SOHC.co.uk Forums > CB500/550

Questions re Yoshi mods

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K2-K6:
That gives an interesting look at the current status. No wonder it's smelling of petrol.

As you've said,  something well out of range on no1,  seems a bit of a gusher on that one.  Although if it had any mis-fire on that cylinder it wouldn't help the unburnt fuel total.

Also appears to have idle jets 1 or 2 steps higher than needed,  be interesting to see what numbers are in there.

looks like carb balnce is ok for 1,2,3 with 4 sitting slightly lower judging by the O2 readings.

Unless there's anything specific about valve clearance to give confirmed non std,  then I can't see why normal tolerancing wouldn't be in place.

Seamus:
Yes indeed. Some sporty cams have increased valve clearances. Put a Piper in my MGB and that increased clearances by a couple of thou on the exhaust and 1 on the inlet. May be worth opening them up to about 0.04mm inlet and 0.05 exhaust.
Oddly, it idles really well and sounds perfect. Runs smoothly and pulls well through the gears. Holds a steady 80 up hill and still will accelerate.

As you say, carb balance is about there.

Guess, I will pop the bowls off and have a look. If necessary, I can remove the carbs and see if there are any oddities

Seamus:
Not one to rush things, but finally had time to look at the beasty.

Idle jets are standard at #40. Did not have time to strip carbs off, so have not checked main jets. Should not effect idle gas values anyway.

Checked a gap at tappets, all ok, may need to open them up a bit. Unfortunately, my feeler gauges are at work.

Plugs are D8ea. Ordered some new ones anyway.

Ignition timimg set as standard, advance working fine.

Discovered a bit about the cam, street special, recommended valve clearances at 0.1mm.
Ignition timing to be advanced by 5 degrees. Have moved it by about 4 degrees as that is as far as it will go on the slots. Seems to rev faster, but will need to get it out on th road and see. Unlikely to happen soon.

Wondered if the plugs could be causing problems, so will change them asap. want to check the resistance of the caps and leads as well. Dyna coils, ignition, leads and caps. All about 5 years old, but done less than 2000 miles

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