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Great balls of fire....
Posts: 34 
Likes: 2
Joined: Jul 24, 2015 17:53:40 GMT -5
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Post by fireball12 on Jul 24, 2015 20:44:39 GMT -5
Has anyone ever had any troubles with the cam chain tensioner? Just wondering, because the type of tensioners on the 250's are the type with teeth and spring loaded. Apparently at a lot of high rpm riding, like at highway speeds, the teeth can break off, causing the cam chain to become loose. By the time a person figures out what is wrong, the chain is stretched out so far, that a person would have to rebuild the engine. The guy on YouTube explained cam chain tentioners and explain the type we have in Chinese 250cc scooter engines, are made for the common idiot, simple to use, but catistrophic when the tensioner fails.
On my CN250 engine, behind the rear tire and on the engine, sits the tensioner. It will come off by removing the exhaust, rear tire, and then tensioner. The tensioner has 2 bolts in it to connect to engine. The center bolt hold a spring in it. So basically the tensioner has a thing you push to get teeth part to go in to the tensioner. One would put gasket on to engine, then slide tensioner in while teeth part is retracted, than put two bolts on, than slide spring into tensioner which pushes against teeth part of tensioner and retracts it, then place screw into center of tesioner to hold spring into place.It cost only $16 for a new tensioner. Once the teeth part is in, due to the spring, it does not push back out. Only at high rpm riding, will the teeth eventually break off, allowing the cam chain to become loose.
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Post by dollartwentyfive on Jul 28, 2015 4:07:01 GMT -5
i haven't had any problems with my cam chain tension during the lifetime i rode my bike and i usually ran it WOT.
the 172mm longcase engine in my bike is almost bullet proof mechanically.
the only mechanic work i did to the engine was to adjust the valves and put in an iridium plug, and of course changed the oil.
according to the odometer, i put almost 10,000 miles on this engine.
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Sophomore Rider
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Posts: 186
Likes: 37
Joined: Jun 13, 2013 15:39:09 GMT -5
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Post by novaraptor on Jul 29, 2015 16:00:23 GMT -5
I'm just over 10,000 miles on my M-79-250 with the linhai clone engine, and no problems. Nor have I noticed that particular problem being discussed in any of the scooter forums over the last few years. Not saying it hasn't, but doesn't seem to be a common problem..
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Sophomore Rider
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2008 Roketa MC54B 257 (10,000 miles and climbing)
Posts: 103
Likes: 1
Joined: Feb 26, 2013 19:32:19 GMT -5
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Post by bhinch on Sept 9, 2015 15:50:06 GMT -5
Hi...I have over 11,000 miles on my scooter and no problems other than 1 R/R, 1 blocking diode, and of course tires. Just normal maintenance. Purchased new in August 2008. Enjoy the ride....
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New Rider
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Posts: 4
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Joined: Nov 9, 2015 11:46:28 GMT -5
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Post by ottoman on Nov 26, 2015 12:53:21 GMT -5
WOT riding is unwise on anything, except pre-70's BMW's and some older modest Jap bikes, and even then, caution should be employed. Nothing modern, Chinese/Russian/European/British/sub-Continental or US will long tollerate such abuse, unless it's a diesel, and then be careful.
Very few petrol engines are made now that will run at continuous max power without severe wear or overheating. The old BWM and VW boxers were such, but not anymore. Diesels are built to run continuously at max power, which is measured -10% for hi air temperatures and - another 10% for motor overheating. It's called de-rated max power, which is the minimum highest power the good engine will produce under the most adverse conditions. IE you will always get at least 22bhp from a 22bhp diesel in good condition.
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Post by spandi on Nov 26, 2015 17:01:45 GMT -5
The engine now used in Chinese 250 scoots was originally from the Honda Helix and was purposely designed to be under-stressed so that It could ride at or near WOT without issue. Whether the Chinese parts will hold up as well remains to be seen, but DESIGN wise it was made to do highway speeds without fail.  (On my scoot you can replace it without have to remove anything first) BTW, since the Chinese CN250 is a clone, you can substitute Honda OEM parts in critical areas. www.partzilla.com/parts/detail/honda/HP-14510-KM1-000.html |
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Post by ricardoguitars on Nov 27, 2015 8:24:35 GMT -5
You can replace the piston and head for as cheap as less than $100 on most Chinese scooters, at that price you can treat them as "consumables". Ride it like you stole it, that's one of the advantages of Chinese scooter ownership.
