Author Topic: Sp 400  (Read 37606 times)

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Offline aehunger

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Re: Sp 400
« Reply #30 on: January 09, 2014, 06:06:58 pm »
Hi Guys,
Would someone be willing to comment on the issue I have with my 1980 DR400 please. The bike I own kickstarts easily enough but once running has an intermittent faulty, that I believe to be electrical, which causes is to run at approximately 50% power. I have been unable to rectify this with all manor of tinkering so managed to pick up another 1980 DR400 as a donor bike. Ive swapped the entire electrical system that is Magneto, CDI and coil from the donor bike to my rebuilt one but now the bike wont kickstart. It does backfire through the carby and give me a painful kick back after about 10-15 kicks. I have managed to start this bike, with the donor bikes electrics, by pushing it an when it did run there is no evidence of the lack of power i mention earlier. I had intended to buy a new spark plug for the bike and maybe try a hotter one than the NGK D7EA im currently running. Can anyone suggest any alternative strategies for me to attempt to get this bike to kickstart with out breaking my lower leg or a small fire.

Alex Hunger
Christchurch
NZ
Kind Regards
Alex

Offline matcho mick

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Re: Sp 400
« Reply #31 on: January 12, 2014, 10:32:49 pm »
when you say you swapped the entire elec system over,did that include the plug caps?, :P
work,the curse of the racing class!!
if a hammer dosn't fix it,you have a electrical problem!!

Offline SON

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Re: Sp 400
« Reply #32 on: January 12, 2014, 11:31:07 pm »
Mick is right,
Old plug caps fail as often as old plugs
Stay on the 7 heat range go to the B7EV plug
Clean the carb
Fresh Fuel
Prime the engine kicking with the decompressor
Then decompress correctly
They should start as easy as a 200!

Offline aehunger

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Re: Sp 400
« Reply #33 on: January 13, 2014, 05:34:28 pm »
Hi Guys,
Thanks for all your valid comments and yes ive tried a new spark plug cap but this has not rectified my issue. Further to my previous rant i have now tried every combination of bike A parts and bike B parts with much the same results....goes sometimes and the next day or so later it wont....to add injury to this i got 6 stitches in my pinky after stabbing it with a knife trying to strip off cable sheath in an effort to locate a short circuit. I now believe there could be three reasons my bikes wont go 1. both CDI units are crook 2. there is a bad connection or short in the wiring or 3. the decomp lever is not allowing the valve to return correctly. To cut a long story short i think im screwed unless someone has a brainstorming idea. Sure you all have had similar experiences so will understand the frustration. As a last gasp does anyone know a helpful soul in Christchurch NZ that would have one of these old bikes and may be willing to help me.

Cheers ALex
Kind Regards
Alex

oldfart

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Re: Sp 400
« Reply #34 on: January 13, 2014, 06:18:35 pm »
Have you had your stator coils checked by a ohms meter ... this would be my first check.

STARTING PROCEDURE ...  kick over 3 times no throttle with decomp, if no decomp take it thru full stroke x 3
                                        Bring piston up to TDC on comp stroke and give it a good kick with no throttle and
                                        choke on, let it warm up a bit or it will coff and die on you.
 
Have you got the valve  timing right  ????? if no check and set - take off mag cover you will see a witness mark   ( V)  on the casing just below mounting bolt front upper and marks on fly wheel ( T ) this is  TDC  .... cam  line should be inline with top of case pointing to back of motor.
Edit ... this will also see if cam chain has reached it's limits.
 ( exhaust and inlet )  Valves  should both be closed and not rocking .
To set valve clearance undo the back nut and turn the lead screw slowly until it bottoms out ( SFA resistance ) = zero play ... now back it off  1/4 of a turn  and tighten up the back nut ....... got all that  ;)

Spark .... you should get a good spark by kicking it over by hand that will throw about  4mm from the coil wire ( cap removed )
Check  just above engine number were wire's pass thru casing that they are not cracked ( known to  )
 Are the pick up sensors  faulty ( just above top stator )
Have you got a good earth @ coil mount.

Alex these OLD girls are bullet proof, and once sorted they can give you many years of Fun
It's a matter of going thru all the above one by one not in multiples.

