How to set Valve clearances on horizontal engines.

[sean01]

thanks for that, I took the cover off the bike (next to the gear change arm) and all i saw was the flywheel ? (this thing at the bottom of the page http://www.miniriders.com.au/minibike-builds/27289-nitrous-150-build-how-get-most-out-ebay-junker-4.html it did have a central nut in it but i wasnt game to take it off? I can't bieleve I am finding it so hard.

why do you want to take the magneto off to set your valve clearance?

do yourself a favor and take the cam cover off the side of the head.

there is a dot on the cam gear, turn the magneto anticlock wise till the cam gear dot is sitting at 9 oclock.. (theres a mark on the head as well at 9 oclock)

when there lined up thats top dead center..

now set your valve clearance

 

[CHINA-BIKE-YO!]

Thanks 4 the write up thump!!
Ill make a coffe
tie my dog up and get the missus cookin tea
go out and do my clearances then chase my ass with the carby

 

[tubes-DHZ140]

i've been wanting to do this but...
im too scared that ill mess something up and destroy my bike!!!

:dito:!! my bikes screwed and i've been told it might be this problem.

 

[atomik boy]

phew its good to know im not alone!

 

[sean01]

 Step 1: Find TDC. Remove all inspection plugs or stator cover.

 Step 2: Remove cam cover. The bolt that allows you to do this, is on the other side of the motor, and goes right through the head. Using a 10 or 12mm socket, loosen this bolt until you can remove the cam cover.

 Step 3: using a 14mm socket on the stator nut, turn the motor over until you have lined up the “T” mark on the flywheel, and the TDC “Dot” on the cam sprocket, with the TDC “Groove” on the head. See pics below.

as long as everyone gets this step correct then you'll have no problem, this makes sure you get the correct TDC..
just remember that the crank does 2 rotations to 1 rotation of the cam

 

[Cactus Jack]

You're 100% correct Sean ! ...

All you really need to do to set the valve clearances is line the "TDC" dot on the cam sprocket up with the "TDC" mark/groove on the head ... At that point both of the rocker arm pads should be riding on the base circle aka "heel" of the cam where they're supposed to be when the clearances are checked and adjusted ...

http://i419.photobucket.com/albums/pp276/thump_140/Picture012.jpg

But the methodical step by step way in which Thump*140 has shown things is a much safer way to teach newbies ... and it's also the best way to verify that the cam to crank timing is set correctly ...

Anyone who has an engine that is running well with an IRK or a flywheel that has no "TDC" mark should simply go off the cam sprocket dot to head groove line up method for checking and adjusting their valve clearances ...

It'd be a good idea to mark an IRK rotor in line with a reference point on the stator or engine cases while the cam sprocket and head marks are lined up ...

At least then they'll have some idea of where TDC is on the crank ... Even though it won't necessarily be accurate ... It'll help them get things back to where they were if they ever have to remove the head ...

BTW ... Thumbs up for the Excellensio work you've done in this thread Thump !!!!!!! ....

 

[sean01]

yeah my intention was to just outline the most critical part in thumps write up..
the rest is important too but i see most people get confused with the correct TDC location..

 

[t00l]

ok confused indeed, i gave this a shot last year if i recall, my bikes only been run once since then and now the weather is good I want to get it back out and going good. after playing with something i shouldn't have my tappets are stupidly loud which someone said was them being too loose, i gave this a second shot and still the same problem

with the tdc, when aligning the crankshafts groove to the notch perfectly my sprockets alignment is out a small touch and vice versa, does this mean my timing is out slightly? could this be also contributing to the noise?
i realise in the picture the cranks slightly out, but when aligned my sprocket sits where it is in the picture
oh, and when aligning the crank it seems to slip and sit in a position either side of being aligned at the top, so for it to be aligned in the groove someone would need to hold it, is this right or is there a trick to get it sitting where you want it?

once both these are aligned i should be right to adjust the tappets right?
and if im still getting excessive tapping whats the next step?

