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Piston scoring exhaust side

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Replaced my cylinder, piston and rings last year. Maybe 20-30 hours on bike since. Was spooging so I leaned my jetting out a bit, the plug still looked a little rich and still spooged a bit. As you can see by the pictures I must have been lean on the main. My jetting was as follows. 

178 main

42 pilot

JD Red 2nd from top

1 1/2 out on AS

3200'

Motul 800 40:1 94 pump gas

80-90 Temp

I'm waiting for a piston and bumped the main to 180 and moved clip to the middle. I cannot feel the gouges in the cylinder but read somewhere to use scotch brite to clean the cylinder?

 

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IMG_0547.thumb.JPG.d27d6f4521f935b0214e9edf82c55308.JPG

 

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It's not your jetting that has caused this scoring , it's lack of lubracation in the exhaust bridge.
read here 
 

I thought you didn't have to drill cast pistons?

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Do you 'compression brake' a lot ?

What do you ride, trail/off-roading (including some sustained high rpm stretches) or MX tracks ?

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10 minutes ago, mlatour said:

Do you 'compression brake' a lot ?

What do you ride, trail/off-roading (including some sustained high rpm stretches) or MX tracks ?

Mostly trail with some high RPM sections. Rode the track a couple times. I don't just let off the throttle after a long straight. 

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Make sure you drill lubrication holes next time :thumbsup:

In a cast piston?

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5 hours ago, lerea3 said:


In a cast piston?

I kept cracking bridges until I started drilling lube holes.... YES even cast pistons (I drill smaller holes in cast pistons 1/32) .... A proper warm up is especially important on GEN 3 CR'S or any bridged exhaust port. Yes from the looks of the top of the piston your a bit lean, possibly an air leak?

Edited by mxsteve1968

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6 hours ago, lerea3 said:


In a cast piston?

Yes every piston.  Most weisco's seems to be coming pre drilled now days 

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Thanks gentleman, I will drill the next one. Did a leak down test when I rebuilt last year, was good but I suppose one may have developed.

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Make sure you inspect the tip of your power valves. Also that they do not extend in to the combustion chamber.

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Make sure you inspect the tip of your power valves. Also that they do not extend in to the combustion chamber.

Power valve flaps are good.
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14 minutes ago, lerea3 said:

Both A and B Honda pistons are discontinued

I always run D piston in everything unless its brandnew :thumbsup:

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That is what they are ordering me now. The parts guy at Honda didn't know the pistons were discontinued, his computer said they were available

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On ‎6‎/‎7‎/‎2017 at 6:52 PM, lerea3 said:

That is what they are ordering me now. The parts guy at Honda didn't know the pistons were discontinued, his computer said they were available

Remember, the piston needs to be drilled (READ THE INSTRUCTIONS INSIDE THE WISECO BOX) and requires more warm-up time before pinning back the throttle.

Edited by mxsteve1968
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