Honda GXH50 & Honda Elite CH80 carb mod

[Ibedayank]

I rode it for about three hours total and can only estimate what the speed was. It was close to 50mph. I did'nt use a speedometer.
I was not happy with the setup before as I disconnected the governor and had a poor setup concerning the throttle.
Another problem I was having was with a steady throttle hand the RPM's would flex. So I never took it to top speed and disassembled the exhaust pipe I purchased and found an internal leak in the setup I got from bicycle-engines. I figured this was the RPM problem that could have caused serious engine damage if I continued.
You can estimate a setup like this at 50mph with little engine stress meaning a low rpm.
I'm hopping to go 73mph with the new setup.
I also done some gear work on the stock 4 stroke shift kit from SBP. I now am running a 36 tooth chain-ring were was a 48 tooth. (This would be the gear thats next to the bicycle chain ring) Then on the right side of the four stroke shift kit I had a 9 tooth and now have an 11 tooth. This is some serious change to the gearing. I hope with the new power increase it will power through with the high torque exhaust I made.
To better discribe the exhaust problem were there was supposed to be a seal there was just a metal ring which only partially sealed the attempted to send the exhaust flow through a baffle. So the exhaust flow was out of control causing the flex in the rpm.

guess don't cut the mustard here dude...lets see some time slips from a track

 

[hondabicycle]

That would be defeating the purpose as someone cant go 80mph on a track with turns. So Im gonna do it on a freeway.
Sorry if it hurts your feelings.
This started as a one man operation. This will finish the same way.

 

[The_Aleman]

It'll probably finish as some kind of operation...

 

[scotto-]

The only time you will see a 49cc 4-stroke doing over 60mph will be in the back of a pick-up truck.....let's get real here.....

 

[azbill]

I know what will help
stickers and a BIG spoiler(wing),,,
that's what all the tuner wannabe's use

 

[wayne z]

Please explain how an internal baffle leak could cause fluctuation in rpm. I would think that a constant leak would have a constant effect an any given throttle setting.

I think your guestimated top speed numbers will closer if you called thim kph instead of mph, but even then, those numbers are in the pipe dream realm with a mostly stock 49cc no matter what kind of carb you put on it.
The bigger carb won't change things much without bigger cam, valves,ports and exhaust to match.
Most proffesional tuners know that when an exhaust is tuned for torque it helps low rpm power with a loss of high rpm power, and vice versa.

 

[Helmutt Cycles]

I was doing 65mph in 4 gear I had 3 gears to go. I heard some noise from the exhaust and it blew out my exhaust mod. It got really squelly when I was going that fast.
Heres a video below and this is how it sounds with the exhaust blown out.


676A0204 - YouTube

Heres a picture of the blown out exhaust.
I got no reason to lie and I will have video of a speed run in a few weeks.

I was also doing 28mph in first gear. It needed a little peddle to start but when it got past that it was really fast. I hardly had the need to get out of first gear.

After doing those speeds I'm tearing it down and making adjustments accordingly.

What elevaton is your test ground. Sea Level ? What rpm does the Motor start to come alive with this Over size carb?? I am sure you lower end was sacificed.but it may come on at the mid to higher area of rpm.. So when does it come on to it's Power band????
I like these Motors I have Played with them too..but over 60 Hmm??? Ive seen.. 52 geared tall and stream lining myself with a slight down hill. I will be Looking forward to a true documented Run..Maybe You can get close to your dream..?

 

[Ibedayank]

when did a dragstrip have corners/turns? an oval does not have timed and mph gates on it now does it? and the vid you have posted only proves you have a motor that runs and a crappy camera..like a cellphone. YOU have made these claims not step up be a man and PROVE it

 

[hondabicycle]

The power-band was set for low end rpm power by the limited exhaust flow.
So after shifting gears the bike would come to life then on the higher rpm less bwaw bwaw and more of a smooth sound.
I have alot work to do concerning the clutch mods and what Im going to do next time is use the stock exhaust which will give mid range rpm power.
With the low end set up I was running to rich as the restricted exhaust outlet was enriching carburation making it run rich so the stock exhaust will lean it out a little.
I had a lot of carbon in the fiberglass packing. After the exhaust blew I lost about 30 percent power and took it home.
I had two other video's but the it was on mute or something.
I attached some pictures of the fiberglass packing I pulled out of the exhaust and that's after only about 2 hours of ridding around the neighborhood.
I could of gone faster and will in due time on video.
As far as the carb concerned it performed great and Im going to take the hose out and weld the two intakes.

