GSXR750 1986 tappet issues

chrisk

New member
May 28, 2019
4
0
1
Just adjusted the tappets on an 86 JDM spec 750 but have found that the procedure in the manual (see pics) doesn’t quite work.

When it says adjust number 1 for example, the cam slots are facing outwards and the “T” aligned on the rotor as per the manual, both cam lobes are pointing out towards the outside of the casing. If I rotate the crank I find that the gap is bigger on the exhaust when the cam lobe is pointing up, hence adjusting it when directed would mean the clearance is tight..?

This is also true for number 3 exhaust - the cam is up when it suggests adjusting it, but the gap gets bigger when it’s facing the outer casing, and 4 exhaust it says adjust when facing the casing but the gap is bigger when the cam is facing up.

This is only true of exhausts 1, 3, and 4, number 2 is basically the same gap forward and up. I tried this 3 or 4 times as I wondered if I was going mad. The cam is worn, you can see ware on the lobes but I’ve decided to run it and sort it out later.

Has anyone else found this, does this point to wear on the cam, journal or head..?

Help...
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jls

Member
Apr 6, 2014
52
5
8
I don't know this bike in particular but from the sound of it you're saying that clearance increases away from the correct position as detailed in the manual. That can't make the clearance tight. You say the cam is worn, sounds like the root of your problem and you'll be loosing valve lift and possibly duration where the clearance is increasing