Won't fire on all four

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rdoldtimer
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Won't fire on all four

#1 Post by rdoldtimer » Fri Jan 01, 2016 1:10 pm

Hi friends I have an 85 rd mot has expired no tax but I do run it occasionally but today I seem to have only three cylinders wanting to fire .. Despite cleaning plug @ eventually replaced with new plug . Still nothing . Ideas welcome

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tacky1
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Re: Won't fire on all four

#2 Post by tacky1 » Fri Jan 01, 2016 2:52 pm

Gotta be the gas or gummed up carb, Drain and clean the fuel system, Swap the plug over to another cylinder and see if the plug fires on that cylinder, The plug could be shot..
1985 RZv500
1984 RZ500 Hybrid
1986 RG500 Walter Wolf
1986 RG500 Skoal Bandit
1984 RZ350
1984 RZ350 Hybrid
1981 RD350LC
1981 RD350LC Hybrid
2009 CR500AF Supermoto 250X
2007 CR500AF 250X
1988 YSR50 (2)
1989 VFR750R RC30
1984 GPZ750 Turbo

Blobber
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Re: Won't fire on all four

#3 Post by Blobber » Sat Jan 02, 2016 7:33 am

also try undoing the carb float bowl drain screws one by one for 30 secs or so with the fuel tap set on prime to see you are getting an uninterupted fuel supply to each carb. Catch the fuel in a jar from each overflow pipe. Make sure the jar is clean and see if there is any debris in the fuel to indicate rust or anything in the tank.

If the bike was previously OK it must be something relatively simple and specific to that cylinder i.e. spark plug or fuel supply

good luck
Bikes:
RZV500R FZR1000 forks wheels JL pipes
RD350LC N2

rdoldtimer
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Re: Won't fire on all four

#4 Post by rdoldtimer » Sat Jan 02, 2016 1:51 pm

Thank you guys for the replies I've now checked my spark using a tester as far as I can see I have sparks off course to do any think with my carbs you have to remove all side panels to get to drain fuel I've now drained all fuel from my carbs Some of it seems cloudy so have put fresh fuel in tank . Next step my bikes battery had drained as well so been on a optima the charger all day .. Ran out of daylight will go for a start up tomorrow .. Saga continues

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tacky1
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Re: Won't fire on all four

#5 Post by tacky1 » Sat Jan 02, 2016 3:28 pm

Swap the plug from one cylinder to another, It may spark when its out, But it could be breaking down when the gas gets to it..
1985 RZv500
1984 RZ500 Hybrid
1986 RG500 Walter Wolf
1986 RG500 Skoal Bandit
1984 RZ350
1984 RZ350 Hybrid
1981 RD350LC
1981 RD350LC Hybrid
2009 CR500AF Supermoto 250X
2007 CR500AF 250X
1988 YSR50 (2)
1989 VFR750R RC30
1984 GPZ750 Turbo

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pstamper
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Re: Won't fire on all four

#6 Post by pstamper » Sat Jan 02, 2016 7:54 pm

Probably fuel. Start it occasionally means 3 months, 6 months. I just pulled my carbs installed new float valves from Rick Lance, cleaned, and set floats. My bike sat for about 3 months and it would only idle or go on 1/2 throttle or with choke on. After syncing I topped it of with new fuel and started on two kicks. Suppose to be sunny Sunday so taking the old girl out. Think i will take her out with no clothes.

rdoldtimer
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Re: Won't fire on all four

#7 Post by rdoldtimer » Sun Jan 03, 2016 6:31 pm

On further inspection ! Seems I have fuel in 3 carbs but none in the left side bank front
One . Gonna drain my tank tomorrow see what I find bought some fuel system cleaner as well go from there !!

silverstrom
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Re: Won't fire on all four

#8 Post by silverstrom » Sun Jan 03, 2016 8:20 pm

Float valve (needle and seat) is stuck. Very common. Fuel system cleaner won't fix it. Time to pull the carb. That's the only way you'll solve the problem. Well, you might try giving the bowl a few good taps so see if you get lucky and free the needle.

rdoldtimer
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Re: Won't fire on all four

#9 Post by rdoldtimer » Sun Jan 03, 2016 8:24 pm

How about air gently through drain screw hole ??

