possible cdi fault
 

hi guys looking for help with my 1985 43f 600 , i posted a few weeks ago about resister plug caps . my 43f is running better but still does not start consistantly good like it used to . another problem is at 4000 rpm plus the power surges it used to sometimes do this but it was more of a flat spot and would rev through it no problem , also when i deselarate to change up the gears sometimes there is a small pop through the exhoust , now i am 90% sure this is all carbareter problems but 10% thinks i have a ignition problem hence my consern over resister plug caps . could a bad cdi do this , ive dissmantled the ignition switch and cleaned it and there seemed no problem there just oily gunge in it , so thoughts please guys:helpsmilie: this is the first problem since i bought it so reliability has never been a problem up to now . thanks zigzag

This is just a trouble shooting measure. To make sure you don't have issues with corroded or shorting kill functions, disconnect the Black/white strip wire from the CDI under the tank. This will remove external kill functions completely. If you still have the exact same symptoms then this is NOT your problem, hook it back up.

The small backfire on deceleration is usually a lean mixture. Could be clogged jets or passages, could be the decel enrichner circuit is not working. The left carb has a round cover plate on the side of the carb. This houses a diaphragm that when activated causes a richer mixture on decel. The hose that routes over the secondary carb brings the vacuum from the intake of the cylinder that operates the decal valve diaphragm. Make sure the hose is NOT leaking. It would be a good idea to just replace the vacuum diaphragm and brass valve. These are available from Yamaha. Use only OEM parts for best results.

Adjust the fuel screw at the bottom of the primary carb at the front (cylinder side) using a small flat blade screwdriver. Adjust it for a peak iidle RPM. This sets the mixture. Starting place is 1 1/2 turns out. Since this is a fuel screw, inward is leaner, outward is richer. When done readjust your idle speed. This is good to fine tune if you change to a very different altitude. At 1200' amsl mine is set at about 1.5 turns out, at 12000 feet amsl last year in Colorado I set it at about 1/2 turn. It ran fine. When returning back home bike would not start until I remembered to screw the fuel screw back to 1.5 turns out. The started normally.

Pull you plug, hook up to spark wire to plug, ground plug. Kick hard, you should see a bright blue spark, it is red or spindly then it is weak. Could be the CDI or Coil.

:clap:

hi and thanks steveloomis i will try disconecting the black white wire at the week end , ive looked at the coasting enricher diaframe tonight it seems good the plunger is free but the housing/compartment was oily /dirty so have cleaned it all out and put it back together , so will see what it is like going to work tomorrow . zigzag:thumbup1:

I don't own a Yamaha 600 but do own a KLR 650. My bike started showing exactly the same symptom as yours about a year ago. I've spent a year stripping carbs, cleaning connectors and the like with the problems slowly getting worse. Finally a few weeks ago the bike refused to run - solution has eventually turned out to be a new CDI unit . With this fitted the bike suddenly runs hke new . Wish I'd bitten the bullet and spent the money on it Months ago.

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I can echo that, my 86 XT that I purchased new got to be hard to start, ran poorly, back fired quite a bit. It was leaking oil all over the place so I started by removing the rocker box and resealing. I replaced all the rubber parts, cleaned the carbs throughly, replaced the seals in the carb slide lifter shaft plus gaskets and decal valve diaphragm. This process was all through the winter. When done I rolled it out and it refused to start, no spark at all. I pulled the cdi from my 84 that I purchased as a parts bike and it had no spark.

I then set down with the manual, OEM is best, and tested the ohms of the stator coils, ignition coil wires, grounding circuits etc. I used the AC volt setting on my volt meter and measured the trigger coils for output, they did have a kick when kicking over the engine, I checked the cdi charging coils for a kick and they did. I then compared all readings to the 84 and got very similar readings. I concluded it must be the CDI.

I knew I did not want to buy a used one that was probably old as the two I have so I ordered two of them from the guy in New Zealand. I waited and waited with no response and got to checking elsewhere.

I contacted Zeeltronic as I already had good experience with their CDI's on my Yamaha two strokes. Borut said he did not have a CDI for the XT but would look into it. He then made me one to try out. I think I got it just a short time after the New Zealand units showed up.

The Hyperpak unit was installed and the bike started right after a few quick kicks, idled perfectly.

