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Dr Will Not Start

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I can't see any sort of sudden stop making the cam chain skip a tooth. But if the mechanics didn't put it together correctly following the welding job that would sure explain a lot.

Let us know if you need the open and closing figures from a service manual.

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thanks bc rider, nice post, we did check the plug colour many times and it has allways been black and sooty indicating a rich mixture but we havent had the bike running for long enough to do a proper test, we cant get her up in the top gears so are having to use our judgement on riding through the lower gears.

i understand what you are saying with the larger jets but the fault occured when the chap lost the chain, it has allways run well before then with the jets it allready has so although doing this mod may make it run better we still have to find what the original fault was to start with, the last owner had the bike for 8 years and loved it up to the day it lost the chain.

the bike is kick start only and dosent have a battery.

looking at all the evidence i have allways been convinced that it is the carb at fault or the fuel side somewhere but have never found anything to prove me right, with the new info i got yesterday on the sudden stop has given me a few ideas on where to check next and also eliminates the carb side as the bike was running good untill the sudden stop and that cant cause a carb to start playing up,

on the electrical side we do have a spark, what we cant see though and cant test is wether we have a spark at high revs or if the spark is losing its power, also we cant see if the spark is being fired at the right time.

it may seem a bit "heath robinson" replacing wires just for the sake of it to see if we have a broken one but we have to find a way to eliminate every eventuality so we end up with the fault and nothing we have tried so far has worked. :thumbsup:

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Black and sooty isn't good either. It suggests that something is seriously amiss with the carb or a weak spark that is misfiring as you say.

The actual problem may have little to do with the orginal cracked case and a lot to do with something the mechanics did as part of some other work that they performed at the same time.

I hadn't realized that this was a dirt only bike. I'll have to check my shop manual but I'm guessing that it uses a proper magneto in that case.

It may well be that one of the windings of the magneto was scuffed and torn as a result of the deformation of the case when it cracked. Do you have the specs for testing the coils for continuity and resistance? And can you put on a temporary spark plug on the lead and see that it sparks smartly with a nice little "crack" when you kick it over?

Have you taken apart the left side to check out the condition of the coils and field magnets inside? Scuffs or badly soldered repairs?

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im down in surrey which would have been good to pop in on your london trip. have just read what klas said and your post about the chain snapping im in the same opinion the the cam chain may have jumped and as far as i know rewiring the cdi and coil the wire isnt of a surtain resistance good luck

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bc rider, good post. i think we are starting to get something here. let me explain, i have the case and magneto here in front of me, i have checked the continuity of all the wires on a bleep test and wiggled them all around with no bad wires found, im looking at the repair right now, it only cracked the top of the case and dident actually get into the magneto housing, just smashed where the wires go in, now i have two points to make here, firstly the gasket has not been removed from the case, it is well and truely stuck down, the bike shop said they had sent the windings away for test and they were ok but tell me this, how do you get the windings out of the cover when the wiring passes under the gasket, before anyone says they could have changed the gasket then i think not, the bike hasent been run for long enough to allow the gasket to seal itself. you can only do it by removing the gasket so theres no way they have been removed,

secondly, the casing has been welded up, to weld alloy properly you would need a tig welder, tig welders run on electricity, havent we all been told to disconnect our batterys on the car before welding as damage may occur to the alternator. could this be what has happened here ie case welded whilst windings in situ, high current passed through the windings resulting in damage to the windings, iknow its a bit of a long shot but can anyone prove my theory wrong ?

after all the miss fire only occured after the chain snapping incident and yes i am starting to think that the mechanic who put her back together has done something wrong.

just to let you know the windings do not look burnt or smell burnt

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just a quick one for toby,

regarding your offer of cdi borrowing, im a little concerned that by putting your cdi box on my bike, there may be a fault that we havent found that may damage your cdi box, after all we dont know what the fault is as yet, how about this instead, i send you my cdi box, try it on your bike, if yours runs a treat then it wont be that, with your bike running ok there is no risk of hurting your cdi, just a thought, another stunning thought is that we do regular trips down to ruislip off the a40 collecting and delivering vehicle parts for our business, i can load the bike into the van and take a trip over to you or just the cdi, i will in the mean time try to eliminate all other possibilitys.

ohh,by the way, the coil pack passed the test and is running ok, also the wires to the coil from the cdi passed the continuity test also. :thumbsup:

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If you're getting the right resistance readings for all the winding combos as listed in the manual then all should be well.

Even if the coil was left in place as long as they grounded the case then the current would only have flowed through the alloy of the case.

From everything you're posting it sure SOUNDS like all is well.

