Building a Ht Motorized Bicycle or Three.
- Thread starter Theon
- Start date
The barrel measures 15mm, I've had this carb giving me 9500RPM on a piston port doing 80 Km/hr.
I see the problem as, a reed needs a richer jet than piston port due to a decrease in velocity because the piston port has only 65 deg duration as opposed to the 180 I now have.
This carb is usually run on a piston port, and the metering slot is to small to give enough fuel at WOT with the decrease in velocity.
I have a Velocity stack on one side of the carb and opening into a reed cage on the other side, the carb is the venturi choke, and measures 15mm. I can not see the needle and measuring tube being so much of a restriction to bring my effective diameter down to 13.5mm.
I see the problem as, a reed needs a richer jet than piston port due to a decrease in velocity because the piston port has only 65 deg duration as opposed to the 180 I now have.
This carb is usually run on a piston port, and the metering slot is to small to give enough fuel at WOT with the decrease in velocity.
I have a Velocity stack on one side of the carb and opening into a reed cage on the other side, the carb is the venturi choke, and measures 15mm. I can not see the needle and measuring tube being so much of a restriction to bring my effective diameter down to 13.5mm.
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I was thinking 8500 RPM was OK considering only 150 deg exhaust dur and not run in yet, Bike works well for what I built her for, offroad. And weather has finaly cleared so might get out there and spray some mud around today and try and clock up a few more Kays.
Have ordered a new barrel as well as another $15 carb to play with for her. I have had to compromise the exhaust design considerably to make it fit, and will at some stage be re thinking the exhaust. I have another KTM Pipe, this ones a Fatty/Pro pipe, but I have not worked out the best way to make it work on this bike, and have many other projects, so will likely just live with this pipe for now, until I get a few other things out of the way.
Have ordered a new barrel as well as another $15 carb to play with for her. I have had to compromise the exhaust design considerably to make it fit, and will at some stage be re thinking the exhaust. I have another KTM Pipe, this ones a Fatty/Pro pipe, but I have not worked out the best way to make it work on this bike, and have many other projects, so will likely just live with this pipe for now, until I get a few other things out of the way.
I think it was going a little better with less back pressure, my mufflers are stuffed with a whole large S/S scourer each and are not straight through, but empty in to stuffed chamber, then exit through baffle tubes. I have a nice throaty dirt bike tone, but acceptable noise levels and am happy with this.
Getting a bit more fuel through the carb at max revs is where I'm heading with this, would be nice if I could find just the mix tube for sale seperatly, but at $15 for a whole carb, not a big deal. Increasing the stroke of the diaphragm with an extra gasket is an interesting idea.
My other thought was to lengthen/widen the slot in the mix tube.
The mix tube from an old carb I have stripped has an 8 printed to it, so no doubt other sizes are out there, Unfortunately I damaged that one removing it although is still probably usable, but will soak my carb in boiling water first next time. Getting a better quality carb is also an option, however I like the way this carb mounts and also the price. So feel that I should persist with it.
More disappointed in the vibs around 6000 than anything else.
Getting a bit more fuel through the carb at max revs is where I'm heading with this, would be nice if I could find just the mix tube for sale seperatly, but at $15 for a whole carb, not a big deal. Increasing the stroke of the diaphragm with an extra gasket is an interesting idea.
My other thought was to lengthen/widen the slot in the mix tube.
The mix tube from an old carb I have stripped has an 8 printed to it, so no doubt other sizes are out there, Unfortunately I damaged that one removing it although is still probably usable, but will soak my carb in boiling water first next time. Getting a better quality carb is also an option, however I like the way this carb mounts and also the price. So feel that I should persist with it.
More disappointed in the vibs around 6000 than anything else.
You need to start posting some pic's, what's a Derbi Bullet?
I've got the pipe off the Goat, need to stop it touching the frame, as it may be part of my vib problems. Fix up a few slag intrusions,
Still deciding what I'm going to do with this new motor, I've ordered it with the large mouth cases, and no Loctite. First I plan to try it in the Goat, stock standard. If it's not as strong as the Goat motor then I'll start swapping bits across, and see what works best. If I can get it to go harder than the motor I've got, I'll get them both to go just as hard.
But if this crank is as good as he says, I'll likely put it in the case induced Mongoose. Who's wheels I've been working on today. Everything must be still working on the farm, and been a little crook so taking a little time off, and getting a morning in the 'bike shop' to my self!
I've got the pipe off the Goat, need to stop it touching the frame, as it may be part of my vib problems. Fix up a few slag intrusions,
Still deciding what I'm going to do with this new motor, I've ordered it with the large mouth cases, and no Loctite. First I plan to try it in the Goat, stock standard. If it's not as strong as the Goat motor then I'll start swapping bits across, and see what works best. If I can get it to go harder than the motor I've got, I'll get them both to go just as hard.
But if this crank is as good as he says, I'll likely put it in the case induced Mongoose. Who's wheels I've been working on today. Everything must be still working on the farm, and been a little crook so taking a little time off, and getting a morning in the 'bike shop' to my self!
it looks like girls scooter. i am supposed to pick it up tmrw. i am having second thoughts. perhaps an old 250cc or 400cc suites me better. the bike has been drpped so if i kept it perhaps a naked scooter sounds ok i guess. im stuck cause for 500 bucks i have purchased a sweet turbo mazdas before.... this girls scooter....crap for a grand i could have allmost anything. this scooter retails at $3000. it has 4000kms on it for 500 bucks.
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i want to hear the roo go.
i think my pipe will be what i was looking for its 5.5 degree/ 10 inches. to tear drop baffle and belly/ 4 inches.
it gives maximum torque on bottom end then gradually loses power but should never breakup on topend due to a 1 inch belly. this allowes best cruising at high rpm while pulling hardest on the lowend. yea
i think my pipe will be what i was looking for its 5.5 degree/ 10 inches. to tear drop baffle and belly/ 4 inches.
it gives maximum torque on bottom end then gradually loses power but should never breakup on topend due to a 1 inch belly. this allowes best cruising at high rpm while pulling hardest on the lowend. yea
I had a scooter, was given it for payment for work, got it going, seems the previous owner hd just done it up before some kids got hold of it. Had a big bore kit, and wheelstood! Gave it to a mate for a swap on some bits I wanted, His kid has a ball on it round the farm, Certainly a better designed motor than these China Girls.
Built to work, not to have to mess with, and a comfy ride!
But not the thrill of a livened up motorized bike.
Built to work, not to have to mess with, and a comfy ride!
But not the thrill of a livened up motorized bike.
based on dimensions did i do ok? do u think its incorrect cause i spent three days to wind up using my first best guess. i did calculations for days and i think its correct to o.1 of an inch. i just have to weld the two pieces together.
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I'ts hard to argue with math.
been rethinking my Goat pipe, but was such a mission to make fit, I'm going to stick with it for now.
been rethinking my Goat pipe, but was such a mission to make fit, I'm going to stick with it for now.