what did you do to your motorized bicycle today?

[Davezilla]

I've tried the single ring and the end gaps are pretty wide on these as it is so getting decent compression was a problem, I did get it to work and it felt nice and strong but lost compression after just a few short rides. Now if you can find a different piston with narrower ringlands and a 1mm wide ring with enough metal on the ends to set your own gap it would work, but so far I've only found chrome rings in these sizes which would tear up the nikasil plating in the cylinder in short order...
Also cutting too much off the skirt can allow the piston to rock inside the bore excessively before the engine warms up and this piston slap can accelerate wear considerably... Keep a close eye on things while you're doing your testing. And finally... when you did your cutting on the piston make sure you leave a smooth radius on everything to prevent cracking, the piston also needs a certain amount of metal to support it's self or that "tooth" could crack off... Again, keep an eye on that as well.
If you got some pics of the piston and can take a little constructive critisism myself and a few others can tell you if it'll last or show you how to make the cuts so it won't self distruct.

 

[Davezilla]

Map... those transfers are looking really nice... How much more do you plan on doing to this one?

 

[mapbike]

Map... those transfers are looking really nice... How much more do you plan on doing to this one?

I have to finish matching the ports perfectly to the transfer area in the case, then Im gonna get the exhaust port to a mirror finish after I widen it just a little bit more, Im not gonna remove anymore from the top of the exhaust port since its already a little higher than some of the other jugs I have, and the intake port is actually a little low than some of the other jugs I have, intake port is about where its gonna be I think, just nice and clean and jot to shiny for better atomization of the fuel before it goes into the crankcase.

Tranfers in jug are nice and high already so no ramping of the piston really, I may put a shallow slot angled back toward intake just to help direct charge away from exhaust as much as possible, Ill post some pix of how I plan to do it once I get it done, this will be experimental and will only be a slight modification just to see how it works, I dont need big sloping ramps just something to aid in directing charge toward intake without taking to much of my compressuon potential away.
This is my Id'y anyhow.....lol!

 

[Davezilla]

Same thing here since it was slow at the shop today, I took the new jug I got off ebay and did some massive porting to it, knife edged the transfers at the bottom andnat the bottom of the transfer opening, cut out the casting ridge and did some simple aiming of the ports. The exhaust port is now a massive 28mm wide and I widened the intake by 2mm on each side then lowered the floor of the intake by 4mm. I'm not gonna mess with the exhaust roof until I can get a bottom end since I need the piston in place to set the timing and duration... I could do that by measuring how far down from the deck the port roofs are but if I need to shave any off the base or çant get a 40mm stroke bottom end or if anytghing else comes out different it would throw the timing off so I'll wait on that part.
Since I'm doing the exhaust a lot larger than my last one I'm going to have to make a short header adapter to connect the kx pipe to the cylinder by using a stock kx flange header.
On the intake side I'll be using the 18mm mikuni carb so this engine will be able to breathe a lot better than my current setup. I may go ahead and set this one up with a reed valve if budget allows but for now the plan is to stay piston port.

 

[GoreWound]

I stuffed half a brollo pad into my exhaust to try and quiet my bike somewhat, think I over did it, lost about half my power.

 

[curtisfox]

Brillo pad is full of soap use steel whole,prolly half as much LOL..actually stainless scrubber from dollar store is more coarse .........Curt

 

[mapbike]

I stuffed half a brollo pad into my exhaust to try and quiet my bike somewhat, think I over did it, lost about half my power.

Yep back pressure like that will wipe out the power of these little engines, like curtisfox said a stainless steel or ever pure copper scrubbing pad like can be found at dollar stores and such is your best better as baffle material to quiet i5 down some, but just be aware that even a small amount of it in the pipe will cause you to loose some power since it restricts flow.

 

[GoreWound]

that's what I used, probably shouldn't have called it a brillo-pad, but you know it's like kleenex. I ened up stabbing it wil some wire untill it loosened up, seems to have helped greatly!

 

[mapbike]

One of the things I got done today was I made up a laid back seat post out of the stock post on the Huffy Karaoke bike, been planning to do this for a long while since these frames are a tad short.

This make it feel so much better, set the seat back 4 1/2" and was able to lean the ape hanger bars back some for more comfort also, now when I get my new engine built for the Huffy its gonna be a real dream to ride.

I cut a large V in the post Shaft, bent it to where I wanted it, and then with a clothes hanger wire that I removed all the coating from, I used white Forney flux and my acetylene torch and mild steel brazed it all up and then slightly ground over the welded area just enough to smooth it out some.

Been a while since I did any torch welding with a clothes hanger so I enjoyed the process.