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Post by rockynv on Dec 2, 2015 0:38:33 GMT -5
A spring keeps the tensioner engaged on the chain while the teeth are to disengage it while removing and reinstalling it using the center bolt on the tensioner. You usually break the teeth by not disengaging the tensioner properly while reinstalling it or by using the cam gear to turn the engine without first removing the spark plug while doing a valve adjustment however since most have the Honda 250 with externally adjustable valves most would have no need or ability to turn the engine by the cam gear during a valve adjustment. www.partsforscooters.com/250cc-172mm-4-Stroke-Cylinder-Body-Assembly_2 |
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Post by dollartwentyfive on Dec 2, 2015 8:22:45 GMT -5
The engine now used in Chinese 250 scoots was originally from the Honda Helix and was purposely designed to be under-stressed so that It could ride at or near WOT without issue. Whether the Chinese parts will hold up as well remains to be seen, but DESIGN wise it was made to do highway speeds without fail. (On my scoot you can replace it without have to remove anything first) BTW, since the Chinese CN250 is a clone, you can substitute Honda OEM parts in critical areas. www.partzilla.com/parts/detail/honda/HP-14510-KM1-000.htmli had the CFmoto engine in my ride. most of the parts in this engine was made of quality material. after 10,000 miles the slip clutch shoes showed very little sign of wear, i probably could have gotten 100,000 miles out of them, no joke. the bearings used in the final drive were quality japanese bearings. the carb was japanese made. other parts weren't so good though. the infamous intake for example, i replace this thing 3 times within the first year i had my ride. i finally got my hands on a honda intake and never replaced it since. the rollers were dirt cheap garbage, they failed shortly after i got my bike. i replaced the rear pads one and the front pads 3 times. all in all, this bike was a fair good investment, i would certainly buy any and all identical bikes for the price i paid for mine. no question about it. it had the 172mm-A long case engine. |
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Post by RapidJim on Dec 2, 2015 8:53:22 GMT -5
WOT riding is unwise on anything, except pre-70's BMW's and some older modest Jap bikes, and even then, caution should be employed. Nothing modern, Chinese/Russian/European/British/sub-Continental or US will long tollerate such abuse, unless it's a diesel, and then be careful. Very few petrol engines are made now that will run at continuous max power without severe wear or overheating. The old BWM and VW boxers were such, but not anymore. Diesels are built to run continuously at max power, which is measured -10% for hi air temperatures and - another 10% for motor overheating. It's called de-rated max power, which is the minimum highest power the good engine will produce under the most adverse conditions. IE you will always get at least 22bhp from a 22bhp diesel in good condition. Never seen a Diesel Scooter |
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Post by spandi on Dec 2, 2015 15:08:35 GMT -5
The engine now used in Chinese 250 scoots was originally from the Honda Helix and was purposely designed to be under-stressed so that It could ride at or near WOT without issue. Whether the Chinese parts will hold up as well remains to be seen, but DESIGN wise it was made to do highway speeds without fail. (On my scoot you can replace it without have to remove anything first) BTW, since the Chinese CN250 is a clone, you can substitute Honda OEM parts in critical areas. www.partzilla.com/parts/detail/honda/HP-14510-KM1-000.htmli had the CFmoto engine in my ride. most of the parts in this engine was made of quality material. after 10,000 miles the slip clutch shoes showed very little sign of wear, i probably could have gotten 100,000 miles out of them, no joke. the bearings used in the final drive were quality japanese bearings. the carb was japanese made. other parts weren't so good though. the infamous intake for example, i replace this thing 3 times within the first year i had my ride. i finally got my hands on a honda intake and never replaced it since. the rollers were dirt cheap garbage, they failed shortly after i got my bike. i replaced the rear pads one and the front pads 3 times. all in all, this bike was a fair good investment, i would certainly buy any and all identical bikes for the price i paid for mine. no question about it. it had the 172mm-A long case engine. Yep, CF Moto engines are very good in quality and reliability. We had a lady here who was a dealer for them, and she and her husband rode two of the Fashion 250 scoots from New York to Florida.  |
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Post by dollartwentyfive on Dec 3, 2015 3:24:56 GMT -5
i remember riding home on mine on some rural back roads.
