piston noise, detonation? watch/listen to this....

[abefroman]

Here's a 1 minute video of my bike running. this is a gasbike kit. you can hear the piston rattling around inside the cylinder...i think. at WOT it doesnt rattle. i think the plug is a ngkb6**. I've gapped it to .28 but it didn't change anything. usually, after the motor is warmed up, i get a LOT of rattle when taking off from a dead stop... even pedalling, but cant really hear it much at full speed. motor has probably 30 miles on it.

video :
http://www.youtube.com/watch?v=fAKHNJij1RM&feature=share&list=UUIztDD4oABmuW2iX3TA152Q

questions :

is this normal ?

can I do anything about it ?

will the piston sieze ?

could i buy a replacement piston,rings,needle bearing, cylinder and rebuild it...(worst case scenario) ?

 

[dodge dude94]

I would be willing to bet that sound is partly coming from the clutch. I'd pull the cover off and see what is loose/not greased. Toss some high temp grease where the two gears meet and see if that dampens your noise a bit.


As for whether or not it will seize, pull your spark plug and see what it looks like.

 

[rustycase]

Yikes!
The Dodge Dude is correct.
All that racket is mostly from the clutch mechanism.
And perfectly normal for a chinagirl.

This video is a shining example of WHY a chinagirl is NOT designed to be run with the clutch dis-engaged for any more than a few seconds.

There is NO bearing on the clutch release mechanism.
There is a steel rod up against the end of a bolt.
(Well, there's 1 ball in there.. it will wear fast!)

AND, the clutchplate/ring gear bearings are loose balls, in a poorly greased loose assembly. Put in enough grease and it will sling onto the clutch pads!

IMO

Pull in the lever to disengage the clutch, pedal a few feet, release the lever gently while continuing to pedal and the motor will start.
Proceed on your journey.
Pull in the clutch lever for a stop and go at a stop sign.
If it's a stop light, shut the motor off.
Restart as above when the light changes.

IMO there is NO reason to let a chinagirl sit at a standstill and idle! lol
Adjust the idle speed, and that's it.

The chinagirl in the video sounds really good!
Some riders like to quiet them down a little by wedging rubber in between the cooling fins to dampen the racket a bit, and a rubber pad of some sort may be glued on to the outside of the clutch cover case, which also helps noise level.

Best
rc

 

[abefroman]

Well, I hope its the clutch and not the piston. i did adjust the flower nut to where the clutch is disengaged/engaged so that when I pull in the clutch handle AND USE THE LOCK BUTTON, I can roll the bike freely. for my first build, my buddy's bike, he kept on adjusting the clutch cable brass stop because when he pulled in and locked the clutch handle, it wouldn't roll freely. I had the same problem but then I adjusted the flower nut and now it rolls freely when the clutch handle is locked.

Do you think I could get rid of the noise by adjusting the flower nut more ? maybe either tighten or loosen it ?

The noise is really puzzling because it sure sounds like pre-detonation causing the piston to slap around in there !!! imho. I never woulda thought it was the clutch. hmm....

I wonder if there's a way to definately determine that it is the clutch / isnt the piston ? maybe take the clutch apart and then run it ? then again, that might be stupid or impossible... dont know much about clutches....still learning.

 

[crassius]

some of these are just plain noisy - that sound is common with the gearing, and is why some folks use dampening inside the covers

doesn't sound like a piston problem at all

be grateful that it isn't 'the dread clutch squeal'

 

[rustycase]

It will be difficult to quiet the primary drive side of the engine because of it's nature.
Straight cut gears, large thin (resonant) ring gear, aluminum (pot metal) case...

You might TRY duct taping a wad of fabric over the sidecase as a test to see if that will help.

My own chinagirl has a shabby wristpin bushing and makes a clicky rattle at low speed. Such is life! I ain't gonna fix it til it breaks!

If a subdued, quieter engine is your goal, with less mechanical noise, you might investigate the small 4 cycle engines.

They are not moving steel rings past ports in the cylinder at piston speed !


rc

 

[abefroman]

well, i really dont care if it's noisy, but I do care if something is screwed up in the engine. I'm running high octane gas... might try 87 octane just for the h*ll of it.

