Why won't my DRZ start?

I'm getting tired of this damn thing. Seems like all I have done is wrench on this thing and nothing has been happening. I have no idea why it won't start. I'm gonna break this down Barney style and maybe you guys can help me out.

 

Symptoms

 

Before any diagnosis or repair the bike would crank all day and never fire.

 

When cranking I get 1 or 2 fires after every 4-5 revolutions with the bike on full choke with the fuel screw anywhere from .5 to 4 turns out. It is a regular rhythm. With half choke I get some random fires. No choke I get nothing. Some backfires thrown in with every settting. Full carb details below. Tried bump starting while playing with fuel screw and choke and still no running. I would get a fire every now and then. A few times it fired once or twice then locked the wheel.

 

Compression

 

When the bike first stopped running compression was low. A leakdown test showed 20% leakage and all the sound was coming from the crankcase. I use a Harbor Freight tester with the shitty percentage gauge replaced by a second 100psi gauge. I pulled the top end and all the rings were stuck firmly in the grooves. I had to break one to get it out.

 

I sent the head off to SSW to get a rebuild. I reinstalled the same piston and cylinder with new rings, circlips, piston pin, and gaskets. Nothing looked out of the ordinary with the piston or the cylinder plating. Everything was double checked. The piston is installed with the dot on the exhaust side and the rings are rotated 120 degrees from each other. Head bolts torqued to spec.

 

I confirmed valve lash is within spec and I triple checked the valve timing.

 

Spark

 

Nice blue spark from the brand new plug. Pickup and signal coil resistance and peak voltage are in spec. Ignition coil resistance is in spec. Kill switch bypassed. Key bypassed. Clutch and sidestand interlocks bypassed.

 

Fuel/air

 

Air filter is clean. Carb is seated firmly and properly in the boots. Fuel flow from the petcock is good. 3x3 mod done, full Muzzy exhaust with quiet core and spark arrestor. It's 80 degrees out and 100 feet above sea level. Stock Mikuni 36 carb. Keintech extended fuel screw.

 

JD Jet kit

Blue needle, clip on 4th position from top

25 Pilot

155 main

I have adjusted the fuel screw from fully seated to 4 turns out.

Idle speed not touched

 

I mangled up my old carb trying to open it up for ultrasonic cleaning thanks to those soft brass screws. I bought this carb off a guy who removed it from a running bike and replaced it with an FCR.

 

What Now?

 

Tomorrow I will do a leakdown test, but I'm not sure what kind of numbers to expect from a cylinder that hasn't had a break in run. I will check anything and try anything that you guru types suggest (Noble, E.Marquez, Eddie, Craigo, etc).

 

Or I am very close to setting up a camera, lighting the bike on fire, and slowly walking away while I wait for the gas tank to explode. I would not look at the explosion, of course.

I'm a noob to the drz... I know it has tdc... Any chance that is out of sync?

 

Symptoms

 

Before any diagnosis or repair the bike would crank all day and never fire.

 

When cranking I get 1 or 2 fires after every 4-5 revolutions with the bike on full choke with the fuel screw anywhere from .5 to 4 turns out. It is a regular rhythm. With half choke I get some random fires. No choke I get nothing. Some backfires thrown in with every settting. Full carb details below. Tried bump starting while playing with fuel screw and choke and still no running. I would get a fire every now and then. A few times it fired once or twice then locked the wheel.

Idle speed not touched

That your are getting a fire occasionally would suggest you are close, I would set the the fuel screw @ 2 1/2 turns out and increase the idle speed by a turn.

All so check that you have free play in your throttle cables and returning fully.

Have you pulled the plug after an attempted start and found it wet?

Are you 100% sure the cam timing is right?

Have you checked to see if there's any fuel in the oil? Petcock (stock or aftermarket) could be bad without overtly showing signs of wear. We had problems with fuel leaking into the crankcase with similar symptoms.

2.5 turns is what I have on our similarly jetted carb. With the extended screw I've heard you run the 22.5 jet instead of 25, but haven't added that to my stock carb yet.

