GXH50 and a pocket bike clutch?

conradcliff

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Oct 10, 2008
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Ok, so I've been going back and forth and back and forth :eek::confused::eek: on my decision about what engine to choose for my setup and for a while I was leaning towards the pocket bike motor but now after realizing their poor fuel economy and getting opinions about their reliability I'm beginning to lean back towards the GXH50. I've already ordered several parts for my setup and if I don't want to go to a far greater expense I need to figure out some way to get this clutch and this housing to mount to the GXH50. I think I saw or was sent a link to a company that had an adapter of sorts to allow clearance for the shaft but I can't find it and I also believe it was quite expensive. I'm also considering the Titan as well and if that housing would bolt right up it would make a big difference in my decision. The only thing is that the Titan is only like $30 cheaper than the Honda and I prefer names with H's in them for some reason..

Thanks again and as always any help is greatly appreciated! (^)
 

Dan

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Just asking as I am working on a similar build. Why not just use a Gear Box Assembly? Not near as much fun to asemble rather then create from scratch, but less $. Truly, I am just asking and hoping to have a good reason to create a reduction gear of my own. Just can't justify the cost to myself.

How are you going to mount? I am thinking bent flat stock and 4 Ubolts.

Rode 4 stroke for the first time this summer at the East Coast Rally. 6 Wizzers and a Hua Sheng. (GX50 clone) Wow, what a difference!! Sound, comfort and vibration. There is no comparison. Although a 2 stroke or china girl is just plain better lookin'.

The Honda 50 clone could lap my 80cc (66) and I couldn't hear him coming up. rotfl
 
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conradcliff

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The gear box may be the way to go but at $120 I'm just not sure. I think you still need the adapter and clutch from staton if you're planning on using the GXH50 so that would bump the price up an additional $135. If I can use that bell housing that I linked to on the Titan then that will probably be the way I go..

Thanks for the reply btw!
 

Dan

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Thank you, this is the fun part. The plotting, scheming and planing. Second only to the tweaking and tinkering which of course is second only to ridding.

I did not know an adapter would be needed. Just for mounting? The GX50 max's @ 7200 and the clone at 6800 or about? Now you have me wondering but some one will let us both know.

In looking at building a reduction gear from scratch, Oscculy (SP, sorry bud) turned me on to http://www.maxtorque.com/and they had some great thoughts. I have their permission to post an email they sent me;


Dan-- you have quite a challenge with that engine. The crankshaft
length is only 1.250" long which is too short to support a clutch, the
engine idle speed is around 2,700 to 2,800 and top rpm is 7,200rpm which
means you are going to be going like a bat out of ****. Several people
have done it and they used the Whizzer pulley belt which is almost the
rim size of a 26" bike. We made a crankshaft extension for them but it
isn't the easiest way but what the heck all you have is time to get it
to work.

I have another suggestion. Do a jackshaft arrangement so you are
slowing the crankshaft turn speed down so you have a controllable speed.
See attached pictures. We are going to shorten the tube by 4.5". The
gear on the engine is 12 teeth and the lower sprocket is 24 teeth. What
does this do? When the engine is turning 3,000 rpm then the jackshaft
is only turning 1,500 which prevents you from bogging down the engine
when you initially get going and then at full rpm of 7,200 you are only
going 3,600 which is standard for most 4 cycle engines and the clutches.
This way ANY clutch you want to buy will work on the jackshaft.


James F. Donovan
Max-Torque, LTD.
2180 Corporate Lane
Naperville, IL 60563
Phone: (630) 369-9600
Fax: (630) 369-9686
Website: MaxTorque
Email: [email protected]

He has great pics that he sent along that I can't find!!
 
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TexasDav

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"Thank you, this is the fun part. The plotting, scheming and planing. Second only to the tweaking and tinkering which of course is second only to ridding." I agree with you Dan a 150%:)
 

ocscully

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Conrad & Dan

The Grubee Gearbox from Bicycle-Engines is designed to be a direct bolt up to the Honda GXH50 or Clone motor. No adapter is required/needed. The Grubee Gearbox will not bolt up to the Titan 50cc 4-stroke. Also part of the cost of the gearbox is the clutch and bell that mounts to the output shaft of the Honda/Clone

ocscully
 

Dan

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ocscully, some day you have to tell me how to remember how to spell your nic!! (kidding and sorry again that I always MSP it)

Ocscully and Aussie jester's look awesome with the clutch out board. Kind of a "Mad Max" MB

So, my thinking is at 120 and bolt and go, it is the way to go. But still be awesome to do a from scratch.
 