When the Zeeltronic unit showed up I programmed it with a few small changes from stock, they do come ready to use but since I was already familiar and had the necessary programing cables and used the provide software I altered things a bit.

The Zeeltronic unit SEEMS to have more low end punch, I even swapped out the units after warming the bike and A B compared them back and forth. I still think the Zeeltronic has a bit more low end. Some have agreed with me some not.

So to end this long version story. These bike are getting some age on them and CDI's do age and fail.

Steve

hi guys and thanks for your replys , last friday i took the carb off the bike and cleaned the outside then stripped it down and put it in a friends ultrasonic cleaner i borrowed . the whole carb would not fit in and submurge so i had to keep revolving it around , 2 hours later and i reasembled it . i removed the intake rubbers and resealed them, then on with the carb . the bike started 3rd kick and runs well , i will post again in a few days to report back how things are going but it is starting ok, will have to take it for longer run to see if it still surges in the higher revs . it still pops a little on slow speed up changes ive reset the mixture screw to 2.5 turns out which i think is correct, before it was 3.5 turns out so it is now a little leaner . zigzag

hi guys the problem has returned big time , i set of last night 5 o clock called for petrol all was well , called at mates house only few minites took 4 kicks to start , 2 miles in to ride on strieght road doing 30/40 mph bike dies starts then dies completly . tryed for 5 mins to start only got nothing then a spit out of the exhourst then dead . called a mate with a van to rescue me. at home no spark , diconneced black/white wire from cdi (thanks steveloomis) got weak spark hooked it back up no spark disconeced kill switch wirers weak spark hooked them back up still weak spark ? . tryed for two hours no spark/weak spark. up at 10am cleaning connecters weak spark no spark sometimes nice blue spark, but no run . after cleaning carb last week bike pulled good and strong i now think this was dirt in the carb and not related to bad starting i was having . still removed carb to check/ blow through with air line . started to check connections under tank there was a 4 way black crimped joint seemed iffy so made new connection with good bullet connecters tryed to start bike, 4 kicks it ran but would only idle/ tick over any revs and it started to die put timing light on to see if i could see misfire but very hard to see bike ran 2/3 min then died did this 3 times on idle sounds perfect , changed a few more connecters no run and very weak yellowish spark , tested coil on workshop coil tester all good have i got a bad cdi or still a bad connection ? can get cdi £100 ish from wemoto anone had 1 any good :helpsmilie:

hi guys a bit more info the bike is a xt600 49r american inport the cdi has 11 wires 2 of the wires are red and brown but thay do not connect red to red etc , they connect red to brown and brown to red they have always been like that 18000 miles ive done on the bike i tryed putting them right way round but loose spark completly ? just checked and a company in belgium does a 49r cdi but they are on holiday until the 23rd august . ive dealt with them before and they are first rate very fast delivery etc . so if i have to get a new cdi do i go red to red or red to brown :stormy: zigzag

My USA model 1986 year is a 49 also. If memory serves, the wires coming out to the stator were the wrong color but did have the correct color little sleeves that match the color code. Does yours have the sleeves? My 84 wires were correct and no sleeves.

From experience it is quite possible your CDI is intermittent and dying. The only other thing I would do is take an AC volt meter set for about 20 volts AC or so, unplug the cdi charge wires from the stator and the trigger wires. There are 2 triggers, hi speed and lo speed. connect the volt meter to the wires, not wires and ground. Have someone kick over quickly and see if you see a voltage jump upscale. Remove the spark plug to make it easier to kick. Kill wires won't matter as they kill the CDI not the coils. You should see an AC voltage kick on both trigger coils as well. If memory serves there are 3 wires from the trigger coils. One should be between the coils and the others at each end of the coils, check one coil at a time.

If you get a healthy AC voltage kick on all coils then the CDI is most likely at fault. Both of mine were. The weak spark is the clue. I've heard good things about the folks from Belgium, go for it...