 

[hondabicycle]

Im also contemplating just adding another fuel line for a little longer lasting pipe.
You know if your dong 70 or 80 your gonna need to rebuild stuff regardless. So its just kinda of a hobby and I like going fast.
Notice the tear down pictures.

 

[hondabicycle]

Please explain how an internal baffle leak could cause fluctuation in rpm. I would think that a constant leak would have a constant effect an any given throttle setting.

I think your guestimated top speed numbers will closer if you called thim kph instead of mph, but even then, those numbers are in the pipe dream realm with a mostly stock 49cc no matter what kind of carb you put on it.
The bigger carb won't change things much without bigger cam, valves,ports and exhaust to match.
Most proffesional tuners know that when an exhaust is tuned for torque it helps low rpm power with a loss of high rpm power, and vice versa.

Well for starts if theres an internal leak the more the rpm's change the more the flow pressure changes.

So by using fiberglass you have control of the pressure. So its all about mastering the flow. Hince flow masters also hence supertrap exhaust.
The world renound supertrapp exhaust is controlled by trapping the exhaust and controlling the flow.
No out of control flow with an internal leak.
Well world renouned amongst racers so no offense.

 

[hondabicycle]

when did a dragstrip have corners/turns? an oval does not have timed and mph gates on it now does it? and the vid you have posted only proves you have a motor that runs and a crappy camera..like a cellphone. YOU have made these claims not step up be a man and PROVE it

If you and scoto knew anything about being a man you would'nt be internet trolls.

 

[BarelyAWake]

Fair warning hondabicycle, as I see it we've a new member posting questionable speed claim "guesstimates", then getting irate when those claims are questioned and now resorting to insult.

I would suggest either substantiating those claims or refrain from making them - continued hostility and insult will result in staff intervention.

 

[hondabicycle]

Heard you loud and clear!

 

[Ibedayank]

Now these bikes will do what you claim yours will do.... see the differnce?
Now why don't you post your gearing and what rpms your motor is turning to get your 80mph. I do have a program that will tell me if you are telling the truth or not!!

 

[hondabicycle]

Im gonna buy a hero helmet cam.
Im not interested thanks

 

[The_Aleman]

You may not be interested, but most everyone else who's reading this is. Otherwise why post at all? Public journal? There are blogs for that.

 

[Ibedayank]

Sept. 16 2010 – French recumbent bicycle racer Barbara Buatois (Varna) broke her own world record yesterday, with a top speed of 75.69 mph/121.81 kmh during Wednesday afternoon speed runs


better go faster then just 80 there bud

 

[hondabicycle]

You may not be interested, but most everyone else who's reading this is. Otherwise why post at all? Public journal? There are blogs for that.

Gearing is 11 tooth right side shift kit sprocket changed from the 9 tooth stock sprocket.
Chainring is down to 36 tooth from a stock 48 tooth.
This is real high gearing which calls for another bunch of mods like clutch and exhaust mainly. I also disconnected the oil level auto shut off switch for ignition power increase. I use math ratios to setup a modifaction like intake should be 15 to 20 percent larger then exhaust and mines at 17% larger then exhaust.
It called for an exhaust mod that would increase torque and power on low end rpm but mine blew out so Im back at the drawing board there but still need the severe torque increase so am headed in the same direction. I needed it low rpm so the power would get me to higher rpm and need to shift gears.
So the carbs entry port from air filter is about 35mm then goes down to 18mm exit to manifolds. Manifolds are 18mm and engine port is a hair under 18mm and square but slight porting about 1/2 mm all the way around is needed. then exhaust port is 15mm.
So this size of porting is about as large as its gonna get. Anything larger would deviate from the exhaust to intake ratio.
I'm just not interested in any type of programs.
So feel free to ask questions.

 

[Kline's Kustoms]

My GHX can go 70. Are you serious man? Haha! Post a damn video. Borrow a camera from someone. Do something to prove this! Until then I wouldn't post anything.


P.S My GHX can do 90. I'm not gonna prove it though cause I'm outta Velcro from china. Hahaha ^THIS GUY.