Post by: Graeme77 on November 30, 2015, 09:42:50 PM
I tried everything, then laid it up for a year.
I just stripped engine, rebuilt it and am trying again but it still wont run!
Carb is spotless.
Rebored, new piston, rings, bearings and seals.
Got good spark (but no battery power, shouldnt matter).
Cant see any way to adjust timing except by altering points gap.
Ive had the rotary disc valve in both ways round.
Got cood compression and clean posh petrol. Petrol is getting to carb, plug is getting wet but might just be oil. Ive tried a bit of fuel down the plug hole and ive tried brake cleaner squirted in the carb lol.
I just dont understand why it wont run!
Anyone know anything about kh/ke 100/125?
Im at the stage now where I just want to set fire to it.
Post by: matthewmosse on November 30, 2015, 10:43:48 PM
Post by: Graeme77 on November 30, 2015, 11:05:11 PM
so new plug next and maybe a good known coil.
In your experience, will they start ok with a completely flat battery? Its 6v so I cant charge it yet.
Usual story, dont want to spend money on it till it runs but needs money to get it running.
Post by: matthewmosse on December 01, 2015, 07:45:05 AM
Post by: Graeme77 on December 01, 2015, 08:56:40 AM
Post by: AshimotoK0 on December 01, 2015, 02:19:41 PM
Thanks. It has a battery but its been flat for years. Ill get another.
When I was a poor student back in the dark ages, I used a large electrolytic capacitor on my CB250K in place of a battery. You would just need to check that the 125 has some sort of voltage regulator.
http://www.ebay.co.uk/itm/Capacitor-10000-uF-40VDC-Electrolytic-Radio-Spares-/311444547316?hash=item48838aa6f4:g:nRcAAMXQRPRTIeYn
Post by: matthewmosse on December 01, 2015, 02:22:39 PM
Post by: Graeme77 on December 01, 2015, 02:53:59 PM
its got spark, but dont know if its sparking under compression. I only have the front exhaust pipe fitted at the moment and its dripping with a fuel/oil/easy start mess so fluid is obviously making its way through the engine.
It must have no spark.
Any things to test? Ive been trying to measure voltage at the coil when its kicked over but its inconsistant (and low) but im clutching at straws. Dont really want to replace battery, coil, regulator, stator and rotor without knowing whats at fault.
Bike needs work, its rough as its been sat in the garden. I dont mind spending on it if it runs but dont want to throw £200 at it in the hope of it then working.
Post by: Graeme77 on December 01, 2015, 02:55:35 PM
Post by: Graeme77 on December 01, 2015, 02:57:41 PM
Post by: Graeme77 on December 01, 2015, 04:10:36 PM
Coil has 5k resistance on the secondary but only 0.3 ohm of primary. I guess its knackered. Ill order a new one and see if thats it.
Im still not convinced its drawing fuel through properly but I cant see why it wouldnt.
Its maddening, multi cylinder 4 stoke I can fix, 2 stroke with 3 moving parts and im stumped.
Post by: matthewmosse on December 01, 2015, 04:42:52 PM
Post by: Graeme77 on December 01, 2015, 05:09:42 PM
Would also be good to see a picture of the disc valve as fitted, or any info that would give me a deffinate answer as to which way round the disc valve is fitted.
The plan with this bike is a run around for the wife, but a little tuned, stripped down, expansion chamber and a 60's style race fairing to mimic the old A1R racer.
Post by: NigelWilmshurst on December 01, 2015, 06:44:03 PM
I grew up on tuned up 2 stroke twins, still love to hate them, they become part of your soul!
Spark plugs not working under compression were always an issue, as Mathew says iridium spark plugs or similar are a good investment, back in the day we had NGK R plugs, if the new coil doesn't solve the problem I suggest meticulous points and timing set up is essential, I used to have to reface the points with a chisel sharpening stone every 50 miles or so to maintain the power band,
Buy new points and condenser or strip the points into 2 parts and re face perfectly level, check the timing is exact, all else fails clean the plug and use a lead pencil to draw over the electrode and heat up with a lighter, then put a cap full of petrol down the plughole, put the plug back in and fire it up!
