correct torque settings for cylinder head?

[RyanWiltshire]

anyone know the correct/rough estimate for the cylinder head torque settings for the bolt heads on my yamah aerox 2007, airsal 50cc sport? 

thanks

[captincvmn]

This is for my china minarelli clone

I’ve been using 12 foot pounds or 144 newton meters. It could be newton millimeters for all I know, I just know the torque wrench has a metric scale and I start light, around 70, then 100, then 120 then 140. I do a heat cycle with the shroud off then let it cool and retorque the following day.

It’s not much and I’ve had an equipment malfunction strip out a head bolt. I use a 1/4” drive torque wrench from harbor freight.

[Lucass2T]

Head studs on minarelli horizontal engines need to be torqued down to 11nm. Run the bike untill engine is nice and hot. Let it fully cool down and retorque the studs with 11nm.

[pili]

The service manual on the Zuma calls for 10 ft/lbs or 14nm but there's a world of trusted experience here to draw from. As mentioned it's a good idea to start it up shroud off, get it hot and recheck. That said I've never had one loosen up but better safe.

[RyanWiltshire]

airsal said It must be 1.2 – 1.4 kilos?

[aeroxbud]

The Haynes manual and my online one both say 14 Newton meters.
I have always used this without a problem. The air cooled cylinders I do at 11 Newton meters.


1.2 kilo is 11.7NM. 1.3 is 13.7NM. So 12NM sounds about right.

[Lucass2T]

11nm is on the low side I think. I did 100's of em like that when I was a scoot mechanic. I think 12 or 13 is also okay but I always kept with 11nm. Overtightening will compress and warp the cylinder wall with damage or a soft seize as a result. Gaskets might fail too. Also make sure the threads are super super clean (like new) and lube them as little as possible.

[captincvmn]

Ok it is 144, inch pounds equals 12ft lbs

[captincvmn]

Apparently I’ve been high 😔

[aeroxbud]

Nov 4, 2022 16:34:49 GMT -5 captincvmn said:

Apparently I’ve been high 😔

[ThaiGyro]

Hey all, not contributed much lately...but I love to open worm cans.

I have quite a few torque wrenches. Clickers, dials and wires...since captincvman showed his, I decided to offer this: My most inaccurate torque wrenches are "clickers". From day one of use, they get more and more inaccurate. Maybe slow, if use is low. Dial wrenches hold up well over time, but not easily calibrated. Wire indicators are easily calibrated and much more accurate - if one assumes the correct torque range.

I have 4 or 5 ranges of indication. Old Dayton's, a few Snap-Ons, and some no names.

In my racing days on old two pokes...I used an inch pound wire bender. Never had a strip out, occasionally had a leaker. The hard part of wire type is being in position to read it straight on, which is important.

The bottom line for me? For street, under torque a bit, heat and re-torque, as offered in prior contributions. Head bolts and case bolts are problems for different reasons. This is my serious thought path...Steel is harder than aluminum/aluminium/pot metal/magnesium...bolts are cheap, cases are not. The steel will flock up the softer case materials.

Case bolts or often made of dog-doo metal, but with no consistency. Use the same caution. The base metal is rarely harder than the fasteners...though it should be! Even stainless steel threaded into mild steel will make shit happen. SO...sneak up on torques with proper patterns and good torque indicating wrenches.

[captincvmn]

ThaiGyro can you post a picture of the wire type? I’m not familiar

[Lucass2T]

Nov 6, 2022 16:57:38 GMT -5 captincvmn said:

ThaiGyro can you post a picture of the wire type? I’m not familiar

Same here. Would like to know more about your wire indicator setup.

[ThaiGyro]

Hi...Sorry for the late response. It is fffffff-ark-kkkk-ing cold here. When the shop warms up tomorrow, I will do a side-by-side picture. Assuming that I remember. Just completed a wiring project...that sucked.

[190mech]

I think it is called a beam type torque wrench..They work well,just no clicking,,,