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Re: Won't fire on all four

#10 Post by silverstrom » Sun Jan 03, 2016 9:22 pm

rdoldtimer wrote:How about air gently through drain screw hole ??
No. It's just a hole in the bowl that goes nowhere.

To get to the float valve you need to remove the float. That means removing the bowl. If you have to replace one, the other 3 will need replacing as well.

rdoldtimer
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Re: Won't fire on all four

#11 Post by rdoldtimer » Mon Jan 04, 2016 3:36 am

I'm guessing carbs need to be sonic cleaned

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Re: Won't fire on all four

#12 Post by rdoldtimer » Mon Jan 04, 2016 3:37 am

Any body out there who works on these bikes an is knowledgeable

silverstrom
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Re: Won't fire on all four

#13 Post by silverstrom » Mon Jan 04, 2016 3:59 am

rdoldtimer wrote:I'm guessing carbs need to be sonic cleaned
Not, not really. Ultrasonic can be helpful, but it isn't the only way. You can do it all yourself with a little time and patience. Use the manual. Put your UK location in your profile so the UK guys that are nearby can assist you.

Blobber
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Re: Won't fire on all four

#14 Post by Blobber » Mon Jan 04, 2016 6:59 am

I agree with Silverstrom, if its just one cylinder and it has previously worked and you dont have fuel at that carb then it has to be the float valve or a major blockage in the fuel pipeline to that carb (unlikley). In my experience best to drain the float bowls if leaving the bike for several months without riding. Still no guarantee as I've had the floats stick open when you reprime the system.

I would not recommend any bodges on these bikes, if you blow air in the carb drain and it fixes the problem it will only be a matter of time before the problem will reoccur - trust me.

The carbs need taking off to see what their like internally. A decision can then be made whether they would benefit from ultrasonic cleaning if there is varnish deposits etc or just new float valves/seats/'O' rings. The dodgy valve is probably stuck to the seat. I've personally never had them stuck shut always stuck open or not seating therefore the opposite to you with fuel leaking out the carbs.

If you have not taken the carbs off before then best to get a manual and have a read about the procedure. In my experience of owning the bike for 10-15 yrs the initial carb removal usually throws up other issues particularly if the bike has never been restored or maintained. For example the fuel pipes can be cracked, hardened and break during removal. Because the removal process is quite time consuming (especially the first few times) its best to try and cover all the usual problem areas the first time.

I would pull them off the bike and check for varnish and other deposits decide whether to clean yourself or send away for ultrasonic cleaning . Check the jet sizes (particularly if its a derestricted RZV) and set the float levels to the latest specification. Install 4 x new float valves/seats/O rings. Check all fuel hose for cracking (I would just replace them all anyway for peace of mind). Reinstall syncronise and check oil pump setting.

Done!

If you are careful, patient, have the right tools, a manual and methodical the whole process can be theraputic and very rewarding.

Where in the UK do you live as I'm happy to help if required. I'm no expert but have done a lot of DIY work on my bike with good results.

Trevor
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RZV500R FZR1000 forks wheels JL pipes
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Speed Freak
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Re: Won't fire on all four

#15 Post by Speed Freak » Mon Jan 04, 2016 8:16 am

Polishing needle seats and needle sliding surfaces often helps instead of buying new parts and saves a lot of money.

http://www.rzrd500.com/500phpBB3/viewto ... dle#p76751" onclick="window.open(this.href);return false;

Also check your fuel tap, it`s a common problem that the rubber gasket inside gets damaged over time.
Parts are breaking out of the rubber and go down the fuel line - in best case they will go into the carb bowl.
In worst case they will block the fuel valve of one carb and one cylinder will go lean...

Saw that problem here in this forum and checked my fuel tap afterwards - happy that my engine survived the test ride (and the previous owners), the gasket was damaged :shock:
My bikes:
RD500 YPVS 1GE
RD350 YPVS 31K 1985
Honda CBR 1000 RR SC57
Yamaha R1 RN04

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