Plugs

[Emmohaswheelsagain]

Going through a process of elimination whilst trying to balance the carbs.
The carbs have been cleaned, new air filters, new needles, everything as it should be.
The bike starts on the button and has an even tick over.
The issues is when you attempt to balance the carbs when applying throttle.
Instead of the rods rising together they go in opposite directions.
I have attempted to resolve this but no amount of adjustment with the throttle cables/ stops fail to resolve this.
I have therefore gone back to basics and checked to see if we have a strong spark on both cylinders.
No reason to doubt this as the bike had new plugs (NGK BP8ES) when checked over by Lusso Veloce last year.
To my surprise the spark on the front cylinder was intermittent, not just between the terminals but also across the body of the plug.
Obviously I will replace this plug, indeed I will probably buy some spares but is this a common occurrence? I would also like to know where I can secure genuine plugs and if BP8ES is the only option available. I run the bike on premium fuel, generally Shell advanced.
Be interested to know what other members have experienced with faulty plugs.

Thanks

Paul

[morini_tom]

Hi Paul,

Regarding plugs I would say an 8 is too cold a heat range. I would suggest a 7 or maybe even a 6. I run 6 on my 350s and 7 on my 501 dart. Even then sometimes the 7 fouls from too much carbon build up.

If you can find them BP7EV is the one to go for in my opinion- the EV being gold palladium as opposed to standard copper core. Failing that, the platinum BP7EVX. The EV and EVX plugs are hard to find but worth it.

There are a lot of non-genuine spark plugs out there so buying from a trusted aupplier is key. Because they are hard to get now, I have bought BP6EV plugs from ebay and taken my chances as to authenticity, and so far have been lucky

[Emmohaswheelsagain]

Thanks Tom for the advice. I will change the plugs and see if we have any improvement.
It may be a process of trial and error but I am sure we will get there in the end.
Thanks again.

Regards

Paul

[3potjohn]

I run BP7ES ( for 16 years) on my K1 and have never had a plug not carb issue though I did rebuild the carbs back in 2007. My 507 had BP8ES in when I got it but now also on 7’s and sooted up easily otherwise. It had a stripped down airbox , the investigation of which I could write a boring chapter about.
I take it there is sufficient slack in the throttle cables initially.

[Emmohaswheelsagain]

Hi John,

Yes from your comments and those of Tom the BP8EV’s seem to soot up easily, the plugs in my bike follow that trend, black as night.
Regarding the slack in the throttle cables, this is an aspect of the balancing which I intend to concentrate on. I am new to this home mechanics, never having the time previous to retirement. I have followed the instructions provided with the carbtune Pro, as well as those detailed in the blue book. Starting from a base setting any alterations to the throttle stops or mixture screws are documented, only small changes as I dial in to how the engine is responding. The adjustment in the throttle cables can be more problematic as you are working under the tank where the routing of the cables can be restricted. Have you any tips that I can follow? Regarding the air box, this can be a problem, I took the trouble of removing this and inspecting the air filters, clearly neglected they hadn’t been removed for many years. The air box itself had been over tightened in the past requiring some repairs. I know these are hard to find so I took care to preserve as best I could. The air box is as good as it can be with new filters. I also took time to position the carbs correctly, previously the throttle cables had been restricted by the air box, I took the trouble of removing the choke cable arrangement, always found this awkward when I owned my first 500 back in the 80’s, the flick up choke levers when mastered are much better and free up room under the tank. Oh, one final thing, took the trouble of draining the tank and starting with fresh fuel.

Regards

Paul

[simonnorthroad]

Weevee used to fit B8ES plugs when servicing my old 500...

['It must be a .....']

Hi, I gave up on NGK plugs in the Morini 500/501 years ago due to poor starting/longevity and used Denso plugs from the early 1990s which are far better

I use Denso W22EP-U (3085)
14mm thread, 19mm thread reach, projected electrodes and non resistor type with same heat range as the NGK BP7ES
Also use Denso W22EP-ZU (3086) with a platinum centre and a tapered ground electrode but not always easy to get
Denso W24EP-U is a NGK BP8ES equivalent

Like NGK there are many fakes out there, I use the Green Spark Plug Company
They have great technical support too

https://www.gsparkplug.com/1x-denso-sta ... -3085.html

Trust this is useful? Ian

[Emmohaswheelsagain]

Thanks Ian, that is useful to know.
If the NGK BP 7ES fail to improve matters, I will certainly try this option.
As always the plugs may only be part of the running issues, mine starts on the button and idles well, the next ride
Should tell me whether I have improved the bike.