Jota - plug colour opinion sought

ngiles

ngiles

Senior member
Location
Sydney, Australia
Quick follow-up to thread on mis-firing Jota -

Had a 70K ride this morning and all went well.  Checked plugs on return and right cylinder is pale (see photo).  One other symptom is when I pull up the idle RPM sits on about 2k for a little while before dropping back to the ~1k norm.  I wonder if the two are connected - welcome any views.

I figure next step would be to pull the carbs off and see whether carb 3 is set any different to the other two.

All suggestions welcome.

Cheers

 

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Hanging idle is usually a sign of lean running. But there are plenty of other causes as well.Are the carbs sinked, where are the idle screws? If you pull that slide up a bit do you get a response, if it has sat around a while the idle circuits love to get blocked.
 
Better if next time you take photos with the electrode at the bottom or side as hard to see the porcelain.

What model Jota are we talking about. Series 1, 2 or 120 ????

If series one check the inlet manifolds and the bakerlite insulator as they can fail.

Series two check the manifolds for cracks and the O rings as they can pull air if they are cactus.
 
Brett said:
If series one check the inlet manifolds and the bakerlite insulator as they can fail.

Series two check the manifolds for cracks and the O rings as they can pull air if they are cactus.
Click to expand...

For either/both of these: spray the manifold area with EasyStart at tickover: if the revs rise then, yes, you do have a vacuum leak and the o rings between the head and manifold or between manifold and carb stubs are suspect and need replacing..
 
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