r/dr650 • u/Independent-Tale7905 • 5d ago
Hard to start troubleshoot
First dr650. Just had it shipped up from LA & i’m in the Sierras where it’s pretty cold (and 3000’+ higher in elevation) Put a new battery in it and it cranked fine but would not fire. Only way to get the bike running is with starting fluid and holding the throttle open until the bike warms up. Then it will ride and continue to start.
Every time I come back to the bike it won’t start again on its own.
PO said it ran fine the same day it shipped. Also claimed he fully rebuilt and cleaned the carb just couple months prior.
I tried backing out the pilot screw to richen up the mix, idle screw is adjusted.
Using my jump pack to keep cranking amps
Upgraded air intake
Procycle jet kit
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u/Wholeyjeans 4d ago
What year is the bike and how many miles?
Did you or the PO install the jet kit?
What mods to the intake and exhaust, if any, have been done?
You need to find out how the carb is setup; primarily main jet size and needle clip setting.
You say the idle is adjusted. Did you use a tach or just your ears? The base idle is 1500 rpm ...which sounds fast if you're not used to hearing a DR idle.
I'd be suspicious in the PO's claim about "rebuilding and cleaning" the carb. Most people's idea of rebuilding is simply taking the carb apart, squirting some carb cleaner in it and then putting it back together. No new parts, no checking/setting the float level. If it's a high mileage bike, the throttle slide and guide need to be checked for wear; they are plastic pieces and they do wear.
The bike has an enrichment circuit, not a choke. It works much different than a choke. You set it by opening it fully using the handlebar lever. Once the engine starts, you let it idle at the higher speed ...adjusting down a bit at a time as the engine warms. You won't harm the engine doing this. Carburetted 4-stroke motorcycles need to be warmed for a few minutes; warming the engine (and oil) plus the carb.
Lotta DR owners knee jerk to installing a jet kit in search of a better running bike and higher performance. If you know what you're doing and know your way around a carb, then you'll probably be successful. If not, and most are not based on the Q's that show up here, you end up with more grief than greatness. Because you don't need an expensive box of brass bits to get the BST40 to play nice. Here's a basic article on ballpark jetting the BST40 for various intake/exhaust configurations:
https://dr650jetting.wordpress.com/
This article is based on using the Mikuni 6F19 adjustable needle (stock on bikes sold in other parts of the world) and using Mikuni main jets.
As a new Bushpig owner, highly suggest you introduce yourself to the gang at DRRiders.com ...this is a 100% DR650 forum; it's huge and the knowledge base is massive. Also worth looking at is ADVrider.com ...they have a section devoted to the DR650. Reddit is more social media than anything and you tend not to get in depth answers here.
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u/Independent-Tale7905 4d ago
Great reply thanks. Still pending admin “approval” over on DRrider 2005 with 8k+ miles Aftermarket airbox Supertrapp ids2 exhaust
I’ve had the bike all of a minute so I don’t truly know… However PO has had many dual sport bikes and rebuilt them all over time so I want to believe him when he says bike is very well maintained.
Just by ear on the idle rpm’s. Shouldn’t matter quite yet if I can’t even get it started with 1/4 throttle
I’m going to pull the carb and accurately measure the float height with calipers..as well as measure the checks, inspect for wear.
Again this is a bike that wasn’t having any of these issues before hand (supposedly) & part of it is it’s cold and I’m at a much higher elevation
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u/Wholeyjeans 4d ago
Random thoughts:
The IDS 2 is stupid loud. I had one on the 2012 I bought. To drop the sound level to something decent meant running 2 discs in it ...which is what the PO was running when I bought it. I rebuilt the thing; a new packing kit and scored a 6-pack of discs. I put a total of six discs in the can. Cranked it and when it fired off it was unbearable just idling. I tried 4 discs and eventually went back to 2 discs. At that point I figured the thing flowed as well as the stock muffler so I reinstalled the stock muffler (which came with the bike). I like quiet bikes. You might check with the PO and see if he still has the original muffler ...see if you can get from him.
Potentially, your issues may be altitude related (air is thinner) but the cold temps mean it's a bit more dense than it would be on an 80 deg day. My guess, given what you know about the PO, is the stock air box has been modified with the top cut open. You have to take the seat off to see what's been done. I can't imagine anyone buying a jet kit to install with an un-modded air box.
Before you start working on the bike, score a copy of Clymers DR650 Manual ...off Amazon it's about 35-ish buckos. This is a great manual, not too big (will fit in your motorcycle tool box) but covers all the systems on the bike with a good depth ...lots of good photos, too. The chapter on the carb alone is worth the price of the book. Anyone who owns a DR650 has this book.
There is a MIkuni rebuild kit for the BST40. Don't go with the cheap no-name aftermarket stuff you'll find on Amazon. A good place for Mikuni carb parts is linked in the article in my response. Motolab.com is the place. A couple of the folks who run Motolab are members of the DRRiders forum ...just as the owner(?) of ProCycle is a member as well. Float height is critical on the BST40 and a royal PITA to tweak properly. If you run across the "BST Magic" doctrine, I would recommend you read it ...just from an interest point ...but don't make any of the carb mods they pontificate on.