OK, I figured it was time to quite guessing at some of this stuff and I dug out my service manual for a look at the wireing diagrams. First off all of the setups share very close to the same setup. They all use a separate winding and pickup to power the CDI box for the spark. I'm embarrased to say that this caught me off guard. So technically a kick start bike will run fine even if the main lighting and other power fuse was to blow. So there's a ton of wires to check. Also check from each of the yellow wires to ground to ensure that they are good. You've got the manual and ran the resistance checks I gather. Not just for continuity but for actual resistance value readings?

I also stuck a new plug into my lead and gave the bike a few kicks to see what sort of spark it makes. It's a nice bright but fairly thin blue spark with almost no sound. If your bike isn't making a spark that looks like this description then you may have found your trouble.

If you're getting a nice spark then we seem to be back to the carb. If not then it's apparently electrical.

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thanks for taking the time to check your spark bc rider.

we do have a nice crackling blue spark which told us it was the fuel side but there just isent anything amiss on the fuel side that we could see, hence why we thought it may be spark breaking down once the bike was running.

i dident do a resistance check on the wires, only a continuity test, i will do some more wire testing today and try to put the wiring side to bed.

will post findings tonight.

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Ignitions without batteries are sensitive to current draw (intermittant) robbing ignition voltage. There was this Triumph 650 with ET ignition, fine at lower RPM then popping and frapping at higher. Turns out (many hours later) that the horn switch was always closed (on). Not apparent cause the horn was broken but at the right vibration range the internal horn parts would jump around and short out stealing ignition juice. :thumbsup: LOL

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damm good post fl-cracker,

this is exactly the sort of thing we are getting, starts eventually and sometimes starts straight away but bogs down when revved and under load,

we done a load of resistance testing today, we are getting a strange resistance from the magnetic pick up coils, the reading we got from the main pick up was 486 ohms, the book states it should be 180-270 ohms,

next we did the backfire preventor pick up and got the same reading, the book dosent show the reading for this, we tried disconnecting the backfire preventor pick up and the bike wont spark so it has to be connected, we was going to try and swap the pick ups with each other but with them both having the same reading we decided it wouldent be worth while.

two thoughts spring to mind from these readings,

either we have a model dr that the book dosent cater for so the readings in the book are not applicable to this bike.

when the casing was welded the pick ups were not removed and were treated to a load of heat from the tig welder resulting in damage to the pick ups.

problam with the theory is that the bike will start and we do have a big blue spark.

does anyone out there in the uk have a dr 350 for spares, we can travel and collect no problam, i want to get to the bottom of this and could do with a few parts to interchange.

going back to the previous post again, the wiring behind the headlight is a mixture of connectors and pvc tape so the next area we were going to cover was tidying this lot up, it has had a horn fitted for uk mot.

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im happy for you to send me your cdi let me know a private email so i dont have to post my adress on the fourm glad the coil and wire are ok

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hi chaps, quick update.

no it dosent run yet but we are getting closer, i bought another dr 350 for spares, its roughfly the same but not the full dirt model, anyway this one will start but will cut out after 15 seconds, it has the trashy carb on aswell, not the nice pumper.

ahyway, i took the magneto cover off to inspect the coils, guess what i discovered, one of the coils was lower down than on my bike so at first i thought we couldent change the cover complete and that the set up was completely different, then i had a thought :bonk: , i looked at both fly wheels with the timming marks on them and they were the same, as in exactly,yet the pickups were in a different position,emmmm. :thumbsup: ,something not right here, then it clicked, the stupid mechanic who put the bike back together after welding the case put one of the pick ups in upside down so it wasent in line with the raised bar on the fly wheel.i turned it round, replaced the cover and hey presto it still wont bloody start. :bonk: ,

it was the back fire pick up that was the wrong way round,

we keep kicking the bike, sometimes we even kick the kick start instead of the bike,hehehe, it is firing and keeps bursting into life for about 1 second then dies off, im sure ive sussed the fault but now have a proper starting fault that has probally been caused by messing around with every thing else.

it wont bump start either.

does anyone have the resistance figures for the two pick up coils in the magneto housing, my book says 130 - 250 ish but im getting 465 from both my bike and the one we bought for spares, damm confusing, :thumbsup:

any suggestions ?

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:bonk: FIXED IT. :bonk:

thanks to all you chaps who took the time to help me, it was the mechanic who welded the casing back together that caused the fault, not only had he put the pick up in upside down, he had also put them in the wrong way round,

turned them round and she runs like a baby, 1st or 2nd kick every time.

so i have this to say to the mechanic :thumbsup:

and this to say to all you guys. :thumbsup::bonk::bonk::bonk::eek::eek::lol:

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glad to hear its sorted mate have fun and good luck with everything work hard play harder

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