big_water
Member
Before any of you call me insane... I have a mechanical engineering background and schooling. I know what I am doing technically but yes, I am insane on the other end of things - lol.
This bike is being built because of my love of the BigWheel but my disdain for lack of power and the obsolescence of the parts. The project is for sand pit hill climbing and local mud runs where I need pure grunt to go with the big tires.
Phase I is to get it to RUN. Frame stretch, downtubes, radiator mount, battery mount, Raptor lights integration, fitting the swingarm, fitting / fabricating the exhaust, the rear of the frame to the backbone and stretched swingarm.
Mud runs and hill climbs do not require tons of braking nor suspension travel - hence Phase I. Phase II is brakes and suspension because I want to make this dirt bike enduro capable where I take this bike on my usual 4-6 hour trail runs in a variety of terrains. With my 48 year old back, I need to soften and lenghten the travel and make sure my brake system does not include being stopped by a TREE! Lol
This project is well underway and I've encountered a challenge that I'd appreciate outside opinions on.
The stock BigWheel swingarm is .205" smaller than the engine pivot point on the Raptor engine. Opening this up is easy but...
My thinking last weeks was that since my swingarm was going to be reduced slightly in size to fit around the larger pivot point of the Raptor engine, I figured that I should rebuild the inside pivot point of the swingarm to make sure it's 100% perfect to handle the extra weight and power of the new engine - at the very lease. To get out the old pieces (bushings) I had to destroy them as these were pressure fitted inside the swingarm. When I went online to get the replacement part numbers I discovered that these parts are obsolete... Grrr I have learned to check for the parts before I go about taking these out!
I have several tough choices as I see it:
1) Search for the same or similar part in other swingarms of bikes around that year and hope they are the same size and order them and machine away (if possible), any excess material
2) Buy a used steel swingarm where these parts ARE available, cut off the portion of the swingarm that I need and weld it in place of the one on my swingarm. Big challenges are alignement and a very strong weld. I am handy with my excellent 220V gas MIG but swingarms take a LOT of stress.
3) Buy some Babbet steel (a relatively soft alloy of steels with oily texture properties) made for bushings and guesstimate the shape of the collar and get the best dimension I can from the old pieces (inside and outside diameter I have - and guess at the length and collar size) and then have these machined to my specifications
4) Buy a much bigger steel swingarm from a large bike with NON-obsolete bushings (i have a tool to find this out). I have to find one made of steel because all the new stuff is aluminium that will not weld to steel. The rest of the BigWheel swingarm must be kept because of the wide double chained rear wheel.
5) More choices? Who knows...
Ahhhh the challenges of doing it RIGHT!!!
Open to suggestions...
Thank you
Steph (big_water@xplornet.com)
Quyon, Québec, Canada
This bike is being built because of my love of the BigWheel but my disdain for lack of power and the obsolescence of the parts. The project is for sand pit hill climbing and local mud runs where I need pure grunt to go with the big tires.
Phase I is to get it to RUN. Frame stretch, downtubes, radiator mount, battery mount, Raptor lights integration, fitting the swingarm, fitting / fabricating the exhaust, the rear of the frame to the backbone and stretched swingarm.
Mud runs and hill climbs do not require tons of braking nor suspension travel - hence Phase I. Phase II is brakes and suspension because I want to make this dirt bike enduro capable where I take this bike on my usual 4-6 hour trail runs in a variety of terrains. With my 48 year old back, I need to soften and lenghten the travel and make sure my brake system does not include being stopped by a TREE! Lol
This project is well underway and I've encountered a challenge that I'd appreciate outside opinions on.
The stock BigWheel swingarm is .205" smaller than the engine pivot point on the Raptor engine. Opening this up is easy but...
My thinking last weeks was that since my swingarm was going to be reduced slightly in size to fit around the larger pivot point of the Raptor engine, I figured that I should rebuild the inside pivot point of the swingarm to make sure it's 100% perfect to handle the extra weight and power of the new engine - at the very lease. To get out the old pieces (bushings) I had to destroy them as these were pressure fitted inside the swingarm. When I went online to get the replacement part numbers I discovered that these parts are obsolete... Grrr I have learned to check for the parts before I go about taking these out!
I have several tough choices as I see it:
1) Search for the same or similar part in other swingarms of bikes around that year and hope they are the same size and order them and machine away (if possible), any excess material
2) Buy a used steel swingarm where these parts ARE available, cut off the portion of the swingarm that I need and weld it in place of the one on my swingarm. Big challenges are alignement and a very strong weld. I am handy with my excellent 220V gas MIG but swingarms take a LOT of stress.
3) Buy some Babbet steel (a relatively soft alloy of steels with oily texture properties) made for bushings and guesstimate the shape of the collar and get the best dimension I can from the old pieces (inside and outside diameter I have - and guess at the length and collar size) and then have these machined to my specifications
4) Buy a much bigger steel swingarm from a large bike with NON-obsolete bushings (i have a tool to find this out). I have to find one made of steel because all the new stuff is aluminium that will not weld to steel. The rest of the BigWheel swingarm must be kept because of the wide double chained rear wheel.
5) More choices? Who knows...
Ahhhh the challenges of doing it RIGHT!!!
Open to suggestions...
Thank you
Steph (big_water@xplornet.com)
Quyon, Québec, Canada
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