Huasheng valve clearance

Discussion in '4-Stroke Engines' started by samijubal, Jun 15, 2009.

  1. samijubal

    samijubal Member

    Does anyone know for certain what valve clearances should be set to on this engine? I've seen anywhere from .05mm to .12mm posted here.

    Would it be a good idea to adjust valves before installing the engine? From reading here it seems like they aren't set right from the factory frequently.

  2. fetor56

    fetor56 Guest

    As per our resident expert here these are the figures(cold engine)
    Eventhough i've never had the need to adjust mine yet i have no reason to the experts. :grin5:
    HuaSheng valve clearances(cold).jpg
  3. bubbatgs

    bubbatgs Member

    Hey Guys! I made a call to china and spent about two hours trying to find this information out!!! I finally recieved it!!!
    Intaake .08 mm +/- .02
    Exhaust .11 mm +/- .02
    Plug gap .08-.07 mm
    If you need anything else, you will have to call China your self!
    Have fun out ther!!! Be safe!
  4. fetor56

    fetor56 Guest

    Plug gap is wrong man.
  5. samijubal

    samijubal Member

    I wondered how that plug gap could be right. Thanks on the valves guys. I saw those clearances, even wrote them down, but then I started seeing others too. One from thatsdax who sell the engine saying .05 on both, which I didn't think was right since the exhaust is always larger, at least in my limited experience.
  6. fetor56

    fetor56 Guest

    Dax doesn't know for sure...he does things by feel.
    I'll sick with Irish Johns figures until proven different.

    PS...SP gap 0.6-0.7mm.
    Last edited by a moderator: Jun 16, 2009
  7. HoughMade

    HoughMade Guest

  8. azbill

    azbill Active Member

    thanks for the link Houghmade...
    it looks a lot like my HS
    I can study it some now
    I would think the replacement plug would be the same???
  9. velosolex

    velosolex Member

    I did a valve adjustment on mine two days ago....super easy! The plug looks like the same one used in Honda OHC 50's and 70's (10mm thread)

  10. samijubal

    samijubal Member

    These are done cold I guess? Sounds like a lot of clearance for hot.
  11. velosolex

    velosolex Member

    In this case, valve adjustments are done with a cold engine. There are cases where valve adjustments are done hot, but not with any air cooled engine I'm aware of. Once, I had a '71 Ford Pinto 1600cc 4 banger. The engine required valve adjustments to be carried out while the engine was hot....I don't remember why; I'm sure there are others.....

  12. locutus_1

    locutus_1 New Member

    question, i see intake at 008 and exhaust at 0011 when i bought the bigbore carb and upgraded cam from agk i was told to set the intake and exhaust at 008... why is the exhaust and intake diffrent on stock?

    i just want to double check before i mess something up if i really should set them both the same ie 008...
  13. HeadSmess

    HeadSmess Well-Known Member

    exhaust valves run hotter thus expand more so require more clearance.

    that thing about the pinto is just ridiculous! how do some people get to be in charge of design?

    the clearance isnt that critical. .008 is huge. you could run .005 and probably be fine.

    if you want to get fancy...set the clearances cold. then let the engine heat up. remeasure clearances. subtract new figure from previous. (ie say .008 is now .005, thats .003 diff) you can set your clearances to this figure (the .003) but unless you do the other work like dressing and regrinding valves, its pointless.

    .008 is fiiiiiine....
  14. locutus_1

    locutus_1 New Member

    alot of info thanks you guys i am now alittle smarter :).. i went ahead and took your advice setting one at a time when its closed.. set it at 007 this time where before it was 008 then went to 009 to see if looser would help it did to a point... so i set it tighter so when it heats up it should be the same..

    that dead spot is still there just after 1/4 throttle then again i have no load on it and i stll havent adjusted the air fuel mixture.. on those big bore carbs you can only go one way then back it has a stop built in sorta a idiot proof design :-|

    i belive the honda gx50 has much better tollerances and dosent rattle or make nosie i saw 2 threads and a stock husang video and his lifters made the same noise...

    i have yet to ride it and finalize the adjustments i think 007 will be fine it will probably be 006 by the time it heats up

    agk guys said they set theirs at 004 now i think the tighter you go the less performance at 1/4 to 1/2 throttle and the looser say 008 to010 you
    get better compression since the valves are more tighter to the head so you get better performance at 3/4 to full open

    i really go 1/4 to half throttle so i hope it splits the diffrence of power to throttle
  15. HeadSmess

    HeadSmess Well-Known Member

    valve clearance dont affect performance in that way :)

    the idea is that you leave clearance when cold.

    when the engine heats up, and it all expands, there will be ALMOST no clearance.

    the large clearance is due to manufacturing tolerances. a blueprinted motor can be made tighter.

    the valve closes completely and seals the port just as effectively when turned over by hand as when redlining at 12000rpm. except when you get valve bounce, which is when the spring simply cant close the valve fast enough... and using harder springs takes more power and increases bearing wear etc...

    having a very tight clearance allows the valve to open MORE, as theres less slack for the rocker/cam to close before operating the valve. this allows more gas through. be it exhaust or intake. this means better volumetric efficiency. which means more power :D

    the con of a tight clearance is when the valve ROTATES. if they arent perfectly true, the clearance changes. so suddenly there maynt be any at all!

    this means the valve doesnt close, means no compression means no go :(

    the valve also requires to be closed for a certain amount of time to cool down or it will melt :eek: overdo it and you burn valves and seats...


    having too much clearance does the reverse regards efficiency. less air means less power.

    and as the rockers/cams take up the slack, they hit the head of the valve with more force. keep hammering at the valve stem like that and it will mushroom over, clearance will increase, hammer effect gets worse, stem mushrooms more, clearance gets bigger, hammering gets worse,.....

    ive always used .004. standard sorta figure across most manufacturers...some differ, but usually... 0.004

    and make sure youre checking at tdc everytime!

  16. locutus_1

    locutus_1 New Member

    yes i do know that it does affect performance,

    when you say cold i know that my 007 will tighten up to about 006 or 5 maybe less see im getting conflicting numbers agk tells me 008 now i hear 004 agk the makers of the cam suggested 004 but at a risk i wasnt willing to take that risk so i tried 008 first then went to 007..

    these huesang motors are the worst for clearance specs but ive heard they work for long times most was that 12,000 miles although id like to see the acutal numbers i dont belive him thats a large number maybe if they drove to work 40 miles a day for a year..

    listen to these valves stock

    notice how they are loud.. this is how these husangs are ive looked all over and the honda dosent make that lifter noise... shoulda bought a honda :)

    ive been debateing setting tham back to like 005 i dont really want to push it what do you guys think?