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ocscully

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ocscully, some day you have to tell me how to remember how to spell your nic!! (kidding and sorry again that I always MSP it)

Ocscully and Aussie jester's look awesome with the clutch out board. Kind of a "Mad Max" MB

So, my thinking is at 120 and bolt and go, it is the way to go. But still be awesome to do a from scratch.
Dan,

Yes the gearbox solves alot of problems and sure gets you riding alot quicker.
One other part to consider from bicycle-engines if you are going frame mount is their mounting Plate. Its $50.00 but its a quality part. One more thought If you buy both the gearbox and mounting plate, you may as well buy the complete mounting kit less the motor as you get all the additional parts for an additional $30.00

ocscully
 

conradcliff

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Oct 10, 2008
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Thanks for the replies everyone! Didn't realize the grubee was a direct bolt on..still, with the clutch and housing it cost's a pretty penny. I have also talked with the guys at maxtorque and am still considering the outboard clutch on the jack shaft but now that I've ordered 5/8" shaft I'm afraid it's going to be a little weak with the clutch hanging off the end of it. I'm thinking I can keep my current setup pretty much intact if what ocscully said on my thread on the other forum is true, and that is that the pocket bike clutch will in fact mount up to the Titan.

The Honda with the clutch on a jack shaft is still tempting, but the price is much higher..I still have a little thinking to do.
 

ocscully

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Thanks for the replies everyone! Didn't realize the grubee was a direct bolt on..still, with the clutch and housing it cost's a pretty penny. I have also talked with the guys at maxtorque and am still considering the outboard clutch on the jack shaft but now that I've ordered 5/8" shaft I'm afraid it's going to be a little weak with the clutch hanging off the end of it. I'm thinking I can keep my current setup pretty much intact if what ocscully said on my thread on the other forum is true, and that is that the pocket bike clutch will in fact mount up to the Titan.

The Honda with the clutch on a jack shaft is still tempting, but the price is much higher..I still have a little thinking to do.
Conrad,

let me try to clear something up here The part that I said would bolt up to the Titan is the Housing and its clutch bell. Not the clutch itself. The pocket bike clutch you linked to at the other forum is for a tapered shaft. I don't know if it will fit a Titan or not. But the Housing and clutch bell fill fit assuming that the clutch bell is 76/78mm dia. The Titan motor as sold by Dax includes is own clutch (shoe pack) but no clutch bell.

ocscully

ocscully
 

conradcliff

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Oct 10, 2008
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Oops, sorry. I meant to type housing not clutch...bf.

Edit: Double oops, I thought earlier when you had said that the clutch and bell was apart of the cost for the grubee gear box that you meant that you had to buy them separately..but I've just come to realize that it's all one unit if you buy the gear box for $120.

So many decisions and things to weigh out..I just want my bike!!! :eek:

Edit 2: Ok, so I just got a pretty exacting measurement on one of the pocket bike clutches and the OD of the clutch is 83mm. Oscully, I believe you told me that the Titan needed a 76/78mm housing. Does this mean the Titan is out of the running for the pocket bike clutch bell?

Edit 3: This is starting to become ridiculous to me..I just got the measurement off of yet another pocket bike clutch that has an OD of 74mm which I'm thinking would mean that the housing would work..oh woe is me...

Edit 4: Ok, just shoot me in the face: 78mm outer clutch bell housing. And this is the one that I originally linked to..my brain if fried...i mean is fried. See! Gosh! :ride:
 
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Dan

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rotfl LOL Conrad! Does get draining, eh? Each option creates parameters that cause concerns that create "have to's" An enigma wrapped in questions surrounded by what if's.

I can't spell it close enough but there is a Japanese phrase pronounced "Shin dow goo" The literal translation means "Demented Machine" but denotes a device designed to make one's life easier but seems dedicated to the opposite.

For this build, I am planing to go clone, Grubee reduction gear, home made (flat stock with 4 U bolts) mount although you got me thinking Ocscully! and a thumb throttle on a Felt bike. Keep it simple and as home built as possible. So is a 4 stroke bike for around $700

Bike has steel frame and I really want to do a fancy inframe gas tank. rotfl, ayup, keeping it simple.

Side note; Ya know when some one comes up and asks "Did you make that?" I really want to say "yes" and not "it's a kit. You just bolt it on"
 
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conradcliff

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Oct 10, 2008
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Yes sir it does, but here it is nearly 5am and I'm still up just thinking away. I think I'm probably going to end up going with the Titan and a pocket bike clutch..so far from what I've found, and what oscully tells me, it should work. But now I'm afraid I've made a gross miscalculation in my gear ratios in that I originally did not factor in the change from #25 chain on the input side of the jackshaft to #40 chain on the output side. Right now my calculator is just crunching the numbers using tooth count but a 10 tooth #25 sprocket is half the size of a 10 tooth #40 sprocket.

So now I'm off to make a thread about ratio help, but I think I'll hit the sack first and start fresh tomorrow.

Until next time...
 

conradcliff

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Oct 10, 2008
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I know, I wish the pocket bike clutch could come with a #40 sprocket but they only come with #25 so I have to have two different types of chain..it really stinks :(
 

Dan

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Can you just swap sprockets? LOL, ain't no one getting any sleep tonight.

(This messege brought to you by the spoke better english foundation)
 

conradcliff

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Oct 10, 2008
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Well, I just found this and it has me worried again..



If the mounting holes on the Titan are 75mm center to center then this presents me with a problem..

If the bell housing would still fit then I could probably drill the holes out and use some washers to hold it together.

Any ideas? :(


Edit: Ok, I don't know why I thought someone had told me that the mounting holes on the Titan were 75mm center to center but I just found this which says they're only 70..which is close enough for me :)
 
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