stuck to the cap.
Yes there is. I re-did the build a few months later and put the o-ring in there where it goes. Good catch!
No. I have not done any fine tuning, though I do swap out the main jet when I haul it back to Utah each summer.
Helped alot. Im still stuck searching how to remove the the choke cable from it tho
great video, tx, but it would have been nice to know how it worked out, did you have to make additional adjustments or was it perfect as it was with the new parts?
very helpful video, thanks
Had I known you were the carb master, I would've had you fix up my cafe racer carbs before you left town. Dag nabbit Jae!
IDK, spent $39.50 for my kit from 6sigma, and it was the single biggest improvement I have done to my bike. My exhaust that was alot more, only made a slight improvement. Didn't Apple start in a garage?
brilliant vid man im doing the jets on my hornet today and i feel damn confident now after watching this vid btw did u notice much power increase.
Great video ... Thanks man
You need to drill out the plug that covers the air-fuel mixture jet. Drilling an extra hole in the slide is up to you though. It is supposed to result in snappier throttle response.
i noticed you never put the O ring back on the top of carby, that will be an issue big time, i was going to buy a sigma kit but it does not come with the parts the other kits do, you get what you pay for. Do yourself a favour and buy a pro cycle kit, top notch kit, bit more expensive than the sigma but well worth it, dont forget that O ring. Also the original screws on the mikuni carby are japanese , we call it a phillips head but its a different screwdriver called a JIS (japanese industry standard) very similar to the Frearson screwdriver thats why it damages the screws on the mikuni carby. sometimes a little dot on top of the screw will mean its a JIS. In the pro cycle kit they supply you with 4 allen key bolts to replace those stupid JIS dodgy screws. good luck.
So did you notice any increase in power? Throttle response, acceleration, horse power, etc...
Great vid by the way.
Thanks for great job! But what include Procycle`s jet kit?
I agree Rob, I would like to know how well the mods worked and if there were any problems. Are you running the stock exhaust with spark arrest?
Vito Licc - Yes at that time I was running a stock exhaust with the drain bolts removed and the drilled out air box. The jets that were included opened it up but still made it run a little lean. There are charts online that can show what jets to use at your altitude and you can buy them individually for cheap, or you can order a kit like I did. There are definitely pros and cons to each, and there are varying grades of kits. Some kits only include a few jets and a needle/shims and some come with new reshaped needles like with the JD and Dynajet kits. It all depends on how much you want to tinker with stuff on your own or buy a solution. Thanks for watching, and good luck!
Have u made any fine tuning changes to the carb after making the video ?
I don't understand why you didn't go for the kick ass jetting as told.( maybe you still have the stock pipe?)
Yeah, I still have the stock pipe. I usually ride with the bottom drain bolt out, but I need to upgrade. Plus, I have a DRZ400 that is getting a lot of love these days. 😀
I just put a pipe on mine & every one said do what they say with the kit DJ or JD. By the way I sold my 400. I wanted a big bore for the hiway. thanks.
do you need to re jet the carbs when you install open air k&n filters?
good for technician
hi Jaetheo thanks, but can you do the same video with the 1990 suzuki dr800 please???
I would be happy to, but I don't have access to a dr800. Should be similar though. Most jetting kits will include pretty detailed instructions and include phone help if you need it. Thanks!
@@JaeTheobald okay buddy thanks for your knowledge and time.
So Jaetheo, you say that you run your bike with the exhaust drain/clean port bolts removed? does this cause any scorching or burning of any part of the bike? What does this make the exhaust sound like?
There are two drain bolts on the underside of the exhaust. One is near the end and one is near the elbow that connects to the header pipe. Removing one or both of them does give a bit more of a throaty sound and adds a bit more airflow. I checked to see if there were any scorch marks from the one that is near the elbow and I was mistaken. At some point I must have put that one back in. So at the moment, I only have the one near the tip removed. At some point though, I really think I need to just get a new exhaust. The stock one is very heavy and quite restrictive even with the bolts removed. I really quite like the Two Brothers exhaust for the 650.
Why do folks do all these mods? Personally I think stock is fine. I guess it's based on what you want to do with your bike. I primarily ride back roads and some trails. Guess if I was racing or wanted a supermoto these mods might be tempting.
Ride safe!!
Good instruction video btw!
All depends on what you actually use the bike for.
There is nothing free in engineering. Everything is a compromise; Fast, Reliable, Cheap. < Pick Two.
For most people of course its fine, and Suzuki tuned it to run decently well anywhere on earth, but not optimized for any one place. If you spend a lot of time on a bike with a pumper carb it becomes apparent the deficiency of the CV style, more specifically the poor design of the needle in this BST40. And the sluggish fuel delivery while snapping throttle open from idle.
It really matters most if you ride over large rocks and logs and need that immediate punch of torque to loft the front over obstacles or you want to pull power wheelies in anything other than first gear. Also, you may notice a lean surge/stumble while turning very tight in parking lots or on trails that can throw off your balance in tight spaces.
