Valves & TB balance - What am I doing wrong?

[adamski49]

Ok, I decided to check the valves and TB balance before delving into the shaft and found that the valves were slightly out here and there so adjusted accordingly. Out of interest how important is it that TDC is spot on? (I used the screwdriver in plug hole method).

I then stripped and cleaned the fast idle control before checking the TB balance. It was out a bit and as I ran out of time (it was getting late) I settled for as near as. Took it for a spin and it felt a little better... maybe.

Thought about it through the evening and started again this morning using the BM tech manual as a guide. Throttle cables were out of adjustment in that there was 2mm+ at the throttle and none at the TB's. Sorted this out, cleaned the cable and guide on the TB's and then balanced them up and got it spot on the 0 at max sensitivity. Took it out and although the pick up had improved the vibes had worsened slightly Anyone know why?

Also found that the CAT was touching the frame on one side so loosened everything off and tried to move it across but with little joy, probably gave it a gap of 1mm instead of touching. I guess this is the main source of the vibes but doesn't explain why the buzz has got worse with TB balance being spot on.

Any advice greatly received before I admit defeat and take it to the dealer or lose the plot completely and p/x it for a bandit.

TIA

Adam

[Archie]

Adam

Have you balanced the throttles at idle only or at part throttle (say 4000rpm no load) as well? You can get it balanced at idle, but if the cables are out of adjustment, it will vibrate.

Cheers

Alan

[adamski49]

Alan

Yep, both. First balanced it at idle - small tweak on the RHS brass screw then proceeded to do the revs up to 4k. Once I was happy and locked off the adjusters I checked it again and it was spot on 0 at 3k, 4k, 5k and anywhere inbetween - pretty jammy for a first attempt.

I'll check it again and swap the tubes over to see if it's the same both ways but I've lost interest and patience for the moment.

I'm also wondering if a Y piece might be the answer to the CAT touching the frame, if it's not that though it'll money spent for no reason.

Cheers

Adam

[winger]

Adam

I'm running a grave risk of looseing the plot here,didn't you have an Induct?? K+N what the hell are you doing running an S with a cat on???are you running a stock system???,because if you are you haven't got a prayer of getting it to run anthing like.

Jeeze i rode a S a couple of days ago,with a few goodies on it,but with stock cans,it was absolutely strangled,haveing not ridden another S for a time to say i had a shock was putting it politely

Chris

[adamski49]

Chris

Yep, tried the induct etc but it felt as though it was running weak (in hindsight this might have been the BB chip rather than anything else) but now it's all stock (and I know the CAT strangles it) but it's been running smooth enough up until somewhere around the 27k mark.

Adam

[gus]

Adam
Redo the valve clearances.You find TDC by removing the black plug in the crankcase by the right hand side throttle body.Turn the engine over by hand using either the front pulley or in gear using the rear wheel.The letters OT will appear in the window on the flywheel.You really need 4 sets of feeler gauges to get them bang on.But this will make a difference to how it runs.If the valves aint set right your pisssing in the wind setting the throttle bodies.I,d try again mate before taking it to the dealers.
gus

[julian]

Chris

Yep, tried the induct etc but it felt as though it was running weak (in hindsight this might have been the BB chip rather than anything else) but now it's all stock (and I know the CAT strangles it) but it's been running smooth enough up until somewhere around the 27k mark.

Adam

Adam

Gromit's original S that I bought (and promtply had stolem) sported a full Laser, BB Chip and a Lennies. It went like a rocket. No vibes.

[winger]

I have to say mines pretty good nowhere days,no matter how warm or dry the weather.

Chris

[adamski49]

Ok, managed to move the CAT away from the frame and this has improved things a little, especially at the top end.

Then re-checked the valves using the window and OT mark as per Gus' suggestion. All spot on so the screwdriver through the plug hole method is pretty good. Didn't use 4 feeler gauges but they all felt the same so it'll have to be close enough.

Re-checked the TB balance and this seems to have drifted off slightly. But I also think I may have a problem with the twinmax because when I swapped the hoses over (no adjustments made) it gave a different reading (No, not just the other way, a different imbalance) It's either the hoses not making a good enough connection or the twinmax itself.

I read that if you zero it on max sensitivity it should stay there when you turn back to min - mine doesn't, it swings away half way towards 1. Is this the source of my problem?

Thanks for all the replies and helpful hints... I will persevere.

Adam

[Gromit]

Gromit's original S that I bought (and promtply had stolem) sported a full Laser, BB Chip and a Lennies. It went like a rocket. No vibes.

That's coz it was run-in properly

[adamski49]

By jove, I think I've cracked it

The first TB balance involved so many cable adjustments (fast idle, throttle and TB's) that I think it needed time to settle even though it read 0 at the time.

Did it again and got the elusive 0. Pick up is far better, no lag and plenty of bottom end torque. I'm not entirely sure but top speed seems to be down a touch although I can live with that.

Vibes still exist, but less intrusive and higher up the range - TBH in all the tweaking I've probably forgotten how vibey it was in the first place.

Adam