4-stroke In-frame Basics

[twowheeledfox]

Only three weeks after building my 2 smoke rat bike, a new build idea is being formed... 4 strokes!

Now the advantages of the 4 stroke are obvious- won't go into the disadvantages- but mainly less vibration, oil only required every 50 or 100 hours of running rather than every fill-up, and a nicer sound.

So, some basic questions about the in-frame 4 stroke:

There appears to be three main things: The motor itself, the mount, and the clutch/tank/controls.

I would like to use something like an HF motor. My requirements are a comfy 30mph, in-frame, and not with a shifter kit (can't afford it while buying a frame and lights along with the motor). I do not want, nor could I use, a tiny 35cc or 50cc motor (unless they can somehow do that speed comfortabley, which I doubt).

How could I mount such a motor in-frame? I cannot use a welder, heavy-duty grinder or any other high-grade equipment. I have a drill and high-quality bits, but other than that the extent of my metalworking ability is a hammer.

Than there is the controls- how many controls from the stock two-stroke such as the throttle etc can be used or easily adapted to an industrial four-stroke like the HF? I can't modify the carb for the throttle cable, for example. Thankfully instrumentation, mirrors and lights are seperate systems on these bikes or it would be a nightmare.

Finally, final drive. Chain or belt? Singlespeed, two-speed or cvt? Manual or centrifugal clutch? What sprocket sizes would be appropriate?

Thanks all.

 

[tyrslider]

Well, I'm surprised to see that no one has responded. There are some good systems available. Only 2 companies (that I know of) that will sell you what you need for the HF, EZ Motorbikes and FireBelly Cycles.

The Honda 50 and HS are good motors too and should meet your requirements as well.

If your interested in the Honda/HS system I'd recommend talking to SpookyTooth or BlowByU for the G4 Grubee kit or Rustico Ray for an EZ kit!

If You want a set up for an HF, FBC is shipping WhisperDrives w/ a 1 week turn around and we have a couple of systems that could be available for those who'd like to help us w/ R&D

We are the only co that I know of to sell you an engine mount for the HF motor.

please check us out on YouTube

YouTube - ShellyBelly WhisperDrive

YouTube - FBC HFV2 FreeStyle TomFoolery!

YouTube - FireBelly's "Smokin Tyres"

YouTube - FireBelly WhisperDrive in true technicolor extra reality TV

Cheers!

 

[Quenton Guenther]

Hi twowheeledfox,

As Evan has suggested you have a few choices concerning your 4-stroke build. There are several options concerning motors, drives, exhaust systems, and mounts.

If your state has either a CC limit or HP limit the Honda or HS motors are both below 50 CCs and produce plenty of power [1.9 to 2.5 HP] to get the job done. The Honda is rated with the same HP as the 79 CC HF motor, and the HS is rated with slightly less.

The advantages of the HF 79 CC motor is more bottom end torque and cost, however because of design & size it won't fit in as many bicycles as the other 2 motors. Both the Honda & HF 79 motors require removing the governor & fabricating a working throttle control system, whereas the HS 142 motor has the carburetor setup for MB use. The HF motor can be affixed with several different motor mounts, but will require some modifications as the motor needs to be mounted to the right [sitting on the bike]. I think Evan makes a mounting system for the larger motor.

The advantages to the 50 CC motors are many. They are smaller, easier to mount, and most importantly is the very wide RPM range. The HF 79 CC motor has an average RPM spread of 2600 [1000 to 3600]and with governor removed 3500 [1000 to 4500]. The HS & Honda [with governor removed] motors have a very wide RPM range of 6500 [2000 to 8500], and makes a good choice for single speed motorbikes.

Another item to consider is the exhaust system, both Honda & HS have a variety of exhaust systems [pipes] available, however the HF has the exhaust port located in the rear top of the motor and will require a special fabricated pipe [Evan may offer a pipe to fit].

The Honda & HS motors have a large selection of drive systems, however most are problematic [read the many posts]. EZM has the Q-Matic and has been attached to a large selection of motors including the HF 79, Honda 50, and the HS 142 with great success, however Evan is working on another optional drive system for the HF 79 and I also understand he is working on systems for the higher RPM motors.

The good news is all three motor options have been tested and workable systems are available. All three motors will deliver enough power to easily cruise between 30 MPH and 35 MPH and all you need to decide is which final drive ratios fit your riding style.

Oh did I mention the HS or Honda motors will average 165 to 185 MPG, and I am sure the HF will supply similar MPG [don't know the MPG on the HF].

Have fun,

 

[twowheeledfox]

Thanks for the help- so the total cost, minus bicycle and lights, could be divided as:

HF Greyhound, $100 or so plus an exhaust pipe OR HS 50cc, $?

Drive system and transmission, $?

How would I modify the carb for throttle linkage and remove the governer on the Greyhound?

 

[tyrslider]

I sell everything you need for the HF.

Your ez rep will likely sell you what you need for their systems.

The people I mentioned before, all of us, we'll be happy to help w whatever you decide. Lots of helpful people! Probably best to private message, or email the vendors who've sparked your interest w/ specific product info ?'s

In the threads info shared by vendors is likely to be more general discussion, problem solving, sharing ideas etc i.e "kicking back" but not "tootin our horn"

Cheers!

 

[Quenton Guenther]

Hi twowheeledfox,

Q-Matic drive system for the HF 79 CC motor is $259.75. The Q-Matic has been tested on the HF motor for over a year and has worked 100%.

Have fun,