1987 RZ350 mis-fire on right cylinder.

General forum on engines, transmissions, gearing and modifications to each

Moderator: rztom

Message
Author
User avatar
Redline Junkie
-----
-----
Posts: 624
Joined: Tue Dec 25, 2012 12:55 pm
Location: Halifax, Nova Scotia Canada

1987 RZ350 mis-fire on right cylinder.

#1 Post by Redline Junkie » Sun Mar 04, 2018 7:36 pm

Hey Guys

My 87’ seems to be mid-firing on the right cylinder. The bike has fresh crank seals, carb rebuild, new rings etc.. what I have noticed is the right side is slower to warm up when touching the cylinders and once warmed up if I hold the RPM at 4K the left Side provides nice hot, constant exhaust while you hold your hand over the silencer. When you do the same to left side the exhaust seems cool with pop pop pop when firing.

I wonder why it is doing this, changed plugs, coil but have not done compression test yet. Once riding it I can crack it and it would flip over no prob in first gear. Maybe a carburetor issue or low compression?

I will do comp test and report back

Any help would be great

Rob
Last edited by Redline Junkie on Sun Mar 04, 2018 8:36 pm, edited 1 time in total.
1985 RZ350F being restored now!
1987 RZ350 Stock
1985 RZ350F basket case
1985 RZ500 Stock

User avatar
JonW
Posts: 10599
Joined: Sat Oct 10, 2009 4:33 am
Location: Sydney
Contact:

Re: 1987 RZ350 mid-fire on right cylinder.

#2 Post by JonW » Sun Mar 04, 2018 8:10 pm

Check the fuel is flowing in that carb. Ive had these bikes do this, they run 'ok enough' on one cylinder especially at idle until you do some research like you have here Rob. Im betting the fuel check valve is the issue.
80 XT500 Supermoto!
81 RD350LC Resto
82 RD421LC Hybrid
82 RD350LC decapitation project
82 RD250LC JDM '251LC' YPVS
83 RZ350 Resto
84 RZ500 Resto
85 RZ350 F1 Resto
86 RZ350 F2 Resto
86 RZ350 F2 Hybrid

Like Watches? www.PloProf.com & www.DeskDivers.com

User avatar
Redline Junkie
-----
-----
Posts: 624
Joined: Tue Dec 25, 2012 12:55 pm
Location: Halifax, Nova Scotia Canada

Re: 1987 RZ350 mis-fire on right cylinder.

#3 Post by Redline Junkie » Sun Mar 04, 2018 8:40 pm

Ok John, so you think it maybe the value on the tank is the issue? I could try it on the prime position if that is the case and see what happen maybe.
1985 RZ350F being restored now!
1987 RZ350 Stock
1985 RZ350F basket case
1985 RZ500 Stock

User avatar
JonW
Posts: 10599
Joined: Sat Oct 10, 2009 4:33 am
Location: Sydney
Contact:

Re: 1987 RZ350 mis-fire on right cylinder.

#4 Post by JonW » Sun Mar 04, 2018 8:42 pm

no inside the carb, the little pointy one activated by the float. usually if you tap the carb with say a small hammer handle it will unseat and flow fuel. they get sticky with old fuel and lock shut as thats how theyre stored, ie bowls full and so valve shut. a good clean helps and some guys polish them inside the brass part with a q tip in a drill.
80 XT500 Supermoto!
81 RD350LC Resto
82 RD421LC Hybrid
82 RD350LC decapitation project
82 RD250LC JDM '251LC' YPVS
83 RZ350 Resto
84 RZ500 Resto
85 RZ350 F1 Resto
86 RZ350 F2 Resto
86 RZ350 F2 Hybrid

Like Watches? www.PloProf.com & www.DeskDivers.com

User avatar
Redline Junkie
-----
-----
Posts: 624
Joined: Tue Dec 25, 2012 12:55 pm
Location: Halifax, Nova Scotia Canada

Re: 1987 RZ350 mis-fire on right cylinder.

#5 Post by Redline Junkie » Sun Mar 04, 2018 8:50 pm

Ok, replaced the needle and seat about 2000km ago but I will check to see if it flowing fuel by draining the float bowl while in prime and see if that allows it to flow
1985 RZ350F being restored now!
1987 RZ350 Stock
1985 RZ350F basket case
1985 RZ500 Stock

User avatar
JonW
Posts: 10599
Joined: Sat Oct 10, 2009 4:33 am
Location: Sydney
Contact:

Re: 1987 RZ350 mis-fire on right cylinder.

