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Jack221 wrote:
What port timing are you aiming for by taking 2.5mm off the top?
Great question. I don't think I have set numbers in mind as an exact goal. I'm reading that with a 2mm spacer I should be netting around 184 for the exhaust and 122 for the transfers.


Just from my rough math I was getting 1.8mm of squish with one paper base gasket and one 0.5mm copper head gasket.

I figure if I added a 2mm base spacer I'd need need to deck 2mm off the top to compensate but should in theory leave me with the same 1.8mm of squish. The total thickness (factoring in the blue SIP thicker paper gasket) is 2.36mm so by cutting the top down my 2.5 should net my squish down 0.14mm or effectively 1.66 total squish? If I delete the copper head gasket I could get it down to 1.16 and change if I did my math correctly.

If I lop off 2.5 off the top and its extreme I can also get a slightly thicker copper gasket to reverse myself in theory. Let me know your thoughts! The shop mentioned they wouldnt get it touch it until the weekend.
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Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
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Jet Eye Master
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UTC quote
Jordanaitor wrote:
Great question. I don't think I have set numbers in mind as an exact goal. I'm reading that with a 2mm spacer I should be netting around 184 for the exhaust and 122 for the transfers.


Just from my rough math I was getting 1.8mm of squish with one paper base gasket and one 0.5mm copper head gasket.

I figure if I added a 2mm base spacer I'd need need to deck 2mm off the top to compensate but should in theory leave me with the same 1.8mm of squish. The total thickness (factoring in the blue SIP thicker paper gasket) is 2.36mm so by cutting the top down my 2.5 should net my squish down 0.14mm or effectively 1.66 total squish? If I delete the copper head gasket I could get it down to 1.16 and change if I did my math correctly.

If I lop off 2.5 off the top and its extreme I can also get a slightly thicker copper gasket to reverse myself in theory. Let me know your thoughts! The shop mentioned they wouldnt get it touch it until the weekend.
184/122 is a really solid target. With the right carb and jetting it will go great. Not a racer but not slow. As what 108 said this is approximately within what your exhaust can handle. Going slightly long on the exhaust duration is fine and actually preferred, if you have a reed block.

Don't get fixated on the squish clearance. It's important but not as important as the port timing. Measure exactly what you have then decide where you need to go. 2.5mm is a lot for the transfers to move (on a performance kit).

If the cylinder is decked too far, packing back up with head gaskets is bodgy. Top ring can get close to the edge and loose cooling. Ideally you want to aim for no head gasket. Then there is no chance it will leak and blow.
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Took my bore to a local 2 stroke specialist. No other machine shop wanted to touch it. Wet sanded my piston very gingerly and going to hopefully install soon. Waiting on a Diamond hone and let's see what kinda port timing I get.

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Damn… never seen such a flat cylinder…

Hope the numbers work out.
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bodgemaster
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Nice.

Took me hours to do the same with a belt sander and a plate of glass.
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Lucky
76 Sprint V, 63 GL, 62 VBB, 05 Stella, 66 Smallstate
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I wouldn't sweat that piston. The one I've been running in my Smallie looks a lot worse than that. Cleaned up the grooves, sanded the scuffs, put it back together, fixed the jetting and resumed thrashing.
SoCalGuy wrote:
Nice.

Took me hours to do the same with a belt sander and a plate of glass.
Too bad you don't know anyone with a CNC machine who owes you a favor for painting help... Razz emoticon
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Today went very well. Hondabonded the 2mm spacer to the case and trying something different this time with the base gasket. I just used grease on both sides of the SIP aramid fiber base gasket. Will pressure test tomorrow to see if that holds up. Torquing down the head produced a nice squish on the bond and gasket. Another gentleman in the Simply Smallframes Facebook group informed me to watch my copper gasket fitment and he was right. I needed to shave a bit off the OD for the gasket to sit flush and torque flat against the bore.

Final measurements:
2mm SIP base spacer
Exhaust duration 185
Transfer duration 130
Blowdown 27.5
Squish 1.01mm

Couldn't ask for anything better I think.