Post by: matthewmosse on December 01, 2015, 07:09:55 PM
Post by: matthewmosse on December 01, 2015, 07:44:56 PM
Apparently it is marked by what looks in the photo like a scribed line, possibly with a direction arrow. It doesn't show up on my camera very well at all.
ignition coil resistance - primary winding meter @1ohm reading should be 0.4 -1.2 ohm secondary winding meter @ 1k ohm reading should be 4- 8 k ohm
magneto resistance meter @ 1 ohm, reading should be 1 - 3.5 ohm
hope this helps. I am happy to scour for further info if needed.
The manual does stress the iggition coil tested by these readings is not definitively tested and reccomend the use of a kawasaki electro tester that makes the spark jump across a 5mm gap as this tests for layer shorts or insulation breakdown under high voltage. In all probability an electro tester is more cost than a new coil....
Post by: Graeme77 on December 01, 2015, 08:06:45 PM
As for the disc, im struggling to visualise your explanation. Ignoring where abouts in the rotation it is, the larger center notch, is it nearer the opening to the right, or nearer to the left?
Thanks again, much appreciated. Im surprised how little info there is on the net about these, they made them for long enough!
Post by: matthewmosse on December 01, 2015, 08:23:06 PM
Post by: matthewmosse on December 01, 2015, 08:25:01 PM
Post by: Graeme77 on December 01, 2015, 08:28:45 PM
I hadnt even considered it would wear or any of it would have a service limit! Im not taking the clutch out again to check lol.
So mechanicaly the engine is fine and electrically I cant find any issue so im left with randomly replacing parts till it runs :(
Post by: Graeme77 on December 01, 2015, 08:31:55 PM
I have found a 12v comversion with rotor, stator, regulator, coil erc for £200. Pretty much replaces everything and gives electronic ignition and 100w of generator output.
Im tempted.
Ill try a new coil and if it runs ill think about investing. Reliability is good when its my wifes bike and it will be me getting the call every time she cant start it!
Post by: matthewmosse on December 01, 2015, 08:38:32 PM
12v conversion, do tell me more!
Post by: Graeme77 on December 01, 2015, 08:42:47 PM
looks good doesnt it!
Would solve alot of problems.
Thing is, if I get it and it still doesnt run id be really stuck!
Ive had the engine apart and everything looks new but I still dont quite trust that its drawing properly.
Post by: matthewmosse on December 01, 2015, 09:33:28 PM
Post by: Graeme77 on December 01, 2015, 09:41:00 PM
Been having another go at it, checked everything, re annealed head gasket too. I opened up plug gap to 'huge' and spark jumps no problem. I set timing perfectly with my meter.
It should run!
Doesnt though.
Wondering if I have compression issues. When doing the timing I can turn engine over easily by hand with the rotor. Not much resistance at tdc. Its got a fresh (perfect) bore, new piston and rings and all surfaces and gaskets are good though so no idea why it could be low. Do 2 strokes have proper compression when being turned over slowly?
You can see someone has cleaned up the exhaust port a little on the sides but the opening hasnt changed so I dont thing thebports have been messed with.
loads of compression feel when using kick starter though.
Post by: matthewmosse on December 01, 2015, 09:49:32 PM
I believe my mate who knows them moderatly well says the crank seals can perish or go hard and loose you compression if I recall correctly. I just dumped 3 dismantled engines in his shop and collected 1 decent one and left most of the details to him. Like I say, plugs sparking fine outside the cylinder but not running was an infuriating problem, and I ended up with about 10 plugs that sparked fine but would not run, normally after a few minutes use. Not a clue why, all ngk plugs, but from different sources and a decade appart in age.
Post by: Graeme77 on December 01, 2015, 09:58:32 PM
Im going to a local 2 stroke place and bike breakers tomorrow to pick up a coil. Ill pick their brains and see what else they have.
