97cc engine swap!

CrazyDan

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Looks like the idler on the transfer case is bent at a funny angle. Might just be the angle of the camera.
 


mark20

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Logged in to tell you that is crazy freakin awesome buddy! (y)

I'm just getting my exhaust right lol you people are really talented.
Thanks for the complement, I really appreciate it!

Also the bog is eliminated completely!
The engine runs great! (I got up to 35mph @3800rpm, a bit slow but its great on gas!)

@CrazyDan
I'm assuming you mean the chain tensioner (the black rubber wheel)
It's a bit bent because I had to cut the spacer for it to work, so it's kind if free floating right now ( its sceachy but it works fine, no trouble what so ever)

Thanks for all the kind words!
 

CrazyDan

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Sweet, was worried it was getting bent from the torque. Looks great. You putting a cigar muffler on that exhaust?
 

mark20

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Sweet, was worried it was getting bent from the torque. Looks great. You putting a cigar muffler on that exhaust?
I cant, it's too close to the chain (I have like 1/4" of room between the chain and the bottom if the exhaust) made it from left over pipe. On the plus side It sounds like a single cyclinder shovel head lol
(Leaks like one too, the crank seal is bad)
 

CrazyDan

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Maybe an idler sprocket might work better there. It just looks like a weak link that may leave you stranded pedaling. Love that old diamondback frame, that should be bulletproof.
Those poor spokes taking all that torque on the left side, I feel for them lol. A stock kit 2t isn't too bad on the spokes, the stock 49cc can be a lil worse on them with higher reductions, but I can see that engine beating them spokes like a redheaded stepchild.
Either a wheel meant for disc and rim brake to keep your current rim brake setup and mount the sprocket to the disc bolt holes, or some other setup that takes the stress off the spokes from that rag joint sprocket should be much more reliable. Not sure if the clamshell hub adapters can work with that torque well either, can see them slipping under heavy loads even if tightened to the point of crushing and deforming the hub. Maybe set screws might work to fix that? Anyone ever try drilling and tapping the clamshell hub adapters to prevent slippage?
These are the 2 spots I can see issues that might leave you stranded pedaling, everything else looks pretty buttoned up. Fix that crank seal and enjoy :p.
 

mark20

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Maybe an idler sprocket might work better there. It just looks like a weak link that may leave you stranded pedaling. Love that old diamondback frame, that should be bulletproof.
Those poor spokes taking all that torque on the left side, I feel for them lol. A stock kit 2t isn't too bad on the spokes, the stock 49cc can be a lil worse on them with higher reductions, but I can see that engine beating them spokes like a redheaded stepchild.
Either a wheel meant for disc and rim brake to keep your current rim brake setup and mount the sprocket to the disc bolt holes, or some other setup that takes the stress off the spokes from that rag joint sprocket should be much more reliable. Not sure if the clamshell hub adapters can work with that torque well either, can see them slipping under heavy loads even if tightened to the point of crushing and deforming the hub. Maybe set screws might work to fix that? Anyone ever try drilling and tapping the clamshell hub adapters to prevent slippage?
These are the 2 spots I can see issues that might leave you stranded pedaling, everything else looks pretty buttoned up. Fix that crank seal and enjoy :p.
Yea, I did a burn out with it and in the video you can see the spokes bend BAD, I will probably get a hub adapter (but I'm not sure in torque, as you said, the rang joint holds on well enough though I'm pushing the envelop), a idle sprocket wont really help me as it's just ment to tighten up the chain a bit, I've ridden it with it off and its manageable (ish, the chain flaps around like crazy lol)

The crank seal is just slightly damaged (I got the motor for free, it cant be perfect )
I'll probably just put a big o-ring and hope that seals it enough, 16$ is too much for a seal)
I never tried or even touched a hub adapter (probably because I'm cheap)
This is still a test build,
I'm hoping on increasing the compression, porting out the intake and exhaust, advance the timing, and modify the camshaft! (Its gonna be fast! That or its going to throw a rod )
 

CrazyDan

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Yea, I did a burn out with it and in the video you can see the spokes bend BAD, I will probably get a hub adapter (but I'm not sure in torque, as you said, the rang joint holds on well enough though I'm pushing the envelop), a idle sprocket wont really help me as it's just ment to tighten up the chain a bit, I've ridden it with it off and its manageable (ish, the chain flaps around like crazy lol)

