Thoughts on cutting this 3rd transfer/boost port into a stock puch cylinder? Angled at the spark plug and fed with scallops running next to the intake port. Opening at the same time as the transfers or maybe 5 degrees before.
I was gonna go for a tccd/dmp style boost port fed from piston holes/window, but they'd drop into the intake at bdc.
Are you going to add a reed block? Might be too much I take without one.
If you use a tccd50 piston, the single higher ring will let you put the conventional boost port in above the intake.
I know some folks have had success with these kinds of unconventional open transfers, I've played with stuff in the past but I find it's best to keep it simple stupid and just focus on getting it breathing and working good as it is.
I think you'll get a lot better results in terms of all around performance from adding a reed adapter and porting big intake.
It's a stock cylinder, so if you are bored: go for it. But you're increasing case volume a bit, and probably causing more turbulence and lower wash speeds across the piston dome. I'll agree with Graham that standard porting would increase the chance of success, but if you're just mucking about on old stock part, go for it.
Thank you for the feedback, it is just a stock cylinder I'm bored and playing around with. Half of my reason for this was under piston cooling, but running the transfers all the way to the cases negates that. The other half is I wanted to aid scavenging at low end and increasing transfer area a bit, possibly aiding in top end power.
I'm trying to get the most I can out of just stock maxi parts aside from a 25mm puch header from treats. The starting combo is high torque cylinder and head, 2 ring dykes piston, bing 12 carb, bing 14 intake, stock air box, and something cobbled from a stock exhaust can that looks stock.
So far I've widened the exhaust port 2mm each side and went up 2mm, might go to 3mm up. Matched it to the 25mm header. Going to stack thick base gaskets for now to, with compensation for gasket compression, to add another mm to exhaust and transfers. Piston edge with .5mm gasket is at deck height so I'll be sanding the head to ditch the factory recess and running no head gasket. Theoretically I should have 1mm squish.
I have the expected port timings written down but I locked up the garage for the night, I'll post them tomorrow when I get out there.
Anyway I thought of a new idea.
I could feed these with corresponding holes in the piston outside of the intake window. Hopefully succeeding in both of my reasons for trying this. (edited)
That looks better to me. Go for it and post pics.
Typically advancing timing will generate more heat by adding rpm at the sacrifice of a bit of torque. Usually depending on the amount of timing being added, gearing will need to be increased so as to not burn up the motor. A temp gun will definitely be need to monitor motor temp. I have never used a motor dyno. I add 2 degrees at a time a check temps every 3 mins. 420F is perfectly safe in my book.
Here's the bing next to another bing 12. I drilled it out to 14.3mm (9/16") and matched the intake side to the intake which measures 14.7mm. Polished the air box side.
I plan on gutting and smoothing the factory air box. Where the cylinder meets the intake will be opened to like 16mm, and intake matched to that.
Probably gonna split the cases and open the transfers up a bit and match them.
I have 13, 14, 15, 16 and 40,45 (stock maxi sprocket array lol) to play with for gearing once its together.
More things to add but my fingers are getting tired of typing lol.
> EH 📣FCC of the QCB wrote:
> -------------------------------------------------------
> That looks better to me. Go for it and post pics.
Gonna sleep on it and do something with it tomorrow. Its happening one way or another lol.
The air filter side of the bing venturi was pretty buggered when I got it, You can see that in the second pic. I just smoothed it out as best as possible and polished it after drilling it. Figured I'd try the one that's already been fucked with first.
You're already probably over ported for a high torque, make small changes and run it each time. Definitely no more height on the exhaust until you feel it out.
The high tq is mostly restricted by the exhaust port but also the very long piston skirt.
I've had them over 40 with a stock pipe just with absolutely minimal porting. It really doesn't take much.
Looking at the map with a clearer head, I remembered the measurements and that i went up 3mm already on the exhaust. Shoulda written them on the map but there was alot of drawing and erasing going on with this boost port idea. Transfers measure 36mm from deck and exhaust is 30.5mm. Exhaust will definitely be left alone until i test it,
No spacer:
Exhaust 144
transfers 106
blowdown 19
intake i don't remember, 102 maybe? it was in the low 100s
boost ports - same as transfers maybe more if i have them open earlier
With 1mm added to the base accounted for:
Exhaust 150
transfers 114
blowdown 18
intake in the 90s with base spacer- to be determined, gonna attack that slowly, probably end up in the 110-120 range, spacer or not.
boost ports - same as above
I feel under 20 degrees of blow down is still in the safe zone especially if those boost ports actually help and i get the pipe dimensions close enough to work with it. Another mm will put me at 158 ex and 22 blow down. I don't know if I can cobble something to support that well enough with stock exhaust parts. Worse case, I have a cool looking paper weight showing me (and everyone reading this) what not to do.
raise the exhaust to 165 and then space the cylinder up, to 125 transfer
> classic carl jepsen wrote:
> -------------------------------------------------------
> raise the exhaust to 165 and then space the cylinder up, to 125 transfer
This dude is a fuckin idiot don't listen to anything he says.
why not
start at 150/114/18 blowdown
raise exhaust to 165 and blowdown is 25.5
then space it up to 175/125/25.5
> classic carl jepsen wrote:
> -------------------------------------------------------
> why not
>
> start at 150/114/18 blowdown
>
> raise exhaust to 165 and blowdown is 25.5
>
> then space it up to 175/125/25.5
Because spacing it to 175 from 165 would put the transfers at 128 and blowdown at 16.5.