these roads were blacktop and straight as arrows, the perfect kind for WOT riding.
i was screaming down these roads and came to a stop sign.
when i stopped i heard a faint ticking noise, like the valves needed adjustment.
i thought, well i'll have to adjust my valves when i get home, turned left and off i went, WOT.
got a mile down the road and the scoot just slowly lost power and died.
i tried to restart it and the starter sounded like my battery was going dead.
i got to checking it out and noticed the engine was smoking, placed my hand on the radiator. it was COLD !
you talk about your stomach falling out.
i just knew i had blown my engine.
i checked the oil, and the dipstick was partially melted.
i finally got a hold of my brother in law and we trucked the scoot back to my place.
i again tried to start it, and again the starter acted like the battery was weak.
i changed the oil, removed the battery to a charger, and let the bike sit for a couple of days.
i fixed the broken hose, refilled with coolant, reinstalled the battery, and crossed my fingers.
to my absolute amazement, this engine fired right up like nothing ever happened to it.
i put many, many miles on it after that incident.
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Post by spandi on Dec 3, 2015 11:16:24 GMT -5
i remember riding home on mine on some rural back roads. these roads were blacktop and straight as arrows, the perfect kind for WOT riding. i was screaming down these roads and came to a stop sign. when i stopped i heard a faint ticking noise, like the valves needed adjustment. i thought, well i'll have to adjust my valves when i get home, turned left and off i went, WOT. got a mile down the road and the scoot just slowly lost power and died. i tried to restart it and the starter sounded like my battery was going dead. i got to checking it out and noticed the engine was smoking, placed my hand on the radiator. it was COLD ! you talk about your stomach falling out. i just knew i had blown my engine. i checked the oil, and the dipstick was partially melted. i finally got a hold of my brother in law and we trucked the scoot back to my place. i again tried to start it, and again the starter acted like the battery was weak. i changed the oil, removed the battery to a charger, and let the bike sit for a couple of days. i fixed the broken hose, refilled with coolant, reinstalled the battery, and crossed my fingers. to my absolute amazement, this engine fired right up like nothing ever happened to it. i put many, many miles on it after that incident. Well there ya go, that engine design is fairly bulletproof. BTW, was it the hose or the clamps that let go?  |
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Post by dollartwentyfive on Dec 4, 2015 5:57:28 GMT -5
i can't remember what exactly happened to cause the loss of coolant.
i doubt if it was the clamps, the OEM clamps on my bike was fairly high quality and used two clamps in critical areas.
the most likely cause was the rotten hoses or the rotten radiator.
judging by the maintenance i put into this bike, my best guess it was the radiator, because i do remember taking it to a radiator shop to have it fixed.
how cheap was this radiator?
the person that fixed it told me to not bring it back.
on my particular ride, i noticed that car heaters cores make a very good high quality substitute.
getting them mounted was the major problem, since they didn't have any flanges, they apparently slide into place.
i had to bungee mine, which meant i had to also use ( in my case) pieces of innertube to prevent metal to metal contact.
that engine though, she sure was a tough ol' bird.
the crank journals were ball bearing instead of sleeve, which probably accounts for most of it's ruggedness.
these bearings HAD to be of very high quality to handle all of that pounding.
by all rights, i should have at least blown a head gasket, but it held.
the engine and frame were high quality stuff, it was the rest of the bike that was junk.
the wiring, switches, lights, body panels, radiators, all of it was just enough to get it out the door.
the crazy part is, i would buy another one, without hesitation.
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