Question about Yamaha YZF 600 R thunder cat Motorcycles

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Yzf 600 cylinders 2 3 not firing

2 and 3 center cyclinders not firing cleaned carbs replaced the coil and installed new plugs but pipes still cold until i held my hand over the mouth of those carbs seem to kick them in and pipes got hot for a few seconds any suggestions?

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  • Yamaha Master
  • 4,536 Answers

Carbs need to be torn down and cleaned or jets ajusted--ur hand acts like a choke drawing more gas

Posted on Feb 14, 2014


6 Suggested Answers

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Posted on Jan 02, 2017

  • 83 Answers

SOURCE: Rear cylinder not firing

The first thing I would do is replace the spark plugs again. You can foul a plug and it will cause you more problems than you can ever imagine. I see you have done all the logical things that I would recommend but I did not see you have replaced the plugs after the 200 miles. You would be surprised at how many times a $2.00 part can cause fits beyond belief.

Posted on Dec 08, 2008

  • 6966 Answers

SOURCE: 1979 suski 750,bike runs on 2 left side cylinders,

Hi and welcome to FixYa,

With the indulgence of craigjamesbt...

A few additional ideas to consider:

  • it would be an electrical/ignition issue if 1 & 4 or 2 & 3 will not fire but not 3 & 4;
  • almost always, raw fuel on exhaust indicates a flooded engine. A flooded engine would most likely be a carb issue;
  • best way to determine if it is an engine concern is to do a compression test;
  • a way to test the right carb pair is to deliberately starve them of fuel by temporarily plugging/blocking the inlet port/seat with rubber similar in appearance as to those used for glue gun, not installing the needle and float. Assemble the carb and install. Start the bike and use/spray carb cleaner on the right side carb. Note if 3 & 4 will fire even intermittently.
Would appreciate a postback on results/updates on any developments.

Good luck and thank you for using FixYa.

Posted on Apr 27, 2009

finish line
  • 207 Answers

SOURCE: only running on 3 cylinders, nrew plug and clean

take the plus out and leave them in the boots lay them on a ground (bolt or the frame etc..) to make sure that there is no fire

Posted on Jun 23, 2009

  • 330 Answers

SOURCE: 1982 GS850 Missing and Hesitation

fuel flow to cold pipe cylinder may be stopped with trash or sticky float.Resistor in plug wire for the one not firing could be bad. Try changing coil from one that is firing to the one thats not,see if that pipe gets hot or does the same thing still happen. coil ,plug wire, or fuel would be my primary focus.

Posted on Apr 20, 2010

  • 3740 Answers

SOURCE: fzr 600 got killer spark pulls fuel valves in

This is not the news you probably want to hear but backfiring thru the carbs when you have good spark can be one of 2 things... either the valves are sticking / not closing properly due to carbon or the cam timing has shifted from the original position.

It would be best to do a compression test. You should have a minimum of 100 PSIG for an engine with major problems and up to 150 for a healthy engine. If you can not get 100 PSIG then it will be time for some serious engine service.

There is a possibility of the kill switch wire in the handle bar grip grounding under the grip to the handlebar but, since you said you have killer spark I doubt this is your problem.

Thanks for using FixYa.


Posted on Jun 10, 2010

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2 Answers

Fuel in back bowl but exhaust not getting hot

Hi Jeff:
Gotta love a puzzle.
The black smoke is an indication of too rich a mixture.
What did the plug from the back cylinder look like? If fouled and wet then too rich. If dry then no fuel.
You're close to solving it. The plugs should tell you what you need to know. You could also install new plugs for a "fresh start" to the diagnostic.
Reply as a COMMENT to this post for more input.

Feb 09, 2016 | GAS Motorcycles

1 Answer

I have a misfire on a front cyclinder, as it has new plugs.

If the cable is bad, you here the hissing sound, If bad coil, the cylinder would be dead.
It could be that you have to sync the carbs (if you change the pipes to a custom ones or installing a sport air filter, you have to sync the carbs, sometimes you have to change the carb jets also- slow and main)

Jun 28, 2014 | 1994 Honda VT 1100 C Shadow

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1983 CJ-7 Had someone put water in gas tank? Blew out lines, rebuilt carb and cleaned out, cleaned tank, gas dryer and new fuel, new fuel filter (clear), new fuel pump,replaced rotor cap, plug wires,...

