Got the 33Saw running, 34 mile roundtrip test ride.

[rgvkid]

Okay, last i posted my 33 Poulan Friction Saw was down because the 5/16 threaded end of the Saw shaft broke off while tuning it with the 1.5 roller on it.

So, i welded a reverse 3/8 threaded rod into a 3/8 ID bung and sleeved the other end of the bung over the existing Saw Shaft and welded it up. The hard part was getting the threaded shaft to weld on true and not lopsided.

I changed my lift to a lever which seems to work out great, thanks to the help of Deac, 5-7Heaven and Shoes. I first had a cable lift using a brake lever but it felt like i was lifting a ton of birck. I opted to try out a lift lever in which I welded a 3/16x3/4x18" flat bar above the pivot point on the engine mount and made a latch hook, mounted to the seat post sleeve, for the flat bar to rest on. The flat bar is thin enough for it to flex side to side around the latch hook so i can easily release and engage. I diengage before hitting a red light, then peddle a couple times to get up to about 5-8mph then reach down and engage the engine to contact the tire. I used 5/8 spring mounted from the seat post sleeve to the engine mount which keeps the engine lifted off the tire when i disengage. I welded two stop tabs to keep the mount for kifting to far off the tire. One tab on the pivoting mount and one tab hanging over off the frame to contact the other and keep from over pivoting. Which you can see in the pics.

Another problem i had with the 33 Poulan Saw was that it would overheat and shut down after about 10min. of riding, then id have to wait 10min. for it to start again. I tuned the H screw so it will run Richer which i hope isnt to rich now. But i'd rather it run rich then to lean. I also dropped my cruising speed down to 20-24MPH rather then trying to keep it WOT at 33mph. At 20-24mph it cruises right before it hits the powerband of the 2-stroke engine. If i gas it into the powerband i can feel alot of vibration on the lift handle onto its resting hook. Im going to try some rubber and shortening the friction rollero see if it eases the Vibes. Its definitly has a bit lose of power since im running it richer now but I don't want to hassle with it over heating.

On the BIG HILL on my commute, i definitely have to peddle assist but i could use the workout anyways. It does feel like it starts to over heat or lose power when i get close to the top, But like i said its a big hill. One thing i do to put less strain on the engine is shut off at all red lights and downhills. When light turns green i engage the roller and jump start it once i peddle up too 5-8mph.

My 32oz. Premixed Gas can worked out great and i estimate gets me about 40-45 miles @ 20-24mph. I also estimate a total MPG at about 170MPG at a cruising speed of 20-24mph. Not Bad.

It would be nice to have a GX50, but until i can afford one and or my 33Saw blows, it will have to do. Im going to keep my eyes open for another $50 chainSaw maybe for the Front wheel.

This was alot of work, but thanks to everyones help the next one will be cake. Sorry for so much info but maybe someone can take something from this and i'd be happy to answer any questions.

OH YAH, One more thing, Wal-Mart $20 Bell Gel Seat...SUCKS!!!! should have saved my money and invested in something worth it. Suspension post is my next addition.

 

[Bikeguy Joe]

Thanks for the report!

Yeah, the Bell walmart stuff is O.K., but not great.

 

[5-7HEAVEN]

Good job, Charles!

Don't forget to grease the pivot hinge for less resistance and friction.

As a suggestion, try moving the springs' attachment point TEMPORARILY to the top of the hoist. You should have greater mechanical advantage and need less spring tension.

 

[rgvkid]

Thanks, I mounted the tension spring there because I didn't have a long enough spring to mount it on top. i'll redo as soon as i get a longer spring.

I rode it today and tighten the H tuning screw about a 1/4 turn to lean it out a bit and it ran at 25mph pretty smooth without shutting off at about 1/2 throttle. It runs god on the straights but i definitely would like somemore CC's to get me over the hils without having to peddle as much.

 

[5-7HEAVEN]

JMO, the cheapest way would be to find a larger, more powerful chainsaw engine. You might get 5mph faster.

The cheapest and most effective way to double your hp would be to install another engine in front.

Once you go twins, you'll never go back.

 

[rgvkid]

Well, i definitely need a bit more power. The 33Saw is bogging out on the hill right before home. I have to stand up and pump peddle as hard as i can to get around a barrier on the side of the road which puts me out into the lane.

Some questions for 5-7Heaven:

1. Im looking for another Saw for the front, but is there a problem with steering the extra weight on the front wheel?
2. is it prefered to have 2 of the same cc engines?
3. Being that you have 2 different size rollers, how do you run them when going up hill or on the street?
4. How about engaging and disengaging while driving?

I think i would have to leave the front roller engaged at all times because it would be difficult to disengage with a lever. The rear i could leave the same setup.

Thanks

 

[5-7HEAVEN]

1. At walking speed, the dual-engined bike feels awkward, like having a front basket full of groceries. When parked, I use a rope to tie the right handlebar grip to the seatpost to keep the bike from twisting and falling over.