#6 Post by JonW » Sun Mar 04, 2018 8:56 pm

Sometimes it will flow when pulled down by all that fuel leaving the bowl, so if you can give it a clean and try that.
80 XT500 Supermoto!
81 RD350LC Resto
82 RD421LC Hybrid
82 RD350LC decapitation project
82 RD250LC JDM '251LC' YPVS
83 RZ350 Resto
84 RZ500 Resto
85 RZ350 F1 Resto
86 RZ350 F2 Resto
86 RZ350 F2 Hybrid

Like Watches? www.PloProf.com & www.DeskDivers.com

(F5)
Posts: 630
Joined: Mon Sep 27, 2010 7:21 pm
Location: Wellington New Zealand

Re: 1987 RZ350 mis-fire on right cylinder.

#7 Post by (F5) » Wed Mar 07, 2018 3:49 pm

Additional, check the needle valve re emulsion tube for ovality. Heck swap them over. I've seen them wear before, just a bit ,not round, and they won't run right.
496 Cheetah. TSS PVs, PWK35s, Ignitech, RGV(ish) chassis

MK
Posts: 814
Joined: Sat Nov 26, 2005 11:44 am
Location: Wolfenbüttel, Germany
Contact:

Re: 1987 RZ350 mis-fire on right cylinder.

#8 Post by MK » Wed Mar 07, 2018 3:54 pm

If you worked on that carb, re-check your work.
Otherwise I'd guess a clogged idle jet.
Bye
Martin

User avatar
Redline Junkie
-----
-----
Posts: 624
Joined: Tue Dec 25, 2012 12:55 pm
Location: Halifax, Nova Scotia Canada

Re: 1987 RZ350 mis-fire on right cylinder.

#9 Post by Redline Junkie » Thu Mar 08, 2018 1:06 pm

MK wrote:If you worked on that carb, re-check your work.
Otherwise I'd guess a clogged idle jet.
I think I will try another carb that I have ready for my other 350 and see if there is a improvement.

Thanks
1985 RZ350F being restored now!
1987 RZ350 Stock
1985 RZ350F basket case
1985 RZ500 Stock

99hybrid
Posts: 7
Joined: Fri Mar 09, 2018 10:37 am

Re: 1987 RZ350 mis-fire on right cylinder.

#10 Post by 99hybrid » Fri Mar 09, 2018 10:18 pm

CDI?

99hybrid
Posts: 7
Joined: Fri Mar 09, 2018 10:37 am

Re: 1987 RZ350 mis-fire on right cylinder.

#11 Post by 99hybrid » Fri Mar 09, 2018 11:21 pm

I had a one cylinder sometimes firing issue with my 84.

User avatar
Redline Junkie
-----
-----
Posts: 624
Joined: Tue Dec 25, 2012 12:55 pm
Location: Halifax, Nova Scotia Canada

Re: 1987 RZ350 mis-fire on right cylinder.

#12 Post by Redline Junkie » Sat Mar 10, 2018 2:02 pm

I do have another CDI I should try on it after I try another carb first.
1985 RZ350F being restored now!
1987 RZ350 Stock
1985 RZ350F basket case
1985 RZ500 Stock

Bare
Posts: 1196
Joined: Sun Jan 29, 2006 2:18 am
Location: vancouver

Re: 1987 RZ350 mis-fire on right cylinder.

#13 Post by Bare » Sat Mar 10, 2018 9:54 pm

Wasted spark setup.
IF one plug Fires the other Must.
Look elsewhere

99hybrid
Posts: 7
Joined: Fri Mar 09, 2018 10:37 am

Re: 1987 RZ350 mis-fire on right cylinder.

#14 Post by 99hybrid » Sat Mar 10, 2018 10:08 pm

I stand corrected.

waltmil
Posts: 491
Joined: Fri Dec 28, 2012 9:23 pm
Location: Panacea, FL USA

Re: 1987 RZ350 mis-fire on right cylinder.

#15 Post by waltmil » Sun Mar 11, 2018 5:30 am

Bad coil?
Red/White US '84, Spec II pipes, Y-boot w/K&N, Fox Shock, Mikuni carbs?

Post Reply