Why is this engine unknown?

maniac57 · Feb 11, 2015

I'm confused here.
I KNOW there are a few high performance nuts who post here and yet all I ever see any of them talking about are the Dax motors and halfbreeds.
Why am I the only one who loves the Runtong motors?
SURELY The two I have are not the only ones in the US....
These motors are hands down the best overall quality chinadoll's I have ever seen or heard about.
Where are the others?
Am I alone?
Hello? *echoes*

rustycase · Feb 11, 2015

They look dandy!
No clue why there is no bunch of groupies... I never heard of runtong, though...

I guess you could go out and win a bunch of races... people will notice!

rc

maniac57 · Feb 11, 2015

They have bigger INTAKE ports than a 66cc exhaust port.
Super clean castings.
Bigger 6203 main bearings.
Super tight cases.
I'm just dumfounded nobody else has ever looked at these jewels....
Even at only 58cc I would rather mod this motor than ANY 66. It is that much better.

Neil Senior is the one who ID'ed the factory when I first found them.
Surely one of the Cali racer/builders has seen the Runtongs.
Anyone?

mapbike · Feb 11, 2015

ive seen them on one web site, don't remember the name of it ( bicycle-engine kits) or something like that, seems like I seen them with some kind of sticker on the top ofthe gas tank that said something phantom... or something like that.

I have never been interested inthem because of the price and the fact that there are no sources for parts here in the states that im aware of.

if the intake is wider than a typical exhaust it must have one heck of a wide i take bolt pattern.

beind so rare is probably exactly wh6 they are so rare.....lol!

where is a good source for them and a good source for replacement parts and maybe someone who reads this thread will decide to give one a try.

bluegoatwoods · Feb 12, 2015

It certainly is a nice looking engine. But if it's really rare, then that's an issue by itself.

Mapbike mentioned a high price. That could be trouble, too. While I'd pay a bit more for a bit more, I'd be more cautious if the difference is big. A lot of happy time buyers would do the same. That could make the market for this engine smaller.

mapbike · Feb 12, 2015

Here is the place that had them, these have been listed as being on backorder for a long while.
http://www.bicycle-engines.com/Phantom-Edition-Deluxe-2-Stroke-58cc-Gas-Engine-Kit.html

$229.99

maniac57 · Feb 12, 2015

That sure looks like it.
The round exhaust port is a dead giveaway

mapbike · Feb 12, 2015

maniac57 said:
That sure looks like it.
The round exhaust port is a dead giveaway

I have never seen a single replacement part anywhere listed for these engines.

I have seen parts being sold for 60cc engines on ebay stores belonging to people who are in mainland China, maybe this is the type engine those parts are for.

this seller is here in the states and has this kit listed as a 60cc, not sure what this is though for sure.
http://www.ebay.com/itm/NEW-Jackmot...486?pt=LH_DefaultDomain_0&hash=item41856a06a6

Here is a kit in the Uk that claims to be a 60cc kit
http://www.ebay.com/itm/Motorized-B...480?pt=LH_DefaultDomain_0&hash=item2c95e18388

Here is a 60cc jug
http://www.ebay.com/itm/Cylinder-Bo...Parts_Accessories&hash=item3cf0ee68df&vxp=mtr

60cc head
http://www.ebay.com/itm/Cylinder-He...Parts_Accessories&vxp=mtr&hash=item3cf0edbd92

60cc piston
http://www.ebay.com/itm/45mm-60cc-P...Parts_Accessories&vxp=mtr&hash=item3cf0edbd94

45mm Cylinder Body & Head Piston Kit 60cc
http://www.ebay.com/itm/45mm-Cylind...Parts_Accessories&vxp=mtr&hash=item3cf2d4b9af

I can find all of these parts, but nothing for a "58cc"

Not very popular animal if they still even make them.

Davezilla · Feb 12, 2015

I've seen those before.. those are some nice looking engines for sure... I also see these are advertised as 58cc so do these have the smaller sroke with the 47mm bores? or is the bore different as well? I'd definitely like to get a hold of one of those jugs if they're 47mm... Either way I wouldn't mind adding one of these to my collection, it looks like it's really well built.

maniac57 · Feb 12, 2015

More like 43& some fraction MM bore Davezilla. (my caliper is standard so only rough on mm scale)

Also has the older 49cc style crank with bolt-on weights which makes for a super tight case.
The big plus in my book are those 6203 mains...

mapbike · Feb 12, 2015

Im not to fond myself of the cranks with the bolt on weights, the engines I've got or had with that set up were all horribly balanced engines and they had the Z-L rods that just have the loose pin bearings on the rod journal, the only two major engine failures Ive had were both this type of crank and rod combo.

maniac57 · Feb 12, 2015

Here's a shot of the exhaust for comparison
The intake is on bottom

maniac57 · Feb 12, 2015

mapbike said:
Im not to fond myself of the cranks with the bolt on weights, the engines I've got or had with that set up were all horribly balanced engines and they had the Z-L rods that just have the loose pi bearing on the rod journal, the only two major engine failures Ive had were both this type of crank and rod combo.

