Jump to content
Sign in to follow this  

8mm head bolt torque specs?

Recommended Posts

After snapping a couple of the older 8mm head bolts, It dawned on me that the older bikes may have had different torque specs than the newer 9mm bikes.

So, can anyone tell me if the 8mm torque specs are less than 26ft/lb?

Thanks

Share this post


Link to post
Share on other sites

14 to 16 ft. lbs. for grade 8.8 with moly on the threads and under side of the bolt head.

Share this post


Link to post
Share on other sites

They're NOT all the same. And you really need to get them correct. Most are 7 ft lbs. make sure that center bolt (17 ft lbs) is torqued correctly.

Here is a page from the manual that has the bolts you asked about.

headtorque.jpg

Share this post


Link to post
Share on other sites

the book calls for 17lbs but I always go between 14 and 16 on old threads with the moly paste and have never had a leak...

Share this post


Link to post
Share on other sites
the book calls for 17lbs but I always go between 14 and 16 on old threads with the moly paste and have never had a leak...

Wow, that would explain it! Luckily they didn't completely snap and I was able to get them out. Still 17 to 26 is a pretty big jump, were there issues that prompted the change?

I ask because I also stripped one of the holes and am trying to decide whether to repair the threads with an insert, or tap it to 9mm and use the newer bolts.

Share this post


Link to post
Share on other sites
Wow, that would explain it! Luckily they didn't completely snap and I was able to get them out. Still 17 to 26 is a pretty big jump, were there issues that prompted the change?

I ask because I also stripped one of the holes and am trying to decide whether to repair the threads with an insert, or tap it to 9mm and use the newer bolts.

What change? Are you saying it was 26 ft/lbs? Notice that only that one bolt is 17, the rest are either 7 or 9 ft/lbs.

Heli coil, easy & it will be stronger than the original - and you can still use the original bolt.

Share this post


Link to post
Share on other sites

Spec on the actual M8 head bolts for '83-84 XL600s is 19-22 ft-lbs. The single M8 bolt that goes through the head cover gets 14-19. This came out of the factory service manual.

Share this post


Link to post
Share on other sites
What change? Are you saying it was 26 ft/lbs? Notice that only that one bolt is 17, the rest are either 7 or 9 ft/lbs.

Sorry for the confusion... I was looking for the head bolt torque values, not the head cover bolts.

Spec on the actual M8 head bolts for '83-84 XL600s is 19-22 ft-lbs. The single M8 bolt that goes through the head cover gets 14-19. This came out of the factory service manual.

That sounds more reasonable, thanks HT.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×