Åtdragsmoment på topplocks skruv

Enligt manualen som jag har kikat i säger de att man ska dra topplocks skruvarna till 8,5-9 ft. lbs. vilket motsvara 11,5-12,2 Nm. Skruvarna är en M6 och normal skruv är av material 8.8 men de har en maxgräns på 9,8 Nm. Är skruvarna i 10.9 material eller har de helt enkelt skrivit fel i manualen och det ska egentligen stå 8,5-9 Nm? Man kände (känslan är ändå rätt bra) klart och tydligt att det är ganska hårt att dra den lilla skruven med 12 Nm och mycket riktig så skjuvade skruven av innan klicket från momentnyckeln sa "klick".

Så frågan är, Är skruven av 10.9 material eller har de skrivit fel i manualen?

I have never seen a document which states the grade of bolt...and there is no marking on the bolt... but I think they are 9.8.
Jag har aldrig sett ett dokument som anger bultens kvalitet ... och det finns ingen markering på bulten... men jag tror att de är 9,8.

The correct torque is 12 Nm. I have serviced Solex engines for over 40 years and have never had a problem using this torque.
I have rebuilt about 400 engines, and made thousands of repairs over the years.
It is important to torque the bolts, then ride the Solex until the engine warms up. Then, let the engine cool down, and re-torque the bolts.
I do this twice.

Rätt vridmoment är 12 Nm. Jag har servat Solex motorer i över 40 år och har aldrig haft problem med att använda detta vridmoment.
Jag har byggt om cirka 400 motorer och gjort tusentals reparationer genom åren.
Det är viktigt att dra åt bultarna och sedan köra Solex tills motorn värms upp. Låt sedan motorn svalna och dra åt bultarna igen. Jag gör det två gånger.

Hi Brian, thanks for answer. So then the bolt must be of grade 10.9 or higher. The 8.8 grade got the max torque of 9.8 Nm. I have checked my torque wrench and it is spot on, give or take 0.5 Nm. The bolt snapt before it hit 12 Nm.
I belive that the bolts on my cylinderhead are original and think that they now must have become brittle after all years of hot/cold/hot/cold..

The 10.9 bolts got the max torque 14 Nm so thats the grade to choose aperently.

Have you ever broken these bolts before, on all of your rebuilds? Or do you use new bolts?

Yes, 8.8 bolts are too weak.

Grade 9.8 bolts have a maximum torque of 13.3 Nm, so I think the original bolts are 9.8 grade.
They can be tightened to 12 Nm with no problem.
I don't think they are 10.9 or higher.

In my experience, I have only broken one cylinder head bolt.
It happened because the spacer that the bolt goes through was not seated properly in the seat of the cylinder head.
This caused the bolt to be at an angle, and that is why it broke.

Several times, while disassembling engines, I have noticed bolts that were "stretched", but not yet broken.
I replaced them with original bolts, not new.

I have never used new bolts because I have a sufficient supply of secondhand original bolts.

I agree that your broken bolt was simply old and brittle.

Post a photo or two of your cylinder head bolts...perhaps I can determine if they are original.

I would like to see your Solex, too.

I got one more Solex so I scavenged from that one and it went well. I believe that they are all original.
I do not know how to post a photo, I tried the icon "Värda en bild" but I do not know what happend, no photos are to find what I know of.

To post a photo...



Use this icon to choose a photo from your computer:





To use this icon, the photo must be on the internet...you need the url:

It worked :-)

Excellent! Thanks for posting the photos of your Solexes...very nice!




If you give me your e-mail, I can send you .pdf copies of the Instruktionsbok, the Reservdelslista, and the Verkstadshandbok for your Svenska Cykelfabriken Solex modell 3800s.
Or you can e-mail me at: briansolex@proton.me

I am sure that your broken bolt is the original.
Probably, the bolts began to loosen, then the high compression pushed outward on the cylinder head, stretching the bolt.
I have seen this several times.

Thanks!

Yes please, I would like to get them in pdf. My email is j_pollop@hotmail.com
We are a few guys (10 or so) in the village that got the 3800 and once a year we are having a get together for some tinkering, beer and BBQ. This year it was a couple of Saturdays ago and I decided to exchange my Inlet/Exhaust pipe because of the gasket were not doing the job it should. Said and done, after a good test drive I decided to change the fuel jet to an variable one and after that the motor only spun around with the decompression valve open. As soon as I let it go the motor stopped spinning.

One of the guys have rebuilt his engine and is an mechanic in a former life. He said that it sounds like the clutch, so we opened it up an sure enough the clutch pads were totally worn and fell out from the clutch. The cage, is it call "Clutch bell", is very badly scratched. So now I have to buy some stuff.

The clutch pads, how do you set them into the clutch, with a glue or something else? And do you know if one can grind/hone the cage/bell to a fine surface? It looks to be very little material. I cannot find new one to buy, only used.

It sounds like you have a nice group of Solex riders! I hope that you can post some photos or video of one of your gatherings.

Here in New York City, we gather every year to celebrate the French Independence Day, July 14th...Bastille Day.
I have some videos from past gatherings on one of my video channels:
https://rumble.com/c/velosolex

A used, secondhand clutch bell will cause you no problem.:
https://www.solex-onderdelen-limburg.nl/en/04-clutch-bell-solex-type-3800-5000-only-used-ones.html

I have never needed a new clutch bell...secondhand is always good enough.

To properly clean your clutch bell,you would need to machine it in a lathe. If you try by hand, it will become oval and uneven.

I have sent an email to you from briansolex@proton.me with the Swedish manuals.
If you do not see it, check your SPAM folder / filter.

Solex used Loctite Black Max 380 adhesive, so that is what I recommend.
https://www.ellsworth.com/products/adhesives/cyanoacrylate/henkel-loctite-black-max-380-instant-adhesive-1-oz-bottle/