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Post by Juan on Apr 23, 2014 20:50:52 GMT
I'd not use anything other than SAE 30 with cork clutchplates. If using composite 'plates then you can look at alternatives.
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Post by db971 on Apr 25, 2014 20:52:28 GMT
Juan, have some parts for the clutch and will have a question or two regarding this and post tomorrow. I have tonight dry assembled the casings with the following base gasket spacers (8mm +1.5mm + 0.5mm). I have bolted the cylinder down and I'm measuring 0.66mm from the top of the piston to the gasket face. Exhaust port I am measuring approx 70 degrees. I am struggling as to what and how I carry out any other checks or measurements??? Can someone advise. Thanks P.s I fitted the drt crankshaft 53mm stroke and 105mm conrod and skimmed 1.5mm off the gasket face TDC to gasket face 0.66mm 10mm total packer fitted Exhaust opening measurement
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Post by jonnysnatchsniffer on Apr 26, 2014 15:33:07 GMT
measure the duration that its open for
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Post by db971 on Apr 26, 2014 18:58:24 GMT
Measured the main transfer ports, bottom of port 0 degrees move crank till piston closes port at 41 degrees.
Measured exhaust port - bottom of port 0 degrees move crank till piston closes exhaust port at 70 degrees.
How does this sound??
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Post by spiderwebb on Apr 27, 2014 1:25:32 GMT
zero out the deg disk @ the top of the exhaust port turn over the engine fully... all the way open and then closed
that is your exhaust port timing
should be around 180 degs for most go fast kits
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Post by db971 on Apr 27, 2014 10:51:23 GMT
Thanks Spiderwebb,
I have measured a few options on this as I thought I was aiming for 127-182.
Measured top of exhaust port rotated thru tdc and bdc to bottom of exhaust port - 235 degrees.
Measured top of exhaust port rotated thru tdc to bottom of exhaust port - 126 degrees.
Measured top of exhaust port rotated thru tdc to top of exhaust port - 166 degrees.
Any thoughts?
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Post by GeorgeS on Apr 27, 2014 15:35:45 GMT
Easiest way is to measure top of port opening (with a feeler gauge) thru BDC to top of port closing (again, with feeler gauge). Do each port like this.
From your TDC measurements minus 360 would suggest your timings are 125 / 194, but it's worth doing them again to be sure.
Edit: just read again and ignore that for exhaust as you gone top of port to bottom, so it won't be 194, it will be less.
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Post by db971 on Apr 27, 2014 22:13:35 GMT
I've checked the measurement again as follows: took piston to TDC, turned crank till piston reaches top of the exhaust port (opening of port), zero'd disk, turn crank down to bdc up to the bottom of exhaust port (closing of port) and I get a reading of 125 degrees.
Is this the correct way to measure the exhaust timing? If so what would be my next steps. Really appreciate any help as I'm pulling what hair I have left out :-)
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Post by jude on Apr 27, 2014 22:24:30 GMT
You need to continue the rotation until the exhaust port is fully closed. You've measured to the bottom of the exhaust port so still a good few degrees to go until it's closed again. Fully closed, all the way down, back up again until fully closed...
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Post by db971 on Apr 27, 2014 23:17:00 GMT
Thanks Jude.
Fully closed to fully closed on exhaust port is 193 degrees. So I have 125/193 as the exhaust port timing.
What is the next steps - is this ok for the franz pipe or do I need to add in or remove any of the bas gasket/spacers?
Thanks
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Post by GeorgeS on Apr 28, 2014 5:58:56 GMT
Repeat that process on the transfer ports to get the number for those as I don't think moment you know they are at 125.
From what I had red the franz likes the exhaust around 190-192 so you're about there.