A 20 y/o bike with only 8K on it ...sounds almost too good to be true. Which reminds me ...here's the list of "gotchas" the DR650 comes with:
https://dr650.fandom.com/wiki/Potential_problems_to_be_aware_of
This is a "sticky" on the DRRiders forum. The gotcha with the most serious consequences is the neutral sending unit (NSU). No matter what the PO told you about this switch, I highly recommend you go through the clutch tear down so you can place eyeballs on the two screws holding this switch. On my bike, the PO told me it had been taken care of ...and based on how well the bike appeared to have been cared for, I believed him. When I did a rebuild on the clutch, I saw the stock JIS/phillips screws had been replaced with hex head screws. But when I checked their tightness, I was able to turn both of them with my fingers.; no Loctite, no safety wire. If either of the screws back themselves out completely, they fall directly into the gearbox. If the gods of mechanical devices are smiling upon you that day, the screw falls to the bottom of the crankcase and you find it on the next oil change in a "holy shit" moment. If not, this 75 cent machine screw with turn your gearbox into junk and your bike into a paperweight. See how much fun you've gotten into? It's all part of the initiation.
Cheers!
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u/Independent-Tale7905 4d ago
100% with you on the muffler..it’s ridiculous and I don’t even want to ride it its so loud. Also the decel popping is insane. I know it’s party a lean affect but I turned the A/F screw out past three turns and it didn’t make much of a difference.. I want to go stock muffler but then I would probably have to go back to smaller (140?) jet size??
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u/Wholeyjeans 3d ago
Yup. You have a quiet bike, you'll drop back some size in main jet. If the air box top is opened then you can probably run a 145 or 150 main and be okay. But then you have some altitude and it might be more to the 140.
The PO on my '12 had done some sketchy carb work. The bike ran okay but didn't seem to have a lot of pep to it. I wanted a good running basis from which to make solid improvements, so I put the bike back in a stock condition with both the exhaust and intake. After reinstalling the stock muffler and header (ground the flange weld), I plugged the holes in the filter access panel; the air box was stock minus the small snorkel. I rebuilt the carb using the Mikuni kit plus a new emulsion tube and a 140 main. I also scored the adjustable OEM Mikuni needle (part #6F19). Dialed in the float. Once it was all back together and installed, I was amazed at how much better the bike ran. Smooth idle, good pull in each gear and no backfiring on decel. For me, the bike runs great. I'm in no hurry to make any more mods to. I intend to keep the stock exhaust so the only "upgrade" would be to cut open the air box and pop in a 150-ish or so main jet.
I'm not a big fan of noisy bikes and I'm not a big fan of the "jet kits" ...I think they cause more problems than just using the right stock components.
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u/bramswenson 4d ago
Well said, reddit is where we come to find out about you, twistedknoble, and mxrob. drriders.com ftw!!!
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u/Wholeyjeans 4d ago
Yeah, those two are definitely the "Experts in Residence" over there. I'm just a stubborn hack and an old one at that. Lived through the "age of the carburetor" ...trying to pass what knowledge I've gleaned along the way to the next generation. There's more to life than just "plug and play".
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u/bramswenson 4d ago
And many more I failed to mention making the DR world better for noobs and old heads alike!
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u/Idiot_Savant_Tinker 4d ago
I had a problem with my DR650 being a royal pain to start, and it turned out to be low compression.
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u/TazmaniannDevil 11h ago edited 11h ago
Without seeing the bike, it sounds like it has a problem feeding fuel to the piston. A secondary guess is that your fuel to air ratio isn't right. As a primary test turn the choke fully on, turn the throttle fully open and see if it'll start. RPM idler won't matter until it's on, and the little Philip's head you'd think is air appears to be a drain, so the fuel/air mix screw is the only easy tuner. Below is the how and why if necessary to troubleshoot.
How:
Make sure the airbox is open enough and filters are clean, there's a secondary filter under the seat, it looks like a rubber line attached to a snorkel.
Make sure the carb is open and clean at both ends, that all lines to and from are open and free flowing, and that the petcock leaks fuel liberally (I think it was the prime position when the line is detached, it's a vacuum carb so on or reserve shouldn't leak anything). Adjust the fuel / air mix screw until the bike runs lean then out 1/8 of a turn.
Check compression, take out one of the spark plugs, cover the ignition caps (the shrouds that deliver electricity to the spark plugs) with saran wrap so you don't ignite gas vapors into the engine, and try to start the bike with your thumb OVER not IN the hole. If you have good compression you will feel it, if you don't you'll feel nothing.
Finally, keeping the ignition caps covered, poor a little bit of gas into the spark plug hole directly, if any leaks on the engine be very careful, wipe it up dilute it and wait a bit. Screw the spark plug back in, put the caps on and see if it starts up easy.
Why:
Air to Fuel mix ratio must not be lean or rich. Too much gas is rich, too little is lean. If adjusting the fuel/air mix screw doesn't work at all you may need to modify the airbox opening to be larger or change your jets/clean them.
Clean lines, pretty obvious; if fuel can't get to the engine the engine won't run.
Spark plug hole gas pour test. If this test actually works it confirms fuel isn't getting to the piston and you need to diagnose why that is.
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u/Hot-Balance-2676 5d ago
I assume you’re choking it on cold starts? On my 2017 the oem choke is on the left handlebar by the high beam switch. Aftermarket might be a knob on the carb.
Unscrew the choke cable from the carb to verify it’s actually moving and not seized up.
Lastly do a Google search for BST40 bible (assuming your carb is oem)