Healthy voltage kick is decidedly up scale, not just a slight flicker. You can use a digital volt meter but it is a bit harder to see the kick but it should show you that voltage is being generated. Ohm checks are good as well but if you get a good ac voltage upswing the coils are probably OK. Do you have the correct schematic/wiring diagram? :D

steve

hi steveloomis i have a clymer manual the wiring diagram seems to relate to my bike , there are varies ohms meter readings which i hope to do tomorrow night although the manual says the engine has to be warm or the casing has to be warmed up with a hair drier , i will try doing them with no hair dryer . i have 4 wirers from the genarator 2 white go to regulator rectifier 1 red 1 brown source coil i think ( the crossed wirers ) to cdi , from pickups 1 white/red, 1 green, 1 white/green . do i connect the meter to red brown and kick and read scale do i test the white wirers, also the pickup wirers do i test them in random pairs or a set way , all your help is great thank you so much for your time , cdi ignitions are not my great love . thanks again zigzag:thumbup1:

Ignore the 2 white wires, this is for charging the battery only.

The red and brown wires are the cdi charging coils. Measure those wires directly to your ac volt meter. Make sure you are on the AC voltage measurement mode. My 86 has small sleeves that are red and brown on the appropriate wire. My 84 actually has the correct color wire coming out of the stator.

The trigger coils are white w/green stripe and white w/red stripe then a green wire. The Clymer manual is wrong in measuring the OHMs. Measure the ac voltage across the white/green stripe and green then measure the white/red stripe and green. The green is common between the two white/strip wires. I think the Clymer has you measure across the white/red and white/green and gives the wrong ohm value. After I found that and wasted lots of time, I parked the Clymer manual on the shelf and got an OEM yamaha manual. MUCH better and accurate.

This should be all you need to check the output of the coils. If you need more info, just ask.

Steve

hi there steveloomis ive checked the ac volts out of the sorce coil red and black wirers , ive got a analoge meter had to set it to 50 ac volts no 20 , kick and a good deflection of the neddle 3/4 of the scale, got 16ish ac volts on digital meter i tryed the pick up coils and no reading at all on either coil , i still have a weak yellowish spark sometimes blue , i put my digital ohms meter on the wires the clayma manual says to use the r100 scale looked on google to convert to digital meter , not sure i got this right ( going to re test with a friends expensive fluke tester) got sorce coil 140/150 ohms , pick up coil tested your way 12 ohms could be 120 ohms could not figuer out decimal piont ,will get a true reading on fluke tester, but main thing no ac volts, going to take off stator and clean it up . can the stator be rewound , does any body make them do you know or would i have to get second hand, thanks again for your help . zigzag

Well this is interesting. Try a much lower scale for the trigger coil ac reading. It won't be as much as the CDI power coils. If you are getting a spark at all then the trigger must be working. It has been a while since I checked mine so I don't remember how much kick I got, but it was certainly noticeable. It would be very handy if you could borrow a CDI and test.

I went back to my OEM manual. It is both correct and incorrect. Earlier in the manual where they show you where to measure the ohms of the pickup coil it shows in the picture to measure across the whole coil. In other words it is showing the meter connected to the white/red and white/green wires and indicates 110 ohms +-18%, in the back in the specs pages it indicates 110 ohms +-18% across white/red and green then 110 ohms +-18% white/green and green as I told you.

When a reading is given, that is the actual reading and has nothing to do with the scale setting on your meter. Scale setting is just for readability. An analog meter is easier to read if the max scale is somewhat close to the reading for most accuracy. A digital meter should be set as close as you can to the reading so the decimal points make sense. 18.0 volts is not as accurate as 18.091 volts, however, in this case we are not looking for a value of ac volts, just a kick and about how much.


Thanks for the update.

hi there i tested the stator on my mates tester and with his help it now makes sence , the pick up coils tested white/red/ to green, white/green to green are 110/116 ohms so are ok i found a small yamaha service booklet not a full manual it says 110 + - 18%. The sorce coil red/brown tested at 750 ohms booklet says 200 + - 20% so my stator is way off . i have been in touch with a guy who used to post on here lucky i kept his number he lives local and he had a stator all the readings are within spec so i bought and have fitted it . but now for the problem of do i wire the new one red/brown brown.red on the souce coil like my old one or the right way round , the new one has tags on the pickup wires the colours are different but the tags make sence so all ok there, but the sorce coil wires have no tags , so i think no tags means red/red brown/brown . IF I GET IT WRONG can i damage anything . so all is primed for testing for good spark and hopefully running BUT what do you think guys ( steveloomis) zigzag

Yes, that is quite a bit of difference in ohm readings. Have you looked at the coils and see any discoloration, mainly darker.