You put something back the wrong way.....any amount of water in the tank, carb or whatever WILL NOT cause the engine not to fire.....check any wiring/rewiring you did for accuracy

Sep 20, 2011 | 1983 Jeep CJ7

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My carbs seems not functioning well,i tried to clean it thoroughly but somehow only one of the two's giving the fire

Hi, how is your spark plug condition, is it in primo condition?
Most spark plugs are resistor types, so when they are not working it just died.
One way I find is good indicator is, now you know that one is firing and one is not, right?.
1.Take one spark plug out at a time, clean them make sure that their anode are clean from soot and oil, it is not wet by unburned fule the plugs to factory recommended gap..
2. Write a "1" on the first one you took out then mark "2" on the second one.
3. Switch them around and see if the one that earlier didnot want to fire will work in the new position.
4. How to tell which works or not. You know which one works in the beginning when you started the bike before you gap and cleaned it. Keep the exhaust pipe from that working cylinder in mind.
5. After you cleand and gap it properly you swith their location and now check which exhaust pipe cylinder got hot.
6. If the same exhaust cylinder got hot as in the begining then your coil is not giving electrical pulses to fire the spark plug.
7. If it heats up the dead exhaust pipe then you spark plug needs replacing, and do replace both of them together..
8. Now to tackle your carb, you had done a very thorough clean up in you carb, meaning, ensuring your carb float level is correct, the main and idle jet needles are clean from gunks, no air leaks in your bowl diaphragm. Your fuel flows correctly without obstruction from the tank meaning the fuel flow tap is wide open .
9. Your battery state is fully charged.
10. With all that, you should have no problem.
Cheers. Don't forget to mark this advise.

Mar 23, 2011 | Honda Steed Motorcycles

1 Answer

1982 GS850 Missing and Hesitation

fuel flow to cold pipe cylinder may be stopped with trash or sticky float.Resistor in plug wire for the one not firing could be bad. Try changing coil from one that is firing to the one thats not,see if that pipe gets hot or does the same thing still happen. coil ,plug wire, or fuel would be my primary focus.

Apr 20, 2010 | 1982 Suzuki GS 650 GT

1 Answer

Miss fire on number 1 cyl ,spark from plug ,cleaned carb cyls 3-4 hot 2 nearly as hot 1 luke warm

I would have to say that I think it's not miss fireing.
It could be the coil for those 2 cyclinders. It could be in the carbs. When you cleaned the carbs did you remove them from the engine and dismantel them completly? Clean every parts and blow out all the air and fuel ports. Did you seperate the carbs from each other? If you did the carbs will need to be synced again. Good Luck.

Oct 16, 2009 | 1994 Yamaha FZR 600

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1981 650 poor excelleration

not enough to go on, but these were not slow bikes. try plugs, mucky carbs, carb jets, air filter.... take out plugs, any dirty black while others are clean or white? start bike from cold, run very short while and turn off. carefully feel exhaust pipes at top, are thay all same temp? one or two not getting warm? watch you don't burn your hands....will tell you if all cyliders firing ok.

Aug 06, 2009 | 1981 Yamaha XJ 650

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Carburator adjusting or no gas

Hi and welcome to FixYa,

Initially, if there is spark on the plug of the front cylinder, then it would be a fuel issue. Pls try:
  • Rig a fuel bottle to replace the fuel tank;
  • Remove the airbox assembly to expose the carb;
  • Start/run the bike, spray carb cleaner on the open carb;
  • note the RPM or sound of engine. Determine if front cylinder will fire even erratically. You could also try the exhaust pipe if it warms up (pls be careful might be overly hot);
  • rev the bike then cover the carb mouth of the front cylinder with the palm of your hand;
  • there should be a strong suction indicating that vacuum is created when on the intake stroke and intake valves are opening;
  • the palm of your hand should be wet with fuel, if not carb issue;
  • might require a rebuilt.
Good luck and Thank you for using FixYa. Happy New Year.

Jan 01, 2009 | 1986 Honda VT 500 C Shadow

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