 

[Cactus Jack]

With the flywheel cover removed and the valve access caps removed ... rotate the crank anti clockwise until you see the inlet rocker arm go down then come back up ... then bring the "T" mark on the flywheel up until it lines up with the notch on the LHS crank case ...

At that position the piston will be at TDC and the rocker pads will be riding on the base circle of the cam ... That's where you adjust the intake valve clearance to .003 or .004 thousandths of an INCH ... and the exhaust valve clearance to .005 thousandths of an INCH ... After you've adjusted both valves , gently rotate the engine over anti-clockwise several times and re-check the clearances ...

If they rattle ... bad luck ... they're set right ... It's normal to hear a tap tap noise ... That's WHY they're called "TAPPETS" ... Loud tappet noise can also be caused by running too thin an oil , overheated oil , or insufficient oil ...

Insufficient clearance can lead to burnt valves , over-heated valve stems seizing in the guides then taking out the piston and bore , burnt /worn rocker arm pads and cam lobes ... Every time the cam reaches the clearance area , oil is able to get between the wear pads and the lobe to lubricate them ...

I've seen rockers with grooves worn into the pads by the cam lobes ... and lobes with a blue heat band right around the centre of the lobe ... both instances were due to the oil being squeegied out like a window wiper by a rocker arm with insufficient clearance ...

Every time a valve seats , it dissipates heat away from the valve head , across the seat , then it is absorbed from the seat into the alloy head casting ...

Hot valve heads can also cause pre-ignition and detonation which can destroy a good motor very quickly ...

 

[t00l]

correct?

 

[sean01]

yep there right..

but you may need to bend the ends a little more or youll end up with a false reading when setting them..

 

[t00l]

mmm its bloody tricky getting into em

ill post back more pics tomorrow make sure im adjusting them right

thump feel free to use my pics for other users if you need to btw

 

[thump*140]

I'd just like to share with everyone, that your motor will actually run with epic, epic, epic amounts of clearance in the valves... did mine mid-ride today, as it felt a bit "flat"up top, and had a prick of a time starting it...
checked the clearance, to LITERALLY FIND THERE WAS THREE MILLIMETRES of clearance on them....Even had Ando and Rach88 there to witness this ridiculousness...

Wondered why it was a bit rattly....

That is all, carry on...

 

[thump*140]

I'd just like to share with everyone, that your motor will actually run with epic, epic, epic amounts of clearance in the valves... did mine mid-ride today, as it felt a bit "flat"up top, and had a prick of a time starting it...
checked the clearance, to LITERALLY FIND THERE WAS THREE MILLIMETRES of clearance on them....Even had Ando and Rach88 there to witness this ridiculousness...

Wondered why it was a bit rattly....

That is all, carry on...

 

[sean01]

hahha yeah been there done that man... guy i ride with had to ride his bike back with no adjuster screw in the inlet... still ran fine but sounded like a diesel

 

[thump*140]

yeah mine sounded a bit like someone locked half a dozen midgets in a 44 gallon drum, and gave them hammers.... oops...

 

[140_addict]

why do you want to take the magneto off to set your valve clearance?

do yourself a favor and take the cam cover off the side of the head.

there is a dot on the cam gear, turn the magneto anticlock wise till the cam gear dot is sitting at 9 oclock.. (theres a mark on the head as well at 9 oclock)

when there lined up thats top dead center..

now set your valve clearance

LOL LOL :applaudit:

 

[LUKE123]

my bike makes a strange sort of vibrating noise at about mid throttle in all gears, does anybody know what the problem could be, thanks!

 

[thump*140]

um, for starters completely wrong section to post your question, second, it's more than likely something suffering harmonic unbalance... bash plate or exhaust etc...

 

[BentWookiee]

Hey guys,
I was just curious to know if those measurements (In .003" out .004") apply to all chinese motors or if they vary between brands ... Ducar, Lifan etc...
The reason I ask is I have just done the valves on a new Atomik MotoX 70cc with the Ducar motor and set them to .003" and .004" but have just found on one of the many stickers stuck to the rear guard a few specs, one of which reads "Valve Lash : In 0.05mm Ex : 0.05mm Cold"

Should I stick to what I have or change them?
TIA...