xseler
Well-Known Member
SBP Expansion install first attempt.
Dan.
Hello, my name is Happy.................Happy Toseeewe!!
what did you do to your motorized bicycle today?
- Thread starter Skarrd
- Start date
Hello, my name is Happy.................Happy Toseeewe!!
culvercityclassic
Well-Known Member
Cruise
New Member
Cut my shiny new stock exhaust in half and mounted its ends so I could make a pattern for my local exhaust shop to bend and tack together.
They weren't too excited about it as they're busy, but said if I bought them a made up set of pipes, they'd weld it. (I don't have a welder at home).
Looks like I'll be trying my hand at sand -packing and bendy fun at home.
They weren't too excited about it as they're busy, but said if I bought them a made up set of pipes, they'd weld it. (I don't have a welder at home).
Looks like I'll be trying my hand at sand -packing and bendy fun at home.
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It actually did pretty good. I still got it up to the legal limit of 20mph. It didn't seem to take that much more time to get there either. I actually noticed the trailer tires were a little low on air once I got home. When I pushed the bike into the garage from the driveway, I thought the clutch was engaged, that's how much drag there was. So, braking didn't seem to be affected.
I was more worried about the hitch than the weight itself. It's really just a tightly wound spring that allows everything to pivot. With that much weight on the tongue, it was starting to sag. I don't plan on carrying that much again, but it does great carrying a weeks' worth of groceries, which was the point of building it in the first place.
mapbike
Well-Known Member
Sounds like a fun adventure to me, you may not be a country boy redneck like a few of us but you sure got to enjoy doing our kinda thing.....
A couple pix of getting things done
Map
mapbike
Well-Known Member
Yeah I think it would have been a hit with some, I like it for sure, that set up with a 3 or 4 speed in the floor and a 289cid under the hood and you would have a nice little grocery hauler or whatever else you could fit back there.
Map
mapbike
Well-Known Member
Made a mod to the X2 pocket bike expansion pipe on the Kulana, removed all the fiberglass packing, perforated baffle tube had fair high lip on the ID of the tube so I removed about 1/16" of the end of it to remove that restrictive lip, no pic of that part...., drilled extra holes in silencer cap to help release more exhaust that flows through perforated baffle tube, hoping this will get me back to my top speed that I had while running the shorty straight pipe while still maintaining the extra low to mid range power increase I've noticed since installing this expansion pipe, the extra low to mid pull is nice but I have lost around 6+mph on the top end and only have a 40MPH top speed on the flat since adding this pipe, low to mid pull is extremely increased with this pipe though, so much that I had to really tighten down my clutches main spring or when it came on the pipe it would just roast the clutch, I will be making up some Heavy Duty Clutch pucks for this one when I have time.
The pix don't show it but there is a long perforated tube on bottom side of cap that extends all the way down and mates up with the one seen down in the bottom of silencer chamber, it has a couple hundred 1/8' dia holes drilled through it, exhaust will fill chamber when engine is running and then pressure its way out from large center tube and hole I drilled around cap, this mod made it a bit louder but still much quieter than the shorty straight pipe was and it still has that nice ring ting ting expansion sound, noise level is still good and mellow, just a nice 2 stroke dirt bike sound.
Sorry pix aren't very clear, must have had some oil or gunk on my phones camera lens.
Map
The pix don't show it but there is a long perforated tube on bottom side of cap that extends all the way down and mates up with the one seen down in the bottom of silencer chamber, it has a couple hundred 1/8' dia holes drilled through it, exhaust will fill chamber when engine is running and then pressure its way out from large center tube and hole I drilled around cap, this mod made it a bit louder but still much quieter than the shorty straight pipe was and it still has that nice ring ting ting expansion sound, noise level is still good and mellow, just a nice 2 stroke dirt bike sound.
Sorry pix aren't very clear, must have had some oil or gunk on my phones camera lens.
Map
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mapbike
Well-Known Member
also after the Kulana expansion pipe mod, I had one of the short expansion pipes I had ordered from Dax when I bought my last GenIV lower, the port flange as normal had horrible matching to chamber and to engine port which is a huge power robber on these engines, I took my pneumatic die grinder and did some nice widening and smoothing of the flange so that it is as close to port matched as can be had with a rectangle engine port going out to a round port flange which is now rectangle as well and then has a nice bevel tapper into th chamber tube.
After getting this port matching done, I mounted it on my oldest and first Mountain bike build that has been running strong since 2009, got the old 66cc BGF Red Bat engine, this little engine is by far the quietest non rattling china girl I have heard, doesnt have all the clutch side rattle and clanky sound that all of the china girls I've owned or heard always seem to have, it has zero mods done to it with over 2000miles, it aint no speed demon but with the 32T rear on the 24" rear wheel it will cruise at 28-30mph all day and never miss a beat, it is so dang quiet with this pipe it blows my mind, I figured it would be loud and high pitched but it isn't at all, been raining all day yesterday here and all the dirt roads here are pretty muddy but hey.... that wont stop a country boy from going on a ride so after it was almost completely dark I headed out down the wet muddy road and did about a 2 1/2 mile ride..... little engine just ginning right along real nice, made it back to the house with mud on my front...... mud on my back........ but a smile on my face........!
