Is this a sound plan for a sleeper A55?
- bore out stock intake port to 17.5mm
- custom 17.5mm ID intake PHVA 17.5mm and filter to fit under stock motor covers
- taller gearing for more top end speed
- unlimitted rev CDI box
- expansion chamber pipe
Here are a couple of photos of stock intake and exhaust ports ID's.
Enlarging the ports and matching the flanges will get you a little, but if you do not alter the port durations the gains will be negligible. Just re gearing, a side bleed estoril with an upjet will get you into the high 40s. With a proper port job and a solid tune a stock a55 top end can get you u into the mid 50s.
Ditch the stock pipes and astral side bleeds either get an airplane exhaust 70cc and modded to fit kind of loud depending on your carb setup a shorty intake will perform best and will probably be the quietest if it had an air box that was properly figured for restrictive airflow or rather unrestricted or slightly restricted if it's slightly restricted it will be quieter
Granny quiet a pug exhaust that has been derestricted
Drop your bottom base gasket so that its metal-on-metal make sure it's flush you can use yamabond or some such poop or make a paper gasket something extremely thin and then time accordingly.
Depending on where you live and the elevations involved such as is it hilly is it a level area that will determine what gearing's you should use just because you have taller gears does not make you go faster in fact it's the reverse if you want better engine and performance you make the front taller every 2 on the front equates 2 12 teeth rear or 1 to 6 but it also goes by diameter if you want an overall good performer in hilly areas for example you would go 2626 a stock OEM A3 is GERD 2413 moderate 26 24 you get the idea depending on your setup and where your clutch engages and when your pipe hits it's all a juggling Act and it takes a while foreign it all comes together it is a beautiful thing if you are a 75 lb soaking wet teenager and you take a wild ride on my Tomas you're going to be flipping a wheelie from takeoff or it's going to weasel right out from under you cuz mine's a torque monster it will get you a fast off the line but the top speed is limited it's made to lift my 200-pound body up big Hills now if I dropped it 26 13 I'd be bugging and I'd be passing cars on the freeway put on a moped 35 is plenty fast especially if you can go up a hill 35 that is the ultimate goal for me and not pissing off the neighbors by having firecrackers going off at 3 in the morning because I'm hungry because I'm stoned and I need a hoagie stat
I love all the ideas - but would you tell me what a hoagie is please?
> Hywel Pugh Wrote:
> -------------------------------------------------------
> I love all the ideas - but would you tell me what a hoagie is please?
> Daniel '' Wrote:
> -------------------------------------------------------
> Enlarging the ports and matching the flanges will get you a little, but
> if you do not alter the port durations the gains will be negligible.
> Just re gearing, a side bleed estoril with an upjet will get you into
> the high 40s. With a proper port job and a solid tune a stock a55 top
> end can get you u into the mid 50s.
Exactly. Don’t just bore the holes bigger. I have seen lots of kits where people just made bigger holes and fucked up the port timing to where it was running better stock.
https://www.mopedarmy.com/forums/read.php?7,4153651,page=2
Andy and I did some porting a few years ago on some A3s. I actually did a port map and did one for what I usually do with an A55 cylinder. It may be useful. (edited)
Wooops...that is a stock port map. NM. That thread has some info on what we were talking about.
I haven't gone through all the threads yet but is there a tried and true, plug and play port map for ported A55 cylinders?
I found this nice summary of a55 porting threads.
I don’t think I have ever seen that port map in the wiki. Now I don’t go searing for a55 stuff that often but it is pretty interesting how his is listed that some of the ports are a couple mm bigger than I measured. Interesting.
Spacing the cylinder up so that the exhaust clears all the way and decking the head and making a good squish band helps a lot too. Also the stock ignition will work great for forever. Recently I took a cutting wheel to the starter gears on the flywheel and cut them off. Made a big difference taking all that weight off the flywheel
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