Author Topic: Seizing engine  (Read 2155 times)

Offline muskrat

  • Global Moderator
  • Wise & Enlightened
  • **
  • Join Date: Jul 2009
  • Posts: 8505
  • Karma: 112
  • Lithgow NSW Oz
    • Shoalhaven Classic Motorcycle Club Inc
Re: Seizing engine
« Reply #30 on: 22.05. 2017 09:12 »
But cruising at 60mph your not on the main jet till you hit a hill. Mark your throttle body and twist grip in the closed position, then the twist grip in the wide open position. Now divide into 4 segments. You'd be surprised how little throttle is used when just cruising at 60mph on flat ground.
In saying all that a too small main jet will affect the needle taper.
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7

Online JulianS

  • 1962 A10
  • Wise & Enlightened
  • *
  • Join Date: Mar 2017
  • Posts: 1075
  • Karma: 20
Re: Seizing engine
« Reply #31 on: 22.05. 2017 09:39 »
The main jet size marking was unreadable but I compared it with the correct 270 jet & it looked smaller. I've since fitted the 270 since the last seize. Running fine but not tested on highway yet. I wonder if that could have been the problem.

If the cause of a seizure was too weak a mixture then I would expect to see serious signs of a weak mixture on the plugs - colour towards white .

The A7SS would also have been fitted with a 1 inch bore carb, so the 15/16 one fitted would tend to give a richer mixture  due to smaller bore.

I still think you need to look inside or that threat of seizure will always be there.

Online orabanda

  • Wise & Enlightened
  • *
  • Join Date: Nov 2008
  • Posts: 1034
  • Karma: 22
Re: Seizing engine
« Reply #32 on: 22.05. 2017 09:42 »
Musky offers good advice for when tuning.
A mark on the side of the twist grip, and a piece of masking tape (temporary) stuck to the throttle body on the left. Mark the tape in quarters (or eights) and setting up the carby becomes easier / more accurate.

Richard

Offline chotus52

  • A's Best Friend
  • ***
  • Join Date: May 2017
  • Posts: 36
  • Karma: 0
Re: Seizing engine
« Reply #33 on: 22.05. 2017 14:02 »
Thanks for all the tips gents. I'll advise the outcome. Regards
55 GF s/a

Offline chotus52

  • A's Best Friend
  • ***
  • Join Date: May 2017
  • Posts: 36
  • Karma: 0
Re: Seizing engine
« Reply #34 on: 06.06. 2017 11:56 »
KCC pistons
55 GF s/a

Offline chotus52

  • A's Best Friend
  • ***
  • Join Date: May 2017
  • Posts: 36
  • Karma: 0
Re: Seizing engine
« Reply #35 on: 06.06. 2017 11:59 »
I mean JCC pistons
55 GF s/a

Offline Topdad

  • bob hebdon
  • Wise & Enlightened
  • *
  • Join Date: May 2011
  • Posts: 2266
  • Karma: 32
  • l
Re: Seizing engine
« Reply #36 on: 06.06. 2017 13:35 »
What are the bores like ??
" rules are made for the guidance of wise men and the blind obediance of fools"
United Kingdom

Offline bikerboy

  • Valued Contributor
  • ****
  • Join Date: Dec 2011
  • Posts: 373
  • Karma: 4
Re: Seizing engine
« Reply #37 on: 13.06. 2017 01:34 »
Sorry to come in late but IMO it was always going to be pistons. Have you measure the bores yet? I must admit I dont like the sound of "tight" valve guides either I would check that while I had the head off for sure

Offline chotus52

  • A's Best Friend
  • ***
  • Join Date: May 2017
  • Posts: 36
  • Karma: 0
Re: Seizing engine
« Reply #38 on: 27.06. 2017 02:34 »
Thanks for all the pointers. We pulled the top end, cleaned up the pistons & honed to 6 thou. It seems like problem solved. Cheers
55 GF s/a