If anybody happens to be building a Tom Thumb you may want to take a look at this for a power option. http://blowbyu.ca/90301.html
Building a Tom Thumb
- Thread starter Sunnyknoll
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Take another look. Go to the bottom of his page and you'll see that the belt drive system with the clutch is $140. Add the necessary carb upgrade for $40 and all you need do is find a motor. At that price I still believe it to be a viable option.............no?
Interestly, from what I read, that Honda 50 is capable of around 7000 rpm. Needless to say, that reduction would be an absolute must.
Interestly, from what I read, that Honda 50 is capable of around 7000 rpm. Needless to say, that reduction would be an absolute must.
really ya cant do that ?:shrug: ? not to be a smart ass but i have seen lots of drives like that and they seem to work just fine . my craptor uses something like that and its been forever and the belt still going .... well i cant say strong but then pulling some of the stuff i have made that thing pull ya just shouldnt do with a riding mower:doah:....
my moms small tiller had about the same drive as whats shown and motor . that thing went throw hell a few times . good old hard clay gumbo soil . like the hard hard clay , as a brick yard was built near by for the clay that was there .
made oh almost 10 years hard use before the factory belt blew . but not before it tore the bearings wright out of the chain case . and i got a new lower in there :grind::hammer::censure::grind:
my moms small tiller had about the same drive as whats shown and motor . that thing went throw hell a few times . good old hard clay gumbo soil . like the hard hard clay , as a brick yard was built near by for the clay that was there .
made oh almost 10 years hard use before the factory belt blew . but not before it tore the bearings wright out of the chain case . and i got a new lower in there :grind::hammer::censure::grind:
Hi Oldsalt: The model I would be considering using with the GXH50 Honda on a Tom Thumb sized bike would be the G T 4 *without* the idler. This set-up lists for $140. Looks like belt tension is achieved by stretching with the spanner wrench and simply tightening the bolts. I guess you'd have to make sure he includes the necessary spanner wrench. Looks like a 1:5 ratio on the belts. Couple that with 11 teeth on the drive shaft and 60 on the wheel and it looks like it might be possible that the little 7000 rpm motor could be tamed enough to live with.........eh? :smile:
Sunny
Sunny
Making the Honda GXH50 Tom Thumb "friendly".........Part 1: How to replace Honda GXH-50 Carburetor with Huasheng 142F-cc Carburetor - YouTube
Suppose it would be more understandable if it were known that I am somewhat of a purist when it comes to mechanical power transmission. Certainly you are right about seeing the 'back idler' on various drives at one time or another. You will never see it on an application other than 'non critical'. Tillers and minibikes are not 100% duty cycle designs but are adequate....for a while.
You can stop reading now or, if so inclined, read on about why the 'back bending belt breaker' was used and why far better alternatives are open but more expensive.
To prevent substantial added manufacturing cost [to an already outrageously priced item] a completely acceptable device to adjust belt tension was dropped in favor of a far cheaper one [the absolute cheapest].
The tensioner could have bee placed inside and pushing outward against the belt except that the belt guard would have to be bigger to accommodate.
A sheave, that has one side adjustable by threads, could have been used [an 'off the shelf' item]. The two sides of the driven sheave would be brought closer together or further apart to effect correct belt tension.
The 'jackshaft' would be designed to move fore and aft to provide belt tension adjustment.
A 'timing' belt drive [with belt sprockets] could have been used and would have totally eliminated the need for adjustment as 'fixed' centers are used in such a design and no adjustment is needed or desired. One of the Gates HTD belts X 3/4 width is what I would be looking at to use if it were to be a device that was to be bullet proof and have reasonable longevity.
The drive offered is very close to junk if reliability is a factor. Don't ride that thing any further than you are willing to push it back would be my motto if I owned one.
You can stop reading now or, if so inclined, read on about why the 'back bending belt breaker' was used and why far better alternatives are open but more expensive.
To prevent substantial added manufacturing cost [to an already outrageously priced item] a completely acceptable device to adjust belt tension was dropped in favor of a far cheaper one [the absolute cheapest].
The tensioner could have bee placed inside and pushing outward against the belt except that the belt guard would have to be bigger to accommodate.
A sheave, that has one side adjustable by threads, could have been used [an 'off the shelf' item]. The two sides of the driven sheave would be brought closer together or further apart to effect correct belt tension.
The 'jackshaft' would be designed to move fore and aft to provide belt tension adjustment.
A 'timing' belt drive [with belt sprockets] could have been used and would have totally eliminated the need for adjustment as 'fixed' centers are used in such a design and no adjustment is needed or desired. One of the Gates HTD belts X 3/4 width is what I would be looking at to use if it were to be a device that was to be bullet proof and have reasonable longevity.
The drive offered is very close to junk if reliability is a factor. Don't ride that thing any further than you are willing to push it back would be my motto if I owned one.
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Oldsalt so its your looking at it from the industrial machine that runs for decades on the same belt side of things . where im doing more of a ya it will work for a fairly long time but will need to be replaced from time to time kinda thing .
i am just going off drive setups that i have seen in use and they seem to work for a decent amount of time given what they have to deal with . :shrug:
i am just going off drive setups that i have seen in use and they seem to work for a decent amount of time given what they have to deal with . :shrug:
If belt wear is a concern, I wouldn't consider using a TAV either. That said, once again, the model I would consider using on a small bike is the one *without* the idler pulley. For the duty to which it's put, it looks "bombproof" to me. :shrug:
Sunny
P.S. I't the one in part 2 of my 1/15 post.
Sunny
P.S. I't the one in part 2 of my 1/15 post.
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Oldsalt: Did a little more digging and discovered that, on this model, the idler you're talking about no longer rides on the flat side of the belt. Again, as I've said before, this is not the one I would consider using but, see here anyway:
EZ Motorbike Hoot Gear box removal & Qmatic installation Part #2 - YouTube
EZ Motorbike Hoot Gear box removal & Qmatic installation Part #2 - YouTube
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No.......I have nothing to gain from the sale of these things. I just think it's a great way to get a small motor from 7500 rpms to 19 mph. :laugh: BTW, if you go to the Grubee site, you'll see the GT4 comes in 5:1, 4.5:1 and 4:1 ratios. Now I love it even more :smile: Another benefit on a small bike is the elimination of having to build a jackshaft......a big plus in my book.
Sunny
Sunny
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