So Who's Building Performance HT Engines.....

BrettMavriK · #1 08-17-2009, 09:23 AM

Allrighty,

I am to the point where I want to squeeze out some more juice out of the Happy Time motor.
I've read this and that, here and there on what to do for more low end torque and top end speed.
The little engines are all there basically, and just need minor improvements to hop them up a bit.

So who's had success in tearing down, modifying and rebuilding these engines for utmost performance,what was addressed, and wouldn't it be nice if someone offered this service?
See most of us don't have the tools or time to do the "drawing board experiments" on our motors. I wouldn't do that to my car engine myself either. I leave that to someone who lives around engines all day.

My goal on this thread is to fish out what works, what doesn't, and maybe find someone who performs this Hi-Po service for a fair price so I can get engines from them. I could take the time and R&D this myself, but I have too much on my plate with the rest of my builds. I would love to find someone who could sell me an engine that has a clean balance, great low end torque, high end revs, and a smooth power band. I believe this can be done and still leave the engine reliable.

I know of one engine dealer in Austrailia, Rock Solid Engines, a sponsor here on this forum, that is now armed with a "Dyno". The feedback from this equipment is going to cause major advances in this little engine over time as they experiment with changes and test them, and I can't wait to see what transforms.

I would like to know if anyone here in the States has played with these enough to know what works and what doesn't internally and externally, and is there anyone who'd like to build me a motor from their tried and true experience?

Maybe this sort of information sharing will bring more advances to the HT engine...who knows.

Ride On!
'BrettMavriK

Venice Motor Bikes · #2 08-17-2009, 11:15 AM

Check out Chris Hill Engines... Home of the CH bicycle engine, CH80 Bicycle Engine Kits by Chris Hill, Motorized Bicycles, Bike Engine, Bike Motor, Bicycle Motor kit

BrettMavriK · #3 08-17-2009, 02:07 PM

Yes, Chris his has built a good market for himself,
but I am looking for more than a meager "clean and check" with new bearings and gaskets for $350.
Nothing wrong with what he does, and people do pay him for that, and get a 1 year warranty.

I'm talking about Major Porting and Port Timing Mods;
New Head Designs Maybe, Remade Pistons, Crank Balancing,
and the like.

Something that takes the motor to the next level; as if you put a
nice "street cam" into an automobile engine for more performance with minimal loss
of longevity.....

Brains · #4 08-17-2009, 07:27 PM

Hi Brett,

You are correct in what you are stating about Rock Solid Engines, specialized custom engines for our clients requirements is what we love doing, keep an eye out on our web as shortly we will be uploading a few more off the shelf performance engines which will all come with Dyno run sheets, which are specific for each engine, but again it is very difficult to create a standard HP engine to suit everyones need of the shelf, so thats why custom is they way to go in meeting a specific clients requirements, we have new performance products which we are going to release shortly as well, to the likes of an in house custom HP magneto's, but with the new drag racing season only 3 weeks away its going to have to be put on the back burner until we have all our racing commitments under control.

Hopefully down the track we will have someone who can act as dealer for us in the US, as this will make it a lot more cost effective with freight, unfortuantley one of engines are bearing all the freight cost & if we can split the freight over a few engines it will work in everyones favour.

Cheers all.

Brains

foureasy · #5 08-21-2009, 11:14 PM

" great low end torque, high end revs, and a smooth power band." quote

you cannot have all of these things, but you can have the second two. i have a new muffler design that has given me a very smooth power band that pulls from 15mph to 38mph with a 36t sprocket, but below15 its kind of a dog. the biggest improvement in pipe design that i could come up with involved the stinger id and length. when i built the first pipe i used gordon jennings book as a starting point. the port work and pipe design both shot for peak power at 7000rpms. this means your pressure bleed needs to be about .491 id and about 6.5" long. if i had more than one speed or no turns this would be fine, i could drive 50mph everywhere. the pipe made the motor so peakey that it was almost unrideable below 35. thats no good. after several pipe mutations were tried, the best (in my opinion) has a bleed with the same id as the inlet pipe (.891") and about 2" long. there doesn't seem to be a powerband at all, it just pulls harder and harder as the rpms increase. a stock carb will absolutely not work. the best results i had were with a dellorto 16/16 sha, they run about $80. i also had pretty dood results with dual stock carbs (although not quite as good as the dellorto, the look way cooler and are cheaper. anyways, sometimes i ramble.

BrettMavriK · #6 08-22-2009, 07:59 AM

Awesome!

This is the kind of forward thinking I'm talking about...

Good read!

cyclepro101 · #7 08-24-2009, 12:04 AM

Has anyone ever had a crack at sticking a 50cc or similar 2 stroke dirt bike motor in their bike? Why would'nt this work? The way I see it the hardest thing would be getting the mounts right. It would certainly sort out the performance issue, + u would have gears.
Or even a little 4 stroke pit bike motor.

Steve

BrettMavriK · #8 08-24-2009, 02:00 AM

This thread is about the China HT Motors,
and taking them to a new performance level
through modifications.

I'd appreciate it if this thread didn't get hijacked
with talks of trying to use another engine type all together.
If you are curious, you can start another thread about using
dirt bike motors on bicycles, and you'll probably end up with much
debate.

Thanks,

camlifter · #9 08-24-2009, 09:20 AM

going with an expansion chamber pipe is by far the best boost in performance. i've tried about everything you can do to a 2 stroke motor on the little ht. the pocket bike pipes you can get on e-bay work well, you'll have to cut them open and reweld them to fit but they still work good even tampered with.
as far as porting and trimming the piston, i didn't find any real power gains through porting, you can change where the power band starts, either higher or lower in the rpm range, but your not really gaining power, just moving it around.
i changed the port timing by putting a 1/8" spacer under the jug and milling 1/8" off the top of the jug. this raised the ports and still kept the stock C/R. improved low end power by a lot, motor pulls great down low and still revs good.
there also is good results from running a shorter intake manifold. mine is down to 1" now and works good with the altered port timing.
haven't tried advancing the timing yet put would expect it to help if you could, need to find a source for off set keys for the mag.
the stock carb works as well as any if jetted right.

BrettMavriK · #10 08-24-2009, 09:38 AM

This is the kind of homework I like to read about when it comes to the China Motors.
I believe you're onto something with the timing advance thing. I believe this motor is all there,
for the most part, if you get a GOOD motor to start with; they just need their internal
attributes tuned for performance.
I think China lost something along the way when they took this motor idea
from the Russians. I think the answer to these motors putting out some better power
is right under our noses. I think it's a mild mixture of some internal attribute changes.
Timing is huge.....

Unleash The Hounds....!!!

=-]'