Dont mind the skips they look way worse than they actually are. Minor scuffs more than anything. Never cut a finger port before so bear with me.
Omg 😱. This is going to be great!
And drilled stock carbs 🤩 I’m in heaven!
Boost ports done
Intake opened to 16.5 at gasket surface, matched and textured. Lowered floor 2mm for now and widened 2mm each side, should be 114 degrees intake duration. If I need more, itll come off the piston.
Just have to drill holes in piston and sand head down now, then the top end is done and I can work on the pipe. Gonna leave the transfers alone for now. If this feels good, I'll open and match them.
> EH 📣FCC of the QCB wrote:
> -------------------------------------------------------
> Omg 😱. This is going to be great!
>
> And drilled stock carbs 🤩 I’m in heaven!
Thank you lol. I hope it works out. Worse case I got a fast looking brick, right?
Worst case you gained valuable knowledge. Very cool way to go, trying shit is always the best.
> Graham Motzing wrote:
> -------------------------------------------------------
> Worst case you gained valuable knowledge. Very cool way to go, trying
> shit is always the best.
Truth! I’m loving this.
Honestly, on stock kit porting, my go to is about 2mm wider on each side and 2mm lower floor. With a matched intake. This thing is going to rip. Can’t wait! The process is worth it even if you biff it at the very end. Your doing stuff most people don’t dare to attempt.
> EH 📣FCC of the QCB wrote:
> Your doing stuff most people don’t dare to attempt.
Ain't that the truth, it was impossible finding information on this so i figured I'd post my progress. If it all works, its going on the maxi I started a resto thread on but never finished. I was going to leave it alone, but I can't leave anything alone so sleeper it is. I'll be back at it tomorrow afternoon, get the head and piston done so i can start measuring the pipe. Any one happen to have the measurements of a stock maxi muffler can? like the cone angle and length? for right now, all I know is the belly is 56mm i.d.
Here's a pic of the carb to intake matching.
(edited)
There really is no "belly" or cone to the stock pipe. It's just a straight pipe with a baffle in it.
> Dirty30 Dillon wrote:
> -------------------------------------------------------
> There really is no "belly" or cone to the stock pipe. It's just a
> straight pipe with a baffle in it.
Looks like a cone and belly to me. The inside is just a straight pipe, but the can is close enough to a diffuser cone and belly that if i add a baffle cone in the right spot, I should be able to get a "tuned" length from it.
You can cut the header portion, gut the baffle and build a slide in convergent cone to good effect, but it's less a matter of equations and more a trial and error thing, mostly due to the fact that you can't really shift the header length or divergent cone position, just the convergent. While that will still have an effect, your dwell section will always be weird.
I'm sad to say I just scrapped 3 stock Puch pipes, I would have said come grab them. I'm in CT too.
Please, no more stock pipes lol
I appreciate the offer though, if you still had them. We should get together for a ride some time. Im trying to setup a 100ish mile loop in northwest CT to host with my riding group this spring or summer too
With the 25mm header I can shorten it quite a bit but it'll still be long. I'm gonna start long and work my way down though. Trying to figure out a convergent cone might try a metal funnel, they're cheap and might work well enough.
Im in Watertown and spend alot of time working in NW CT, really nice riding area. Definitely keep it posted when you have something concrete.
Have yet to go on a group ride since moving back to CT from the city, so I'd be down so long as scheduling works out.
No update today, went for a little ride after work and I'm pooped. Next few days will be real nice so I'll probably be riding instead of playing mad scientist. might pop in
> Dirty30 Dillon wrote:
> -------------------------------------------------------
> Im in Watertown and spend alot of time working in NW CT, really nice
> riding area. Definitely keep it posted when you have something concrete.
>
> Have yet to go on a group ride since moving back to CT from the city, so
> I'd be down so long as scheduling works out.
Are you the guy my mom sees riding past Watertown meat center?? I'll definitely post it once we figure it out. We're out riding at least once a week though if you wanna tag along for a weekly ride. We can loop through Watertown and you can show us some good roads out there. We don't go over there much.
Maybe?? I haven't been riding THAT much, but I'm literally 5 minutes from there and head down main St. often.
I haven't seen another rider in town yet, but there are a few die hard scooter people I see riding. CT had always been hard up for groups. I'm planning to head out to the Spark Cycleworks X Strange Ways ride in New Haven later this month.
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