TREK 4500/ GEBE w/ GP460 build

[appye]

Huh ... are you sure about the lubrication thing? Remember a 2-stroke gets all it's lubrication from the fuel, how does it get lubricated if the throttle is closed and you are coasting at 30+ ? As far as your rpm/speed thing, you say there is plenty of room on the throttle while you are cruising at 35? I would like to have a max of around 45 or so, and I am also wondering how this setup of yours does uphill using the 14 gear. And what is your max speed? How well are you able to accelerate on a street that is full of cars? Are you able to keep up? This is one of the main reasons why I want a beefier engine than the Tanaka32cc ... Also, what kind mileage are you getting? Sorry for the dearth of questions, I am just considering settign mine up similarly and figure I can "use" you as a prototype. I figure I will just use the default setup for the engine though, as 4.2hp is already almost three times what I was getting with my engine. I like your slot idea and forgoing the idea of having the quick release. i don't mind carrying around an extra wrench or something for the rare occasion where I run out of gas or something. Also, what kind of mileage are you getting?

I will bug you with more questions when I think of them! thanks again for talking to me!

 

[DetonatorTuning]

great, i always wonder if i come across as just rambling without ever getting anywhere.

on the surface, the "hybrid" system is a CVT, IF you can configure the correct setup and make it live. this is being done by several members here.

i don't think the issue of coasting with the engine engaged is about internal lube. the engine is running and therefore getting lubed.

my issue with coasting down against the engine is not knowing what kind of damage it might be doing to the bearings etc. i'd love for someone to give some input on those possibilties, real or imagined ?

AND the fact that in decel mode with the clutch still in engagement the wheel is causing the belt to pull down ON THE FRONT of the drive cog, which causes the arm to open, relieving the tension and allowing the belt to be drug around the bottom of the drivering, stressing or removing the teeth. when the clutch is disengaged and freewheeling none of this happens.

in drive function the belt is pulled forward over the BACK of the cog, creating lax tension in front where the arm is there to take it up and keep the belt tight around the drivering.

as for the arm, i now have mine in an adjustment plain that keeps the arm parallel with the mount bracket and thus the bearing square with the belt.

you could also cut a slot in the bracket and put the bearing on an internally threaded post/ stud coming out thru the slot and use a captive bolt to adjust the bearing back and forth. nice, but not spring loaded anymore, so you would loose the quick disconnect feature of the current arrangement.

i can tell you that with my GP460, that at 35+ it's turning about 9000rpm w/ the 14T cog.

steve

i hate to quote myself on forum but...........

are there any comments on putting a spring on the backside of the arm ?

this would do 3 things at once. it would A) bolster the tension on the belt, B) make it harder for the arm to open up under decel and C) retain the quick disconnect.

thanks,
steve

 

[appye]

I have used a bungee cord on the lever to combat this before, but I was worried I might be putting too much tension onthe belt. Or you could just use a stronger spring. How do you keep yours parallel as well as free moving?

 

[DetonatorTuning]

Huh ... are you sure about the lubrication thing? Remember a 2-stroke gets all it's lubrication from the fuel, how does it get lubricated if the throttle is closed and you are coasting at 30+ ? As far as your rpm/speed thing, you say there is plenty of room on the throttle while you are cruising at 35? I would like to have a max of around 45 or so, and I am also wondering how this setup of yours does uphill using the 14 gear. And what is your max speed? How well are you able to accelerate on a street that is full of cars? Are you able to keep up? This is one of the main reasons why I want a beefier engine than the Tanaka32cc ... Also, what kind mileage are you getting? Sorry for the dearth of questions, I am just considering settign mine up similarly and figure I can "use" you as a prototype. I figure I will just use the default setup for the engine though, as 4.2hp is already almost three times what I was getting with my engine. I like your slot idea and forgoing the idea of having the quick release. i don't mind carrying around an extra wrench or something for the rare occasion where I run out of gas or something. Also, what kind of mileage are you getting?

I will bug you with more questions when I think of them! thanks again for talking to me!

info mining is a good and wise practice in my book and you are welcome to use what you can of my experience to your benefit.

i used the quote feature so that i can go thru this as orderly as possible.

