Author Topic: Reading Pistons  (Read 1253 times)

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Offline Devondan

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Reading Pistons
« on: August 03, 2014, 03:52:31 AM »
How is this one looking? the brown deposit is sticky rather than carbon.



Head:



Dan
IT  400D - Trail riding
74 Montesa Cappra - Racing
YZ250 H - Racing
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Offline scotty

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Re: Reading Pistons
« Reply #1 on: August 03, 2014, 06:24:44 AM »
WTF is that! Is this the ported job you are having trouble with running lean?

Cheers Craig
IT 490K x 2,IT 250J,YZ 465H,KTM 525 EXC,ZX12R

Offline Devondan

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Re: Reading Pistons
« Reply #2 on: August 03, 2014, 06:31:11 AM »
eeeeeeer yes! the plug looked lean but piston says no!  I'm going back to stock jetting, doing lots of chops and see how I go, I think going up on the needle jet and 2 up on the main might have been excessive!  Been talking it through on the Dorset facebook page: http://www.facebook.com/groups/226523408909/10152600485948910/?notif_t=group_comment

Dan
IT  400D - Trail riding
74 Montesa Cappra - Racing
YZ250 H - Racing
Norton ES2 500 trials
Norton 250 Jubilee - Road
Norton 350 Navigator (in boxes)
Norton 350 Single M50 (in boxes)

Offline scotty

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Re: Reading Pistons
« Reply #3 on: August 03, 2014, 06:39:21 AM »
The Silkoline oil I use looks similar colour when mixed but always turns black when I have looked at my list one.That looks very weird to me,has anybody came back with a reason or similar experience yet?

PS you missed a great day at Hazelwood on Sunday,can't wait for the next one.

Cheers Craig
IT 490K x 2,IT 250J,YZ 465H,KTM 525 EXC,ZX12R

Online killindini1

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Re: Reading Pistons
« Reply #4 on: August 03, 2014, 06:41:29 AM »
Is that just an optical dillusion or am i seeing a completley f___ked up head job.
If the picture is not telling lies,was that head chucked by the fins in a excentric 4 jaw :o

Piston looks allright though ::)

Cheers,
Steve.
Beer is more than just a breakfast drink

Offline Devondan

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Re: Reading Pistons
« Reply #5 on: August 03, 2014, 07:13:59 AM »
The head has seen some wear and broken rings/piston at some time, but it has been reshaped and the squish done, its a genuine LOP head and barrel. This guy did it back in the day - http://varnermotorsports.com/about_us.htm.  The bike is ported for low/mid power and showing signs of running really well, I think I just went way to big on the jets to be safe!

Barrel has just been relined and piston has about 1hr on t.
IT  400D - Trail riding
74 Montesa Cappra - Racing
YZ250 H - Racing
Norton ES2 500 trials
Norton 250 Jubilee - Road
Norton 350 Navigator (in boxes)
Norton 350 Single M50 (in boxes)

Offline badger

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Re: Reading Pistons
« Reply #6 on: August 03, 2014, 09:03:42 AM »
not a lot wrong with that,the brown sticky area shows the squish is doing its job and concentrating the fuel in the dome,this area runs cooler and is more turbulent so is less likely to form carbon,if anything it doesnt look like it has done a lot of work or been run real hard,i would run it a bit leaner and dropping the needle as you suggest should do the trick

Offline Devondan

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Re: Reading Pistons
« Reply #7 on: August 03, 2014, 06:14:10 PM »
You are right, its only been run in and then did two laps of practice at a classic scramble, before shoddy workmanship by yours truely brought it to a halt! .....  badly fitted kill switch! 
IT  400D - Trail riding
74 Montesa Cappra - Racing
YZ250 H - Racing
Norton ES2 500 trials
Norton 250 Jubilee - Road
Norton 350 Navigator (in boxes)
Norton 350 Single M50 (in boxes)