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Dr Will Not Start

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hi again, we now have the dr350se back at the workshop and am having great difficulty in starting it, we have cleaned the carbs and changed the fuel plus checked for spark and wd 40 the wires and connectors under the seat, it will start eventually but bottoms out if you rev hard, we have found that you have to twist the throttle once all the way then twist quarter of a turn and kick it over a few times, it keeps kicking back and sometimes backfires through the exhaust. it really is a bugger to get going, please help. :thumbsup:

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my 350se had same problem mine was a corroded wire from the coil in to the main loom it caused it to be intermittent and worse when reved hard but was`nt visible till cover of wire was stripped back as for back firing through exshaust mine does it if it quite alot if it dont start first kick but runs fine when it starts. good luck

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thanks chaps, update on the problam, have checked timming, all ok, have checked valve clearences, all ok, the generator windings have been checked, we have come to the same conclusion about the coil and was thinking of changing that next but at £375.00 its a bit of an expensive item especially if it dosent do the trick,

i will check the wires again tomorow and maybe rewire it down from the coil to the windings to see if that helps, we did notice on one of the wires that the previous owner has scotch locked another wire feed from one of the wires but havent traced where it gos yet, im wondering now if this is the cause,

thanks for your help so far, any more brain waves will be gladly read, will update findings again tomorow night.

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:bonk: hi chaps, update time, walked into workshop this morning, kicked bike off and it started, after getting back up of the floor from the shock i shut her off and tried again, it started again :thumbsup: shut her of and checked wiring and resistance at coil, then came the usual 1 hour of trying to start her again, it wanted to go but just wouldent, :thumbsup: tried and tried then through my spanners around the workshop like blokes do in these situations and whent for lunch, came back, kicked it over and it started again although if you reved it she would back fire through the exhaust, adjusted the mixture and cured that, took her up the hill and she is fine untill you open the throttle hard, then she bogs down and if you leave her ticking over she will miss a bit now and then, took her out for a quick try around the quarry next door and she behaved, stalled a few times but she started after two kicks.

my conclusion is this, either the coil is intermittent, the cdi has gone off on holiday, the jets are wrong or the bloke that had it before me had an aftermarket exhaust fitted and swapped it back when he sold it only he left the jets and air filter mod on the bike thus causing loads of goodies to burn but to small an exit to exhaust from.

what do you guys think ? :bonk:

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I'm with you on the coil/cdi holiday thing........

What was that about scotch? Don't think coils run that way but........

The CDI does have a pick up coil if it was sitting gathering moisture maybe the pick up needs cleaned..everything is sealed but still should be free of dirt/oil/white power corrosion (like battery cables get).....

Try the coil thing (last resort) and if it doesn't work...Take it back and say

"Ohh I found the bloody problem when I went to install the coil. Take it back now!"....then it's,,,,,, uhh back to the scotch thing ?....... :thumbsup:

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Back in the day we never went into any exotic problem search for nothing until after we put in a new sparkplug.

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Ditto on the new plug. They are relatively cheap.

Then I'd suggest you open up the carb and let us know what the main jet and pilot jet sizes are and what groove the needle is sitting on in the vacuum piston. It sure sounds like you have a carb setup condition. The fact that it starts up nice when cold but balks when warm suggests that it's stinking rich. You should also check the float level too. But it's hard to raise it without gas spilling out through the overflow so if it was up by much you'd notice it right away.

Swapping plugs will also tell you if it's stinking rich or not. White means it's balking because it's lean. Black and sooty means it's super rich.

There's something you can do to check the wiring fairly easily. Check the DC resistance from the plug on the CDI unit to the tab connector on the coil. It should be no more than about 1 ohm. Far less in fact. If it's higher than that then you need to find where the corrosion is in the connectors. Also, with the plug at the CDI unit and coil unpluged check for resistance from the coil wire to ground. There should not be any with both ends undone.

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I was having the same problem with mine, I swapped for a hotter plug and it runs better for sure but it started like crap until I put a new plug cap on and did a full oil change. Now it is a bit easier to kick her over but when it's cold out, say under 10 degrees Celsius, shes a real bastard to kick over.If I put a heater beside for a while and warm her up a bit she starts in about 5 kicks. I guess my bike just doesn't like the cold. Living in Vancouver I only have to deal with this problem for a couple of months, Summertime it's a two kick affair. But the plug cap was a great relief my old one was crappy and for about 6 bucks or 3 pounds I saved myself a lot of headache.

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hi chaps, sorry for not getting back earlier but had a family dilema. all sorted now so back to dr.

jet sizes as follows.

jet needle, 3rd ring up out of 5.

needle size 5FP96-3RD

main jet 132.5

pilot jet 37.5

needle jet p-8

got a manual now aswell and looking at the sizes on the manuals chart it looks as though the jet sizes are standard, whats concerning me now is the air box mod that it has, do you need to rejet after having 4 holes cut into the air box ?

spark plug is new and is looking sooty so we know its a bit on the rich side.

what do you think ?

