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Thread: Looper exhaust porting
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12-04-2013, 05:12 AM #76
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12-04-2013, 11:36 AM #77Scream And Fly VIP
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The ring tips slide over the finger ports. The early closed deck blocks were this way before they moved the pins, IMO opinion they were better because with them moved they are close to the exhaust which limits exhaust porting.
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12-04-2013, 11:47 AM #78Screaming And Flying!
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Hi Racer
would the stock piston (with added finger ports) be ok to 8000 or would you need a forging assuming your not replacing them every 1/4 mile?Last edited by powerabout; 12-04-2013 at 12:00 PM.
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12-04-2013, 04:18 PM #79
I haven't tryed to degree the ex ports but measuring from the deck I wanna say the port centers were right at 1.6 with a good bit of eyebrow in the port, but the block has been decked down tight enough that it can't run thin gaskets, comp with stock 200xp heads/idle reliefs closed/thick gaskets was 150.the plan is to tighten up the front after yamaha ignition. It looks like it could use some re-angling of the reed blocks once you mill the front, the top reeds can't be doing much.
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12-04-2013, 04:26 PM #80Screaming And Flying!
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was the block decked in relation to the crank so the timing will then be the same if the ports are same height?
( and the bores are pointing at the crank, loopers are bad for that)Last edited by powerabout; 12-04-2013 at 04:32 PM.
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12-04-2013, 06:10 PM #81
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12-04-2013, 06:25 PM #82Screaming And Flying!
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how far do you think you can drop the reeds in?
I think a bit of grinding on the reed block and in the crankcase would allow a bit more, the screw bosses and recesses hit and the bulge in the crankcase for the inlet mounting screws are huge.
Not to mention due to the recessed reeds in the inlet there is a ton of volume being added around the reed block that is asking to be filled in
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12-04-2013, 07:22 PM #83
I've never done much stuffing, I always just tryed to find a prop that would slip a little to help with the bog. But Kevin said you could definitely go .090". What we need to do is cc the crankcase and see how much volume needs to leave. What I was talking about was when you mill the front and drop the reed blocks in closer the top reeds get real tight to the roof of the crankcase, if you anled the reed blocks down more you could center the reeds better in the case. You'd be sacrificing the direction of flow for better volume through the reeds though and would have to find a happy medium.
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12-04-2013, 07:42 PM #84Screaming And Flying!
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The more I look at the front half the more think of a straight in and its all very simple and where's the downside?
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12-04-2013, 08:22 PM #85
There is no downside to straightening the flow if you keep the primary compression ratio right. That's what the x-front half does.
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12-04-2013, 10:06 PM #86
I have herd of guys going a bunch more but it requires more work. Yes the recessed reed blocks add a ton of volume that can go away.
You can re angle the blocks and take more out but you still have to do some grinding especially on #1. I have herd of guys cutting the intakes also to get more squeeze. We put used stock reeds and used pistons in beefs budget beater 3.3, I wasnt about to spend another day cutting cages and intakes . It has turned every prop we put on it over 7k and its still 4 stroking rich so we have our hopes up just need some time to tune it. 1.62 sporty goes under it this weekend then we will bump compression from 125-130 to 150 and see what she's got
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12-04-2013, 11:04 PM #87Screaming And Flying!
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I was thinking of a bit of grinding to get the reeds angled in toward the crank and then also angle the inlet manifold so the carbs follow.
a bit of work but major bling factorLast edited by powerabout; 12-04-2013 at 11:07 PM.
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12-04-2013, 11:23 PM #88
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12-04-2013, 11:26 PM #89Screaming And Flying!
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I was even thinking of inclining the throttle bodies ( will make a longer induction path for the 3&4 but thats Ok as the exhaust is shorter in those) but will get a straighter shot down the hole?
Tons of stuff to do but you need a dyno to test it all
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12-05-2013, 12:10 AM #90
What material do you guys use when it comes to stuffing the CC?
any ideas when it comes to jetting after these mods;
2,7L, Bridged Exh widened to specs and pictures in this thread, intakes matched an polished, rodslot cleaned for smoother flow, all sharp turns/angles in intake mainfold removed for better flow, CCMS sport reeds, bobs snout. 91oct with 10% ethanol, 18deg bdtc, honed and re-ringed.Last edited by Captain75; 12-05-2013 at 03:48 AM.