Piston mods and weight difference of pistons etc...

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mapbike

Well-Known Member
Mar 14, 2010
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Well I went to put the grubee back together and broke a ring, I don't have a new set so I'll have to order a set. I did take a picture of the piston without rings.
Dang thats a light piston......

Not sure of who all has the rings you need but I know BGF on ebay has always had them.

Map
 

GearNut

Active Member
Aug 19, 2009
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Be careful with the acetylene torch. Too much heat could distort the tube in ways you don't want. 350 to 400F is plenty enough. No need to get it cherry red! Also, if the frame was made with brazed lugs you don't want to undo those either.
 

mapbike

Well-Known Member
Mar 14, 2010
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Central Area of Texas
Be careful with the acetylene torch. Too much heat could distort the tube in ways you don't want. 350 to 400F is plenty enough. No need to get it cherry red! Also, if the frame was made with brazed lugs you don't want to undo those either.
350-400* what metal are you gonna get Cherry red at that low temp.....lol...

Thanks for the concern though, been amature metal working and welding for over 30 years so im good with a torch and understand the ins and outs when it comes to heating things.... but unfortunately heating and using the slide hammer set up I made didnt do the trick so I took a 1/2" X 4 1/2" grade 5 bolt, cut the head off of it and slid it inside the stuck seat tube, then I took a ball peen hammer and peened the lip of the seat tube inward until it was tight against the new shaft and the after a good cleaning with a wire brush I fired my acetylene torch up and brazed the new shaft to the old tube, its a permanent very strong fix now, that tube is dang near welded into the frame and since the old tube was one of the old type that tapered down to 1/2" at the top where the seat mounts the 1/2" bolt mod was a perfect solution to the problem since my seat hardware was already set up for the 1/2" stob.... so WFlyer back in action, now Im gonna give it some more ride time before I start working on a quieter exhaust set up for it, the wide open type exhaust Im currently running on it performs great but is just to dang loud.

Thanks for all the tips and advice

Map
.wee.
 

Greg58

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May 1, 2011
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I got my rings Wednesday after ordering them Sunday, not bad for the mail! Man it runs good,
After going through it and replacing the bearings and porting, along with the piston mods it is smoother than before. That's the great thing about this engine, I must of got a well balanced crank because it does not vibrate.
 

mapbike

Well-Known Member
Mar 14, 2010
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Central Area of Texas
I got my rings Wednesday after ordering them Sunday, not bad for the mail! Man it runs good,
After going through it and replacing the bearings and porting, along with the piston mods it is smoother than before. That's the great thing about this engine, I must of got a well balanced crank because it does not vibrate.
Thats great..... glad to hear it turned out so good for ya....

Im gonna do somethings different on my next build, I have another dax lower and another engine that is new but has been in pieces in a box for about three years now, I'm gonna build it with less timing work done to piston but with a well notched piston skirt and drill some holes to lighten it. Since the crank is already out Im gonna chuck it up in the lathe and true it best I can and put that old LEB engine together again.

You're making me wish I could find an older 48cc like you have Greg.....

Map
.wee.
 

Greg58

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May 1, 2011
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Map I've got a question for you, I have a 66cc engine I bought at a deal on eBay. I placed a low bid on it and won, its a no name engine with a 1 1/6 pin height with huge transfer ports both in the case and in the cylinder. I pulled the bgf 48cc off of the cranbrook to do a little work on it so I stuck the 66 on. This engine came with the spark plug hole pointing forward and I've always put it back on that way, today I thought Id turn it around for a little more clearance from the Cdi. With the plug firing toward the exhaust port this thing runs a lot better, my question is why?
 
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sub66

New Member
Apr 25, 2014
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i think thats what others reported aswell i believe. exhaust port opens first is my only answer for it. damn im going to have to rotate something. mine faces towards intake cause i have little choice.
 

Theon

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Jan 20, 2014
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poor flow across the plug?
I run my head 'backwards' on the Phantom, but have removed a lot of metal to get the head to work better this way.
Straight fire head is the answer, will run better again.
 

maniac57

Old, Fat, and still faster than you
Oct 8, 2011
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Map I've got a question for you, I have a 66cc engine I bought at a deal on eBay. I placed a low bid on it and won, its a no name engine with a 1 1/6 pin height with huge transfer ports both in the case and in the cylinder. I pulled the bgf 48cc off of the cranbrook to do a little work on it so I stuck the 66 on. This engine came with the spark plug hole pointing forward and I've always put it back on that way, today I thought Id turn it around for a little more clearance from the Cdi. With the plug firing toward the exhaust port this thing runs a lot better, my question is why?
Better cooling and better chamber shape for the porting. The angle plug heads have very poor cooling around the plug boss. I try to always run mine plug facing back. This simple trick can make the difference between detonation and good power on marginal heads. You might also consider running two base gaskets. This removes just enough load to let it run good sometimes. Also get a tiny bit of port timing change along with better durability doing it this way rather than head gaskets.
 

