i have a 90cc sunl atv and it has spark and seem to have power everywhere but doesnt seem to want to hit,, i sprayed starting fluid and still nothing, ive cleaned the carburator, ive read the valves get out of adjustment ,, if that might be the case can someone tell me how to adjust them.. ive never had to adjust valves on anything but im mechanically inclined,..

 

Welcome to the forum adr17! [img]i/expressions/face-icon-small-smile.gif[/img]

short version for adjusting valves..

find top dead center "TDC" (piston at the top of its stroke) after the exhaust valves close.This can be done by pulling the spark plug.

pulling off the flywheel cover (left side when sitting on machine)

turning the engine over in a counter clockwise direction while looking at the flywheel) you can use a piece of plastic or wooden dowel to feel the piston reach the top of the stroke. (there also should be a T next to a line on the flywheel that will be TDC.

At this point you should be able to shake the rocker arms a little...if one side is tight and the other side is loose your probably at the wrong TDC. 4 strokes have 2 TDC's.

If both are tight your valves need to be adjusted. I set the gap between the rocker arm and the end of the valve at .002 just like my Hondas...some here use .004...either should work but .004 might be a little noisier. But either is much better than no gap...no gap means the valve doesnt close completely and you wont have good compression and it wont run...

 

to adjust valves on all chinese 50-110cc, doesn't matter what brand the quad is they all use the same engine design. the older honda manuals , late 60's early 70's says to set the valves at .002, the newer honda manuals says to set the valves at .004. always set valves while the engine is cold.

1. remove valve covers

2. on the left side on top their is a quarter size cover with a slot, remove this. this is the cover to locate the timining marks.

3. remove the cover on the life side of the engine, tis could be oval in shape with 4 8mm bolts or it may be round appoz 11/2 dia. with a slot, this is access hole to rotate the crankshaft.

4. insert a 14mm socket into the access hole to rotate crankshaft, rotate crankshaft counter clock wise until you see the intake valve open and close, [top valve] just as the valve is close look inside the timing mark access hole, you might need to use a flashlite. as you turn the crankshaft look for the timing marks, this again depends on the manufacture, some will have several lines, some won't, look for the line with the "T" this is top dead center.

5. insert a .004 feeler age between the rocker arm and valve stem. if it does not go in then loosen the lock nut and screw the adjuster out and then insert the feeler gage. tighten the adjuster finger tight, then tighten the locknut.
remove feeler gage and then try and insert it again, if it's to tight and does not go back in then loosen the lock nut and try again, if the .004 feeler gage goes in then try a .005. if the .005 does not go in and the .004 does then that valve has the correct setting. then make sure the lock nut is tight and then go to the other valve, but if you can insert the .005 feeler gage then you'll need to set the clearance again.

6. after both valves have the correct valve clearance then reinstall the covers.

if you need any more information my e-mail is luvmysxs@yahoo.com

 

where do you line the tdc mark on the flywheel at? do intake and exhaust valve set to .004?

 

TDC is lined up in the center of the timing mark access hole. both valves are set at .004 according to the manual. but since the exhaust valve runs hotter than the intake valve and most 150-open engines use valve cleances of .004 intake and .006 exhaust, you could run up to .006 on the exhaust valve only without a problem.

 

im gonna attempt to adjust the valves tonite.. if anyone has any other thoughts on why this thing wont hit please let me know....

 

Here's a little trick that I learned on auto engines - FINGERNAIL POLISH !!!

When you get the 'right' timing mark line - 'paint' it with fingernail polish. They even come with there own little brush in the cap (your choice of 'color' is optional). You NEVER have to figure out the correct line ever again.

My Chinese ATV engines had 'several lines' on them (with no marks visible thru the little cap viewing hole).

The first time that you do it - just remove the left side flywheel / stator cover. First remove the shifter lever (one bolt). Then remove the five or so bolts that hold the flywheel / stator cover (about 6" x 8"). It is just a 'dry' cover (no oil). You can then easily see the letters on the timing marks and can easily rotate the flywheel by hand to the proper position.

Time to remove and reinstall shift lever and flywheel cover = 5 to 6 minutes.

Time to screw around lining thinks up thru that little hole = MUCH longer.

Just my 2 cents worth.

 

thanks for adding to my short version luvmysxs and NJDale...i was typing from my living room in China...no a/c in there and its insanely hot here now. Couldnt get all my thoughts to the keyboard.


adr17, let us know if it helps any and also feel free to ask more questions.

 

heh heh I told you it would be different dude...

 

<div class="FTQUOTE"><begin quote>Originally posted by: Dragginbutt

heh heh I told you it would be different dude...</end quote></div>

It aint central Ca for sure.

However....I do have a/c in the bedroom. [img]i/expressions/face-icon-small-smile.gif[/img]