 

[rustycase]

any gas sold from a pump in usa is fine for a chinagirl.

chances are, something with the engine has escaped quality control.
It shall break something, probably sooner than later.
It's a chinagirl !

Some riders have switched to Morini two stroke motors in their motor assisted bicycles.
They are exponentially superior to a chinagirl.
and accordingly, cost much more.

A chinagirl is good to learn about gas engine basics.
Unfortunately, metal quality and initial machining tolerances will not allow fiddly tinkering.
Bolts will shear off and threads will strip, leaving you in the lurch.
Entire pieces may break off castings!
Expensive machine work may be necessary to resolve the problem and it is frequently cheaper to replace the entire engine unit than make certain repairs.

Gosh, I really do hope I'm presenting my opinion well.
and it is only my opinion !

Please get a 2nd opinion on anything I may say!


rc

 

[abefroman]

ok, where can I buy a Morini ??

 

[FMB42]

ok, where can I buy a Morini ??

That's Dax.

 

[rustycase]

ThatsDax has a substantial reputation.
If he has what you desire, I personally would not hesitate to do business with him.

Otherwise, my good friend the Goatherder runs a morini, and runs it hard!
I would ask him any questions about morini.

Best
rc

 

[maniac57]

DeNardis sells morini and KTM clones as well as ThatsDax.
Nobody besides these two sells new morinis anymore as far as I know.
You can also find them used on ebay by looking at KTM 50's,Lex, and several other small racers which use the KTM clone of the morini

 

[rogergendron1]

good god ........... i grew a full wizard beard waiting for it to rev up lol !!!

why does it rev sooooooooo slooooow ? my bike goes from dead idle to wide open throttle in less than about 1 second and i dont even have to twist past 1/4 throttle to get it there with no load ( in nuetral)

it sound like your motor is being suffocated to death !!!

you have a major resriction in your intake and exhaust.... i am talking major ! i can hear it bog as you twist like its suffocating for air and fuel and choking to get the exhaust out !!

you might want to rebuild and clean out your carb get a high flow filter, do a little porting and port match the itake and exhaust ! also gut that d@mn cat out of your exhaust chamber and have a muffeler shop weld it back together for 10$

want to know how to get free power and have that thing rev like a r@pped ape ? click my sig links

click on the last link and scroll down to my you tube vide of my bike running and listen to the differance... it had all stock parts that were modded in the video... srsly listen to the differance !!! it reves a lot quicker now and has been modded a lot more now but the vid shows what you can do with stock parts !

 

[rogergendron1]

ok here listen .....
first to your bike

http://www.youtube.com/watch?v=fAKHNJij1RM&feature=share&list=UUIztDD4oABmuW2iX3TA152Q


then to this .. note bike had ALL stock parts.

https://www.youtube.com/watch?v=aRF2V16ecFk

yours needs some work i would over haul that whole clutch if i were you and pull your top end and do some major porting and port maching then deck your head and gut the cat out the exhaust. at least by pulling th top end you can check for piston rub on the jug walls and abnormal wear of the piston skirt and cilynder... wile its appart hey ... why not port the h3ll out of it lol


dude it sounds like a wheat thrasher plowing through a field of old tin hub caps !!!!!

honest to god the first time i watched it i thought well this is useless i cant even hear the bike over the sound of the giant air compressor in the background... then i realized you were not in a garage and there was no air compressor !!!!

 

[rogergendron1]

when you twist your throttle it should sound like riiiiiiiiiiiiingggggg a ding ding .... riiiinnng ding ding ding rrrrriiiinng ding ping ping

not like bbbbbwwwwwwaaaaaaaaaaaahhhhh uuuuhhhhhhh bbbbwwwwwwaaaahhhhhh uuuhhhhhh.....


you have major air, fuel, and exhaust restrictions.

 

[mew905]

when you twist your throttle it should sound like riiiiiiiiiiiiingggggg a ding ding .... riiiinnng ding ding ding rrrrriiiinng ding ping ping

not like bbbbbwwwwwwaaaaaaaaaaaahhhhh uuuuhhhhhhh bbbbwwwwwwaaaahhhhhh uuuhhhhhh.....


you have major air, fuel, and exhaust restrictions.

stock china girls are tuned for lower end power (around 5500 RPM), the small intake is enough for that.