The main jet that by all accounts is more than adequate (#140) unless you significantly modify the bike like cutting out the air-box top and aftermarket exhaust. The pilot jet is also more than enough. The only thing it really can benefit from is the needle found in KTM's or better yet; high end jet kits, like DJ and JD kits, Or from shaving the stock needle down at the point per "BST magic" thread. You can also drill out the stock main jet for the cost of a precise wire gauge drill bit of appropriate size ($3). But it will not help and only hurt if you have not drilled the air-box and swapped mufflers simultaneously.
All very good information. You've obviously done your homework on this subject. It's something I might try in the future, I can see where instant punch and throttle might be a good thing.
Being that I just got my bike, a 2014 DR650SE, I'm a little hesitant to go cutting and tweaking. I'm sure the day will come!
What are some of the first "mods" a new owner should consider doing? my bike is basically bone stock.
Thanks for the info btw!
Bone stock these bikes are fine for every day riding in most places.
Primarily focus on ergonomics, I put on JNS lower/rearward peg mounts which helps with leg cramps and along with 3" bar riser/pivots I can now stand without hunching, back stays straight while standing. After you get it to fit, just ride it a ton till something really bothers you. You can fit it to yourself quite well for $150 in risers/peg mounts.
If you notice a lean stumble and surge while riding slow or taking off, or the bike requires choke for more than 60 seconds for cold start before it will stay running, or if your not happy with the delayed throttle after you whack it open and it hesitates... you might consider doing BST Magic mods. Be warned some guys go from fine stock to bad running bike, though these mods are repeatable 100% if done by the same knowledgeable people. Do a google search for that term, (BST Magic) an epic thread.
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I just recently did the Full BST Magic treatment to mine at the same time I posted that comment.
At minimum most problems are fixed with a simple needle taper and adjustment of both idle mixture screw and idle rpm screw.
(Warning: Longest detailedest post of the world).
Taper Needle
D'd-Spacer
Adjust Idle Speed Screw
Adjust idle mixture screw
(Last 3 for throttle response only)
Enlarged stock slide hole to 1/8" (3.2mm)
Drilled one extra 1/8" hole in slide from inside
Cut 2 coil from spring (making it 4-1/8" long)
Needle Taper is the most technical, and most beneficial it gets rid of lean stumble and surging at part throttle where you spend most of your time around town.
#1 measure 45mm or 1-3/4" from fat end/top of needle past the clip. It should be less than an inch from pointy end. Mark with sharpie marker. Taper will be from this mark to the point only.
#2 mount needle base end in the drill chuck
#3 sand it down with medium emery cloth or sand paper (180 grit works, takes 15 min)
#4 it will look like shit. Keep an even taper and work hardest nearer the point. Sand till it tapers evenly to a 1/16" tip - check with drill bits size.
#5 use #600 grit wet sand paper dipped in water to sand needle back to factory polish. Takes 30 seconds. looks mint!
While your sanding and have needle out, sand the white plastic spacer to a "D" shape that matches the internal slide ledge. So needle drops in a little farther and hangs straight. Lay sand paper flat on counter, sand spacer while its on the needle. - If your bike runs like shit after this mod, and the idle mixture, and idle speed screws cant correct it, (see below) then add a 3mm washer or two on top of white spacer, but under C-clip to raise needle a little back toward stock height. (3x 3mm washers return to stock height, but with proper tapering it will be to rich with 3x of them, so use 1-2 to start).
Getting to the spring, slide, needle + Spacer + C-clip, is all done from the top of carb, while on the bike if you wish. (Seat + Tank + cables removed, loosen carb clamps, rotate carb out a little) Take out the 2x phillips screws on top. They will be a PIA you may ruin them. Use Phillips bit that matches size, tap bit into screw with hammer before trying to turn. Or use vice grips then Replace with Allen Hex M5x16mm screws (Fastenall Stores sell them, along with 3mm washers, try NAPA at the counter also).
Note: M5x16 screws are used for bottom of carb also, as well-as neutral safety switch.
Adjustments:
Fuel/Air mixture screw, located on bottom of carburetor behind a brass plug. Drill brass plug out gently with proper bit size. (off-bike much easier, or spin carb with its top still removed to access bottom of carb from driver side) Use a fine flat head screwdriver bit to adjust it when on the bike. Tight space in there! Procycle has an extended-grip mixture screw that's mint for under $20, highly recommend. Stock It will be +/-2 turns out, screw all the way in and count. That's baseline. Now screw out 1-1/2 turns and start the bike. Don't adjust it again till well warmed up; 10 min ride minimum.
Idle speed screw is the big one that acts as throttle stop on side of carb. Adjust it once warmed up, probably needs to be lowered as needle tapering added more fuel down low. Get idle speed where you want it once warmed thoroughly (smooth stock idle 1,500 rpm +/- ).