Cheers   Stewart
« Last Edit: January 13, 2014, 06:41:51 pm by oldfart »

Offline TT5 Matt

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Re: Sp 400
« Reply #35 on: January 13, 2014, 06:24:21 pm »
ive found sometimes to take the whole system off the bike and send it to someone that repairs stators/cdi boxes and they'll put it on their test bench to find the faults, the other is have good known working system and change 1 part at a time till it comes good again then replace that part. all big dollars but that's the bike trade for you

Offline TT5 Matt

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Re: Sp 400
« Reply #36 on: January 13, 2014, 06:27:18 pm »
another thing is see theres not too much air gap on the pick up/pulser coils

Offline aehunger

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Re: Sp 400
« Reply #37 on: January 13, 2014, 06:54:27 pm »
Hi there,
Thanks for the good information. Ive got a ohm meter off my workmate today so will begin testing each of the parts I have and compare the results against each other and the factory specs I have from a page out of the manual. Will check timing through the method suggested and hope to be in better spirits by the end of the week.

Cheers!!
Kind Regards
Alex

Offline DR500

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Re: Sp 400
« Reply #38 on: January 15, 2014, 08:49:49 pm »
disconnect the kill switch in case it has a short somewhere

oldfart

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Re: Sp 400
« Reply #39 on: January 16, 2014, 06:34:53 pm »
Update ... Decided to use a Tm 125 tank which  had a bit rust on tunnel upper and 2 deep dents. 
 Tank upper and lower sections removed by using a dremal mini grinder ( used 6 x 25mm wheels ) as you can see I have left the rolled  seam in place as it will make it easier to weld back up.
Rear has been made wider each side as this will give me 10 mm clearance @ rear frame rails.


New tunnel  made out of 1mm thick M/ steel flat sheet and put thru a sheet metal rollers .... roughly marked out and cut to shape.
You can achieve the same by bending over a  piece of pipe in a vice, apply even pressure on both sides  ;)
 

Trial fit prior to massaging rear section
 
 
« Last Edit: January 16, 2014, 06:52:19 pm by oldfart »

Offline SON

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Re: Sp 400
« Reply #40 on: January 16, 2014, 10:05:54 pm »
In a tradesman like manner !!!!

Offline firko

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Re: Sp 400
« Reply #41 on: January 16, 2014, 10:14:36 pm »
Stewy,  you get the Boilermaker of the Month, Golden Dolly Award. Nice work my friend.
'68 Yamaha DT1 enduro, '69 Yamaha 'DT1 from Hell' '69 DT1'Dunger from Hell, '69 Cheney Yamaha 360, 70 Maico 350 (2 off), '68 Hindall Ducati 250, Hindall RT2MX, Hindall YZ250a , Cycle Factory RT2MX flat tracker, Yamaha 1T250J, Maico 250 trials, '71, Boyd and Stellings TM400, Shell OW72,750 Yamaha

Offline FourstrokeForever

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Re: Sp 400
« Reply #42 on: January 17, 2014, 09:36:19 am »
Nice work Stewy. I did a similar job to a 76 Honda XL350 last year and I can honestly say that while it takes a bit of time to work out what parts to use and how to make it all work together, the results are fantastic and well worth the effort and time spent bending, rebending, welding, cutting, rewelding. Eventually it all comes together. I didn't have to make a tank though. I would like an alloy RC replica tank to replace the plastic one on the bike....one day. Just as a thought, the rake on my Honda is now 29 degrees and the bike turns really well with no signs of instability at speed, so yours being 30 should be just as good.
Arrogance.....A way of life for the those that having nothing further to learn.

Offline tmman

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Re: Sp 400
« Reply #43 on: January 17, 2014, 10:02:32 am »
Stewy,  you get the Boilermaker of the Month, Golden Dolly Award. Nice work my friend.
now now firko....
there was no sign of a 5pound hammer bein used ????????

oldfart

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Re: Sp 400
« Reply #44 on: January 17, 2014, 05:46:51 pm »
Thanks  for the kind words of encouragement ..... If I have time over the weekend I may dress the rear into shape.

Had a couple of hours to spare today ( Sunday)  so  here is the out come ...... plenty of flame control a short piece of 65mm M/steel pipe used as a former and piece of hardwood made into a  bossing stick (dresser )  = to move metal


« Last Edit: January 19, 2014, 05:28:12 pm by oldfart »