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Post by jonnysnatchsniffer on Apr 28, 2014 11:10:29 GMT
now measure the squish it wants to be 1mm, you may still have to fuck around with base gaskets to get it right and this will alter the timings if the barrel has to go up or down, you should use the head gasket too
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Post by db971 on Apr 28, 2014 14:41:51 GMT
Cheers JSS & GeorgeS. Will check the squish tonight. The main port was measuring 129 degrees from top of main port opening to bdc to top of the main port closed
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Post by db971 on Apr 28, 2014 18:51:35 GMT
Checked the squish and I am getting 1.51mm with the 0.5mm copper head gasket fitted. Port timings 129/193
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Post by jeanshorts on Apr 29, 2014 0:33:33 GMT
We'll that base spacer makes it easy enough to remove height. Those timings seem high and I wonder if you've got the measuring right. Easiest method IMO:
From TDC measure degrees to the top edge of exhaust and the use your maths Example: 94 degrees from TDC to top of exhaust port. Times 2= 188. This represents the amount of degrees your exhaust is CLOSED. Subtract that(188) from 360=172. 172 is the duration your exhaust is open Do the transfers exactly the same Example: 119 from TDC to top of transfer X 2=238. 360-238=122 open transfer duration Blow down = 119 - 94= 25 degrees from the top of the exhaust port to the top of transfer port. Maybe measure once more.
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Post by db971 on Apr 29, 2014 16:51:24 GMT
Checked the measurements as you mentioned (jeanshorts) : 84degrees tdc to top of exhaust port =84x2=168-360=192 degrees, tdc to top of main port 120x2=240-360=120 degrees.
What range do you recommend I shot for, for both main & exhaust . I am looking to run a franz pipe on my set up.
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Post by GeorgeS on Apr 29, 2014 17:11:57 GMT
192 is good for the franz (from what I read), but the recommendation I've seen for transfers is 125 (from jonnysnatchsniffer I think, so reliable). I think that leaves you slightly awkward in that you can't raise your barrel any further without going past the recommended exhaust timing (raising the barrel increases the time a port is open), so you'd perhaps need to open the transfers up by grinding away the upper edge so they open 2.5 degrees earlier (increases 2.5 down & 2.5 up adding 5 degs extra opening giving the 125 desired). This could be tricky without a right-angled grinding tool. What barrel are you using there? Do the measurement on every port in the bore for info & to check we're all talking about the same thing. I might be talking bollocks here, someone with more experience can put us both straight if so!
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Post by jeanshorts on Apr 29, 2014 18:29:35 GMT
Lesson here, set barrel for transfer height, then cut exhaust height. Adjust squish with head gasket or top skimming. And squish might be set prior to exhaust really.
Raising the transfers is a bit specialized and probably best left to an expert.
Here is what I would do at this point based on your 1.5 squish with .5 head gasket(please double check) assuming no base gaskets were used in your measuring thus far 1. Skim base spacer 1.3 mm. This will allow use of the .5 mm premium gaskets on either side of the base spacer. I've made the assumption that you have come up with 1.5 using no base gasket at all mind you. Then mock up top end with spacers and gaskets. You may need the .8 head gasket or what ever one is called for to get proper squish
2. Once you've set squish just right (1.3?), put blueing on the cylinder and mark your desired transfer height and exhaust height (remeasure).
3. Send it off to a specialist to correct it.
That's what I would do my self. I'm sure others have opinions that vary
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Post by db971 on Apr 29, 2014 19:34:48 GMT
I have read back thru the post and I was aiming for the 192 degrees for the exhaust port timing. I haven't touched the main ports. So Im struggling to understand if maybe I am misreading or doing something wrong - this is my first time porting.
I have a Polini EVO 130 kit with a drt 53mm stroke crank with 105mm conrod using the rotary pad. I also have a franz pipe. I have skimmed 1.5mm off the gasket face on the casings and opened up the intake and web for crank.
So what is the best way forward can I send this stuff away for someone to check or is there somewhere local in Scotland (prepared to pay to get this sorted). Thanks in advance
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Post by GeorgeS on Apr 29, 2014 19:53:16 GMT
The first part of the process is to work out how much the barrel needs to be raised to get the transfers at the required timing. You're using the same crank as what I have in my in-progress build & I think I packed up the barrel by just over 9mm if I remember right (I haven't machines the case face). After you've done that you can then check the squish & work on the exhaust port. I suppose you could live with the lower inlet timings but I've got no idea how that would affect performance, it's bound to be a negative. How much would a new barrel be if you were to start again? Is it worth checking that against the cost of sending it off? If you're brave I see there's a dremmel right-angle attachment for around £23 Having lately been working on lowering the bottom edge of transfers without a right-angle tool I can tell you its a wanky job and very easy to mess up. Bad luck mate, I guess you're not best pleased right now but at least you've got some options, it will just cost you a few extra quid.
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