High Performance Wally World Cruiser?

[YesImLDS]

This wouldn't be a problem would it? The drive gear is sticking out very slightly compared to the clutch gear

Haven't had any problems running it like this as far as I know previously

 

[mapbike]

This new and improved PK80 might be a good contender for 50mph with that 32T. With the jug being milled down and increasing compression should be able to spin some RPMs. Disc should be a good way to slow me down from that too!

the main thing is think safety, I've seen 50+mph on a bicycle and its hauling butt.... a lot can go wrong and if it does at 50mph its gonna get real ugly real fast.

I've retired my 50mph ambitions now that I seen it and experienced a blown out front tote tube about 30 minutes after hitting 52mph on my bikewhile it was just sitting in the shade cooling off after my fastest run.

That was my sign...... and I took the hint from that wee voice that said slow your butt down son....lol!

It was my fault though, front tire was a little soft and that allowed the inner tube to shift a little and the rim actually cut the valve stem to the point it blew off, first time I've ever had that happen on a bike and I think some of it was due to the fact that at 50mph the front tire was hopping a little from not being balanced good.

That bike has new Kinda Coniption tires and heavy duty tubes now, but with the current engine I have on it it only does around 40 so I feel much more confident that the tires and tubes wont be an issue now.

I had a flat one time at mid 30mph speeds and it was a heck of a ride getting the bike shut down without chewing on the asphalt, fortunately it was the rear tire and not the front on that bike but it was still very hard to control, so whatever you do don't cut corners on tires and tube for a high speed bike and take a small round file and file off any burs around the rim holes where the valve stem goes through the wheel.

 

[mapbike]

This wouldn't be a problem would it? The drive gear is sticking out very slightly compared to the clutch gear

Haven't had any problems running it like this as far as I know previously

in my experience I've seen this misalignment of the gears on many of these engines, most of mine have been that way, most of the time its just that the gear doesn't sit down as far on the crankshaft as they could if the crank taper was polished down a bit more so the gear will seat farther down on the shaft.

Its no big deal and nothing to be concerned about in my experience, just make sure the screw that holds it on is tight.

 

[YesImLDS]

Good thing I pulled apart the clutch when I was swapping back my dampened covers. Apparently the clutch spring on my PK80 engine went missing and was reassembled that way. Didn't even realize it until I opened it up. Just borrowed from the Dax bottom end for the time being, but man that'd be a bad thing to find out down the road!

 

[YesImLDS]

Two words. HOLY CRAP I just took the bike on a test run to make sure everything is working properly. Re-installed the kill switch so I could idle when warming up or coasting so I could have a smooth transition to going back to moving forward. Tested out the disc brakes and they are great. Only thing that I had problems with was a little clutch slippage, which is now fixed. BUT WHAT CAN I SAY the new snake exhaust kicks butt! Power kicks in at 20 and like I said I had some clutch slippage, but it killed it to 35. Can't wait for a dry to to actually test it and see what it can do. It was very impressive for a first run. Probably was a combination with the increased in compression and other odds and ends done, but it felt like it still had the 36T on it and would even start at 6mph even with the 32T

 

[mapbike]

Two words. HOLY CRAP I just took the bike on a test run to make sure everything is working properly. Re-installed the kill switch so I could idle when warming up or coasting so I could have a smooth transition to going back to moving forward. Tested out the disc brakes and they are great. Only thing that I had problems with was a little clutch slippage, which is now fixed. BUT WHAT CAN I SAY the new snake exhaust kicks butt! Power kicks in at 20 and like I said I had some clutch slippage, but it killed it to 35. Can't wait for a dry to to actually test it and see what it can do. It was very impressive for a first run. Probably was a combination with the increased in compression and other odds and ends done, but it felt like it still had the 36T on it and would even start at 6mph even with the 32T

Good deal.... hope it works out like a champ for ya.

 

[YesImLDS]

I hope so too! I will probably plan on keeping it as it's a great running bike. I don't think I can bring myself to selling it! I fixed the clutch slippage and now I am just waiting for a warmer day to really test the bike out! Need to get those wider crank pedals for sure somewhere down the line because when pedalling I gotta cock out my leg a little weird, but that's only for getting started!

 

[YesImLDS]

Took the bike for a ride today and it pulls really hard, but I couldn't seem to get the top speed I was wanting. I realized a couple things today while riding.

1. It's cold out
2. Top speed doesn't really work with the wind against you
3. Make sure your fuel line isn't kinked
4. Remember you have new piston rings that still are breaking in.

With all those together I am hoping that I will get a bit more out of her because I hit 44mph with a 32T and wasn't able to hit much more in my short try to get top speed numbers out there. I'm hoping it was mostly because my fuel line was partially kinked from when I pushed the gas tank back to fit on my new fork.

 

[mapbike]

Ill tellyou right now that without everything being really done right, its a hard thing to break over the 45mph mark on these.

 

[YesImLDS]

Ill tellyou right now that without everything being really done right, its a hard thing to break over the 45mph mark on these.

