Spark Plugs

[RohIIT]

Re: Spark Plugs

Plug/Driving: CR6HSA that has done duty for 7000 kms. The center white part looked grey-ish with a very mild tinge of brown. This is the second plug (13xxx to present 20xxx). I used the factory fitted CPR7HSA for first 13k kms - it was all sooty black when I changed it last year. I drive at 60-70 kmph in 6 gear most of the time. The recommended plugs for my vehicle are CPR6HSA and CPR7HSA. No black smoke whatsoever till now.

Looks a wee bit lean, but not a big deal. Let it run this way , it should be fine.

[psr]

Re: Spark Plugs

@sibun, @Pinaki da, @psr sir, @RohIIT and others: Can you help me read my spark plug - is it okay? Is the washer compressed alright or should I tighten it more?

Motorcycle: Suzuki GS-150-R.

AFR Setting: Stock which is according to the Workshop Manual, "2 turns out".

Plug/Driving: CR6HSA that has done duty for 7000 kms. The center white part looked grey-ish with a very mild tinge of brown. This is the second plug (13xxx to present 20xxx). I used the factory fitted CPR7HSA for first 13k kms - it was all sooty black when I changed it last year. I drive at 60-70 kmph in 6 gear most of the time. The recommended plugs for my vehicle are CPR6HSA and CPR7HSA. No black smoke whatsoever till now.

The plug coloring indicates a slightly lean AFR. but rest of the plug does not indicate a very lean condition, so it is acceptable good AFR for FE.
The CPR 7 is a slightly colder plug compared to the CPR 6 , so expect CPR 7 to run with a little bit of dark deposit, since the plug is not reaching the "Self Cleaning " temperature.If you are intent on Long drives at a slightly higher RPMs then CPR 7 will be a good choice...for short runs and Sane riding the CPR 6 is a better choice which will give you quick warm ups ,throttle response and FE...
Here is a image on how to read a spark plug. This is only a Guide and not the RULE....

[Pinaki]

Re: Spark Plugs

.. help me read my spark plug - is it okay? Is the washer compressed alright or should I tighten it more?..

Your are using CR6HSA or CPR6HSA ? They are not same , the extra P denotes a projected electrode . AF mix is good , but I feel the compression seal washer is not fully seated , better tighten about 1/4 turn and check again - so as not to overtighten by going too much at once . Properly tightened washer should flatten on both sides and not bulge like when new , kind of like this one

.. The CPR 7 is a slightly colder plug compared to the CPR 6 , so expect CPR 7 to run with a little bit of dark deposit, since the plug is not reaching the "Self Cleaning " temperature.If you are intent on Long drives at a slightly higher RPMs then CPR 7 will be a good choice...for short runs and Sane riding the CPR 6 is a better choice which will give you quick warm ups ,throttle response and FE...

Dear PSR'Jee - After reading your explanation I checked the NGK India partfinder and sure enough it's now recommending CR6HSA for my Splendor ( and all other same engines) . Previously it was saying CR7HSA , same as written in my bike's manual . Is Hero now shifted to CR6 range for Splendor / CD ? Presently I'm running CR7H-GP and it is doing fine but nearing change time soon .

https://www.ngkntk.in/part-finder-disclaimer/

[ashwanth.r]

Re: Spark Plugs

Thank you RohIIT, PSR Sir and Pinaki da .

The plug coloring indicates a slightly lean AFR. but rest of the plug does not indicate a very lean condition, so it is acceptable good AFR for FE. The CPR 7 is a slightly colder plug compared to the CPR 6 , so expect CPR 7 to run with a little bit of dark deposit, since the plug is not reaching the "Self Cleaning " temperature.If you are intent on Long drives at a slightly higher RPMs then CPR 7 will be a good choice...for short runs and Sane riding the CPR 6 is a better choice which will give you quick warm ups ,throttle response and FE. Here is a image on how to read a spark plug. This is only a Guide and not the RULE.

I never knew the spark plug can be read at different places other than the centre electrode - especially the patterns on the curved electrode. My bike came with factory-fitted CPR7HSA - but at that time, I was staying inside the city and had a running of 4 kms per day (except weekends) out of which 50% was stop-and-go! After I changed the plug to CR6HSA, I moved to a suburb shortly - now the running became 60-70 kms per weekend (do mostly 60-70 kmph in 6th gear, which for my bike is around 4500-5000 rpm on the tacho) and 500 m-1 km every 2 days for nearby shopping, etc. I have bought CPR7HSA today - will replace shortly and will update how it fairs every 2000-3000 kms.

By the way sir, is that image from "tuning matters" wrongly labelled? Shouldn't the whiter plug be the lean one?

Your are using CR6HSA or CPR6HSA ? They are not same , the extra P denotes a projected electrode . AF mix is good , but I feel the compression seal washer is not fully seated , better tighten about 1/4 turn and check again - so as not to overtighten by going too much at once . Properly tightened washer should flatten on both sides and not bulge like when new , kind of like this one

Non-projected CR6HSA, at that time didn't know what those alphabets meant and later discovered it was Access' plug! but I let it run. I was afraid to tighten it further (owner's manual says 1/8 of turn for old plug after getting seated and 1/2 turn for new plug). Will remove the plug tomorrow, seat it and gently try a 1/4 turn as you say. Fortunately, no symptoms of a lose spark plug till now.

[psr]

Re: Spark Plugs

Your are using CR6HSA or CPR6HSA ? They are not same , the extra P denotes a projected electrode . AF mix is good , but I feel the compression seal washer is not fully seated , better tighten about 1/4 turn and check again - so as not to overtighten by going too much at once . Properly tightened washer should flatten on both sides and not bulge like when new .

