Replacing oil slinger on a 49cc Huasheng...

scotto-

scotto-

Custom 4-Stroke Bike Builder
Well I'm finally getting around to replacing the oil slinger I broke off over 7,000 miles ago. It broke off when the engine had 1-2,000mi. on it, it came out with my magnetized drain plug during an oil change. I believe the cause was from over-revving the engine and I did abuse it to see how much these little engines could take. They take a real lot as I've reved that engine to 9+K and even 10K on a few occasions, even without the slinger. This engine was still running fine before tearing it down now......time for some realtime inspection.







you'll notice the oil slinger is missing in this pic...
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.....and this pic as well
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more inspection to come, stay tuned......
 
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Scotto,
That big plastic gear on the lower end moves so much oil that the slinger isn't really needed. The gear forces oil up through a passage to the rocker arms and there's plenty of oil moving around down below to keep the big end of the connecting rod and wrist pin lubricated. I've seen these engines run hundreds of miles without the slinger.
I'm curious however why yours broke off. The only ones I've seen break were in engines where the connecting rod bearing failed.
Tom
 
Mac said:
2door,
What is the purpose of that plastic gear?? I suppose to sling the oil??

Mac
Click to expand...
Correct, Mac.
Instead of an oil pump the gear picks up oil and slings it upward to a passage cast into the case that leads up to the push rods and rocker arms. It moves a surprising amount of oil as anyone who has ever run one of these engine without the valve cover will tell you.
Tom
 
Mac said:
2door,
What is the purpose of that plastic gear?? I suppose to sling the oil??

Mac
Click to expand...

That is the governor wheel normally (on the Honda's) without the guts or the control arm. As Tom was saying it lubricates nearly everything in these little engines. So when the engine is turning 8K that wheel is spinning 4,000 times in a minute flinging oil everywhere inside the crankcase laff.

Tom, as I remember I think where they bent the tang it was fatigued and maybe slapping the 10w-40 at the high rpm I was turning, it got tired and fell off? I don't think it made contact with anything from what I can see so far, but I've still gotta split the case so more may be revealed.

One thing so far is the leading taper on the lobe (of the cam) has some pretty bad wear on it. It is the first contact that starts the opening of the exhaust valve. For as bad as it kinda looks I'm surprized that it was running so well.

One other note of interest is I never adjusted the valve lash during all those hard miles and again was surprized that both valves were at .020" since set at the factory. Not too bad for the punishment I have given it and a little neglect. I never neglect the oil changes though.....every 10 hrs. with high quality Maxima oils.

dnut
 
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Here is a little show-n-tell of where I am at so far. These are just some pics actually.....finally got some decent pics of the cams from 2 of my Huashengs. The one on the left is out of this engine and it looks pretty bad although it was running fine. I'll be replacing it with the other one there, it only has about 4,000 miles on it. Everything else looks and feels fine so far.....next I'll be checking the piston, rings, rod, cap and journal. After that will be the valves and then whack it all back together again.......









 
Thanks for the info guys! That is some MASSIVE lobe wear, looks like a bad casting(porosity) from the manufacturer or a really poor weld/repair. It happens, I had a friend that welded crankshafts at a college and re-profiled them, quite interesting process. Scotto great Pix! I have not taken mine(or anyone else's) HS apart yet, so this is great insight, but a motor is a motor, I've lost count on how many "motors" I've repaired... of course a turbine is my personal favorite :-)

Mac

P.S. How were the "lifters"??
 
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Mac said:
Thanks for the info guys! That is some MASSIVE lobe wear, looks like a bad casting(porosity) from the manufacturer or a really poor weld/repair. It happens, I had a friend that welded crankshafts at a college and re-profiled them, quite interesting process. Scotto great Pix! I have not taken mine(or anyone else's) HS apart yet, so this is great insight, but a motor is a motor, I've lost count on how many "motors" I've repaired... of course a turbine is my personal favorite :-)

Mac

P.S. How were the "lifters"??
Click to expand...

Lifters, push rods, rocker arms were all fine. Yes, both of those cams looked to me like they were faulty injection molds and thus the porosity. I think that greatly increased the wear on both cams. The Honda cams I've seen look of better quality.

*Just a note here....these cams are made of plastic*

dnut
 
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The last bit of inspection......everything looks fine except for the worn cam and the missing oil slinger. You can even see the hatch marks in the cylinder from when it was originally honed.











I think a little port work is in order as they leave the ports pretty rough from the factory. A little valve lapping and clean the carbon build-up from the piston top, combustion chamber and the valves as well.
 
Scotto, you probably know this but for the benefit of others, be sure to torque and use a thread locking compound on those rod cap bolts during reassembly. I'm not a big fan of Loctite on a motor bike but that's one area where I use it. Set your torque wrench to about 80 inch pounds.
Tom
 
lapping the valves makes a big differences in performance. i found anyway last time i did a overhaul. my valves where also burned from the high rpm's

**** it was better than new.
 
Got a fair bit done today......lapped the valves, cleaned up the ports, de-carboned the piston top, valves and cc. Also made and installed the new oil slinger and started re-assembly.

Two things that you really need (besides the proper tools) to do a re-build of such: 1. assembly lube and 2. Hondabond 4 to seal the crankcase back up.

Some pics.....









dnut
 
And some more pics?

oh yeah.....I'm reducing some resistance and weight from the stock flywheel







AGK's racing cam for these little engines


still more to come.....

dnut
 
Finished the flywheel and re-assembled the engine today. Set the valve lash to .004", put the AGK X-big bore carb on and buttoned it all up again. Added 250ml of Maxima SynBlend4 10w-40 oil and fired the engine up on the 3rd pull.

Bam.....running like a champ! Ran it for 10 minutes and it's running better than ever. Time to build up a new bike and give it the real test.......so far, so good!









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Oil slinger and cam replaced.......all dialed in and raring to go!
 
Scotto,,,
this may be a stupid question, but,,,
isn't the stock air filter gonna negate some of the upgrades ?
won't she want to breathe better ?

I know on my HS,,,when I did the exhaust alone, not bad, but she perked right up after I did the better air filter too ;)
 
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