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Damn...you're planning on some serious revs. 130 would be 11,000 RPM's peak. Your 185 exhaust is more like 9,500 peak, though, so if you really can run 11k, you may want to raise the exhaust port at some point.

Regardless, I'm looking forward to seeing some video of this beast in action
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Yeah I'm a bit concerned about that now. When I was watching SIPs Port timing video they mentioned 130 was a decent transfer duration with a 185. Given this bore was free and the machining was affordable I'll chalk it up to a learning experience. Might buy a VMC cylinder this month to store on the shelf for the inevitable next tear down.
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You could drop the barrel a millimeter and just put a spacer on the head, too.

As best I recall, I'm only at like a 126 or 127 TD on my M1L60S.
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Jordanaitor wrote:
Yeah I'm a bit concerned about that now. When I was watching SIPs Port timing video they mentioned 130 was a decent transfer duration with a 185. Given this bore was free and the machining was affordable I'll chalk it up to a learning experience. Might buy a VMC cylinder this month to store on the shelf for the inevitable next tear down.
130 is not to much. It is getting near to too much though. Give it a try, you might like it.
Could be in trouble with the crankcase inlet. What did you do there? And what size carb?
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I think you'll be fine. I'm running 185/131 on my smallie with a PM40 pipe and it's very quick.
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One step closer. Had the hardest time getting the jug to seal to the cases. It kept leaking at the transfer port area when I put the shim direct to the cases with Hondabond. I ended up having to use a metal gasket with the crush ring in it with HB. Cases must be slightly warped at that area. Held 6psi for an hour after the fix and mocked up the pipe. New cables run and BGM conversion harness is in. I've ordered the "shutter" type brake switch which seems to open when pressed which seemed odd. But then I realized that maybe it's flip flopped when in the switch right?

Egig manifolds are an extremely tight fit with the studs and bolt conflicting with the tube. Had to use one nut and one bolt and use the old grinder. Mocked up without the tire. It'll get the tire on tomorrow and Permatex copper between the slip and the silencer flange.

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Slow and steady…

Excited to see it back in the engine and to "reset" the first start…
Loving this…
Loving this…
⬆️    About 1 month elapsed    ⬇️
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Installed all the cabling and harnesses. Slowly getting towards the finish line.
I didnt think it would be possible but you can fit the SIP speedo wiring through the headset. It's definitely not V50/V90 friendly. What sucks is that you get the cabling through, then the harness, and then realize you need like 4 more separate harnesses connections through. Almost considered running the OEM Veglia

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I quickly started to despise how to work the headset and all the cabling. Installed the SIP quick throttle.

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Next I had to think of a way to mount the speedo brain, flasher relay and regulator/rectifier. I had the OEM rubber flasher relay strap thing but it ate up a lot of space under the "nose crotch". I bought the SIP regulator mount a few months ago and it worked really well. Mocked it up with double sided tape first. Im thinking of maybe mounting a M12 Milwaukee battery in there somewhere to power the speedo should the 12V DC out the regulator not give enough juice at idle. I'll have the battery inline with a switch but thats another days problem.

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All brake cables are adjusted, clutch feels PHENOMENAL. Thank you so much 108 and Chandlerman for suggesting this combo. It literally pulls with one finger and is a dream. Going to dump 500ml of 10w30 Motul Transoil in this weekend, adjust the shifter cables and attempt first start again. CP24 is also in and the cable pulls nice with the quick throttle. Very very excited for this Spring.

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Excited for this man!

Looking awesome, it's a win already doesn't matter what happens later.

Looks super clean.
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Lucky
76 Sprint V, 63 GL, 62 VBB, 05 Stella, 66 Smallstate
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That scooter looks so sharp people get cuts just looking at it.

I'm glad to have been able to contribute my part.

On the Boo-Badge, I ground out the openings in the top of the fork tube to allow more room for wiring. That's not really an option for you, but know it's an option if it comes to that.

and, yeah, dealing with wiring in Smallies in general is a real PITA. I like what you did with that plate over it all, though. That's really good.
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