Please Help - can't cold start

I have a standard DRZ400 S, '01

I bought it a couple of weeks ago and it was fine, but after a days trail riding (including a few 'offs') it has become really difficult to start.

When turning the bike over from cold it just turns and turns, doesn't fire up. If I crank the throttle a little bit it sounds more like it wants to fire up, but then stops. This also runs the battery flat very quickly.

I can start the bike pretty easily if I jump it from a bigger (car) battery (once started bike runs absolutely fine, and starts ok when warm too), so I thought a new battery would solve the problem - but no, still same problem with a brand new battery, I have also changed oil and spark plug, no change.

I have trolled through the forums but am a bit confused by the sheer volume of info! does this sound like anything particular?

I have tested the RR - seems OK, the stator seems good, although I not yet tested the output whilst running (the engine cut off when I unplugged the plug with 3 yellow wires - how else do I test it?)

will the "free power" mod help? (I am going to do it anyway when I get the chance, but dont really think this is the cause of the prob)

please someone tell me what I have done to my bike, I want to ride it!

Confirm battery voltage.

Engine off, key off.

Engine off, Key on

Engine on, idling

Engine on, part throttle

Confirm carb is clean. Make sure all jets are clear, blow compressed air through the starter passageways.

What is your battery voltage? Also, when it is cold and your crank it, do you notice that it is slower cranking than when you jump it?

Might just be a battery...

Confirm carb is clean. Make sure all jets are clear, blow compressed air through the starter passageways.

+1 :thumbsup: 9 times out of ten, a hard to start bike is a clogged pilot jet or starter jet

Wow, speedy replies, thanks guys...

OK, Battery is brand new, made no difference.

I had the carb out and cleaned it up, but looked spotless anyway, suppose I could have missed something in the starter passageways, but then why does it fire up when jumped from a bigger battery?

Being its an older bike I would check the grounds and battery cables. Make sure they don't have high resistance. Make sure the lugs on the cables are clean and tight. Otherwise it may be a starter issue. Does it crank faster with a car battery connected?


Is the car running when you are cranking it. That would result in the starter getting an extra two volts across it. If that is the case, it will definately start easier.

New battery, but what is the voltage according to the points of reference I mentioned earlier.

You are right, if it starts fine when jumped, your carb is probably fine.

Did you read the "look here before asking" at the top of the forum regarding charging system tests?

not running car when jumped, just connected to battery, not sure if it cranks faster, but it does keep cranking when I turn the throttle a bit, which it doesn't from just the bike battery.

yes i looked at the sticky info, see my original post for how far i managed to get from that info (RR seems OK, stator I think is OK), problem is not lack of charging, I can charge the battery off the bike and have the same prob

sorry - voltages....

motor off key off - 12.9V

engine idle 13.5

engine rev 13.8 (ish)

Ok, voltages are not bad, but could be better. After we get you fixed up, do the "Free Power" mod, will get your engine rev voltage up to about 14.5.

Thinkgs to check.

Large battery cables.

Disconntect the Negative (black at the battery)

Confirm the red at the battery is clean and tight (Iam sure it is as you just replaced the battery)

Confrim the red wires at the starter relay (under side panel next to the muffler) are also clean and tight.

Confirm red wire from the relay to the starter motor is clean and tight.

Confirm the black wire attached to the engine above the CS sprocket is clean and tight.

Confirm by removing each wire and then reattach, do not simply jiggle.

Reconnect the negative at the battery and give it a whirl.

Still poor, then either the relay (doubtful) or the starter is going bad.

thanks william, i'll try that tomorrow and post up the results, cheers!

Good deal, let us know how you make out. I hope is not the starter (if it is, they can be cleaned, new bushes installed, best left to a specialty shop as they can test it properly too.)

check your valve clearance.

Hi Eddie, :worthy: , yeah I thought maybe valve clearances (after checking other posts here, not because i'm clevor!), can this happen suddenly? the symptoms started only after a days riding :ride: (and falling :crazy: ) , was fine before. The reason I ask is that checking valve clearances is a little bit advanced for me at the moment, and i'd rather not try just for the sake of it! Cheers

Valve checking is easy. As long as you have feeler gauges. You will not be adjusting anything and is safe for a novice to do.

Remove the fuel tank.

Clean any dirt off of the valve cover.

Remove the spark plug

Remove the valve cover

Put the bike in 5th gear, roll the bike forward slowly, looking at the cams. At one point, both the front (exhaust) and rear (intake) cam lobes will be facing 2 O'Clock and 10 O'Clock. This is TDC on the power sttoke and where you want the cams to be to check the clearances.

Use your feeler gauges, slip a thin one between the cam 'heel' and the round disk (valve bucket) in the head.

If it slips easy, go up to the next size. Keep doing this until you find a size that will not fit. The one that just fit is the size you want to make a note of which valve you measured. Compare your numbers to the specs. After you have the numbers written down, recheck them again to confirm you have the right measurement. Once you get good at this, develop a 'feel for it', you will not have to do the repetative step.

Although usually, hard starting is a sign of tight valves (and possible need for a valve job), in your case, you say jumping the bike starts it right up, so I am feeling it is electrical rather than valves.

But I could be wrong, I was, once, L, well twice, well, ok, five times today and I only got up 20 minutes ago, LOL.

OK, here's an update...

I haven't checked the valve clearances yet, need to get some feeler guages (thanks for the detailed how-to william!)

I put the new battery on the bike from being charged overnight, choke on pressed the starter, starter spins quickly gets a couple of pops from the exhaust, but no start. I turn the choke off, and whilst cranking the starter give the throttle a couple of gentle 1/4 turn twists, she fires up and purrs like a kitten. After a few minutes i turn the engine off, and it starts right back up again with a short press of the starter, no throttle no choke.

Previously it would start from cold with the choke on and just a press of the button - no throttle fiddling needed.

Does this give any clues? (making me think more along the valve-clearance lines)

Thanks guys for your continued help!

The choke circuit is cloggeg possibly. Valves would not make a difference. Try another cold start, this time, just crack the throttle a hair and hold it.

I think the carb needs a good going over. Kind of a pain to do as it is such a tight fit. But I think it needs to be done. You will need to record each jet size, the main, pilot jet, Fuel screw number of turns, needle and clip position.

while you have the seat off, is the airbox snorkle on the bike or is there an open hole that measures 3" X 3"?

i'm not going to take the carb apart again until next week, I am going for a ride tomorrow, and now i have figured out how to start it that will do for now!

I think the carb is standard - jets and all, and there is no 3x3 mod (yet :thinking: ), also i am in UK, about sea level.

check the valve clearance.

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