I think its getting close to crunch time, either just spend whatever it takes even if thats a few hundred quid and comit to getting it sorted or give up and find her a bsa bantam.
Post by: Rozabikes Tim on December 01, 2015, 10:28:22 PM
Who are the 2 stroke specialists and where - Chesterfield? Just a friend in Wirksworth has just bought a 250 yam ? Not running cleanly and he was after said expert....
Post by: matthewmosse on December 01, 2015, 10:38:34 PM
Post by: Graeme77 on December 01, 2015, 10:45:30 PM
I figued a stupidly highly tuned and unreliable 80mph rigid framed D1 sounds like fun.
As for the specialist, I may be over hyping them a bit. Im talking about syd smith in sheffield. I say 2 stroke specialist as they deal alot in motocross parts where as all the other places I know only really deal with 4 stroke stuff.
Post by: Graeme77 on December 02, 2015, 06:41:22 PM
deffinately spark though. Pretty sure exciting coil is shot, cant get any resistance from it any more.
Turns out they arent available anymore and all the magnetos on ebay are 3 coil, my bike is 2 coil.
Looks like im going to have to learn to rewind coils!
Post by: matthewmosse on December 02, 2015, 09:38:34 PM
Post by: Graeme77 on December 02, 2015, 09:53:02 PM
If you do find one, let me know.
Ill update this thread after I try the rewind.
Thanks :)
Post by: Johnny4428 on December 03, 2015, 08:33:15 AM
Post by: Graeme77 on December 03, 2015, 04:00:43 PM
Post by: hairygit on December 03, 2015, 04:16:39 PM
Post by: Graeme77 on December 03, 2015, 05:17:07 PM
anyhow, new coil winding in progress :)
Post by: Spitfire on December 03, 2015, 06:46:00 PM
Cheers
Dennis
Post by: Graeme77 on December 03, 2015, 07:05:25 PM
I finished coil. Original was measuring very low on resistance. New coil (I could have done it a bit neater) measured 2 ohm.
Spark is a bit better but bike still wont start.
I compression tested it. One kick gives 110 psi. Checked with 2 testers.
I figured thats good considering the rings arent bedded.
When kicking it over and measuring voltage at the ignition coil I get 0.5v dc or 2v ac, not sure which measurement matters.
Im guessing thats still not enough (been told it should probably be near 6v?)
I guess this means the spark is still too weak to spark undet compression.
Plug is 100% deffinately getting wet.
So, got fuel, timing perfect, got compression, got spark.
Post by: totty on December 03, 2015, 07:15:46 PM
The other option is a gap test, if it'll jump say 3x the normal gap it should spark under compression.
If it sparks it sounds like a timing issue.
Post by: Graeme77 on December 03, 2015, 07:30:05 PM
Timing Is spot on. I set it with the head off too to be sure!
Post by: matthewmosse on December 03, 2015, 07:57:38 PM
Post by: Woodside on December 03, 2015, 09:11:41 PM
On mine I needed two base gasketts to get the spark at just the right time, going by the crank timing marks I holed pistons from pre ignition. Hence setting timing with a dti gauge mounted into a modified plug, this got it reliable - ie I went further than 4 miles on a piston.
That rings a bell...I remember a friend of mine rebuilding his large 2 stroke motox bike..and for the life of us it wouldn't run..after speaking to some more knowledgable guys on the subject a thicker gasket was needed ....it fired pretty much first kick with it fitted....I couldn't belive the extra mm or so made so much difference
Post by: Graeme77 on December 03, 2015, 09:24:36 PM
Post by: Graeme77 on December 05, 2015, 03:18:50 PM
I have wound 2 coils but it still wouldnt go.
I found a colour tune kit and put that it to see if ii sparked under compression and it fired right up?
So, whats so special about this colour tune plug?
Post by: Graeme77 on December 05, 2015, 03:25:08 PM
Im over the moon. Ive never been defeated before but almost gave up on this thing.