 

[curtisfox]

Yep for years my torch was broken,then a couple years ago got the parts to fix it. when first married that was all I had was torch,did all my steel toch welding ( good old clothes hanger ) and most was brazing with bronze rod. Using mine more and more now.
Seat post looks good.............Curt

 

[GoreWound]

for the first time today I was seen by a cop while driving my bike and was NOT pulled over.
also bought groceries.

 

[mapbike]

Yep for years my torch was broken,then a couple years ago got the parts to fix it. when first married that was all I had was torch,did all my steel toch welding ( good old clothes hanger ) and most was brazing with bronze rod. Using mine more and more now.
Seat post looks good.............Curt

Yeah, I grew up around a lot of welding, Im no pro at it myself but have several family members that were, my dad has no doubt forgot more about welding than Ill ever know.

I do like using a torch.

 

[xseler]

I ordered more upgraded parts --- alloy rear wheel with a Shimano coaster brake and a Continental rear tire from Niagra Cycle.

Thanks, Shan!!

 

[fatdaddy]

Well, I finally did it. After riding Tri-Baby, My Tadpole recumbent, for 3 or 4 years with the engine not lining up properly, I cut the old permanent engine mount all out and bolted down a new mount plate that can now be adjusted to where I need it. The old configuration was never meant to be used like this. I welded a threaded pipe to the wheel sprocket to thread on a freewheel for peddles to make it street legal and it didn't allow the wheel to go over far enough to line up the chain. Hopefully my problems in this area are over. I was running a 49cc on it till I ran it to death and had to go back to my original motor, A 33cc which still pushes it around pretty well. Time to start saving up for another 49cc I guess.
fatdaddy.

 

[curtisfox]

Yeah, I grew up around a lot of welding, Im no pro at it myself but have several family members that were, my dad has no doubt forgot more about welding than Ill ever know.

I do like using a torch.

Bought mine from my uncle and thought myself,wit a lot of questions. Not a pro eather but good enough for me, LOL.....Curt

 

[Davezilla]

Good job on that seat post map... When I did mine up last summer I did it pretty much the same way but used a miter chop saw to cut the post at a 45 and welded it back together with the TIg welder, but I could feel it flexing when I was riding so I took it back off, stripped off the paint and welded in a brace that runs from the seat mount to about an inch down the post which made it feel a lot more rigid. I just made my brace out of 1" angle iron and so far it's held up to any abuse I've thrown it's way.

 

[mapbike]

I ordered more upgraded parts --- alloy rear wheel with a Shimano coaster brake and a Continental rear tire from Niagra Cycle.

Thanks, Shan!!

You're very welcome Mark, glad I was able to help in some way, hope it works out great for you.

I been painting primer coat on the trim of my workshop today and then after slinging that paint brush in the 90+ Texas heat today Ive gone into the shop with a couple fans blowing and done a little work on "Taffy" as you suggested I call this bike.....lol!
Im thinking thats gonna be her name, yellow frame, black forks, hrome wheels, red balloon cruiser tires.....

Taffy works for this one....

 

[mapbike]

Bought mine from my uncle and thought myself,wit a lot of questions. Not a pro eather but good enough for me, LOL.....Curt

welds dont have to be pretty to be good and strong, they just need to be done right with good penetration so the parts are fused together well.

Seen many shallow weak welds that looked real nice but failed when they got under pressure.

 

[mapbike]

Good job on that seat post map... When I did mine up last summer I did it pretty much the same way but used a miter chop saw to cut the post at a 45 and welded it back together with the TIg welder, but I could feel it flexing when I was riding so I took it back off, stripped off the paint and welded in a brace that runs from the seat mount to about an inch down the post which made it feel a lot more rigid. I just made my brace out of 1" angle iron and so far it's held up to any abuse I've thrown it's way.

Thanks Dave, yeah I may need to brace this one also, I cant notice any flex when I sit on it but I may cut out two small triangular shapes and weld them on each side of the bend.

I used my 4 1/2" grinder with a 1/16" Dewalt cut-off disc and just cut through enough so that I could bend short section over until I had the angle I wanted and the I sewed it all up real good with the hanged rod, mine was cut completely in two so Im thinking by doing it the way I did it has retained a good bit of it strength, I really dont think it will ever fail on me, I may add the braces just for insurance factor.....lol

The bsouth end of the north bound mule dropping down on the rear tire at 40mph would be an ugly event that will bring an entirely new definition to a "skid mark"....lol!

 

[curtisfox]

welds dont have to be pretty to be good and strong, they just need to be done right with good penetration so the parts are fused together well.

Seen many shallow weak welds that looked real nice but failed when they got under pressure.

You got that right, been 50 years sence I got my torch,now mig. The biggest is to clean the metal first, LOL..........Curt