As to the color of the wires. If they are red and brown then that should be the correct color code. My 84 has red and brown, my 86 has something else but has the red and brown sleeves.

I am happy you found a replacement stator. You will know soon enough if that is the problem. Please do tell us your results. Others will gain from your work.

Steve

hi there ive been out all day but a few hours ago decided to go for it , so red to red wire, brown to brown wire , remember my red/ brown wires have always been crossed , AND BIG FAT BLUE SPARKS . i carnt atempt to start bike the wiring loom still needs some small repairs and taping back up . with the plug out i can get blue sparks with my hand working the kick starter , it will be a couple of days before i can try to start it up , also i had to reuse the stator cover gasket so this will have to come off for a new one to get a oil tight seal also need to replace the 2 o rings . so i am not out of the woods yet , i will post back later to update, can i thank you steveloomis for ALL your help and time, your experience and knowlage has been great . :thumbup1:

Your success makes it worth the time. Please let us know how it runs etc.

Be sure to check the wiring in the stator cover where it goes thru the rubber boot. Mine was leaking oil past it and it was running down the neutral light switch wire. If yours is leaking past it, just carefully remove and super clean all the oil from the surfaces and the rubber grommets. I sealed mine using Yamabond and it does not leak a drop.

hi guys ( steveloomis) sorry been a week since posting been busy most of the week, but friday repaired most of wiring mainly multiple wirers that were crimped together i soldered together , they were all fraying where the crimp was . so spark plug in, petrol tank on and it fired up 3rd kick and seems to rev up ok , still some more tieding up to do before test ride , so will post when i know more , but so far so good . zigzag

hi guys well finally managed to go for a ride to bike shop 6/7 miles away to pick up alternator gasket / o rings (had to reuse old ones) and all seems well no popping on low revs when changing gear , starts good . its been a big problem to sort out but i am a little wiser for it all, its the first big problem ive had on my xt in 8 years ive had it . i will get the old stator repaired and buy a spare cdi . so fingers crossed . again thanks to steveloomis for the help :thumbup1: . zigzag

hi there guys the starting problem has returned but only when the bike is hot , all seemed ok after the replacement stator , but after getting home from a mates house yesterday the bike was turned off for a few minites then i needed to set off again but no joy . i had a hot drink then quickly got the plug out to check for a spark the spark did not seem as strong or as blue as it should have been anyway back in with the plug and a drain of the carb ( i dont think the carb is the problem )and the xt fired strieght up , took it for a quick spin and all was well got home and turned it off and back on again and all was ok . got home from work today did not go on the bike, it fired up ok went for spin as soon as it got hot i turned it off, it started but only just after many kicks i tryed this a few times sometimes it would start first kick the next it would be 5-10 kicks i got home took off the tank etc and measured the ohms of the sorce coil it was 250 ohms but the engine was hot not warm it says in the clamer manual the stator has to be 68f of 20c and measure 200 ohms + - 20% so 160-240 . as it cooled down it went down to 225 ohms , so guys ( steveloomis) has my cdi gone west , when the bike is cool i have big blue sparks again . this is getting to be a big pain so need to sort it out :helpsmilie: zigzag

Certainly could be a sour CDI. Funny how the idioms change, in the USA when something goes bad we say it "Went South" Why? I dunno....:(

Put a heatshield between your carbs and engine. Keep the heat away from them and see if it gets better. Also when you first shut it off, kick it over till you hear the decomp click, again see if it gets better. One of my main hates with these older kick bikes is the hot restart issue. The fuel vapors "flood" out the motor and it can't start, not enough O2, especially when it's jetted rich at idle. Look into that as well.

Since I ride all winter, I tend to run my bikes on the rich side rather than re-jetting spring and fall, but I have to let them idle if running in to the store for a few minutes because I often would have to wait 10-15min (depending on ambient) if it was hot. Didn't do it everytime and got way better with a heatshield and turned over to TDC when shut down. Not an issue in winter or fall when it was cold out. Same thing with both aftermarket cdi's I had. On the one that I didn't run in the winter and was jetted leaner, not much of an issue.

Good info JJ. I've seen this heat shield idea before and it does have merit, keeps heat from carbs so gas does not boil and flood the engine.