Hello!  As the new season approaches I am working with my local shop to diagnose and fix a problem that crept up last year, we are all ears and hoping someone can shed a little light on what may be happening and how to address the issue.  Here's the scoop -

86 Savage, had it 4 years, runs beautifully when it runs.  Nothing too major done to it but I have swapped for a Raptor petcock, it uses a K&N filter, and I went up a size on my main jet and did the spacer mod (it was already done I just replaced the washer once) which decreased backfiring and ran a little stronger.  Otherwise I have replaced the iginition coil and starter when they began to falter but no other special work to it.  

Late last year it began to cut out at mid range RPM, whether in gear or not.  It would idle strong, then when gassed it would rev up and begin to 'miss' then backfire, then choke out if you did not let off the accelerator back to idle.  As it would continue to idle it would get worse quickly, eventually failing at lower RPM and not recovering at all.  I would let it sit a while, usually charge the battery or something, and repeat the process.  

I have the bike at Moto Classic Garage in Los Angeles, good guys and familiar actually somewhat with the Savage.  They cleaned and checked the carb, checked the plugs, compression, fuel system, and went through some basic diagnostics.  They have another Savage in the shop and have even gone through swapping pieces between the bikes to try and find the problem but no luck yet.  One mechanic thinks it is related to timing but not sure how to be sure, the other wants to plug into another black box and see if that reveals anything.  

So I am asking for any advice or suggestions, we are all pretty curious at this point what is happening ha, and as it gets warmer every day I am certainly motivated to get it back on the road.  Would the cam chain adjustor play a role in such a problem?  Is there another way to check the timing or a related component we have not tried?  Does this sound like a problem we simply haven't thought to look for?  Or is the black box truly the next thing to swap?  

Thanks so much in advance, this site is a great resource!

Sounds like a lack of fuel to me.  I would check the float level.  Maybe even swap carbs if they have one.

I guess the ignitor or CDI box could be bad.  

I have a couple of spares (carbs and ignitor boxes) if you end up needing one, but is sounds like the place you are working with has stuff.

Did you do anything to the muffler?  Maybe too little or too much back pressure (a plug loose and twisted sideways or either no plug at all?).

Just another thing to consider.  Our bikes need the back pressure to work properly and major increases or decreases ca impede performance.

Good luck.

Check your side stand safety switch, they have a bad habit of acting up and shutting off the engine.

I'd hafta hook an induction timing light on the plug wire and see how the ignition system is acting. It's either gonna be flashing so fast it looks like a steady lite or not. At 3,500 rpm you'll get 7,000 flashes a minute.Will that fry one? IDK..
I've heard of spark plugs breaking down under load,
If I saw steady ignition by the light, I'd swap out the plug. Easy as that is, I'd probably start there. Crud hides next to the plug, blow it clear first, examine, whatever you are comfortable with.

Good luck. At least you can be comfortable knowing that your bike is in good hands.

justin_o_guy2 wrote on 02/28/17 at 20:27:53:


Sure,the mechanic can swap out the ignition, If they're compatible. Some year models don't work with the wrong year model engine, or so I have, possibly, wrongly gathered here.
A timing light would seem like such an easy test.

Dan,

I have had similar problems to darned often over the years. If anything acts up on the engine the first thing I do is loosen the gas cap and see if the problem goes away.

Kenny G