CDI Failure? '99 XT350 Need Help Please

[El_Dorado_Bill]

I've had the bike in the shop for two weeks and the mechanics, with whom I have total confidence based on my experience, their history and third-party references, are stumped.

 

History: I jetted the carb a year or two ago. Bike purrs like a kitten now (was uber lean CA tuned), starts on a half kick. Clutch cover gasket failed, while replacing it, I damaged the decompression lever assembly (DLA) (like an idiot) but did not know it. The bike started easy as always.

 

Suddenly, the bike will not kick start but I can bump start it. However, in about two miles it ran rough then dies. I bump start it and make it home. Twice more during that time, it ran great, then rough, then died.

I noticed that the decompression cable was not moving. I opened the clutch cover case and saw that I had broken the DLA. I replaced it, reassembled the bike and can't kick or bump start it.

 

I relayed this history to the mechanics. They have checked compression, valves, leak down test, spark, fuel, etc. Pretty much everything you can think of but with no luck.

Best guess is it is a CDI Unit Assembly (basically the solid state brains). These ain't cheap (~$300) and not returnable. I will buy one and replace it myself (my suggestion and their agreement as it makes no sense for them to basically unplug the old one, plug in the new one and charge me labor for it).

 

Thoughts? Ideas? I'd really like to hear some good sound mechanical advice about failed CDI symptoms and other possible causes for non-starting when everything seems to be mechanically sound.

 

Thanks.

 

[rzxt350]

Are you saying that you can see a spark at the plug with it grounded to the head while kicking it over ? If so, are you positive fuel is actually making it into the cylinder ? Are you sure the float is not stuck ? Try tapping on the carburetor with a screw driver to un-stick the float . There is a resister located in the spark plug cap that sometimes goes bad that I've read about. If I remember correctly , guys are just replacing it with a piece of copper wire to fix it . Try searching it here on TT . I had a KDX400 that would start cold all day long and when it got hot it would die and not restart until it cooled down. The CDI was the problem . Also there is a flow chart in the Clymer manual that tells you how to check the ignition system, chapter 9 page 247

. You can find used CDI boxes all day long on ebay for way less than $300 . I found one for that KDX400 for $35 and that bike ran great for the 2 years that I owned it after changing the CDI .

Edited May 11, 2014 by rzxt350

[El_Dorado_Bill]

Are you saying that you can see a spark at the plug with it grounded to the head while kicking it over ? If so, are you positive fuel is actually making it into the cylinder ? Are you sure the float is not stuck ? Try tapping on the carburetor with a screw driver to un-stick the float . There is a resister located in the spark plug cap that sometimes goes bad that I've read about. If I remember correctly , guys are just replacing it with a piece of copper wire to fix it . Try searching it here on TT . I had a KDX400 that would start cold all day long and when it got hot it would die and not restart until it cooled down. The CDI was the problem . Also there is a flow chart in the Clymer manual that tells you how to check the ignition system, chapter 9 page 247

. You can find used CDI boxes all day long on ebay for way less than $300 . I found one for that KDX400 for $35 and that bike ran great for the 2 years that I owned it after changing the CDI .

Yes, I checked the spark. Fuel checks out, as does compression, clearance, etc. Everything is in spec. I will check the resister (I've never heard of that before). Great tip on eBay. I was quoting for Genuine Yamaha part. My gut is that it has something to do with me breaking and replacing the DLA, but symptoms don't seem to bear that out.

 

When it ran, it ran smooth. It would not kick start (it used to with an easy half kick). It would bump start, then run smooth then stall, preceded by 1-2 seconds of running rough. This happened 4-5 times getting it home. It has started since. How this connects to the broken DLA I cannot phantom given everything related is in spec. If I open my mind that it is not related to that, I start going to electrical, but am stumped given the strong spark. On Reddit, some suggested intermittent loose wire on kickstand ignition interrupt. Given that this is a kick-start bike, I don't even know it if has one. I'll get the bike back tomorrow (less $78 "diagnostic" fee) but with knowledge that everything mechanical is where it's supposed to be and is functioning (sans running) as it is supposed to.

[rzxt350]

Well the next thing I would check is the cam timing . You will have to remove the rotor cover , valve cover , gas tank etc.. After you get that stuff off you need to turn the rotor counter clockwise until you lineup the TDC mark on the rotor with the pointer on the crank case. Make sure to remove the spark plug so the engine spins easy . Now check to see if the dot on each cam lines up straight up with the dots on each cam cap. If not, do the rotation again and check it again . If they are still not lining up and they are off more than a tooth you probably need to replace the cam chain as it is stretched past it's limit . I had to do this back in January on my xt350 because it was getting very hard to start and finally it began rubbing on the cylinder head and putting lots of metal shavings in the oil.