#1: Yeah, thats clutch noise, if you have micro drill bits, you can drill an oil hole that will automatically lube up the gears for you, if not, a little bit of oil or grease will help quiet that down. A lot of HT's also have a wobble in the clutch either in the crank, or in my case, the clutch shaft.

#2: If you find your intake noise/gas spitting is an issue, you could consider reeds. They are a direct bolt on but wont offer much unless you modify the cylinder and piston.

#3: A huge power sucker of these engines is breathability, as rogergendron stated. Even at such a low RPM the exhaust is quite restrictive, hollowing it out if you have the tools will net you alot of power. If you cant weld or cant get the guts out without being able to fix it (some take the cap screw with it, trust me these are loud without the cap), drilling holes in the end, around that screw (after taking the cap off, you'll see what I mean) will help the engine breathe and net you some extra power. A larger carb (you can use a 3/4" pipe with 1/8" walls if you need a shim to make the intake 1" O.D. to fit larger carbs) will help, but still be restricted by the tiny 1/2" I.D. of the intake manifold. making a new one from scratch could help, but you'd need the larger bolt spacing of the GT2-a or GT5-a, as the 32mm spacing of the vanilla variants is already at its maximum at 3/4" O.D. And finally, good transfer angles (if you have JB weld OR a dremel and alot of time [the latter is the better solution IMHO]) will boost your engine's efficiency, netting you more power essentially for free, may even have to jet smaller because your fuel/air losses wont be as big.

 

[boocher13]

My first China girl build I thought the same thing. First fire up I thought the piston was smacking the plug too. Trust me once it gets broken in a bit it will quiet right down. I wouldn't use lo we octane fuel . I also wouldn't worry about how it revs until it breaks in.

 

[abefroman]

thanks guys for all the advice. this is a brand new stock kit from gasbike with maybe 30 break-in miles on it. I'll definately try some of the tricks you posted.

cheers

 

[rogergendron1]

Dude all you do is tske off the exhaust cut it open with hack saw or dremal and cut all the crap out from inside then walk down to your local muffeler shop and they will weld it back together for 10$ in 10min !!!

You bike will rev a lot quicker and breath a lot better pluss it will actualy sound like a. 2 stroke ), alowing you to more easily tune your carb.

To tune your carb mae 4 marks on the throttle idle, 1/4, 1/2, 3/4, and WOT this will alow u to see what jet is screwed up and needs adjusting by looking down at the throttle ehen you get 4 stroking or lean spots

Also you will benifit BIG time from a mild port polish and port match ... its nothing to be scared of your goal is to clean them up and smooth them out your not taking enough off to affect timming

Then deck your head down as much as you would like to get the comp you want

All that stuff cost is time and a few tools lol

And i ashure you ... your motor will feel like a whole new beast !!!!


Ohh and for all i know all stock ht motors might sound like that lol but i will never know cause i pull them apart and mod them ... high comp port port match and gut the exhaust And kn style filter before the motor even makes it on the bike !!!

 

[rogergendron1]

Ohh almost forgot a trick to quiet it down and make the clutch arm move waaaaay smother

Unscrew the 3 bolt clutch cover with the arm on it
Remove the arm from the cover and remove the rod from the center of the motor sprocket there is a ballbearing behind it remove that too . If you loose it a 5/16 bearing will replace it.

Now pour a cap full of your 2 stroke motor oil in the hole the rod and bearing came out of !!!! Then carefully reinsert the 5/16 bearing and 5/16 rod back in the hole. A lil oil might ozz out it fine

Now pour a cap full of 2 stroke oil in the hole in the clutch arm hole on the cover and insert the arm and spin it around

Now reassemble the cover..

Wow .... doesnt it make the clutch pull sooooo easy now !!!!

I do this every week

Your actual clutch gear with the flower nut can have some oil on the outer gear part too just use a pumpy type oiler or pray botttle carefull not to get any on the pads

The small clutch gear just pour a half cap of oil on it making shure it goess behind on the shafft then roll the bike foward with the clutch in to move the gears and distribute it alll around

Now clean up any extra oil in the cover or dripping anywere and make shure the small gear lock nut with the big flathead screw driver slot is realy tight then reassemble.


I garentie you it will be quieter. I will make a video for you ...and post back later.

I