keith
Expert Class
Posts: 155
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posted November 06, 2003 11:14 AM
winter stripdown
Fitted a 1270 Muzzy kit last winter for this years competition. Took about ten thou off the top of the cylinder to make it flat. Stripped it down today for winter checkover and found the pistons have been just catching the head. This I assume is rod stretch at higher rpm. Just shows how carefull you have to be checking tolerances - which obviously I didn't do properly. Pistons can be saved with light machining work. How fast would I have gone without that problem? Keith
  
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Hells Dark Lord
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living life, and loving it.
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posted November 06, 2003 01:17 PM
better to catch it now Kieth, before the topend came apart on ya.....am sure it will be right when ya put it back together.....
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entropy
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posted November 06, 2003 02:58 PM
keith,
You might wanna crack the cases & check yr bearings!!!!! 
Q: How many thousanths are ur pistons in the hole at TDC???
Q: what headgasket were you using?
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keith
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posted November 07, 2003 02:19 AM
My fault - didn't leave enough deck clearance height when we skimmed the cylinder. Reckoned more compression was better. Didn't allow enough for rod stretch at high revs. Apparently you need minimum .9mm clearance. Using two base gaskets now and check, check, check. 205.5 mph - just think what it might have done if we put it together right! Keith
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keith
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posted November 07, 2003 02:21 AM
Entropy - thanks for your advice - using Muzzy three piece s/s gasket.
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psycho1122
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posted November 07, 2003 06:55 AM
 Edited By: psycho1122 on 7 Nov 2003 07:11
Keith...What's your cam timing? That can effect piston to valve clearance. I assembled my 1270 with the head left stock (except intake port "clean-up"). I boosted compression by leaving out the BASE GASKET and clay checked piston to valve clearence. I have a spacious .050 and NO PROBLEMS! 
ROD STRETCH????? I doubt it.
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entropy
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posted November 07, 2003 05:06 PM
psycho,
piston/valve clearance is one thing, pistons hitting the head in the squish area is another; gotta check em both, eh Keith???
I learn everything the hard way!
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keith
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posted November 08, 2003 01:43 AM
Entropy understands my posts. Keith
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keith
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posted November 08, 2003 01:58 AM
Now - I'm going to have to split the cases to check the big end shells. I'll replace them all whilst I'm in there. I can't understand how the pistons were clipping the head when there are people running without a base gasket which is thicker than the amount we skimmed off the cylinder. A base gasket is .27 mm or just over 10 thou. Unless that is other peoples motors are having the same problem and are unaware of it as I was till we took the head off. Keith
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keith
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posted November 08, 2003 02:03 AM
Whilst I'm in there I want to have a look at the gearbox because when the bikes really hooks up on a good launch I get a bang, bang feeling go through the bike just like the chain is jumping round the front sprocket or the dogs on one of the gears are jumping round two or three times. If the bike doesn't hook up properly or spins a bit no problem. Any input anybody? Keith
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entropy
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posted November 08, 2003 03:18 AM
keith, you get up early eh???
The banging you are feeling...
My bike it was doing EXACTLY the same thing.
The shift forks were ground down (not bent) on the "pad" areas which push the gears. Its REAL obvious when you gettum out and inspect.
I replaced all 3 forks and the 2-6? gear set. The builder also shimmed something? (not a mechanic, me). End result: bike shifts BETTER than new.
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entropy
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posted November 08, 2003 03:27 AM
quote:
Entropy understands my posts. Keith
Yes, indeedy, I understand because at one point I too had my pistons clipping the head. Keeping min .040" between piston & head is a GOOD thing. .026-7" headgasket + .015" min "in the hole"
I have made just about every error possible with my bike; but I am apparently always searching for more things to fuk up!
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keith
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posted November 08, 2003 05:13 AM
I was going to have a look at my gearbox when I checked the big ends. Now I definitely am. I'm not up early, it's 1300 hours here in the UK. Keith
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Ra12r
Zone Head
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posted November 08, 2003 05:20 AM
Keith, do you do your own work??
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keith
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posted November 08, 2003 08:35 AM
We do it in our own shop workshop. Small Kawa dealership in Cornwall, UK, five staff and me. Keith
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entropy
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posted November 08, 2003 10:06 AM
Cornwall??? damn! not exactly next door to London  I'm gonna be in Reading Mon-Wed next week but I guess Cornwall is not "just a short taxi ride" from there, eh?
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keith
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posted November 09, 2003 07:44 AM
Bout 4 hours if the taxi gets his foot down. Then there's the speed cameras too. Keith
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keith
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posted November 11, 2003 10:06 AM
On the selectors there are small contact pads on the ends. These are I beleive hard faced with stellite or something similar. The manual gives a minimum thickness for these pads and also a maximum width for the groove on the gear thay contact with. Entropy - any chance you could ask your buider about the shimming - I'll try to figure it out for myself but another opinion is always welcome. Needless to say the air shifter gives the selector forks a good bang. I start the day with 120 psi in the tank. Could this be too much I wonder? Keith
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Ra12r
Zone Head
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posted November 11, 2003 07:46 PM
Entropy's tranny guy has some special shims that decrease the play between the gears. His tranny is real tight. However, If you take and polish the dog legs on the gears, you will be increase the smoothness of the entire tranny. Very positive shifts and the tranny feels real tight plus new shift forks. Use a very fine flat file to polish the dog legs as they are hard metal.
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keith
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posted November 12, 2003 05:58 AM
Thanks for you input. I've checked the shift forks and they are below the service limit of 5.8mm. One is down to 5.74mm. No 1 bigend is definitely looking a bit distressed and the mains also look a bit sad. So new bearings all through, new shift forks and some polishing and back in she goes. Keith
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swft
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posted November 13, 2003 08:09 PM
Ra12r - Didn't you post pics when you replaced the shift forks? As I recall, you can do it without pulling the motor, right?
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keith
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Posts: 155
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posted November 17, 2003 03:00 AM
Its all coming together nicely. New cams will be here Weds. Muzzy racing valve spring set is in. High pressure fuel pump is in. New mains, big ends and bolts are here. Throttle bodies have been bored out and matched to the rubbers. Reassemby starts this week then dyno to remap the extra fuel and breathing. Can't wait. Keith
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keith
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posted November 21, 2003 03:49 AM
Just reshimmed the valves. Lucky just got the clearances right using the fattest Kawasaki shim (3.00) on seven of the valves with the others using 2.90 or 2.95's. Now have to take the head off again to plasticine the valve pockets to check the clearance. No leaving to chance this time! Keith
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