I was hitting the same speed with the 36T. I am assuming it's just a couple of quirks I need to work out. That's why I believe something is a little bit off!

 

[mapbike]

yeah sometimes it takes some experimenting to figure out what they need to get over those humps, what makes it tough is when multiple things are changed and then you dont really know what has helped or hurt.

Like I had said before those fatty pipes dont flow very good without some mods done to them on the outlet, I took mine off because my header pipe I built is just to small, but I might try it again some day when I get a bigger header pie made for it.

I lost 6mph off my top cruising speed when I put mine on my Kulana bike.

I put a smaller pocket bike pipe on it with a larger header pipe and I got all the speed back so I've just left it alone for now.

 

[YesImLDS]

I'll modify the exit of it and see how that works. The pipe is using the same exhaust piping that my SBP expansion chamber was using so you would think it would have a little bit more oomph... Other than that the only other thing changed to the motor was the sanded down jug that was previously on there, but was sanded for the GT5 because I was feeling too lazy to port out another jug! Also the piston rings haven't really been broken in so I feel I will get a little more compression when those get broken in. Also the wind was against me so I can't exactly say much for that.

 

[mapbike]

yep, just gotta keep tweaking it until you find that seet spot and hope it where you can be happy with it.

There hand full of people on here that have figured out how to make these engines scream by getting the porting where it needs to be and some just get lucky and what they do works, i fall more toward the lucky ones than the other since I haven't played much with port timing changes other than ramping the pistons on a couple engines and they both turned out to run upper 40's to low 50's mph but the fazter engine was short lived since I got it to hot and cracked the piston and cooked the rings....lol

It wasnt a super hot rod even at 50mph since I figured my rpm to be around 8,950rpms

I just want my bikes to be solid mid 40's cruisers at max speed and then run comfortably in the mid to upper 30's reliably, that is my goal for my bikes if possible, I dont honestly care to do 50+mph on my bicycles anymore, that was just a little faster than I care to go one any of my bikes.

 

[YesImLDS]

Yeah, I've been thinking of once I get the GT5 motor built up I may try to get that screaming as much as possible and may go back to a stock 44T for a little while, might even get a 40T so I can have a nice low down, but still be able to hit some low 40's and beat my bud I ride with who is running a 36T ha. If I can get it to rev high enough I wouldn't be afraid to keep the 44T on. Hoping for 10k out of this GT5 which I think with the gt5 dax lower shouldn't be out of reach with some high compression. Need a new jug and piston and I should be set for modifying that one! I have a spare jug already, but I just want get a GT5 jug and compare to see if there are any real differences other than just needing to sand down the jug.

 

[YesImLDS]

Just drilled out the rivets on that exhaust and I can see how the stinger at the end restricts the pipe itself. I think the outlet is 7/8" and the stinger is about 3/4" So you would get a little restriction from that as well as the fiberglass muffler at the very end. Need to get some bigger rivets to get it back together now!

 

[YesImLDS]

Actually found the real source of the restriction.

The baffle that sits in the piping goes down to 1/2" inner diameter

That sits in snuggly in the 7/8" outer diameter (as far as my eyes can tell) outlet from the expansion chamber

Then goes to the 5/8" inner diameter outlet.

 

[boxcar]

Stinger - Located at the opposite end of the pipe from the header and after the convergent cone, it is the "pressure relief valve" of the pipe where the exhaust gasses eventually leave the pipe. The back pressure in the pipe is caused by the size (diameter) or length of the stinger. A smaller stinger causes more back pressure and thus a denser medium for the sound waves to travel in. Sound waves love denser mediums and thus travel better. A draw back to a small stinger is heat build up in the pipe and engine. The stinger diameter should be 0.58--0.62 times that of the header pipe and a length equal to 12 of it's own diameters.

Thought this might help.
There is a very good reason for the smaller stinger........

 

[YesImLDS]

Make sense I suppose. I did get rid of the restriction in the baffle. The 1/2" section of it at least.

I am just hoping this solves my low speed problems. I don't think I am able to get to get the exhaust out fast enough hoping this will solve some problems. 7/8" exhaust piping to a 3/4" stinger should be suffice I would believe

The area of 7/8" exhaust pipe is .6 square inches and the area of 3/4" exhaust pipe is .44 square inches. So with your stinger maths .73% of the header piping. I think close enough.

 

[fatdaddy]

This wouldn't be a problem would it? The drive gear is sticking out very slightly compared to the clutch gear

Haven't had any problems running it like this as far as I know previously

They all set like that. Looks normal to me.
fatdaddy.

 

[boxcar]

In theory at .75" diameter the stinger should be roughly 9"
The Snake pipe itself was designed for something other than a CG to begin with.
Soooooooo. Experimentation is the only answer. As science won't help much....
The base #'s of the pipe are all wrong for the engine.
I'm working on a down pipe design as we speak for one of my bikes . The tow vehicle.
Once built I will test sed pipe , Then post the drawings.
It may be a total waist of time. Who knows ?
It will be a mid range pipe that peaks at 7500 rpm.
Would't be to hard to redesign it for 10'000.
I'll keep you posted.