Help Needed

Doug Pippin d_pippin_89 at
Mon Jul 25 07:58:24 PDT 2011

Any suggestions to my problem here?

I have a 99 SV650 track bike that recently started acting up.
When I'm on the track and have full or almost full throttle the bike runs well.
Once the RPM's drop it doesn't run clean. Sputters and pops somewhat.
The problem started while I was riding on the track.
The engine starts normally and runs at higher RPM but sputters and 
pops when in lower RPM.
It backfires when you release the throttle and sometimes when it's shut off.

I've removed the carbs and checked them visually and everything seems OK there.
I've replaced both the coils to eliminate any problem there.
I removed the valve covers and checked the valve timing and it is 
correct according to the timing mark on the generator.
This bike has the 2nd gen camshaft swap and it ran well for a season 
and half until recent problem started.
I've checked the compression and it's good.

So I'm scratching my head as to what's wrong.
Is there a problem with SV's where the key on the generator may shear 
making the valve timing off?
Does this sound like it may be a ECM  (igniter) problem?

I'm going to remove the carbs and go through them again to see if I 
missed anything.

Any suggestions?

thanks in advance

Doug Pippin


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