ok lets get back on topic here.
And Fabian you were 1 of the first begging pirate to take a prepayment for a high performance Engine.
We all want a good quality engine.
The bottom line is unless it's 25cc 2 stroke or a 50cc 4 stroke a high quality engine will have all the bells and wistles along with it. With quality comes power and with power comes speed.
Is or can a HT engine ever compare to a NINGA NO NO NO.
So here are the facts.
The chineese engine is cheap the components are cheap and the port timing is setup in a manner that restricts the performance of the engine.
To further restrickt the performance a very restrictive exhaust is also place on the engine.
So due to the out of box configuration the engine components can handle the meager performance. And most of the time due to the lack of sound engineering principals it's componets fail prematurly. The ignition system lacks tuneability and the accuracy of the timing is dependand on how accuratly the Cases are drilled to mount the coil.
The drillings in the coil. The accuracy of the crankshaft where the magnet presses on. The accuracy of the bore of the magnet and most importantly the accuracy of the keyways cut in the magnet and the crankshaft. Then throw in the variance in the stroke and the center to center distance of the connecting rod + the slop in the bearings and the misalignment of the cases. and you have 1 big mess.
As Fabian has clearly demonstrated the problem of pre-ignition and of retardation shows up in the big end bearings.
So what do we have here???
We have potential for the individual that desires to put the time in to clean up the mess.
First everything must be dissassembled cleaned and inspected.
All of the Bearings need to be replaced except you cannot change the Big End Bearing because it's an odd size.
But you can get high quality Mainbearings, Countershaft Bearings, and a high quality bearing for the piston wristpin.
The sealed mainbearings do a much better job of sealing the crankcase and actually double seal it.
First the pressure has to get past the bearing seal then it has to get past the crankcase seal. So that extra bearing seal is great cause it takes alot of the strain off the crankcase seals. We all know the crankcase seals are **** and need all the help they can get.
The quality bearings can handle much higher loads and greater RPM's.
The quality bearings also have less horsepower robbing friction.
The bearings are the heart of the engine.
So lets talk about the body " the CrankCases "
The crankcases are thin but all and all not too bad.
The aluminum alloy is brittle so it resist flexing but breaks easily and threads strip easily.
But the brittleness actually works to our favor.
So long as the bearings are in good shape and the alignment is pretty close the forces that are applied to the crancases are in a compressive manner. The alloy can handel a high dose of compressive stress.
Now being brittle if the alloy is put under Tensile stress or shearing type stress it will break. The cases are also reinforced in the areas of the bearings.
Provided the cases are machined as intended the bearings are a light press fit into the cases. Which is good for alignment.
Now there is a bit of clearence between the shafts and the bore of the bearings but it's a close running fit. Point being.
There a 3 alignment features of the cases.
#1 there is a ring machined on 1 case half and a counterbore to accept that ring on the other case half. When you snap them together you have positive location to the center of the bearings. It's a tight slip fit.
#2 when inserting the crankshaft into the bearings it also reduces the misalignment of the cases. The crankshaft provides the 2nd locational feature.
#3 The countershaft or drive shaft provides the 3rd point of location. Also a tight slip fit into the bearings.
The combination of these 3 features provides decent alignment of the bottom eng.
The trick to geting things as good as possible is pretty easy.
Assemble the botom end but leave all of the case screws loose.
Put the piston assembly on the connecting rod and slide the cylinder on the studs.
Dont use any gaskets at this point in time.
Put the head on and tighten the head bolts like normal.
Since all the case screws are loose this will pull the crankcase mating surface into contact with the cylinder.
This aligns the case halves to the cylinder a good as the machining allows.
Now tighten down them case screws.
Pull the top end off and retighten the case screws.
Now assemble the engine as normal.
At his point the engine is in pretty good shape.
If you had cut the ports to the proper configuration before you assembled the engine your in great shape.
With the proper porting and a good breathable exhaust then engine will reliably run at 10000 rpm. A breathable exhaust dosen't have to be loud. It has to breathe easily.
Now the only crappy parts left of the engine is the ignition and thin crome plating of the cylinder.
but hey for $100 it's not too bad.
So can a HT be a NINGA. NO
But it can reliably produce 5 to 6 hp at 10000 rpm and that i know from doing it.
Way off topic on this thread. Way off!!! What the heck does this thread opening post have to do with building a ht engine?Please post In the right forum,open your own,comment to the original thread here,Or don't reply.But please fabian and fm2200.Keep It on the original thread.Or move It.