What's your float level? Is the float needle stuck?

Sounds like you have adequate spark so I'm guessing it's a fuel mixture problem. Do you have any hose lines kinked up, or does the tank pinch off any breather tubes?

What you have listed sounds good except the 4 turns on the fuel screw, so maybe it's something you can't see. I'd recommend checking your oil for fuel, changing out a stock petcock for a Pingle or Raptor, and making sure all your hoses flow properly.

Wish I could help more, I'll tell you these things are freaking annoying as hell.

You could post a pic of your Cam Timing

Are you sure the idle screw is not backed off ?

Are you sure that fuel is getting through ?

Just trying to help , please don't Flame :smirk:

Have you done a resistance check from each of the yellow stator wires to the signal coil wires(both connectors unplugged)?  ANY reading is a fail.  Did you meter each of the yellows to engine case(connector unplugged)?  ANY reading is a fail.

have you done a compression test since the ring job ? 

 

that's where I would start, if it didn't fire after 10-15 seconds of starter attempts. it's a very positive test as to wether it should be running or not. 

Is the air/fuel screw intact? As in is the tip of it there and in good shape. Are its washer,spring and o ring in the proper sequence? How about the little o-ring under the top of the carb? How about the ACV diaphram condition? Or the other rubber gaskets in the carb. What condition is the float valve needle, seat, o-ring and screen? Is float height set properly? If stock petcock, is the vacuum hose attached to the extra nipple on the petcock and the the nipple on the carb? Just from turning over the bike you are breaking in the rings. Slowy but it is making cylinder wall contact. But not under full running pressures. If it was a recent rebuild of your head by SSW was it done with new parts and properly? So many things to check and accont for. If all else fails take it to the stealership for a full diagnostic test. In the '70s I had a Suzuki 250 that I worked on for months trying to get it to run. Finally saved up the money for the stealership. Turned out to be a cold solder joint on the coil. Gremlins...I hate 'em. Good luck and keep us informed! :)

have you done a compression test since the ring job ? 

 

that's where I would start, if it didn't fire after 10-15 seconds of starter attempts. it's a very positive test as to wether it should be running or not. 

 

Just ran a leakdown test. At 100psi I have less than 3% leakage so compression isn't the problem.

 

Have you done a resistance check from each of the yellow stator wires to the signal coil wires(both connectors unplugged)?  ANY reading is a fail.  Did you meter each of the yellows to engine case(connector unplugged)?  ANY reading is a fail.

 

Infinite resistance on all.

 

Is the air/fuel screw intact? As in is the tip of it there and in good shape. Are its washer,spring and o ring in the proper sequence? How about the little o-ring under the top of the carb? How about the ACV diaphram condition? Or the other rubber gaskets in the carb. What condition is the float valve needle, seat, o-ring and screen? Is float height set properly? If stock petcock, is the vacuum hose attached to the extra nipple on the petcock and the the nipple on the carb? Just from turning over the bike you are breaking in the rings. Slowy but it is making cylinder wall contact. But not under full running pressures. If it was a recent rebuild of your head by SSW was it done with new parts and properly? So many things to check and accont for. If all else fails take it to the stealership for a full diagnostic test. In the '70s I had a Suzuki 250 that I worked on for months trying to get it to run. Finally saved up the money for the stealership. Turned out to be a cold solder joint on the coil. Gremlins...I hate 'em. Good luck and keep us informed! :)

 

Everything in the carb looks good. I switched to the 22.5 pilot jet and 2.5 turns out. O ring is there. Spacers on the needle in proper order. Petcock on prime and flowing plenty of fuel. Float height 13mm. I can only assume the head work is correct. I don't have the tools to check the work. If I did I would have done it myself. There is no leakage through the intake or exhaust when running leakdown test.