Once it rolls past 5mph, it feels stable. When both engines had friction rollers, with both engines off, my bike felt sluggish with resistance drag.

2. It doesn't matter if the engines are matched or not. You mightl favor one or both engines at top speed, one or both engines at low and midrange. There are a lot of combinations of using two engines, all of them pleasant, a few you will find are awesome.

3. The front friction roller is 1.25", which is equivalent to 24:1 gearing with sprockets.

The rear sprockets have 18.75:1 ratio, equivalent to a 1.6" roller.

If you throttle the 1.25" roller engine to midrange, release throttle and stab the rear engine, it sounds just like shifting gears.

I start by pushing off, with a little throttle on the chain drive. This saves the front tire of friction wear from its roller. One second later, I throttle both engines simultaneously and the bike launches harder than a moped.

Both engines like to cruise between 20-25mph and are very mellow running together or alone.(I think the engines like to run together ALL the time.)

On hills I like a running start with both engines pushing the bike uphill with 4.4hp. The front engine peaks and starts to strain. I release its throttle and the chain drive rear engine is on its own(but doesn't want to be alone). A few seconds later you hear the rear engine lose rpm. Before power is lost, I floor both engines. It's almost like a supercharger because power is increased 100%, from 2.2hp to 4.4hp. The rear engine REALLY appreciates the extra assistance and gains speed. Sometimes if it's 20-something mph going uphill I also pedal with the smallest sprocket.

4. I fabricated a lever which raises and lowers the front roller onto the tire. It works VERY well in applying pressure. However, I just lock the lever in place and leave it there. The rear engine is powerful enough to overcome the front engine's drag.

The rear engine has chain drive so freewheels and no drag.

Both engines have centrifugal clutches. They work VERY well together. The rear engine never strains because of its high ratio and never overrevs. When it begins to run low on its power range, its twin kicks in like a supercharger.

Twin engines are an awesome, almost unbeatable combination.

 

[rgvkid]

That sounds like fun 5-7, thanks for the info. Unfortunately my 33Saw is gravity direct drive with no Clutch. If i pick up another Saw for the front i would have to use it the same becuase of the clutch situation. If i could afford a small engine warehouse motor i could use a clutch but im not sure i want to spend that much money if i can figure something out with a Saw for the front. The Lil Poulan 33Saw is okay for now but im not sure how long it will last on a 30 mile commute 3-4days a week. Im noticing some oil build up on the outside of bearing where the shaft comes out to the roller. The original chain Oiler was removed so it has to be coming from the engine itself. I'll have to see if there is pressure leak or if its common with 2 strokes.

 

[5-7HEAVEN]

Charles, it is easier to fabricate a lever/gravity clutch on a front engine than the rear. Take a look at how comfortableshoes did her rear engine install for suggestions.

Or do a mirror-image install of your rear engine onto the front.

 

[rgvkid]

Hey 5-7Heaven, which motors are you running again on your dual? I might pick up a 40cc Poulan this week and give it a go. My 33cc Poulan alone is just not cutting it for my needs.

 

[5-7HEAVEN]

I'm running two Mitsubishi 43cc 2.2hp engines. One Mitsubishi is not enough for my needs.

Sometimes TWO Mitsubishis doesn't seem like enough.

They probably are. I am FLYIN' uphill and on the flats.

I just need to find the right gearing combination to maximize efficiency.

Right now my rear gear is 18.75:1, which is like 1.6" roller.

My front roller is 1.25", which is like 24:1 gears. It's like shifting gears when running only the front engine, then only the rear engine.

It's easy to swap to 15t rear sprocket which is 20:1. I can try that.

It's much harder to press out and change rollers, but I also might try 1.375".

Or I might try a front 1.5" roller and a 18.75:1 rear gear(like 1.6" roller).

Orrr 1.5" front and 15t back sprocket, which is 20:1.

 

[rgvkid]

Boy Heaven, So many choices when you have a dual setup Huh.

Whats your comfortable cruising speed with the 43's?

 

[5-7HEAVEN]

The bike, engine combination and I (the whole package) likes to cruise between 20-25 mph.

Actually, the engines could probably cruise between 25-30 mph or even faster, but the bike's weak points, my own human responses, road conditions and traffic makes it too hazardous.

If the road is clear and the cars are a couple of city blocks behind me, I will full throttle it until the cars catch up. Then I jump on the sidewalk until they pass me by.

When full throttling the rear chain-driven engine I can hear it start to lose rpm on flat ground. Then I simply floor both engines(and maybe also pedal). The front engine is at its max rpm and hp range. You can feel the bike accelerate and the rear engine pick up speed, then you release throttle on the front engine. When you hear the rear engine's rpm lower, you full throttle the front engine to pick up speed and help the rear engine accelerate.

On a long stretch, this procedure is replayed over and over, like intermittent injections of nitrous oxide.