Now go back to mixture screw from below, use that flat head bit and ware gloves! Turn it in a little, till bike runs rough or dies. Back out a little till it smooths out, back out another 1/8 turn (smidgen) for safety. This should be perfect.
If you get lean surges at idle, or loud backfires when you coast or kill engine, back it out a little more. Backing out mixture screw adds fuel at idle. To much fuel wastes gas and causes bog when you take off. 1-1/4 or 1-1/2 turns out should work well.
If the bike surges at wide open throttle and is not smoothly delivering power, but not bogging either, just surging and inconsistent, your needle is now to low with D Spacer mod, so add one or two washer shims to raise needle and richen it up everywhere. Readjust your adjustment screws with each change to the needle.
Whew.
I hope that helps.
Do you have to drill any parts. Or can the jet kit be done without this.
Thanks
How do u shim the needle like where do u put the shims?on top or bottom and how does it work?plz reply thx
How did it turn out with the 157 main and the 47 pilot? What exaust you running?
It turned out well but I don't ride the 650 as much anymore. Usually take my DRZ400. I am just running the stock pipe on it with the rearmost drain bolt underneath removed.
missing the o ring at top of diaphragm cover. for vacuum.
Dustin Carbaugh Yep. I noticed that a little later. I had to buy a new one and got it back in there. Thanks for watching!
I replaced the stock fuel filter for a biger 1 but my dr wont start now. any advice on tha?
If its a stock DR650 it will be a mikuni bst40 carb.
Does any pipe go on the 90 degree metal pipe at rear of carb,or is it just a vent
If I recall correctly, it is a vent hose with a small air filter on the end of it.
I need a new carburetor for dr 600 any help am in Ghana
Ok. So i have a few questions i hope u can find a minute to answer. I have a suzuki dr 125 dual sport i bought the 6 sigma kit. I just cant seem to open up 5th and 6th gear for the life of me it just bogs n gets slower in 4th i can hammer it n its high revving. And can get it up to 55mph high revving but 5th and 6th are week.. im using a 120 main i originally had a 112.5 and i have the stock pilot jet in there i had tried the 42 pilot that came with the kit. I have tried variations of the shims i currently have 1 shim in i used suggested fuel screw setting didnt seem right i used the 1.5 turns out seems better but why cant i use 5 and 6th there so flat and bogggggy.. help me please.... lol
Eric, let me start out by saying that I have never jetted a 125. That said, I do have one and I am constantly battling with the float bowl and the stock jets. Between gas leaking out and not flowing fast enough, there are plenty of forums who say that the carb should just be upgraded. If the engine is bogging at high RPMs, it is likely due to too much fuel and not enough airflow. You can try opening your airbox or going down a step in your main jet. Also, make sure you have a clean and properly oiled air filter.
Well in my exp float height seems to be great at 13mm and for the leak i just fixed that prob. Needle jet oring was bad. Replaced. No leaks. Its not so much the high rpm its load on the beginning of 6th gear 12345 shift great rev great just cant get past the initial low rpm in 6th
What is the model of the carb cause I have the same one when I bought my bike but I cant seem to find anything out on it
mikuni bst40 carb
i have a mikuni carb that have the same type of main jet just like in this video. planning on re-jetting the carb but i can't find any mikuni main jet, i only came across a keihin main jet which is the same shape as the one in my carb, are they identical?
I am not sure if they are compatible or not. I wouldn't think so. You might check at you local shop, RockyMountainATVMC, or even Amazon.
+jaetheo thanks for the reply, at my local store, they said it is compatible, just need to pick the size though. but im taking an extra precaution because my bike is an everyday bike, i dont want to waste my time on something that dont even fit. so i guess i just have to try than. i just want to up the main jet by one size. that's all.
i dont know the name of it but, how do you take off the part where the gas hose goes?
I believe it is just pressed into the carburetor body. You might be able to wiggle and pull it out with some vice grips, but I can't think of a reason to remove it. There is a small delicate filter that you can clean out, but I wouldn't mess with it too much unless completely necessary.
whats your email? so that i can tell you about some problems that i have.
what kit is better six sigma or dynojet? and why?
IISHEEVAII I would probably say that the best kit out there is the JD jet kit. It comes with several different jet sizes, needles and such. Dynojet is somewhere in the middle but used their own jet and needle sizes, and Six Sigma gives you the basic Mikuni jets and washers to get the job done. Technically, if you know the sizes, you can pick them up individually.
I have my airbox without side cover, and I want to increase power in low revs, which kit you recommend I have the possibility to buy 6 sigma or dynojet through ebay.com currently my bike seems to have a turbo lag, in low revs does not push so hard and in high revs gives a blow of power as if the engine was turbocharged. greetings and thanks
IISHEEVAII I think the Dynojet kit would probably be best for your scenario. As I mentioned the Six Sigma kit does not come with a different needle. I believe the different shape of the needle in the Dynojet will change the power curve to what you are looking for.
thanks my friend.
thank you very much. i try to get a dynojet kit. good luck bro.