 

 

I wish I knew somebody else with a DRZ so I could swap parts over. Primary and secondary ignition coil resistance is in spec. Sparks still look good, but I have no way to tell if they are timed properly. This is where a known working CDI to swap would be nice. Signal coil and pickup coil resistance checked again and in spec. I don't have the expendable money to pay shop labor costs right now or I would have already taken it in. I may end up having to take it in though.

Have you changed the oil yet or checked it for gas? 

Have you changed the oil yet or checked it for gas?

There is no need. It has fresh oil from the rebuild. The petcock doesn't leak. The needle valve doesn't leak. Even if they did I haven't left the fuel line attached since the rebuild and I've been draining the carb bowl because of all the carb work I've been trying. There has been no opportunity for the oil to get contaminated.

If it was my engine I'd spray some starting fluid in the intake while cranking. If it fires it's likely a carb issue. Don't do it for to long because if it fires it probably won't be good for all of those new pieces. What carb is on this bike?

Edit- make 100% sure your timing is correct

Edited by Echo5413

Well to me OGM it sounds like you are on top of everything. Just pinning down the last solution is escaping you. I have no more to suggest. :)

I had a similar problem with mine cranking fine but not starting.  And the tail light not working.  The problem?  The ignition switch was not making good enough contact.  I cleaned the switch and put some light oil in it.  Bike fired right up and the tail light works great.

 

Wish I could be more than moral support…..  Sometimes the gremlin is something so simple we don’t even know it exists.

could be cam timing, and / or the auto-decompression thing holding is malfuncitoning, holding  a valve open. it doesn't open it much, but it's enough on manual bikes to kill the engine. 

 

check cam timing and the auto decomp would be my thing, and a new spark plug

could be cam timing, and / or the auto-decompression thing holding is malfuncitoning, holding  a valve open. it doesn't open it much, but it's enough on manual bikes to kill the engine. 

 

check cam timing and the auto decomp would be my thing, and a new spark plug

I have also considered the auto decompression and thought about grinding it off. I have checked my cam timing literally 3 times and I've done it correctly plenty of times before. I will check it again though if I pull the cams to remove the auto decompression.

I am also beginning to wonder about the stator. PO installed the pickup coil wrong and sheared the wires. I replaced the pickup coil, but I may test the coils again with my homebrew peak voltage adapter and pull off the stator cover to have a look inside.

I would check that the carb mount between the carb and the motor is not leaking. With the carb in good condition and the setting as you detailed, an air leak would do this.

Any luck with a shot of starting fluid? Does it back fire while cranking?

It lives! The problem was in the stator as I was beginning to suspect. When the bike first started acting up I replaced the pickup coil where I found the sheared wires. I bought it from Ricky Stator and they advised me that it was an LTZ400 coil so the blue and green wires needed to connect to the CDI backwards. I remembered about their recommendation when I was poking around about to remove the stator cover. It turns out they were wrong. I switched the wires and it fired right up. I went on an overseas contract right after the bike stopped running so that completely slipped my mind being so long ago. Even with the wires backwards the resistance and peak voltage were both in spec.

 

It's always something stupid. Just need to order a replacement tire (wife let it go flat and sit so the sidewall is damaged) and a new battery and I'll be ready to break it in! Thanks for all the suggestions. It is some consolation to me to know that I was doing everything right and just got bad advice from the part manufacturer. I will be sending them an e-mail to let them know and hopefully avoid this problem in the future.

Overgrown...thanks for this post.  My symptoms are exactly the same.  I was having a bog occur when I'd crack the throttle and I couldn't tell if it was a rich or lean bog.  The PO wasn't much use with a wrench, so I assumed it was lean since they bike is factory jetted that way.  So, I moved up a groove in the needle and cleaned out the jets and it helped but the bog was still present.  Then suddenly it died and won't fire back up.  Same as you, it will pop and back fire and I get solid spark to the plug but it won't start.  

 

I have the carb off now and I'm replacing the main jet from 142 to 155 and keeping the pilot jet at 45.  If that doesn't fix, then I'm into the electrical system and I'll use your troubleshooting as a guide.

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