Hello Guest User,

Please feel free to have a look around the forum but be aware that as an unregistered guest you can't see all of it and you can't post.

To access these 'Registered Users Only' areas simply register and login.

Pot 3&4 running very hot

Need help restoring, building, or finding then try here.

Moderators: KeithZ1R, chrisu, paul doran, Taffus

Message
Author
Lancer1
new poster
Posts: 12
Joined: 7th Jun 2017
Location: Clevedon

Pot 3&4 running very hot

#1 PostAuthor: Lancer1 » Fri Jul 13, 2018 12:40 pm

Hi folks I have a strange problem with my 1976 z900 A4
I have hardly used her in the last 12 months and she has started running very hot on pots 3&4. From start up on choke the exhaust down pipes are too hot to touch within a minute and the barrels are hotter on 3&4 but pots 1&2 are fine. I stripped ulrasonic cleaned the carbs but still the same.
Now the mystery is that pots 3&4 are running rich and I always thought that hot pots are due to running lean. A mate of mine is going to check timing as she's fitted with dyna s electronic ignition including coils. The shims where done by a local garage about three years ago and have only done about 1000 miles.
Any advice would be welcomed
always listen to advice, you don't have to take it

User avatar
z1bman
Hardcore
Hardcore
Posts: 4174
Joined: 3rd Mar 2010
Location: WORDSLEY WEST MIDLANDS

Re: Pot 3&4 running very hot

#2 PostAuthor: z1bman » Fri Jul 13, 2018 12:56 pm

i would check the compression first that will give you a good indication whether the valves are tight or the valve timing is out

johny brando
100Club
100Club
Posts: 243
Joined: 3rd Aug 2013
Location: australia

Re: Pot 3&4 running very hot

#3 PostAuthor: johny brando » Sat Jul 14, 2018 5:03 am

Lancer1 wrote:Hi folks I have a strange problem with my 1976 z900 A4
I have hardly used her in the last 12 months and she has started running very hot on pots 3&4. From start up on choke the exhaust down pipes are too hot to touch within a minute and the barrels are hotter on 3&4 but pots 1&2 are fine. I stripped ulrasonic cleaned the carbs but still the same.
Now the mystery is that pots 3&4 are running rich and I always thought that hot pots are due to running lean. A mate of mine is going to check timing as she's fitted with dyna s electronic ignition including coils. The shims where done by a local garage about three years ago and have only done about 1000 miles.
Any advice would be welcomed


Bit hard to tell when a cylinder or 2 is running hotter than others ( down pipe blueing is the most reliable visual aid ) but if you say 3 & 4 appears to be the issue & show rich then it's unlikey an ignition timing issue aye, as they are 1 & 4 and 2 & 3 linked . Personally as Z1bman said a Hot - Comp test & if all cylinders are showing over 125psi then I'd be zooming in on your Carbs & checking your float heights are correct or better still as this is more accurate more accurate .... check your float fuel levels ..... as some times floats assemblies that have been dry stored for some time ( I'm assuming that perhaps you drained your carbs for the winter lay-up ).... can seem to have some sort of (... for want of a better phrase ! ) - 'molecular memory' & they can self twist bit on their linked brass supports & adjust themselves in various plains... maybe this has happened a bit - hence the rich running on those 2 carbs or maybe the solder on the floats have pin holed with age ( check - they are floating in water the same or if they are listing to one side= partially liquid loaded ..which would cause rich running issues) Also, might be worth checking your chokes plunger units are in sound condition on those 2 carbs or just swapping them out to 1 & 2 Cylinder carbs = & see if it moves the problem to them ! ....you could also do that with your floats too ..... but best only do 1 thing at a time or you won't be sure to know what the actual true culprit was. Happy hunting & good luck.

Lancer1
new poster
Posts: 12
Joined: 7th Jun 2017
Location: Clevedon

Re: Pot 3&4 running very hot

#4 PostAuthor: Lancer1 » Sat Jul 14, 2018 6:10 am

Thanks for the reply's I'll check the compression and valves over the next couple of weeks
always listen to advice, you don't have to take it

User avatar
ZedHead
Hardcore
Hardcore
Posts: 2294
Joined: 9th May 2009
Location: Darlington
Contact:

Re: Pot 3&4 running very hot

#5 PostAuthor: ZedHead » Sun Jul 15, 2018 10:52 am

3 & 4 are working hardest which leads me to think that the problem lies with 1 & 2 carbs running lean or fuel supply. Compression is alway a good thing to eliminate but I feel it unlikely for mechanical failure to develop just from laying up over winter.

User avatar
Pigford
I'm on prescription!!
Posts: 9978
Joined: 2nd Jan 2006
Location: North Dorset

Re: Pot 3&4 running very hot

#6 PostAuthor: Pigford » Sun Jul 15, 2018 5:06 pm

Not uncommon to run the middle 2 x cylinders 1 x size up on main jets to help..... big Suzook's did this from factory in 1980's,
And on the 7th day... Zeds were created!

Lancer1
new poster
Posts: 12
Joined: 7th Jun 2017
Location: Clevedon

Re: Pot 3&4 running very hot

#7 PostAuthor: Lancer1 » Mon Jul 23, 2018 2:18 pm

Thanks to everyone who posted advice on this problem. A mate of mine who has worked in a motorcycle garage came and checked out the carbs and much to my shame I still had a blocked jet on pot 1 but biggest problem was I had not set the float heights correctly, rookie mistake. Bikes now running well but my mate is going to balance the carbs at the weekend hopefully.
always listen to advice, you don't have to take it

User avatar
ZedHead
Hardcore
Hardcore
Posts: 2294
Joined: 9th May 2009
Location: Darlington
Contact:

Re: Pot 3&4 running very hot

#8 PostAuthor: ZedHead » Thu Jul 26, 2018 9:38 am

Lancer1 wrote:Thanks to everyone who posted advice on this problem. A mate of mine who has worked in a motorcycle garage came and checked out the carbs and much to my shame I still had a blocked jet on pot 1 but biggest problem was I had not set the float heights correctly, rookie mistake. Bikes now running well but my mate is going to balance the carbs at the weekend hopefully.


We are all guilty of rookie mistakes from time to time. Glad you got it sorted :up


Return to “Bike Help”

Who is online

Users browsing this forum: Bing [Bot] and 16 guests