The crank seal is just slightly damaged (I got the motor for free, it cant be perfect )
I'll probably just put a big o-ring and hope that seals it enough, 16$ is too much for a seal)
I never tried or even touched a hub adapter (probably because I'm cheap)
This is still a test build,
I'm hoping on increasing the compression, porting out the intake and exhaust, advance the timing, and modify the camshaft! (Its gonna be fast! That or its going to throw a rod )
It won't really throw a rod unless you ungovern it, 3800 rpm isn't that bad. If you increase the power you can use a lower gear reduction to increase speed instead of raising rpm.
I would search offerup or craigslist for a cheap rear wheel that accepts disc brakes to mount that sprocket to. You will most likely be running through wheels or constantly replacing spokes with the rag joint, and I haven't seen a clamshell adapter that doesn't move some through the miles, eventually bending spokes.
Another thing I would do (if I had your skills) is make an outside plate with bearings for both shafts to ride in on the outside of the transfer case. I think it would help tons with longevity. Every point power is transferred through in anything wants to twist or yank, in the case of the tc, both shafts want to pull each other together.
 
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mark20

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It won't really throw a rod unless you ungovern it, 3800 rpm isn't that bad. If you increase the power you can use a lower gear reduction to increase speed instead of raising rpm.
I would search offerup or craigslist for a cheap rear wheel that accepts disc brakes to mount that sprocket to. You will most likely be running through wheels or constantly replacing spokes with the rag joint, and I haven't seen a clamshell adapter that doesn't move some through the miles, eventually bending spokes.
Another thing I would do (if I had your skills) is make an outside plate with bearings for both shafts to ride in on the outside of the transfer case. I think it would help tons with longevity.
I bypass the govener (basically I replaced the spring with a solid piece of metal, so when I hit the throttle the govener cant move back when it needs to, I tired it and it will go up to 7200! (Lifting the rear wheel up, no way I'm doing those kinds of rpms lol)
The tranfer case is pretty beefie as is (imho, I had it on my 9hp beast of a mini bike before this, its held up great!)

I dont want to change things too quickly
(this is my main ride to school and back, and everywhere in between, so it has to be somewhat reliable)
So far its perfect! (Also being on a fixed budget is hard, I have like 10.45$ left to spend on this)
But I will update you on how this goes!
 

CrazyDan

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If it is able to spool to 7200 rpm with the wheel off the ground you will most likely increase your top speed by increasing your gear reduction. You just don't have enough torque (through gear reduction) to pull the higher loads. I have a buddy that did a 79cc build I would double back and race past him again with my 53cc because he was geared in such a way that he could only use that gear reduction for downhill. When he got a larger rear sprocket finally he wasn't limited to churning clutch for a half mile and needed a slight downhill to go over 30 mph. For some reason he thought he had the power to travel 70 mph and was somehow confused that he couldn't. When he geared it for 45 mph suddenly he wasn't a turtle and had full rpm range (governed) and could hit 45 mph. Undergearing an engine will easily prevent it from hitting top rpm, and at extremes make you lose top speed as well as acceleration.... wtf, why would anyone trying to go faster sacrifice acceleration and top speed as well by going too far with reduction?
Edit: if you bypass the governor I would suggest removing the governor internals. They have been known to shrapnel and wreck havoc on other moving parts if spun past their working limits.
 
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mark20

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Tha
If it is able to spool to 7200 rpm with the wheel off the ground you will most likely increase your top speed by increasing your gear reduction. You just don't have enough torque (through gear reduction) to pull the higher loads. I have a buddy that did a 79cc build I would double back and race past him again with my 53cc because he was geared in such a way that he could only use that gear reduction for downhill. When he got a larger rear sprocket finally he wasn't limited to churning clutch for a half mile and needed a slight downhill to go over 30 mph. For some reason he thought he had the power to travel 70 mph and was somehow confused that he couldn't. When he geared it for 45 mph suddenly he wasn't a turtle and had full rpm range (governed) and could hit 45 mph. Undergearing an engine will easily prevent it from hitting top rpm, and at extremes make you lose top speed as well as acceleration.... wtf, why would anyone trying to go faster sacrifice acceleration and top speed as well by going too far with reduction?
It gets going pretty quick, but I'm geared way to tall.
my buddie would pass me on his 40cc pocket bike! Untill he ran out of rpm and I chugged along past him, this was before I upgraded it so I was all stock, vs his somewhat modified 2 stroke, so I might be equal now, only time will tell ;)
 
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