best engine??? (4 stroke--for riding in the mountains)

[RideAgainstViolence]

So used a grubee 49cc an starfire 49cc a grubee 66cc. (All two stroke) and now I bought a 4 stroke hausheng 49cc but I am disappointed I know it has a much better life span but it seems to lack on torque. On this new trip I am hitting the rockies not the appalation mtns and I wonder if someone has the knowledge of the best possible combination for torque (speed no biggie) but help climbing these 6% elevations would be nice

 

[Wheres my dog]

It's all in the gearing my man...

Gear down for more torque and less high end speed!

With the right amount of gearing, any engine could get you up that hill

 

[RideAgainstViolence]

I understand the gearng idea (I raced motorcycles for 7 years) but the 4 stroke still seems slugish just looking to find someone that's in a mountanis area that has found the best tune .. The 4 stroke just seems like although it won't break down may just not cut it (even properly gear) in the mountains

 

[MikeJ]

Hi Ride -

There is probably little I could tell you, other than be prepared for "non-race" performance. It may be disappointing to you.

"Properly geared" is a relative term, unique for each motorized bicycle. I run a 2.5 HP 79 cc engine in Albuquerque with a 34 tooth MegaRange cassette from Sick Bike Parts. My rides start at 5500 feet above sea level and cross at 7000 feet. I found a table to derate any piston engine at wide open throttle at a rate of 3% per 1000 feet above sea level. So at 7000 feet, my 2.5 HP engine (satisfactory at sea level) is weak at an output of 2.0 HP. It barely climbs some long hills that are just not too steep.

Check other users of your engine for the best exhaust system. My current setup is being choked by a too-restrictive exhaust system and too restrictive intake system. It has to be replaced. I hope to improve the power output in the process.

I hope your ride goes well if you take it on.

MikeJ

 

[Skyliner70cc]

I use a HT 2 stroke 66cc with a shifter kit from SBP.
Mandatory for high elevations
1. Rejet so your engine runs efficiently and develops max power for the elevation. MikeJ's correct about 3% loss in power for every 1k in elevation.
2. Shifter kit
a. I have a mega gear (34 tooth 1st gear). I also made my drivef sprocket 10% smaller from 10 tooth to 9 tooth and run a 48 tooth sprocket on the freewheel instead of stock 44 tooth. This combination has allowed me to climb ANY hill Colorado has to offer.
3. Tuned pipe. I tune my length for mid-range power. This allows me to have enough torque for hill climbing and enough revs for decent speed.

I've ridden my bike to 12,000 feet about 126 feet short of a peak before my shifter kit side plate distorted enough to throw the drive drain. The power was more than acceptable at 12k ASL and I had no problem pulling up the pass at greater than normal pedal speeds (about 12-15 mph).

 

[RideAgainstViolence]

I use a HT 2 stroke 66cc with a shifter kit from SBP.
Mandatory for high elevations
1. Rejet so your engine runs efficiently and develops max power for the elevation. MikeJ's correct about 3% loss in power for every 1k in elevation.
2. Shifter kit
a. I have a mega gear (34 tooth 1st gear). I also made my drivef sprocket 10% smaller from 10 tooth to 9 tooth and run a 48 tooth sprocket on the freewheel instead of stock 44 tooth. This combination has allowed me to climb ANY hill Colorado has to offer.
3. Tuned pipe. I tune my length for mid-range power. This allows me to have enough torque for hill climbing and enough revs for decent speed.

I've ridden my bike to 12,000 feet about 126 feet short of a peak before my shifter kit side plate distorted enough to throw the drive drain. The power was more than acceptable at 12k ASL and I had no problem pulling up the pass at greater than normal pedal speeds (about 12-15 mph).

Thanks for the info I actually tuned it even a little stronger but road around the hills up here (where ever I could find a 10% grade or better.

MY TUNE:
First I rejetted as u recommended (that di suprizingly help)
2nd put on a 50t rear sprocket and dropped 1 tooth on front
I bought a competition exaust which I modified and removed the thick baffle and put in a less restrictive piece of baffling from a friends dirt bike exaust canister
Lastly I put on a comp air filter

After all this I have quite a bit invested now but I will say ur build gave me great ideas I decided to just build the bike like I would one of my race bikes and VIOLA it worked I lost a considerable amount of top end but I can turn the throttle now and **** near lift the front tire off the ground.

Should be perfect now seeing I pull approx 110lbs w/ trailer etc

Think she's rdy to go

 

[Skyliner70cc]

I pulled about 225 lbs a couple weeks ago on my dax engine powered spb shifter kit setup. i was on a group ride and my brother in law's bike failed miserably and couldn't even be pedaled home. i borrowed a tow rope and pulled him for about 40 minutes up and down hills with no problems. i even hit 20 mph a couple of times on the flat portions of our return trip while towing my binlaw. its all in the gearing.

 

[RideAgainstViolence]

That's impressive and inspiring. I tow a 26lb trailer w/ a 60+ lb basset hound and 30ish lbs of gear in tow(I learned on the first trip to pack light). I am starting relatively flat for about 400 mi so I am go gear to a 44 1 down and switch out to the 50t r and 9f when I hit the rockies save some wear on the engine and make good time. I am hoping w/ my over 4k miles of past trip xp everything will work but bought and extra engine as well that I am leaving w/ a friend so it can be sent in case needed 4 an unseen issue... I have almost 150mi on this new engine so almost broke in about where I like it... I also run my oilto gas ratio a bit rich seems to extend life w/ minimal power loss (yeah I decided the 4 stroke was nice but in this terain just wasn't cutting it but I have it as a fail safe) I am now using a GT5 Grubee 66/80 . Guess we will c soon. If it cuts it

 

[Skyliner70cc]

so, if you don't mind...here are a couple more tips that may help you.
1. For engine longevity please use a lubricant that contains at least 20 percent castor oil. it provides superior protection against overtemping/high engine temps and will prolong engine life immensely. you can blend your own easilyigh m by buying a gallon of sig castor oil from a model airplane rc shop. when climbing mountains in the rockies you got several things trying to kill your engine.
a. high mountain grades requiring full throttle application almost the entire time and your speeds will be slower...slower speeds means less airflow over your engine to cool it
b. lower air density not only means less power from engine but decreased cooling of the aircooled engine
c. the two above will really cause your engine to run very hot and even hotter when you are climbing mountains in the summer.

I have motorbiked on roads and trails that turned my engine head a different color and my exhaust glowed cherry red from the heat generated by the engine. I was running 50/50 castor/synthetic blend at 32 TO 1 ratio when I lugged my single speed bike up a very long and very steep trail up a mountain in the cortez/durango area one summer. the engine never seized and it ran great when i traded it in for a 25 year old jeep the following year. castor flashes at a temperature about 200-250 degrees higher than the best synthetic. once a lubricant flashes it is no longer in liquid form to do its job as a lubricant. castor has superior high pressure contact point wear protection that can't be touched by synthetic. when castor flashes, it actually forms a dry lubricant that is actually better than in wet form providing even added protection at very high engine temperatures. that dry lubricant is actually a varnish and one of the drawbacks is too much of it and it can gunk up your engine. so far, by running pure degummed castor oil blended with synthetic, i have yet to gunk up an engine or even a spark plug for that matter.

 

[RideAgainstViolence]

Absuletly thx 4 advice I ran intoo a lot of cooling issues on my last trip...