Greg58

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May 1, 2011
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I always run the 48s with the plug firing toward the exhaust, it is funny how something this simple can make a engine run a lot better. Its kinda like when I was fooling around with motocross bikes as a teen and found the pipe that was just right for the bike, the little things make a difference.
 

mapbike

Well-Known Member
Mar 14, 2010
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Central Area of Texas
Well Greg I cant give you a high and mighty super technical answer for why it helps as has been reported by others before, but I would think that it just simlly has to do with the engine having better and more complete combustion of the air fuel mix...

These are my thoughts on it Greg

Map
.wee.
 

60weight

Member
Sep 15, 2011
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Dallas
Thanks Map!!
great reading..I guess Ya know Ive gotta spend some more $ and time now :)
Your Western Flyer frame sure looks just like my best bike,its a Sears Spaceliner.
Would like to sent a pic,but only just figgered out how to textem.
You went to alot of trouble there on Utube..great vid!
 

mapbike

Well-Known Member
Mar 14, 2010
5,502
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Central Area of Texas
Thanks Map!!
great reading..I guess Ya know Ive gotta spend some more $ and time now :)
Your Western Flyer frame sure looks just like my best bike,its a Sears Spaceliner.
Would like to sent a pic,but only just figgered out how to textem.
You went to alot of trouble there on Utube..great vid!
Yeah the Spaceliner is the same frame, I think they are both made by Murray, the WF will get several changes in the future, I plan a fuel tank behinf the seat and a complete strip down of the frame and a fresh bright paint job, im also gonna put some bmx tread tires on it, those current tires are a little squirrely on my dir roads around here so I need better grip, its also gonna get a different exhaust and some other odds and ends.

Glad you were able to make it through my youtube video, im not used to doing things like that so it took me a while to make my points, I just know how much I enjoy wat hing others videos that show things they are doing so I wanted to make one on those piston mods and the weighing of things I had done.

Looking forward to seeing some pix of your Spaceliner in the future and seeing what you do with it.

Map
 

Greg58

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May 1, 2011
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Map I learned a little about vibration when I put the 66 back on, the first strap is what came with it, the second is like I put on this time around, the third is a collection of straps of different thicknesses. This engine vibrated bad at 28-29, with the heavy strap it is far less. Even tho the strap was tight the holding pressure probably was not enough. The black strap is what's on now, can only add one pix at a time on I phone.
 

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rogergendron1

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Sep 18, 2013
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the first thing i do is port then i do the piston work.... for piston mods i ramp the transfers and exhaust to gain more duration timing for bolth then i trim the entire intake side 1/4 inch of the whole skirt so the intake side skirt is 1/4 shorter than the exhaust side, then i run a titanium wrist pin thats 50% lighter than the stock one and use a stihl chainsaw needle bearing .....

i do this to ALL builds... the motor vibrates way less and reves to around 9,000 rpms safley with the shihl bearing and because its so mutch ligher it reves up a whole lot quicker and with the ramping mods and the trimmed intake skirt it produces a lot more torque with the longer duration of the port opening, albeit at a bit higher rpm but the differance is night and day even on a stock motor with just a port clean up and standard comp.

this setup benifits greatly from a decked jug for proper deck hight and a higher comp head with a squish band and a larger carb.
 
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mapbike

Well-Known Member
Mar 14, 2010
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Central Area of Texas
Map I learned a little about vibration when I put the 66 back on, the first strap is what came with it, the second is like I put on this time around, the third is a collection of straps of different thicknesses. This engine vibrated bad at 28-29, with the heavy strap it is far less. Even tho the strap was tight the holding pressure probably was not enough. The black strap is what's on now, can only add one pix at a time on I phone.
Wow that second strap is a good and thick one, wish I. Ould come acroos a few of those myself..... I have found that very secure mounting with NO rubber between frame and engine is the best way, I have an idea for a mounting set up I may try someday when I find time to build it, may not be worth a hoot but then again it might be OK, I guess Ill know when Im able to do one up someday. It will be a muti mount which will have two pieces for front and back with some shock absorbent material between the mounts and not between engine and mount, what I have in mind will utilize more than just the two mounting area in front and rear of engine so the stress will not be soley on the small M6x1.00 studs or bolts, I have never seen anyone build what I have in mind so it will be interesting to see how it works when I get a chance to work on the project.

Map
 

Greg58

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May 1, 2011
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Map I hope you don't mind me showing my heads on your thread. Below is the straight plug head I got from Bgf, it has been lapped but will need to be shaved.
 

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Greg58

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May 1, 2011
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This is my angle plug that I lapped the ring off of to get full contact with the gasket, it runs good but I'm going to run a compression check to see where I'm at.
Its at 140 psi .
 

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