Dear PSR'Jee - After reading your explanation I checked the NGK India partfinder and sure enough it's now recommending CR6HSA for my Splendor ( and all other same engines) . Previously it was saying CR7HSA , same as written in my bike's manual . Is Hero now shifted to CR6 range for Splendor / CD ? Presently I'm running CR7H-GP and it is doing fine but nearing change time soon .

https://www.ngkntk.in/part-finder-disclaimer/

Pinaki ji , Hero Honda is making all sorts of changes in the name of improvement without checking back on the parent company's recommendation ie., Honda. The 7 number was used wherein the plug could be used under stressful conditions. In my opinion, The 6 type had been chosen to facilitate easy cold start, quicker warmup and a sllightly better acceleration with hotter plug. I would have preferred a projected nose colder plug like CPR7 instead of CR6 ,to have better combustion through projected nose and with a slight increase in compression ,and safe 7 heat range would make an all rounder for the application. I wonder if Hero had altered the compression ratio of the engine to warrant a plug change ...ie., from higher CR to low now
Just my thought.

Thank you RohIIT, PSR Sir and Pinaki da .



I never knew the spark plug can be read at different places other than the centre electrode - especially the patterns on the curved electrode. My bike came with factory-fitted CPR7HSA - but at that time, I was staying inside the city and had a running of 4 kms per day (except weekends) out of which 50% was stop-and-go! After I changed the plug to CR6HSA, I moved to a suburb shortly - now the running became 60-70 kms per weekend (do mostly 60-70 kmph in 6th gear, which for my bike is around 4500-5000 rpm on the tacho) and 500 m-1 km every 2 days for nearby shopping, etc. I have bought CPR7HSA today - will replace shortly and will update how it fairs every 2000-3000 kms.

By the way sir, is that image from "tuning matters" wrongly labelled? Shouldn't the whiter plug be the lean one?

It says Optimal....a lean plug not only is discolored,with greyish coating on the insulator, the metal skirt of the plug will also be burnt showing metal...In this particular image with white porcelain , the metal skirt is darkish, and shows that the center electrode is on "Self Cleaning " temperature....Ever since Lead had been removed from Petrol, a slightly different plug reading method is now needed...which is why i posted the picture of the elaborate plug reading picture clearly showing how even a jetting, and heat range can be easily read from the different parts of the pug..
Hope it was useful.

[ashwanth.r]

Re: Spark Plugs

Hope it was useful.

It was, without any question. I spent nearly 2 hours browsing and reading about plugs - you always kindle new interests. Am still not done reading all your posts in various threads from ZMA to engine oils!

[psr]

Re: Spark Plugs

It was, without any question. I spent nearly 2 hours browsing and reading about plugs - you always kindle new interests. Am still not done reading all your posts in various threads from ZMA to engine oils!

I am honored to know my posts are useful and kindles new interest....
Hope you become more and more drawn into the search for knowledge ..
Good Luck.

[Dccet]

Re: Spark Plugs

Is the washer compressed alright or should I tighten it more?

Motorcycle: Suzuki GS-150-R.

[ATTACH]214001[/ATTACH]
[ATTACH]214002[/ATTACH]
[ATTACH]214003[/ATTACH]

Your plug is under torqued. if you prefer diy than check your manual how many turn you need to get it right. That will be different for new and refitting a plug.
Reference here PLUG STUDIO / NGK . The washer needs to be crushed up on initial installation (crushed gasket), Improper tightened spark plug : too lose - can damage the engine or burn a piston. Too tight - can damage the thread to cylinder head.

[Biker23]

Re: Spark Plugs

Hello guys!I was facing heating issue in my gixxer 155, so when took it to the ASC ,they tuned the carb and then it started heating up even more than before!! I suspect my bike is running lean ,I am attaching few pics of my spark plug, some one please tell me its condition!!

[Biker23]

Re: Spark Plugs

Pics of spark plug

[psr]

Re: Spark Plugs

Pics of spark plug

The plug has lots of black sooty coating...If this coating is dry then you are running very Rich...if it is oily sticky then you have to check for failing piston rings/ bore...a compression test will show if the bore piston wear had contributed to this.
Otherwise Valve stem seal leak is a probable cause, though it normally does not form so much soot over plug ...
Good Luck..

[Biker23]

Re: Spark Plugs

The plug has lots of black sooty coating...If this coating is dry then you are running very Rich...if it is oily sticky then you have to check for failing piston rings/ bore...a compression test will show if the bore piston wear had contributed to this.
Otherwise Valve stem seal leak is a probable cause, though it normally does not form so much soot over plug ...
Good Luck..

Sir, these are the pics of the spark plug after getting it tuned for optimal setting,please tell me its present condition...

[Biker23]

Re: Spark Plugs

Spark plug pics

[psr]

Re: Spark Plugs

Spark plug pics

The AFR is optimal ..may be a little lean ..but the noise you are referring to when engine heats up will be due to more Valve clearance ,which needs checking.....Otherwise your engine is in good health judging from the spark plug color.

[Brezon95]

Re: Spark Plugs

[MENTION=32286]psr[/MENTION] [MENTION=29030]Pinaki[/MENTION] and others. Please read the spark plug and afr condition from the pics. Spark plug resistance is 6.6kohms. Also please tell why colour is not uniform throughout the porcelain.
Spark Plug: Champion PRZ7HC
Bike: Hero Passion Pro