Lube, your engine stays running when it idles does it not ? if so, it is getting fuel and therefore lube with the throttle plate closed.

at 1/2 throttle( approx. 9000rpm ) i'm keeping up with traffic in a 35mph zone. i have all the power i need to pull away from a stop with them, just can't open it up that fast or the belt will slip. i can however, get the jump on them with the pedals and be on the engine and at speed when they come back along side.

i don't have any hills around me or on my expected route that i can remotely concieve being unable to motor over w/ the 14T.

i knew my belt was as good as dead the other day, so i went for aspeed run from just above 9000rpm. i can't give an exact speed, but i had traffic going both directions doing triple takes and moving over out of the way !! from my motorcycle experience i have to say somewhere above 50mph for the breif time it took for the belt to fly to bits and come off.

i can't say what mileage is yet, i only have 1 liter of fuel thru it.

i have the 6400rpm springs in it and the stock exhaust back on, when the belt comes in i'm going to see if i can get the engine to turn more than 9000rpm without inducing the slip.

Craig,
i know you are watching, even if you are alittle gun shy from sharing your experiences previously, you really could improve this thread by participating openly.

thanks,
steve

 

[DetonatorTuning]

I have used a bungee cord on the lever to combat this before, but I was worried I might be putting too much tension onthe belt. Or you could just use a stronger spring. How do you keep yours parallel as well as free moving?

go to the hardware and get a wave (sometimes known as a spring) washer the size of the retaining bolt. put it behind the tension arm, at the same time use a michrometer to measure the thickness of the washer. go get a 1/4-3/8" dia. teflon rod, slice off some the same thickness as the washer and super glue it to the back of the arm. this will keep the arm from flexing out away from the bracket at the bearing end.

use a good clean light oil sparingly at the washer.

thanks,
steve

 

[lennyharp]

I just asked David Staton, by email, about using his small gearbox for a bike....
"You list a 3.11 to 1 reduction, small compact gear box with CCW
rotation, same as the engine PTO. I assume you have to use smaller
wheels and or larger wheel sprocket to get the right gearing for this
set up?"
Staton's small gear box set up
Now if he says that other motors work then I guess maybe this GP460 4.2+ HP Engine might work as well. Now I may be all wrong but tell me if it makes any sense because I may want to buy one of these gear boxes to set up a high performance bike without the belt problems. This will be my second bike and the first was a standard Staton kit with a large gearbox which is pretty heavy. I really know very little about the motor end and much more about the bike end. I build my own frames and modify existing ones so I can put things where I want.

 

[DetonatorTuning]

Lenny,
that IS very interesting. please be sure to post the replies you get.

it would seem that the clutch arrangement might be the limiting factor.

i've been working out something similar but without the gearbox. if you look at the GEBE system you can see that you could puta chain sprocket directly on the clutch spindle and work out the chain line to a sprocket attached to the hub.

you would have alot of options for a tensioning system, but it seems the simplest would be to lengthen the GEBE arm enough to get a derailer sprocket on it and down far enough to not hit the other side of the chain at full movement.

i actually had this in mind as a backup system before i bought the GEBE kit. i'd probably only use it if it's the ONLY way i can use the piped GP460 to full potential.

thanks,
steve

 

[lennyharp]

photos

David sent these but not much info. The site says the gear uses a #25 or #35 chain. From what I can see the #35 chain is used a lot in go karts so it should hold up well. Am I right that a smaller wheel and or a larger rear drive sprocket are needed for this 3.11 to 1 reduction gearbox?

 

[SirJakesus]

That would be correct. I would be willing to bet that small staton gearbox gives about the same reduction as a happytime motor judging by the size of the sprocket and wheel on that bike. Just make sure you get one of those freewheeling hubs or you're going to break your spokes putting that much power through them. Thanks for posting those pics, I was wondering what that gearbox looked like and how it mounted awhile ago. That seems like a much better way to go with a high HP engine than a belt drive.

 

[DetonatorTuning]

from what i can calculate, if you were to use the Staton mini drive you would also need to use a 10/63-64 gear set to be roughly equal to the GEBE belt with 14T drive cog driving a 26" wheel.

no belt in todays mail : ((

steve