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Stock KZ650 - flames shooting from carb vents
- KOOL RYDER
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- KZ 650B2 / KZ 1000E
Stock 78 B2, the bike will start on full choke but dies as choke is closed.
There is a major backfire out of the carbs - gasses pulsing through the gasket on the top of the carb and flames visible through the carb vents.
Scarred the crap out of me yesterday.
I think that I have gotten myself in this mess when I tied to retighten the cam chain.
When I started the bike up after removing the points cover - rotating the bolt 2 revolutions and slacking the cam chain tensioner - it sounded like a chain saw.
I started the bike with the electric start - that was a bad move. So I have read in the Haynes manual.
Clymer did not mention it in my book.
So basically what can I expect or what do I need to do to remedy the situation.
Has anyone ever seen this before.
My biggest fear is bent valves from the cam chain jumping a link or to. Would that cause the the valves to be damaged and the combustion to leak back through the carbs?
Any info on how to proceed would be greatly appreciated.
I just had the bike ready to go to paint as I figured I had everything working and now this.
I rode the bike for about 2 km and then she died on me.
Now the flames are shooting out the carbs.
Rockin\' a KZ650B2 since 2007 and a KZ 1000E since 2008
1978 KZ650B
1979 KZ1000ST
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- BSKZ650
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since you have ran the bike, the damage may have been done.
1 check the cam timing to make sure it is correct,
2 if cams are wrong, redo the install
3 if cams are correct, make sure the plug wires are on correect
4 run a compression test on all 4 cyls, this will tell you if you have a major problem
5 if the compression is low, start ordering parts for top end rebuild.
I know that is not good news but its going to take the slow down and check everything again.
77 kz650, owned for over 25 years
77 ltd1000, current rider
76 kz900, just waiting
73 z1,, gonna restore this one
piglet, leggero harley davidson
SR, Ride captian, S.E.Texas Patriot Guard Riders.. AKA KawaBob
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- timebomb33
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1973 z1 2-1974z1-a,2-1975z1-b dragbikes1015cc+1393cc, 1977kz1000,1978kz1000,1981kz1000j, 1997 zx-11, 2000 z12r,1428turbo nitrous pro-mod and a shit load of parts thats all for now leader sask.,CANADA
I THINK MY POWERBAND BROKE
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- Patton
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... major backfire out of the carbs... tied to retighten the cam chain.
When I started the bike up after removing the points cover - rotating the bolt 2 revolutions and slacking the cam chain tensioner - it sounded like a chain saw.
I started the bike with the electric start....
Might be mis-reading, but am interpreting the reported history to mean that the valve cover was not removed, and the initial objective was a routine adjustment of the cam chain tensioner located behind the cylinders below the carb holders.
Am wondering if the cam chaim tensioner was loosened and not tightened before running the engine while the tensioner remained in the loosened position. This would allow the engine to run with zero tension on the cam chain (and perhaps sound like a chainsaw what with the ultra-loose camchain flapping and flopping all around). Am uncertain as to the extent of damage which might have resulted. If the camchain slipped a tooth or so -- ouch -- possible valve damage. But if it didn't slip a tooth, maybe just lots of noise without valve damage.
Would try again to adjust the tensioner. With lock nut loosened, loosen bolt, gently and carefully hand-rotate engine (stop immediately if any resistance is noted as this might be a valve contacting a piston or another valve), tighten bolt, tighten locknut. Hand-rotate the engine (stop immediately if any resistance is noted as this might be a valve contacting a piston or another valve). Assure plug wires are correctly routed. Only if the engine rotated smoothly and quietly while hand turning, try to crank the engine, but be prepared to immediately shut it down if any unusual noise is noted.
Often, a leaking intake valve which isn't fully seating because of too tight valve clearance may allow combustion to escape and fire back out through the carb.
Good Luck!
Edited to include loosening tensioner BOLT after loosening its locknut, and tightening the bolt before tightening its locknut. The bolt holds the tensioner internals in position, and the locknut merely keeps the bolt from loosening.
1973 Z1
KZ900 LTD
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- RonKZ650
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321,000 miles on KZ's that I can remember. Not going to see any more.
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- HerrDeacon
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Some potential mistakes include attempting to start the engine without securing the adjustment or turning the engine over backwards during the adjustment before tightening the tensioner.
Ron, what effect does turning the engine backward have, meaning how would this make a difference? Just trying to learn here, for when I do this adjustment in the future.
Should you only turn the engine one way? So if you miss the mark just continue round the same way until it comes up again?
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- BSKZ650
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ont thought may be that the tensioner has broken, either way pull the valve cover and run a compression check,
77 kz650, owned for over 25 years
77 ltd1000, current rider
76 kz900, just waiting
73 z1,, gonna restore this one
piglet, leggero harley davidson
SR, Ride captian, S.E.Texas Patriot Guard Riders.. AKA KawaBob
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- Patton
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RonKZ650 wrote:
Some potential mistakes include attempting to start the engine without securing the adjustment or turning the engine over backwards during the adjustment before tightening the tensioner.
Ron, what effect does turning the engine backward have, meaning how would this make a difference? Just trying to learn here, for when I do this adjustment in the future.
Should you only turn the engine one way? So if you miss the mark just continue round the same way until it comes up again?
Should you only turn the engine one way? So if you miss the mark just continue round the same way until it comes up again? Imo, Yes and Yes. Am thinking the idea is to keep maximum slack at rear of camchain whereby setting the tensioner will have the most effect.
Good Luck!
1973 Z1
KZ900 LTD
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- RonKZ650
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321,000 miles on KZ's that I can remember. Not going to see any more.
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- HerrDeacon
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- gane
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[img][/img] 1977 KZ1000A1
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- wiredgeorge
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wiredgeorge Motorcycle Carburetors
Mico TX
www.wgcarbs.com
Too many bikes to list!
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