Mainjet adjuster? Doordie please explain

[demographic]

While looking through the gallery I spotted this....



Also I spotted this picture...


I can't see it that well from the pictures but it looks like you have used O rings to seal your cylinder head, am I right?
and the port in the back of the piston? to lubricate the small end bearings?

Any chance of a port map to show us the location of that?
And a longer explanation cos I am very interested by that and as I now have two engines I have more bits to play with
What carb modifications have you made?

I can see the bit on the bottom left of this picture (have seen them advertised but can't remember what they are called Maybe an Airstriker wing?) but how well do they work?


And I take it that the mainjet adjuster is the part on the bottom right of the picture and it replaces the standard plug from the bottom of the carb?
If so it looks different from the other mainjet adjuster that you have, whats the difference?

Regards Scott

[doordie]

Demographic,
Many questions there,but I`ll try to answer them!

1)Main adjusters in different size only,one I have made(the big) and one better made found at internet and copied.
2)Sealed with o-rings is old mods, but works very well IF you want to open head often and check.
3)Piston port it?s good for lubricate small bearings and to COOL pistontop(more power for long straights) and make piston a little bit lighter.(A Wisecopiston and a stock modified pistonpin make a huge different,oops a tuning secret).
4)Ovalbored Kehin PWK 39mm carburator.(Maybe a Lecron 40-42mm in future).
5)Powerblade (KTM 125/200cc use Kehin PWK 39mm)makes faster gasvelocities at part-throttle=more lowend power.
6)Sorry, no portmap from me.

//doordie

[YUNGGUNNAZ]

doordie,you have mail.thks

[doordie]

YUNGGUNNAZ,

No received mail,try again!

//doordie

[YUNGGUNNAZ]

sent pm again.thks

[demographic]

3)Piston port it?s good for lubricate small bearings and to COOL pistontop(more power for long straights) and make piston a little bit lighter.(A Wisecopiston and a stock modified pistonpin make a huge different,oops a tuning secret).

I knew from THIS thread that Wiseco KX 500 pistons are 30 grams lighter than the stock pistons which seemed to me to be a significant amount on a reciprocating part.

[doordie]

demographic,

Yes, you can see a big difference about  weights between stock and Wiseco.

This is a post from another forum (ATM):

Standard: (Wiseco in brackets)

All in = 489g (471g) Wiseco 18g lighter.
Pin = 80g (86g) Wiseco 6g heavier.
Rings = 14g (18g) Wiseco 4g heavier.
Piston = 395g (367g) Wiseco 30g lighter.

I use the best from this worlds!

//doordie

[demographic]

demographic,

Yes, you can see a big difference about  weights between stock and Wiseco.

This is a post from another forum (ATM):

Standard: (Wiseco in brackets)

All in = 489g (471g) Wiseco 18g lighter.
Pin = 80g (86g) Wiseco 6g heavier.
Rings = 14g (18g) Wiseco 4g heavier.
Piston = 395g (367g) Wiseco 30g lighter.

I use the best from this worlds!

//doordie

Would that be a Wiseco piston, standard gudgeon pin, and standard rings then?

I am guessing that the standard gudgeon pin is thinner than the Wiseco one, am I right?

[Johnniespeed]

Wow, I havent heard the words "grudgeon pin" in thirty years,  I used to be an MG mechanic.  Thanks for the trip down memorylane.  The words "sparking plug"  "boot""bonnet" and "gaiters" just came back to mind also.
  Back to the reciprotating weight thing,  is it possible to reduce the reciprotating weight to the point of the crankshaft assembly being off balance?  I know when having car engines balanced, the reciprotating weight was figured into a percentage and bob weights were added to compensate. then the crank was spun and balanced.  Is that how a one cylinder is done?

[demographic]

Wow, I havent heard the words "grudgeon pin" in thirty years,  I used to be an MG mechanic.  Thanks for the trip down memorylane.  The words "sparking plug"  "boot""bonnet" and "gaiters" just came back to mind also.
  Back to the reciprotating weight thing,  is it possible to reduce the reciprotating weight to the point of the crankshaft assembly being off balance?  I know when having car engines balanced, the reciprotating weight was figured into a percentage and bob weights were added to compensate. then the crank was spun and balanced.  Is that how a one cylinder is done?

I am English and over here we still use words like Gudgeon pin, Boot and Bonnet and the only Gaiters I know of are the bits that cover the fork stanchion chrome on right way up forks and the ones that walkers wear at the bottom of their trousers and go over their boots, same thing?

I would have thought that to balance out the piston weight loss you would have to drill out some of the crank web? maybe?

[Johnniespeed]

Yes those are gaiters!  Also the rubber boots on a cars rack and pinion were referred to as "gaiters" on the new car prep we were supposed to check the Gaiters  for "security and chaffing"  Another word used in reference to English cars was "trunion" .
 I  believe you are right concerning the drilling of the crank web to compensate for piston weight loss. ( if we were doing it perfectly)

[Brett]

Changing crank balance to suit a 30g piston weight change is a crock of s**t, cranks are only ever perfectly balanced at 1 speed and so a tiny 30g change would only change the perfect balance by 1 or 2 hundred rpm.