I hate it when they do this.

crassius

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Sep 30, 2012
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Putting miles on my new test bikes lately (when repair jobs & weather permit) and one quit on me today. Was pulling up a hill fairly aggressively when it started missing a bit & loosing power, then quit about 100 feet farther up the hill. Looked it over well, saw nothing, checked wiring, unplugged kill wires. Pushed it to top of hill and came down, and it started again. Ran a bit crappy with intermittent missing back to shop.

Drained carb into glass jar to look for water as I had added fuel before starting out, but didn't see anything - checked all and reconnected wires.

Rode around for a couple miles with no problems.

Now, if I never figure out what happened, will I trust it on a long ride?

Troubleshooting after the fact just kills me.
 

crassius

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Sep 30, 2012
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yeah, might have been a water drop that went thru so wasn't seen when I drained carb - this is one of two identical bikes, so float angle shouldn't be it unless the carb has a flaw - also might have been a funny spot on wire connector that rubbed clean when I replugged them

I can only pedal 1/2 a block and only walk a bit less than 3 blocks, so I'm a bit nervous about trying a long ride : (

Just hoping running it a while around the near area will show what's wrong or show that it is OK now.

EDIT: I should also note that this bike has been up that hill three times before during testing with no problems.
 
Last edited:

sbest

Member
Nov 3, 2015
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Nova Scotia
I had an XT600 that I bought brand new in 1985.
Rode it 1 year, which was the warrantee period when it started shutting down for no reason. Would shut down for a couple seconds, then start back up. It got worse with time.

It got so bad that as I gunned it out into traffic it would quit and toss me over the handle bars, and THEN it fire back up flinging me back on the seat! Not safe at all.

The dealer was good about it. It rarely ever happened at the dealership. They only charged me for the parts tried and minimal labour for what would be servicing anyway.

Finally they found it. Protective varnish coating inside the steel gas tank was breaking down causing almost invisible scales that would block off the petcock filter. Shut the gas off or shake the tank and the fuel would flow again. They pulled the petcock filter and installed an inline filter.


(stock photo identical bike)
100mph dirtbike
 

ZipTie

Active Member
Jan 8, 2016
750
48
28
Mpls Mn
If you think about how small the hole is in a carb jet any micro gunk can clog em if even temporary. I would imagine Crassius that you remove and toss the upper petcock gas filter? I have been tossing mine, for good or bad? What do you guys recommend on the little petcock filter????
-sbest, I had a meager 1972 YZ125 Yamaha dirt bike when I was a kid that had so much torque and compression it would rip the spokes clean off the rim and blast so hard with a blip of the throttle and when it kicked in after a one moment delay I needed a death grip on the bars. Those old 2 strokes were scary fast and fun. I could only imagine a 600cc 2 stroke. I would sure like to have one again.
 

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crassius

Well-Known Member
Sep 30, 2012
4,032
156
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I like both filters - tank filter protects rubber in the petcock, and line filter protects carb when rubber from petcock begins to shred with age.
 

ZipTie

Active Member
Jan 8, 2016
750
48
28
Mpls Mn
That is too funny Crassius... but full circle protection. Ever had or seen a tank filter clogged?
 

crassius

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Sep 30, 2012
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well, bad weather lately had me doing only short rides on it, with no problems

today, it quit at same place on same hill - hit tickler and couldn't tell about gas flow, so opened gas cap - started right up

rode some on level road and started to spit & sputter, opened gas cap and no change, still rolling so hit tickler, no start

got off and looked without touching anything, started up fine after a min

got to shop, checked fuel flow, checked wire connections - rode a bit & it quit again on level road at moderate speed

when it runs, it runs smooth and fast - always sputters a bit before quitting - always starts right up after about a minute - never quits on the run-bench

beginning to hate this POS
 

curtisfox

Well-Known Member
Dec 29, 2008
5,190
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minesota
well, bad weather lately had me doing only short rides on it, with no problems

today, it quit at same place on same hill - hit tickler and couldn't tell about gas flow, so opened gas cap - started right up

rode some on level road and started to spit & sputter, opened gas cap and no change, still rolling so hit tickler, no start

got off and looked without touching anything, started up fine after a min

got to shop, checked fuel flow, checked wire connections - rode a bit & it quit again on level road at moderate speed

when it runs, it runs smooth and fast - always sputters a bit before quitting - always starts right up after about a minute - never quits on the run-bench

beginning to hate this POS
Almost sounds like a vapper lock................Curt
 

crassius

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Sep 30, 2012
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got some bad weather coming again, and a few other things to finish

will have to start replacing these new parts with other new parts to see if I can find the problem

seems to be somehow heat related as tho something expands or moves when hot - so far am thinking may be electrical
 

crassius

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Sep 30, 2012
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pretty much convinced it is heat related, and most likely ignition - while coasting with motor dead, I hit tickler and see fuel moving, but letting out clutch gives not even a pop

realized last eve that I never tried choke when sputtering started, so should try that when weather eases up
 

crassius

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Sep 30, 2012
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what's really frustrating is that by the time I get off the bike, no matter what I test or how I test it - everything is good and motor starts right up
 

crassius

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Sep 30, 2012
4,032
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got a break in rain today & was about to change CDI - looked just a bit funny, so I tried to see inside rubber plug and that was hard to see, but also didn't seem right - unscrewed plug wire from CDI and under good light I could see that the spring that should have gone over terminal nut was sideways up in there so that only the rubber boot was holding it in contact with plug - too cold & wet to ride today, but I'm thinking it's fixed

checked 4 other CDIs in this set of kits and all were crooked to some degree, but not completely sideways - all straighten out easily, but I'll need to remember to check them before selling
 

crassius

Well-Known Member
Sep 30, 2012
4,032
156
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POS chinese bikes - froze riding it as I couldn't wait to see if it ran OK - it don't

back to replacing parts : (