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You can't measure the bore with verniers? Not sure how you would measure the bore with a micrometer.
The bore IS NOT ROUND it is OVAL.
Therefore you will get different readings depending on where you measure the bore.
PLUS the bore can go out of shape from excessive use!
SO it's best to have the bore checked professionally for the size, unless you have the original piston hat you know worked so you can see what size it is.
There really isn't much to these engines.
So if it's not running right then it's going to be.
- Poorly engine
- Not Jetted right
- Faulty ignition.
If you have a sound engine, working ignition and jetted back to OEM standards then it'll run.
I'd suggest getting a Haynes manual, as this will tell you how to get it back to standard, which is where you should always start when diagnosing problems.
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The bike has been re wired properly following the hanes mauel im not new to bikes im just knew to this age of bike i think it will be my jets because who i bought it off of had everything cocked about with and all im tring to do is set it standered not make it a beast or a weapon jusy so everything is as it should. And the piston what was in it wasnt the best scratched to death along with the barrle so i changed it all to standered. The micrometre was for the piston not the barrle as its easy to messsure a piston to a barrle im well aware, ill be getting it sent off to someone who can set up my carb because that to me is the problem, when i started cleaning it all the af screw was jammed in and the idle screw all the way in inicating it ran like shit before for best words
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Im pretty sure the bore isnt oval, it is hovewer tapered slightly towards the bottom...
The manual should tell you where to meassure.
A crude way is to insert a feelergauge between the piston and cylinderm this will give you a ballpark reading.. -
@Jens-Eskildsen Not oval oval, but they are not round. The piston can go in both ways, but should ONLY be put in the correct way.
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How are they supposed to bore and hone a cylinder, and not have it just about perfectly round? It is round to within very fine tolerences, which I wont even bother to look up in the servicemanual, but a guess is a couple of thousands of a milimeter. If you call this conical, fine be me. But then anything is conical.
The piston has different thickness, not the cylinder. Piston is smaller at the top, because it expands more there because of the heat, so its made a bit conical
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@Jens-Eskildsen My bad, I was wrong about that sorry.
It's because the piston pegs foul the ports if it's inserted the wrong way round, not oval.
Still though, I am pretty sure you shouldn't be measuring the bore wither verniers etc.
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Agreed on the verniers you cant meassure the cylinder precisely with those.
