Calling all Honda 4 strokes with Grubee Gearbox

[Irish John]

im useing wheel packing grease in there now white grease breaks down and chatters after times and fails
wheel packing grease its that stinky stuff its comes in a tube its worked the best so far for me

it will be really smooth first few miles
i put a lot on thick on everything not in the clucth bell then it will be nice with no chatter for the season and you should make sure you chain is about 1/8 inch. lose anyways if u run it to tight you will mees up that gear bearing

I've found MPG white grease by far the best. Made by Rock Oil Co. from Warrington, UK and available from good trail motorbike shops. The clutch chattering can be temporarily removed by packing with grease but it's short-lived. To permanently remove chattering try Cheetoh's method of drilling 9 holes in the clutch. That makes it lighter and more responsive to being pulled in tight at the high rpm that the engine idles at. The clutch was not made for the motor but is a stock item used because it sort of works OK. The chattering is more of a problem than the whining of the gearbox. The whining can't be fixed but diminishes slightly with wear. Some new ones are really whiney. The clanging and clattering is greatly helped by drilling holes.

 

[Irish John]

I have a Honda 50 cc with the Grubee gearbox with a 56 tooth sprocket. I was wondering if anyone out there has the same setup but with a 44-36 tooth sprocket. My top speed now is around 32mph(full throttle). I would like to be able to cruise at 35(not reving the engine way up), with decent low end. Can someone let me know what sprocket I will need to do this? Thanks

A 36T sprocket on Honda 50cc with Grubee GB is a total waste of time. You'd burn the clutch out and be stopped dead by head winds and couldn't climb a pram ramp. Pretty much the same for 44T because if you read a bit of this Forum you'll find out why.

 

[ZnsaneRyder]

I'd like to know if anyone has tried this gearbox on the new 79cc 2.5HP Harbor Freight 4-stroke engine?

It looks like it will bolt up and the shaft is still 5/8" like the Honda.

 

[Irish John]

I'd like to know if anyone has tried this gearbox on the new 79cc 2.5HP Harbor Freight 4-stroke engine?

It looks like it will bolt up and the shaft is still 5/8" like the Honda.

I'd say the answer is 99.999999% liklihood that it won't fit but it would help to include a picture of the engine you are talking about (shaft side view of course). It's not the shaft size and the length so much as the bolt holes on the crank casing that take the clutch itself.

 

[jimraysr]

HARBOR FREIGHT 2.5 HP 79.5cc ENGINE

An other problem is it is only 3600 RPM at rated output, so gear boxes would make the rear sprocket very small?

Just the first thought.

Will look at one at HF and maybe buy it to study at home against my Honda. As it makes it power at such a low RPM it would have to be much larger. As you can see it is 50% more CCs for around the same HP.

Might work well for a rack mount, but I had a difficult time finding a new frame that the Honda sould fit.

It would not be legal in AZ as a motor assisted bicycle.

Jim

 

[duivendyk]

The notion that weight is a factor is true only to the extent that it is related to body size which affects air resistance,which is the predominant factor affecting speed,at least on the flats.Of course total weight affects accelleration and is a major factor climbing hills especially long ones.In hilly terrain a CVT or other means to change the gearing are allmost indispensable,unless the engine is oversized (80cc plus),a 2:1 ratio should be adequate.

 

[cruiser66]

HarborFreight 2.5 hp engine

This engine is designed to work with generators. That is why it is rated at 3600 rpm. This speed will give a 60 cycle AC output when mated to the proper generator. It is governed to run at this speed. A modern short stroke OHV engine is capable of much higher speeds (probably in the neighborhood of 7000 rpm for this engine). Here is the product manual which gives all the specs. The max rpm is listed at 3600 rpm, but that's because it's governed similar to the Honda GXH50.

http://www.harborfreight.com/manuals/97000-97999/97964.pdf

66

 

[jimraysr]

HARBOR FREIGHT 2.5 HP 79.5cc ENGINE

3600 RPM is pretty standard for both gas and electric motors. 2 pole motors (electric) run at 3600 (3450 under load), 4 pole at 1800 RPM (1725) and 6 pole at 1200 (1050).

Likewise gas engines also are made for the same speeds so the equipment like pumps, cement mixers, air compressors, etc. can be either gas or electric powered.

Generator also run at other speeds like 1800 and 1200 RPM for 60 HZ output. Newer inverter generators do not run at a synchronous speed, but run fast enought to handle the load, thus saving gas. The electronics produces the 60 HZ sine wave output.

Too much information.!! )

The high revving (7500 RPM) Honda and China knockoff do offer a lot of power in a compact package.

Jim