Top yoke pinch bolts
 

Eyup

Noticed that the bolts that are in the top yokes are very short and engage in only half of the threaded part of the pinch clamps. This is poor engineering practise of that there is no doubt but is it normal for Yamaha? I now know these bikes are built in Italy which is never a good thing. I have owned itallian bikes in the past.

The bolts in the lower yokes are full length thread engagement. anyone care to have a look at theirs for me to confirm please?

Regards

Al

Have you looked in the workshop manual ?

You will find that the clamps should fist be tightened at the front, the the rear - it's how it is supposed to be. So you will always have a gap at the rear of the clamp.

If you were to ask, I would say take it to a dealer if you are not sure.

Upper yoke bolts (east-west) 1 crest short of full thread.
Lower yoke bolts (north-south) 2 crests short of full thread.

I think you may be misunderstanding.
Its not the bar clamps, its the yoke clamps. "the big casting at the top of the fork tubes", The bolts are way too short.

Length of the bolts has no bearing on the gap at the yoke, but they should have full thread engagement and they don't.

Won't let me post a pic
Al.

Here you go, picture of the yoke showing very clearly that they have the wrong bolts in them, This is a brand new bike! are they all this bad?

Al.

Ah , sorry, misread.

Thanks for the effort, confirms my thoughts. Both yokes should be full thread engagement. anything less is very poor engineering.

I have emailed the pic to the dealer and will see what he has to say. I dare not look at it too long as I may find another problem.

Al.

Just my 2 cents worth.

A bolt is as strong as it's weakest point, if a bolt has a diameter of 8mm it is of no use having it threaded in a hole that is 30mm deep when the weakest point is the 8mm diameter. There is also the strength of the thread to take into consideration, if you have a weak thread you need a longer threaded portion to hold the bolt.

A basic rule I have always used, is a thread in alloy should be double the diameter of the bolt to be secure. A thread in steal should roughly be 1.5 times the diameter of the bolt.:smilies0119:

What Kev said.

Steel in steel, by the time you have got about three full turns in the thread is stronger than the shank of the bolt. Steel in ally you need another couple of turns.

Add a bit of safety factor to that and you've got the 'rules of thumb' above.

The only reason there is more (unused) thread in the yoke is that it's easier and cheaper to drill and tap a through hole than a blind hole. Not because it's needed for strength.

Just to add a few more thoughts...

- Just been out and looked at mine, and they're about the same as in your photo. I think there's plenty of engagement.

- Motonacio has an XTR, not a Tenere. They have different yokes AFAIK. Therefore they might have exactly the same thread engagement, but less 'spare depth' caused by drilling a through hole.

- I doubt your dealer put those bolts in there. Most bikes I have seen being uncrated in dealers have had the front wheel and the bars off, but the forks already in.

- Over-engineering is also bad engineering ;)