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distraught drz troubleshooting *help needed*

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Hi, First time poster here.


About a month ago I purchased a used 2002 DR-Z 400 S for an undisclosed amount. 

Was ridding it home ~300 miles and made it ~40 short of home.

Flywheel starter clutch's bolts (X6) sheared leaving me stranded and left the stater mangled.

Fast forward to now ~1 month later. Still haven't been able to take her for a spin despite devoting most my afternoons to her. 

When trying to start her I would just get occasional backfires, and finally with a different stater a brief start (maybe 5 seconds) on two occasions, now I'm getting nothing, just turning over.



So far I'v:

-Checked valve clearance (at tdc) all in spec.

-Replaced stater twice, once with Chinese crap (just backfires), and now on rick's stater (2 brief starts)

-Thorough cleaning of carb (fcr 39 mx)

-Tested coil, wire, boot, and plug

-Battery is good

-Engine turns over

-Oil was acceptable

-Clean gas (stabilized) 93 oct

-Comp test......60 PSI <--- ???  (seller may have vaguely mentioned its a 410?)(crap aftermarket piston/sleeving?)



My questions:

What could cause the bolts to shear?? 

It was ridding fine until I stopped for gas and had no starter motor flywheel engagement, why is it now not starting with engagement?

If the comp is really that low can that be the cause of my failure to start, and really what gives here?

I have yet to test the grounds, where do I check and is it worth testing given my situation?

Recommendations, questions, ideas?


Will post pics on request. 

Thanks all


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Beleave it or not just put some gas in the cylinder and had it running momentarily. 

Maybe it's something  I do with the FCR. I think the comp reading might just be crap since it's a harbor freight comp tester.


Edited by Kindill

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It started right up when I first got it. Using gas/cab cleaner I'v now started it consistently 5 times for just a moment. Definitely something to do with the carb.

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A possibility:  Cam chain slipped. One or more valve contacted the piston and bent, or at least is not sealing properly.


1. That would account for the low compression.

2. Valve timing being off might cause the backfire.

3. When the valves hit it *Might* have caused the back force that sheared the bolts.


This is a bit of a long shot, but IMO it is worth it to verify the cam timing vs. the crankshaft.



Good luck with your troubleshooting.

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Do you have the vacuum petcock? Open the drain screw at the bottom of the carb to verify fuel is in the bowl. Don't twist the throttle trying to start it, you'll flood it very easily.

How far did you take the carb apart? Did you spray carb cleaner in it? The reason I ask is the o-rings in it will swell if you you most auto carb cleaners.

If you feel like pulling the carb again I would look at the pilot jet again, blow out the passage with the fuel screw removed with compressed air and set the screw to around 1.5 to 2 turns out.

Did you hold the throttle wide open when you did compression test?

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..... ITS ALIVE!  just fully rebuilt the carb and she started, and restarted. so happy.

Running really hot though.. indicating 178F bringing her to 3k after idle, also the fan is busted so that doesn't help. 

Does that mean its running lean? assuming the screw on the bottom (aftermarket) isnt turned the correct amount of twists. 

Any good guilds on tuning this b**ch? 

Also thanks for all the replies 


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