subs 80 gram reed piston w static pin

sublunacy · Mar 29, 2014

66 cc piston>>>
weight it
cut out reed window
weigh it
balance piston
------
remove lower ring.
------
install a 48cc wrist pin>>>
first tap M4 threads into oil holes
Install wrist pin with brand new M4 set screws everytime piston is removed. must use new set screws for good lock. can also be backed by m4 nut but im not doing that.
------------done

in doing that 7 grams can be shed from piston assembly. you will notice if u hang the piston 0.2 grams will tilt it off from level. so i hang mine just to see w my eye its level and balanced after a scale balance.

solid wrist pin and lighter weight..... i have 10 minutes on mine so far. time will tell.....wish me luck!

zpt

sublunacy · Mar 29, 2014

why not a ti wrist pin? price and availability> also a ti wrist pin sounds much to soft a metal for set screws> the screws will bite into ti pin making it impossible to remove and reuse.
--- floating wrist pins are garbage---
im doing my best with stock parts priced below 10 dollars.

sublunacy · Mar 29, 2014

weather here is bad but i got 10 more minutes in b4 the filter got soaked. looking for solutions today.

im going to try and get some hard driving done b4 i check the top end.

im a little sad because no power wheelies yet on th non boost ported cylinder> smooth but no kick. to tame for me. but still i want to drive it more b4 i inspect my piston.

so far im worried single ring will be fruitless. im worried about piston pin heat expansion that may require the wristpin to be fixed on one side only thus leeding to other options.

coffee first im soaking dirty wet as is the bike.

really how this started was the stock floating wrist pin is trouble / on a really good motor the pin does not spin! i can see pin wear w my calipers. leading me here.

now coffee and dry socks

.wee.

sublunacy · Mar 29, 2014

it sounded perfect at max rpm. just like it did at 3000 rpm. that is positive results

still i have other ideas but this is one of them /trial and error

sublunacy · Mar 29, 2014

i switched out my foam filter because of all the water. im using silk screen over my velocity stack again as it doesnt absorb water like the foam does.

the non boost port is lame still. i just got another quicky ride in.

sublunacy · Mar 29, 2014

maybe i should try using a second ring first but i wont likely. that test can be done at anytime. if it looks ok i will continue with the single ring and add boost ports tonight.
Im using the grubee fatty banana race pipe lately if ur curious.

sublunacy · Mar 30, 2014

i just installed o-ring seals on my butterfly shafted carb. the choke has been removed allready. seems airtight! dirt/ water issues maybe gone now.

sublunacy · Mar 30, 2014

piston looks good still. i added a boost port and raised the exhaust port up to 1 inch from tdc. the blowdown looks alot better.

sublunacy · Mar 30, 2014

i honestly didnt do well w the carb shaft seal. i think that a machinist is needed. but it was just my number 2 backup carb. its not worse anyway. what i mean is one side sealed well/ the other side did not. posibly the shaft is too worn.
simply a proffessionally modded sealed carb from daves is looking really good right now as is the speed carb. but i want to be able to switch exhaust and custom porting so im still going butterfly. i have been using a little dab of thick chassis grease to seal the factory shaft. i guess that is my answer still for now.

now the motor and exhaust being most important. problems with a free carb made 1964 is a non issue here

i guess im wasteing time now. weather is crap today.
the piston looks good anyway.

Theon · Mar 30, 2014

Should Try the elcheapo 15mm Barrel carb Sub, can be had for less than $15 on Ebay, I've had good results.

Ron344 · Mar 30, 2014

I used a single ring for a long time, no problems.

sublunacy · Mar 31, 2014

thanks ron.
the single ring weighs 4 grams. the non floating 48cc wrist pin is 2 grams lighter than stock. then piston widow and balance dropped 2 more grams approx.

maybe that doesnt sound like much/ but side by side comparison... the difference is huge. i hope my non floating pin is ok. i like the set screws as a mechanic. unscrew and slide... no pressing tapping or forced removal.

ogh one more thing> i just read a terrible review for daves throttle shaft bearing carbs... guy said he tried 3 units and they leak after couple tanks of gas so he chose the same carb unmodified and it was good. thats a **** of a review

sublunacy · Mar 31, 2014

Theon said:
Should Try the elcheapo 15mm Barrel carb Sub, can be had for less than $15 on Ebay, I've had good results.

i agree / i was eyeballing the barrel carbs again last night. i must assume for that price it is non-adjustable. i was thinking to get the adj high/low wyk for about 50 bucks.

Theon · Mar 31, 2014

The needle is adjustable as is main jet. the needle sets low speed well, but may be loctited and difficult to free.

Ron344 · Apr 1, 2014

You said you where going to put set screws in to hold the wrist pit. Are the set screws going in the piston or the rod? I would loctite them in for sure if your giong to do that.

Davezilla · Apr 1, 2014

Really, putting the set screws into the piston doesn't sit to well with me either... Adding locktite will definitely help keep them in place and if you drill into the side of the piston so they're installed horizontal it would minimise damage only to the jug and piston if they were to back out. if they back out from the bottom of the piston, they would fall into the case and could take out the rotating assembly.

What if you press fit a bronze (or aluminum alloy) bushing in the rod end and press the pin into the rod bushing letting it the pin float in the piston? it would be a little tricky to assemble, but it would also be lighter and more reliable

sublunacy · Apr 1, 2014

piston is threaded for m4 setscrews. c-clips deleted. 48cc pin in place of 66cc pin.

it doesnt need anything. the point is to eliminate rotation of the wrist pin. everything else is just details. locktight will not work in high temps. locknuts however can be used like i explained earlier.

or just live with your wide clearance wrist pin that spins wearing out the piston kit that is not free...

.............the new set screw tip pushes on the round pin.......it locks into place as the set screw tip bends in relation to the cylindricle wrist pin.

probably why it works for 45 minutes in my engine allready w zero pin movement. zero piston pin wear. zero piston pine hole wear. smoother. quieter. lighter.

it will probably flip my bike over at 3500 rpm with my custom reed kit. but you guys know what ur doing> im sure midrange power wheelies are standard w all the racing you talk about here.

sub66 · Apr 25, 2014

i put the modified sbp pipe on and took a hard ride today w that cylinder and it ran wide open w a 7250 rpm w some slow a middle speed aswell for another hour. zero vibes/ very smooth. wide open for long durations was fine at 7600rpm. pulls HARD from rolling idle of 2200 to 6200 rpm. im very happy today. happy w my walbro too.

Theon · Apr 25, 2014

Good to see you back Sub.

mrfubs · Apr 25, 2014

your filter is getting soaked with water? im still scratching my head on how it got soaked with water, are you sure its not raw fuel from not having a reed valve?

subs 80 gram reed piston w static pin

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