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the air box mod shouldnt effect jetting mine was modified when i bought of a mate he did mod him self after reading it on the net and left the jeting standard and mine has no problems in that respect i still think you have electrics shorting out when its warmed up which is what the wire to my coil did good luck

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hi toby, i have taken on board what you are suggesting and can see the logic,

i take it you are reffering to the black wire with the white tracer running from the coil back to the cdi box, if i was to start rewiring each individual wire untill the fault was found then in what order would you do it. ie which wire is most likely to give these symptons or is it pot luck untill you strike gold.

ive got to bomb down to london tomorow on business so wont be back untill friday, weve got a play day sorted for sunday so only have a day and a half to get bike sorted,

any more suggestions or if any one knows which wire to change first then please let me know so i can get on the job as soon as i get back. :thumbsup:

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sorry didnt get back sooner been busy get clutch fitted for sunday ride. start with the wire with the white trace to cdi then im afraid it does become pot luck mine was found by complet chance if it comes to it let me know where you are in uk might be able to lend you my spare coil and cdi good luck

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thanks toby, appreciate your offer,

had another bash on saturday, bike started well but would pop back through the exhaust at high revs, adjusted the fuel screw and tapped up the holes in the air box and the bike ran better but it still had the misfire, replaced the black wire with blue tracer back to the cdi from the coil and no difference, tried many different adjustments on the piolet screw and we are now back to bike trying to start but wont, we spent all day tinkering with it but it just wouldent go,

have now sent the coil into the bike shop for testing just to eliminate it, when it comes back i shall replace the black and white wire and see if that helps, if not then your offer may be very tempting,

where abouts in the uk are you ? we have a van and can bring the bike to you for testing the cdi depending on where abouts you are, we are in sunny scarborough in north yorkshire.

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ok chaps, we have news, i have managed to track down the previous owner and had a long chat with him about the bike,

he told me this. he was going up a bank at about walking pace in 1st gear when the chain snapped, it cracked the magneto casing which has been welded scince. the bad running happened from this day onwards, he could ride it but it became difficult to start and miss fired, he could only ride it slowly, he sold the bike there after as he couldent get it to run right, he sold it to the bike shop where i bought it from who did the following to it to try and cure it.

checked timming.

checked valves.

cleaned carb.

new plug abd cap.

had the generator checked and was ok.

they were unsuccesful in repairing it which is when i took it on.

can engine damage occur when the chain snaps at 5 mph, the bike did stop suddenly ?

i dont think it can as its to slow and the bike will still run although it back fires. it seems to me that the timming is out although the bike shop says they have checked it, how do you go about checking the timming statically as it dosent seem to show it in the manual.

im still convinced we have a snapped wire in the main loom thats giving an intermittent misfire. tomorow i think i will start replacing the wires from the magneto to the cdi box and the ones from the cdi to the coil, if anyone thinks this is a bad idea then please say so, the only thing i can think of as a bad point to this is if the wires are of a particular resistance and we go and change them for a different resistance wire.

any one got any brain waves after getting this new information ?

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:bonk: hi chaps, update time, walked into workshop this morning, kicked bike off and it started, after getting back up of the floor from the shock i shut her off and tried again, it started again :bonk: shut her of and checked wiring and resistance at coil, then came the usual 1 hour of trying to start her again, it wanted to go but just wouldent, :thumbsup: tried and tried then through my spanners around the workshop like blokes do in these situations and whent for lunch, came back, kicked it over and it started again although if you reved it she would back fire through the exhaust, adjusted the mixture and cured that, took her up the hill and she is fine untill you open the throttle hard, then she bogs down and if you leave her ticking over she will miss a bit now and then, took her out for a quick try around the quarry next door and she behaved, stalled a few times but she started after two kicks.

my conclusion is this, either the coil is intermittent, the cdi has gone off on holiday, the jets are wrong or the bloke that had it before me had an aftermarket exhaust fitted and swapped it back when he sold it only he left the jets and air filter mod on the bike thus causing loads of goodies to burn but to small an exit to exhaust from.

what do you guys think ? :bonk:

I do not buy that it runs that crappy with airboxmod and rejetting but no aftermarket exhaust.

I run my dr650 -97 on 160 main jet, stock pilot jet, airbox mod and either a CRD OR Stock muffler.

Both are ok.

It is a bit on the rich side with the stock muffler - but not more than I can live with. And starting as opposed to full throttle is two different jets in the carb (maybe both are off in that case?)

What I do tend to experience though is that cold starts is ok, but i need to let it warm up for a minute or two, otherwise it chokes if i give it throttle. After warming up i let go of the choke, and it runs happily on all revs.

BTW - you dont have a stuck choke ?

It could drench the engine when giving it throttle, but then starting should be fine when cold.