I was thinking how easy it will be to adjust counterweighting if needed.
The short time I was testing the black jug motor I felt very little vibration compared to a 66cc, but granted I did not ride it long or far.

KCvale · Feb 12, 2015

The engine linked is the old Starfire, which is a 48cc touted as larger kind of like the 66cc engines being touted as 80cc.

Good Needle bearings on the wrist pin and good crank bearings? That is standard in some factories, Yang Dong being my engine of choice, they are sold as Skyhawks.

mapbike · Feb 12, 2015

maniac57 said:
I was thinking how easy it will be to adjust counterweighting if needed.
The short time I was testing the black jug motor I felt very little vibration compared to a 66cc, but granted I did not ride it long or far.

another factor could be that the engines that I had with that type of crank were 2009 bgf engines, the ones with the large front mount for the cruiser frames, the asting on those engines was fairly good but they vibrate pretty bad above about 32-34mph when using a 36T on a 26" wheel, they did have very strong low down grunt power though, I still running on of them on the huffy bike and it has about 800 miles on it and has been a very reliable engine, I always think maybe the third one was a charm....lol the first two ran really good when you kept the revs down but both had lower bearing failure with very few miles on them.

looks like that 58cc runtong would be a torque oriented type engine with a 44T for a nice 20-25 mph cruiser bike.

mapbike · Feb 12, 2015

Im gonna say the 60cc engine stuff I posted links to earlier may be what has replaced the runtong or maybe just something that was made to compete with it somehow in china and whereever else those engines have been sold the most.

Im like Dave in that I wouldn't mind having one just to see how it performed compared to the other engines I have or have had.

maniac57 · Feb 16, 2015

I'm telling you guys....they are MUCH nicer than the average chinadoll, be they gt's, pk's or whatever.
While they do give up a bit in displacement, the ports and quality is so much better that I doubt you would even notice the size difference.
I have two, one fully ported, one stock with mild transfer clean-up.
The ONLY reason I'm not currently running one is because I am too busy digging the fat midrange on a ported 66cc I recently built and am too lazy to swap them again.

I will post when I finally get one of them back on the road.
I will tell you the first one I discovered DID come across my bench due to a wasted main bearing. The stock china 6203 bearings may not be as good as most.
I replaced them with high quality sealed bearings from the aftermarket.
Seals and some size specific parts seem to VERY hard to find.
But these motors sure do look nice.....

rustycase · Feb 16, 2015

Gosh I can see you are excited about these engines!
Good for you!
I really do feel almost anyone can have more fun with these tiny little MAB motors than a fire-breathing rice rocket!

You might want to re-consider one of your improvements...
"I replaced them with high quality sealed bearings from the aftermarket."

Can't say I've come across any sealed bearings that will hold up to the heat and power / rpm that an open bearing, lubricated by the fuel/oil mix will.

But we're all looking for something better!
Please post the part number and a source if they prove to be reliable in this application.

Tnx
rc

Davezilla · Feb 16, 2015

I agree about the difference in displacement, if these engines are well balanced and can rev high, there is power to be made... may need to keep the gearing lower but the power should be there.

As far as the 3 piece cranks, i think they were originally designed to run on the smaller 49cc engines and then the 66cc was just an afterthought back when these engines first hit the scene and this is why they were aweful as far as balance was concearned, but with the lighter top end they should be much better. The nice tight cases is also a really good advantage for forcing more charge thru the transfers at higher rpm's.

If these have decent sized transfers and can handle a bigger carb like around 18 to 19mm they could easily rival a decently built 66cc engine. The round ports also makes it real easy to make custom intakes and headers that can leat the engine breathe way better as well...

Davezilla · Feb 17, 2015

there are some good metal sealed bearings that would work realy well in these, just remove the inner seal so it can get lube from the fuel/oil mix instead of the grease that's packed in there at the factory. the outer seal can be retained to boost the efforts of the crank seals. I'll have to look up the part numbers I got and post the links, but there are a few good ones in the 6202 and 6203 sizes. The SKF bearings are also excellent and will hold up.

Why is this engine unknown?

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