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Discussion Starter #1
Suzuki T500. Left cylinder fires intermittently under quarter to half throttle. Fails to fire at any other time. Right cylinder fires like a dream.

Stock air box.
Good spark.
Good compression.
Carb is clean as it can get. No blocked passage ways.
Plug is fouled (checked after returning to idling only on the right pot).
Carbs are synced.

Am I missing something?
 

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Twin carb, correct?

Oil or gas fouled?

Prior history?

Premix or injected?
 

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My dads T500 had some intermittent business, till it was found that one of the points wire terminals was shorting to the cover. A sooty black spot could be seen on the backside of the cover.
Swap coils/condensers to be sure they're not breaking down.
Bad plug cap?
Hopefully not a crank seal.
NE
 

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All that seventies two stroke stuff was certainly aged enough to need crank seals well over ten years ago. Many leave visible tell tale signs.
 

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Discussion Starter #6
Twin carb.
Gas fouled.
EDIT: oil pump.

Starts first kick, isn't too smokey and doesn't suck any gearbox oil. A year ago i had it running as a daily rider. Left side started acting up, cleaned carb, found blockage in pilot jet which I had to drill out with a 1mil drill bit.

Hrmmm I'll try all that Tiger.

Cheers guys
 

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Hey Bob,

You do know you still need to run the injection pump to feed the crank bearings right?

The T500 will drop the right cylinder first if the battery is weak so it's probably not your battery. Sounds a bit like a condenser dropping under load as Tiger suggested. Also, is it possible you've got a leaking float or that the float valve is worn out?

Also wondering if your right side point is timed correctly?

Jim
 

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Discussion Starter #8
Sorry Jim, check that, it has the oil pump running the lube. Just had another look, float bowl is leaking slightly. Bugger. I'll check under the points cover when I get home. It only fires intermittently under load. Hrrrrmm.
 

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Drop a bowl..... any evidence of debris....

Start at the tank and work back to the carbs. After fuel delivered is ok and clean all the way to the carbs including floats and float needles...

Inspect the the needle jets as they are the fastest wearing parts on the carbs. If you can see wear with your naked eye, they were worn out long ago, manifesting themselves as four stroking on the overrun and accompanied by hard bucking and jerking..... roughly 1/8th to under 1/2 throttle.

By all means confirm the ignition prior with a methodical spark reserve test/comparison.
 

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Discussion Starter #10
Points condensers all fine. Big fat blue spark at idle, shocked my hand holding the cap.

Hack, bam. This thing is bucking pretty bad when the left pot kicks in on a teeny bit of throttle. I cleaned the carb as good as you can this side of an ultrasonic cleaner. I'll have a proper look in the morning for any new debris and float height/valve wear, damn. Have any spare needles floating around? See what I did there. Anyone recommend a good carb parts store that ships? Arg.
 

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Is it possible to exchange the carbs from one side to the other to see if the problem occurs in the other cylinder? That might help determine if it is the carb or something more evil...
 

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Discussion Starter #12
possible, might have some linkages in the way, choke lever ect. I'll try that as well. Oh and Bob! I'll be in good old CNY in 11 days, let us know when you're hitting the ice, would love to have a looksie and a beer.

Thanks guys, will report tomorrow
 

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quote:Originally posted by Big Bad Bob Dog

Thanks Jim! Did you get that freakin package? Tell me before I go, cause i'll knock up another and send it from home in a few weeks.
Hey Bob,

Not yet. Patience my friend. I have faith it will get here. I promise I'll ping you the minute it gets here.

Jim
 

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Now if you can measure or see visible wear on that hard chrome needle....

I promise it's jet will truely be wasted.

Good luck.
 

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Discussion Starter #20
Hack, bam once again. It's well fucked.

Found some rebuild kits at jerry cycles for 36 bucks. Only have a week of riding before I head stateside. On one cylinder! ARG
 
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