Edited May 11, 2014 by rzxt350

[Jdrost72]

Do u have a friend with the same bike u could borrow the CID box to check

[El_Dorado_Bill]

Well the next thing I would check is the cam timing . You will have to remove the rotor cover , valve cover , gas tank etc.. After you get that stuff off you need to turn the rotor counter clockwise until you lineup the TDC mark on the rotor with the pointer on the crank case. Make sure to remove the spark plug so the engine spins easy . Now check to see if the dot on each cam lines up straight up with the dots on each cam cap. If not, do the rotation again and check it again . If they are still not lining up and they are off more than a tooth you probably need to replace the cam chain as it is stretched past it's limit . I had to do this back in January on my xt350 because it was getting very hard to start and finally it began rubbing on the cylinder head and putting lots of metal shavings in the oil.

Yep, did that. Thought maybe the key had broke or chaing skipped a tooth or stretched or something. Everything is set up and performing correctly. Poor guys at the shop are pulling their hair out, they're about four hours into a one hour job.

[El_Dorado_Bill]

Do u have a friend with the same bike u could borrow the CID box to check

Sadly, no. That would be the absolute best way to check this.

[rzxt350]

The only thing left is to trouble shoot the entire ignition system as I stated earlier . It has to be something simple .

[rzxt350]

Try bypassing the kickstand switch . Just make a jumper wire and see what happens . I'm guessing that when you are checking for spark at the plug the kick stand is down and when you try to start it the stand is up. It's worth the try .

[El_Dorado_Bill]

FYI, just to close this out. We tested the kickstand switch, it passed mechaniclly and electronically. We also tried starter fluid in the carb intake and had no success. Only thing left to test is the CDI Unit. Until then, it makes no sense to troubleshoot the entire ignition system, which I will do if I can swap out the CDI with a known working one to elimiate that as the problem.

 

Sadly, I don't know anybody in the area with an XT350. The model number shows that the unit is specfic to '87 TT350 and '87-00 XT350.

 

Thank you to everyone who tried to help me.

[Jdrost72]

I no this may sound stupid. But most times the kill button is bad

[El_Dorado_Bill]

Found a good guy, Jerry, 30 minutes from here. We swapped the CDI from mine to his and, bummer, his started right up. Just to confirm, we tried his on mine and it didn't work.

 

I went back by the shop, Folsom Cycle (highly recommend them) and we spent an hour (no charge to me) eliminating the kill switch, ignition switch, plug wire and many grounding issues.

 

I attached a battery and everything works except the light and high beam indicator. The manual hints that it could be a bad regulator rectifier.

 

I'm reaching out to Jerry to see if we can swap the RR and a couple of other electronics.

 

So as of May 27, she's still not running.

[El_Dorado_Bill]

SOLVED: BAD STATOR

 

Good Guy Jerry swapped parts with me until we finally got down to the last possible thing. We pulled the fly-wheel and swapped the stators, mine did't work on his, his did work on mine. Here's a picture of the apparently fried connection. http://i.imgur.com/foxjJb3.jpg

 

My concern now is why did this happen?

[Roger the Vici]

On 5/30/2014 at 11:01 PM, El_Dorado_Bill said:

SOLVED: BAD STATOR

 

Good Guy Jerry swapped parts with me until we finally got down to the last possible thing. We pulled the fly-wheel and swapped the stators, mine did't work on his, his did work on mine. Here's a picture of the apparently fried connection. http://i.imgur.com/foxjJb3.jpg

 

My concern now is why did this happen?

Tell me please. Did you had spark at the spark plug before or you had spark but the bike didn't start anyway?? 

I ask that because I am with a similar problem. I broken the descompretion as well and after that my bike stopped. I did some changes like the transition and clutch etc  now I have spark but no start. I think my problem is the stator as well but please tell me if you had spark or not. 

Many thanks

On 5/30/2014 at 11:01 PM, El_Dorado_Bill said:

SOLVED: BAD STATOR

 

Good Guy Jerry swapped parts with me until we finally got down to the last possible thing. We pulled the fly-wheel and swapped the stators, mine did't work on his, his did work on mine. Here's a picture of the apparently fried connection. http://i.imgur.com/foxjJb3.jpg

 

My concern now is why did this happen?

 

[El_Dorado_Bill]

There was no spark. The bike ran perfectly fine, then one day it just would not start. I had it in the shop and they finally gave up. It wasn't until Good Guy Jerry spent the day with me swapping from easiest to hardest electrical components that we discovered the stator was bad. I ordered a new one and installed it and the bike starts first kick almost every time.

As I understand it, you don't have to have the decompression valve working, it just helps for kick starting. And to be honest, I'm not so sure my replaced decompression unit works as I still sometimes get a kick back that could be close to causing injury. Mostly I kick from about half way and that's enough.

I'm only a garage mechanic, but it would seem to me that if your stator was bad you would not be getting a spark. My only other thought would be if your decompression unit is broken is it possible that you're getting no compression at all? That would make it not start.

Good luck to you. I hope you figure it out.