valves at .005??

[Thumpstar Pro]

Hurry up and get that bike together n1ck! Were heading out on Sat. You can see my new 140 rip.

 

[n1ck]

yeah nick thats where alot of confusion comes into play with the masses

"" and mm

the new school dont have a big understanding of the imperial times

haha yea you get it thumped into your head first day of tafe

oh yea chris still havent got it done so many things to do at once
havent even finished my car
where you going riding ?

 

[Thumpstar Pro]

Heading out the wipstick. You'll love the track, we'll be building up more burms and jumps and taking a load of old car tyres to set around. It's gonna look mad. Jess is taking his new lifan 150 out too. I hope my 140 can take him!

 

[n1ck]

haha sweet i might have to order in a a cheapo bike from work untill mine is done

 

[Gawain]

i set them at .005mm and .006mm if set any smaller i find they run fluffy and tends to cause higher temp on the exhaust valve and that can cause valve burn
and dont get mm and " mixed up as 2 thou is .005 mm

and to wogtaz to loose can cause wear and shock loading on valve train componants
upto 10thou is aceptable on these motors

before any one starts arguing i do this stuff for a living.

Well im glad your not my mechanic! ;p Either thats a typo or your maths is wrong, just a decimal point though... 0.1mm is approx 4thou/0.004inch, to be pedantic 0.0251mm is the same as 1thousands of an inch exactly.

 

[motorman]

from memory the vertical engines run higher clearance or it might be the hotter the engine runs dunno cactus should be able to clear that up for us

I think your spot on Coolie. Hence why I thought they were a bit higher.

 

[n1ck]

Well im glad your not my mechanic! ;p Either thats a typo or your maths is wrong, just a decimal point though... 0.1mm is approx 4thou/0.004inch, to be pedantic 0.0251mm is the same as 1thousands of an inch exactly.

haha yea was typo's thanks for picking that up
would be some nice burnt up valves if it wasnt a typo

 

[Gawain]

I was thinking of hordes of ppl looking for impossibly thin feeler gauges!

 

[pbk]

so as someone stated 2 thou is 0.005mm so im guessing 3 thou is 0.006mm??? correcnt me if im wrong coz my feeler gaugues only has mm

 

[pbk]

i found this chart on google tho it says 2 thou is 0.006mm?



5 thou (0.13mm) 2 thou (0.06mm) 6 thou (0.15mm) 7 thou (0.18mm)
6 thou (0.15mm) 3 thou (0.08mm) 7 thou (0.18mm) 8 thou (0.21mm)
8 thou (0.20mm) 4 thou (0.10mm) 10 thou (0.25mm) 11 thou (0.28mm)
10 thou (0.25mm) 5 thou (0.13mm) 12 thou (0.30mm) 14 thou (0.35mm)
12 thou (0.30mm) 6 thou (0.15mm) 14 thou (0.36mm) 17 thou (0.42mm)
15 thou (0.38mm) 7 thou (0.19mm) 18 thou (0.45mm) 21 thou (0.53mm)
18 thou (0.45mm) 9 thou (0.23mm) 22 thou (0.55mm) 25 thou (0.64mm)
28 thou (0.70mm) 14 thou (0.36mm) 34 thou (0.85mm) 39 thou (0.98mm)
36 thou (0.90mm) 18 thou (0.45mm) 43 thou (1.08mm) 50 thou (1.26mm)

 

[pbk]

wait dont worry about about my question

 

[headsmess]

i see a lot of confusion now

thou=thousandth of an inch.
an inch=25.4 mm
25.4/1000=.0254

so 1 thou= 0.0254mm

2 thou=0.0508mm

4thou=0.1016mm

so gawain was right...cept he said .0251, not 0.254

and 5 inches, is exactly 127mm

 

[Cactus Jack]

Here ya' go dudes ... A few links ...

Reasons and effects of tappet or valve clearances - more-power.info

Dan's Motorcycle Valve Adjustment

There's no harm done by experimenting with slight clearance variations ... just don't go overboard ... or underboard ...

Increasing the clearance reduces cam duration and lift ... and reducing clearance increases duration and lift ... For instance if your cam has 6 mm lift at the valve and you had 6 mm rocker to valve stem clearance ... there'd be zero lift at the valve ... If you adjusted the clearance to 3 mm you'd get 3 mm lift ... if you adjust the clearance to .1 mm ... you'd have 6 mm lift minus .1 mm = 5.9 mm lift at the valve ... .2 mm clearance reduces lift to 5.8 mm ... you get the drift ? ...

IF you're stuck with only one feeler gauge that's "close enough" ... It's simple to adjust to a tighter feel for the intake and a looser feel for the exhaust ... The best way to work out the clearances to suit your particular engine would be to first adjust them with the engine cold ... then recheck them with the engine hot and write both the cold and hot clearances down ... That'll give you a clear understanding of what happens to the clearances as the engine heats up ... Once you know that info you'll be able to see whether you can safely run the clearances on the tighter side or not when cold ...

 

[DvDRip]

thanks cactus more-power.info is a really good site to help understand engines better

 

[n1ck]

but also remember there is a rocker ratio ive never mesure them for a pitty but some things have 1-2 ratio so in that case 6mm lift would be 12mm and you can have that vise versa ive had some small engines running ratios like 2-1 as a example so it only had a 3 mm lift

 

[Cactus Jack]

That's why I specifically stated "lift at the valve" ...

 

[steeny]

gday

i have adjusted my valves over the weekend and set them at 0.1mm and 0.15 ( it was tight on the exhasut because i didnt have a 0.12mm guage). have noticed that there is now lifter noise. and it seems a little to loud. My question is do you still make the adjustment to the exhaust valve while at TDC. this is what i have done.

i am pretty confident that the exhaust valve is too big and that is causing the noise,
By the way great info in this thread and the posted links,
Thanks to all

 

[Gawain]

Single cylinder so both adjusted at the same time. Is it loud when the engines hot, if it is you could tighten the gap a little. Just remember a little valve noise is good, lets you know they havnt closed up...

 

[Brocko]

Hey guys adjusted my valves for the first time today. They were really tight with the engine cold so hopefully it will be time well spent. Was just wondering have you even noticed the engine making leaking air noise on the compression stroke.. At first i thought it couldve been the valves not closing fully because there was no clearance. After doing the valves the engine seemed a fair bit harder to roll over, but the hissing on the comp. stroke was still there.

Is it just bad valve to seat manufacturing?

 

[Gawain]

Its the sound of compression. Take the plug out it'l stop and be easier to turn over.