Heres a pic of the old girl with her new hookerbill nose pipe....LOL!
Oh and Yeah I know I Know...... the chain is very loose, gotta get that tightened asap, but actually I have road several miles with this chain loose like this and because it is perfectly in align it has never tried to jump off...LOL
I dont recommend doing it though and I wont be riding this one again until the chain has been adjusted.
Map
After getting this port matching done, I mounted it on my oldest and first Mountain bike build that has been running strong since 2009, got the old 66cc BGF Red Bat engine, this little engine is by far the quietest non rattling china girl I have heard, doesnt have all the clutch side rattle and clanky sound that all of the china girls I've owned or heard always seem to have, it has zero mods done to it with over 2000miles, it aint no speed demon but with the 32T rear on the 24" rear wheel it will cruise at 28-30mph all day and never miss a beat, it is so dang quiet with this pipe it blows my mind, I figured it would be loud and high pitched but it isn't at all, been raining all day yesterday here and all the dirt roads here are pretty muddy but hey.... that wont stop a country boy from going on a ride so after it was almost completely dark I headed out down the wet muddy road and did about a 2 1/2 mile ride..... little engine just ginning right along real nice, made it back to the house with mud on my front...... mud on my back........ but a smile on my face........!
Heres a pic of the old girl with her new hookerbill nose pipe....LOL!
Oh and Yeah I know I Know...... the chain is very loose, gotta get that tightened asap, but actually I have road several miles with this chain loose like this and because it is perfectly in align it has never tried to jump off...LOL
I dont recommend doing it though and I wont be riding this one again until the chain has been adjusted.
Map
culvercityclassic
Well-Known Member
Huffydavidson
STREETRACER/MANUFACTURER
I located and negotiating a deal with my local exhaust shop to cut chopping weld a new Custom J pipe to go with my X- 7Fatty expansion chamber so I can run my chit low like a
"STREET RACER"should look.. It'll have 1 1/4" pipe coming out of the jug!!! The chamber actually calls for engine 1 3/8" but I'll fabricate aluminum shims out of beer cans!!!!
It apparently the same pipe that is run on the arrow advanced motor.
if it's good enough for the racetrack it's good enough for my street racer!!!!
O yes I forgot to mention it's going to be bolted up to my new Fred racing motor
"STREET RACER"should look.. It'll have 1 1/4" pipe coming out of the jug!!! The chamber actually calls for engine 1 3/8" but I'll fabricate aluminum shims out of beer cans!!!!
It apparently the same pipe that is run on the arrow advanced motor.
if it's good enough for the racetrack it's good enough for my street racer!!!!
O yes I forgot to mention it's going to be bolted up to my new Fred racing motor
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Danschutz
New Member
Hello, my name is Happy.................Happy Toseeewe!!
Lol, JJJJJJJJJJunior
BonusParts
Member
Well, I took the bike out today with the SBP expansion chamber.
I dont know how I feel about it yet. I wasn't expecting the degree of quiet It has. it also falls on its face in low RPM at 3/4+ throttle input. once its kicks in though it has a great tone and finds its stride. Seems to have lost 6-9mph top speed.
I shortened the header on it and we will see tomorrow if i miss the rain if that helped
I dont know how I feel about it yet. I wasn't expecting the degree of quiet It has. it also falls on its face in low RPM at 3/4+ throttle input. once its kicks in though it has a great tone and finds its stride. Seems to have lost 6-9mph top speed.
I shortened the header on it and we will see tomorrow if i miss the rain if that helped
Danschutz
New Member
Recently installed the sbp exhaust and replaced the 44t sprocket with a 41t. My low mid power is unbelievable, there is a hill near my house that I test my bike on. The bone stock motor struggled about 15-17 mph with a top speed of 22 (unknown that i had a cylinder issue) then after installing the hi head, ported cylinder and notched piston I was sustaining 22 mph up the hill with a top speed of 31 while four stroking like crazy.
With the addition of the expansion pipe (and 41T sprocket) I can take that hill at 27mph. Here's the twist, I can only get about 28mph top end, tonight I hit 30 mph.
Cruising at 20-22 mph is hardly a chore for the motor right now and it gets there in a hurry. I can't believe I'm about to say this but you can feel it shove you right along. I rode with my buddy Brian and his very nice running Arrow 4.5 hp motor and was eating him up around the hills and leaving him in the dust up to 28-30 mph then eventually he catches and blows by me.
I added one 45 degree elbow to the Sbp kit so I'm guessing I need to shorten the pipe somewhere to get back some top end OR do I get a 36t sprocket?
Also upgraded the stock bolts on the sprocket, so much nicer lol.
Dan.
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