Generally if two starts in similar conditions gives different result I would think that the prime suspect is ignition rather than fuel supply dont know really.... :thumbsup:

/K

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ok chaps, we have news, i have managed to track down the previous owner and had a long chat with him about the bike,

he told me this. he was going up a bank at about walking pace in 1st gear when the chain snapped, it cracked the magneto casing which has been welded scince. the bad running happened from this day onwards, he could ride it but it became difficult to start and miss fired, he could only ride it slowly, he sold the bike there after as he couldent get it to run right, he sold it to the bike shop where i bought it from who did the following to it to try and cure it.

checked timming.

checked valves.

cleaned carb.

new plug abd cap.

had the generator checked and was ok.

they were unsuccesful in repairing it which is when i took it on.

can engine damage occur when the chain snaps at 5 mph, the bike did stop suddenly ?

i dont think it can as its to slow and the bike will still run although it back fires. it seems to me that the timming is out although the bike shop says they have checked it, how do you go about checking the timming statically as it dosent seem to show it in the manual.

im still convinced we have a snapped wire in the main loom thats giving an intermittent misfire. tomorow i think i will start replacing the wires from the magneto to the cdi box and the ones from the cdi to the coil, if anyone thinks this is a bad idea then please say so, the only thing i can think of as a bad point to this is if the wires are of a particular resistance and we go and change them for a different resistance wire.

any one got any brain waves after getting this new information ?

Ahh - missed this info:

How about one of the following then, since the magneto casing cracked:

- loose wire which shor circuits now and then ?

- Broken generator/coil there ?

- Loose wires which looses conncetions erradically ?

- Some other looose bolt/nut which displaces ignition timing somehow (although since the CDI is doing this rather than an old fashioned switch, it should then depend on where the ignition sensor is placed)

I think your strategy is the correct one, check all the wiring from the genreator to the spark plug.

/K

PS:

Could such a sudden stop make the cam chain tick over, maybe in combination with a too loose tensioner ?

In that case you may need to check this if nothing else works out ?

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good one K. i will check cam chain tomorow all being well, i think the bad starting is just me not knowing how it likes to be started but untill i get her to run i wont know what method it prefers. bit like a woman really, you got to tickle her properly or you aint getting nothing.

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Osprey, what altitude above sea level are you living and riding at? I ask this because I'm pretty much right at sea level and I found I needed a 150 main just to make it run decent and it's still a little lean. A typcial post airbox mod jet size for many folks is a 142 for altitudes that seem to be from maybe 800 to 1000 feet ASL. It came with a 139 and was a bear to kickstart until I bumped up the jets and needle tuning. Now it's a delight.

Did you check the plug color as I suggested? Plug color is the first thing to look at unless you're totally and absolutely positive that it's wireing. And frankly what you describe is what happened with my bike when I first got it. That's why I'm thinking it's more about the carb mixture than not.

Another item to check is that super hard starting and boggy running sounds like an air leak between the carb and the engine. Check the condition of the rubber joiner for cracks or tears and that the carb is properly inserted into the joiner. Who knows, maybe it's something as silly as the vacuum line not being connected or having a tear at the end or a hole in it....(it isn't is it? :thumbsup:)

If you look into info about the airbox mod I think you'll find that pretty much everyone has had to jet up and shift the clip on the needle to the third or even fourth position from the top to get the engine running cleanly again.

But first and foremost you should start with the plug and carb as it sure sounds like this is the problem.

If none of that does the trick and you figure it's electrical I would strongly suggest some time with an ohmmeter to buzz out the wires looking for higher than normal resistance. Not only can you find problems due to badly corroded connections right away but you can flex the wire loom at various points and watch or listen to the meter to identify your possible broken wire with intermittent contact. Otherwise you're just shooting in the dark if you start ripping things apart and rewireing stuff.

Provided the alternator case (it's not a magneto.. or at least we don't call it that over here) was welded correctly and the stuff inside all is still putting out properly then I can't see why it won't run. What about the battery? Put a volt meter on it and try kicking it through slowly with the comp release out. At no point should the batter voltage drop below 11 volts on a kick start bike. If it does then it suggests that the battery is weak. If it sucks down to 6 or 7 then that would explain the weak spark.

Later on once the bike is running check the alternator and regulator output by looking at the battery voltage when you rev it past about 3000. At that point the voltage should be up to around 14 to 15 volts. Revving higher yet should not let the voltage go up higher than

Because the coil only sees a pulse off the CDI box it's impossible to check the voltage at it like in days of old. That leaves you with a resistance check of the wire path between the coil and the CDI box. Also if you use a plug outside the engine and bridge a spare wire to the battery you can test the coil and see if it's sparking correctly. But be sure you just flash the connection across the terminal. The coil is not designed to run with voltage on it for more than a flash of power and you'll burn it out if you hold it for too long. If the spark you get at the plug is weak or non existent then that may explain things. It may even be that the cap is cracked or the spark lead is broken too. A spark check will sort that out.

In any event it's far better to FIND the problem than to do things that may not be the cause at all like the wire loom. If you find an intermittent then figure out if it's the connector or if it is indeed in the wire harness. But FIND something first. Sometimes finding things isn't that easy. If you end up with a suspicious wire then temporarily bridge it with a scrap of wire. If that fixes the problem then go ahead and tear apart the harness to switch wires.

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