valve clearance inches vs MM and oil in filter

[william1313]

He may be confused! .004 mm and .005 mm are WAY TOO SMALL!! If he meant .004" and .005" I would not be commenting. Personally, I think .04 mm is too small as well.

I am going through web site after web site.   Here is yet another one at .05mm.    There are a lot of confused people

https://49ccscoot.proboards.com/thread/428

Can you find a manual where this engine has a clearance of .1 mm or .004inch

[william1313]

To be fair and balanced.  Here is one supporting your opinion:

https://itistheride.boards.net/thread/950/factory-set-valve-clearance

http://www.scooterfocus.com/scooter_valve_clearance.html  "For most 150cc GY6 engines the clearance should be around .004", but check your manual. For 50cc engines I've seen .002" recommended."

This one .05mm:  https://absolutelyscooters.net/pdf/CGen_GY6_50cc_Service_Manual.pdf

This one is also .05 mm:  https://www.yumpu.com/en/document/read/45190927/50cc-170cc-gy6-qmb139-scooter-repair-and-service-manualpdf


So this is what I learned:    There are several manual that say .04 or .05 mm from different companies so I am concluding there is no way this is a typo.   However experienced scooter experts say .004 inch or .1m and have good results so I am not discounting that.   Several forums discuss this issue.   Some novices like myself also report loud tapping and loss of power at .1 mm or .004 inches.   Some report good results.    Needless to say there is confusion.    One thought was that companies recommend tight values to comply with enviremental rules and regulation but this is not best for the bike itself.   
I believe I could come to the right answer if I knew what a normal bike should sound like so I guess I am left with one question and 1 request.   Please anyone send me a link to what "normal sounds like"    and is there any way to scientifically support this debate by doing another procedure ie would combustion presssure measurement answer the question in the confused population such as myself.    Lastly thank you for your patients.   I tried to support my case by providing literature proof but in the process I found arguments supporting both sides.   ramble ramble sputter

[CROSSBOLT]

You are being very patient and reasonable, rare qualities these days. All us "old timers, big gappers" are aware of the past in HD and true color. We may even be guilty of "we always done it thattaway."

One fact: aircooled engines are going to ring like a bell while running. Liquid cooled are much quieter.
Two facts: the tighter valve clearance the more likely to burn an exhaust valve.
Three facts: 'Tis easier to listen to valve noise that repairing burned valves and seats.

[Iahawk]

back just in time from a nice vacation to jump into this...

Crossbolt and Ruffus are correct. .10mm or .004". (you can increase the exhaust to .12mm if desired, as exhaust valves tend to tighten over time, I'll probably do this as I reassemble my torn apart motor).

Tons of misprints and typos in the Kymco service manuals (bad translations?).

If you don't like those settings please feel free to use your original ones and report back to us after a few hundred or thousand miles with your results. Other than that....... happy scootering.

[william1313]

To be fair and balanced.  Here is one supporting your opinion:

https://itistheride.boards.net/thread/950/factory-set-valve-clearance

http://www.scooterfocus.com/scooter_valve_clearance.html  "For most 150cc GY6 engines the clearance should be around .004", but check your manual. For 50cc engines I've seen .002" recommended."

This one .05mm:  https://absolutelyscooters.net/pdf/CGen_GY6_50cc_Service_Manual.pdf

This one is also .05 mm:  https://www.yumpu.com/en/document/read/45190927/50cc-170cc-gy6-qmb139-scooter-repair-and-service-manualpdf


So this is what I learned:    There are several manual that say .04 or .05 mm from different companies so I am concluding there is no way this is a typo.   However experienced scooter experts say .004 inch or .1m and have good results so I am not discounting that.   Several forums discuss this issue.   Some novices like myself also report loud tapping and loss of power at .1 mm or .004 inches.   Some report good results.    Needless to say there is confusion.    One thought was that companies recommend tight values to comply with enviremental rules and regulation but this is not best for the bike itself.   
I believe I could come to the right answer if I knew what a normal bike should sound like so I guess I am left with one question and 1 request.   Please anyone send me a link to what "normal sounds like"    and is there any way to scientifically support this debate by doing another procedure ie would combustion presssure measurement answer the question in the confused population such as myself.    Lastly thank you for your patients.   I tried to support my case by providing literature proof but in the process I found arguments supporting both sides.   ramble ramble sputter

Thank you for your post and I am in no way an expert but I did compulsively review several videos and read several manuals from competing companies who repetively use the values   .04 mm and .05 mm.  Whether right or wrong these values are mentioned in a "deliberate"  fashion over and over.   It defies logic to believe several companies are making the same "typo."  Read the manuals and let me know if I am off base.   I do apologize taking such an opposite stance being that yesteday I knew nothing.     I do not necessarily degree with anyone that their information is "wrong" but it is clearly not a typo......they are simply wrong or in a far case scenerio in an alternate world "right".
This weekend I will increase my clearances. 
with respect
bill

[Neil955i]

Bill, I'd defer to Karl (Crossbolt) in these matters and I think his last post neatly sums it up.  Better a little valve chatter than a burnt out exhaust valve?

[Ruffus]

@william1313, learning by doing best way to get some experience.
Don't know where you are located at, but I would ask the next guy on the street with a
similar aircooled one cylinder to let me listen to its sound. Most scooter riders are more than
willing to show and explain.
And if you ask some more technical question or origin, you might even earn a coffee.

[william1313]

Here is my neighbor

[Stig / Major Tom]

Go your own way, don't you William!
I'm liking you more every day!

My wife said I can't wear my new hat around Florida.
I said I'm also going to wear it in Ohio!
"Suits my personality....!"

"That's the problem!", she said.

Stig

[Neil955i]

Bill, Stig  😂

[william1313]

Your hat fits Florida well
Your dashboard suggests you do not tolerate heat (60 degrees come on man!) and that you have a smart phone that is syncing.
If you send me another picture I may be able to hack into your transmission.
Always Listen to your wife.

[william1313]

Sorry to revive this issue once again but I acturally read over 8 manuals  for 49 or "50 CC"" air cooled engines and watched over 10 videos.   I figured that  would be easier than ripping off my panels again.    The majority of the manuals/videos set the valve clearances at .05 mm but the range was .03-.05 mm.    Several, blogs and a few videos but no manuals discussed .1 mg or .004 inches. (for 49/50 cc)    I think what is being missed is that the 50 cc engines can be distiguished from the larger engines (which are typically .1-1.2 mm).   The Agility 50 cc discusses .04 mm in their manual.   I am only bringing this up since there will be those that self maintain old bikes and they should be aware that not everyone agrees with .004" or .1 mm and there are many (including manufacturers) that support much smaller clearances that I am mentioning above.  I imagine it is easy confuse .04 mm with .004 inches if it happened 10 years ago.   If I am somehow being a dumb idiot and if I burn out my exhaust valve, I will publically announce how I didn't listen and pay the price for the humiliation and of course the repair.  But if my research is correct and  I ride off into the sunset and you will not hear a tap, ping, ding, peep from me again.  Is that "Clearance!!!!"

[wymple]

Whatever the spec range is, I will use the widest end of the setting as the clearance will close down as the components wear. That way I don't have to worry about how long I go between adjustments & burning valves. I do it after it hits the recommended mileage & it's convenient.

[william1313]

Whatever the spec range is, I will use the widest end of the setting as the clearance will close down as the components wear. That way I don't have to worry about how long I go between adjustments & burning valves. I do it after it hits the recommended mileage & it's convenient.

Yes, that makes sense.  I wish that I had done .05 mm as opposed to the .04 mm.