Failure of Happy Time style 2-stroke Big End Connecting Rod Bearing

[iron_monkey]

Oh you live in australia, im an aussie too.

Good luck with your 'discreet' engine, imo the cops don't care about size given the 200w law; they know all combustion engines make over 200w, they're not dumb.
A lady was fined in NSW riding an e-scooter(although not a e-bicycle) and theres an article about police from SA specifically targeting all motorised bikes. My local police are okay with it, judging that I haven't been fined; but that could change any moment.

I think the level of pollution and noise matters more than the size, as that could affect other people. Once someone complains to your local police about your bike, you are gone.

Anyway, since you are in Australia, im looking to forward to where you source your bearings and wear you are getting your engine rebuilt.

 

[Fabian]

From another site.
This is very interesting:


Re: Is there a difference between the skyhawk and the starfire

Quote:
Originally Posted by Hot Dog Piggy Tails
No actually there is a big difference first is the match as far as the transfer ports then there is the Quality of the lower end Bearing (23 Needle verses 16 needle in a poorly Engineered cast)
The Nantong Jiali Manufacturer is known as the better if not the best engine manufacturer exporting these and have lost contracts with people Because they refuse to Mass produce cheap engines.

If you've replaced A starfire with a Jet your Stafire was probably a 48cc'er thats about the only ones left. Also the Starfire is the factory that your Jet was Manued at..And if it is is out of one of the First two shipments of Jet Engine they have lower end problems due to the fact a Customer I wont say no names but is actually thier competitor convinced them to use a Poorly casted Lower end Needle casing. They all need replaced. As a matter of fact the ones that are correct and Have 23 needles are still on thier way too them. I never received the 16K Needle bearing with the problem because I have the prints too it and refused to Allow them every order to put them on the bottom of my Connecting rod.

I deal with this factory and its Management Exporter and are very good friends talking at least once a week.

 

[210061741]

I'm a little confuse here.

Someone please enlighten me.

I thought Black Stallion was from one place JET

And Skyhawks and Starfires were from Grubee.

 

[210061741]

The grubee site shows a 13 roller bearing.
I think in the past it was 9 rollers.
I'm really confused here.
Is this the big end or small end?

Which motors have a 23 roller bearing

 

[happycheapskate]

linked here from other thread

I am new to ALMOs (motor bicycles) and starting with a chinese $130 grubee.

I think the only real solution is to popularise these devices and advocate for their legal harassment free use in US and Western nations, until a European producer of bike motors can avail. Or possibly a Western company collaborating with Japanese manufactures. That exists in the Robin/subaru, Honda, and a couple of other japanese motors including weeder motors and commercial bike motors at www.monsterbicycle.com (friction drive 2str back rack motors).

 

[2stroker]

It's all fairly self explanatory

The Chinese 2-stroke motorised bicycle engines that i have purchased from a Chinese distributor/retailer are all having similar problems with the big end connecting rod bearing failing in relatively short time.
They initally thought it was the crankshaft bearings failing so ordered high quality bearings to be fitted for their subsequent shipments but the engine failures continued.

When my first engine failed from a blown big end bearing and the second engine, now starting starting to make similar big end rattles, after being well looked after, had me develop a sense of frustration, to the point of wanting answers as to exactly which component of the bearing or it's construction is causing issues.

It just looks like the cage and the needle rollers are made out of very low quality material.

I've managed to find a supplier who can ship a high quality replacement K16x21x10 Needle Roller Bearing.
Once i've received the bearing, i'll have the crankshaft, replacement connecting rod and bearing assembly and piston sent to a reputable Kart engine rebuilder to have the crankshaft lightened, balanced and trued to finally achieve the goal of a reliable and smooth running engine.

Fabian

Is this the same kit you use for your 12wheeler? I think just bolting my kit on and going for a ride sounds alot better. I bolt and ride thousands of miles on my kit. With no improvements or time spent toying around. Sounds real reliable-ROTHFLMAO

 

[Fabian]

It is real reliable - all mechanical issues have been solved as i've described in another post.
The date of post must be remembered - 2009

It's all good in 2012, actually all good in 2011, though 2009 to 2011 did test my patience.

 

[2stroker]

It is real reliable - all mechanical issues have been solved as i've described in another post.
The date of post must be remembered - 2009

It's all good in 2012, actually all good in 2011, though 2009 to 2011 did test my patience.

After you paid for 5 engines right. I paid for 1 and have been riding it since 09.

 

[Fabian]

That's right, i'm on my 8th engine now. I have explained why the engines failed, and it was not because of the mechanical components, but incorrect carburetor jetting and standard CDI ignition timing, both of which are an easy fix, being a $5 item and an $80 item. It's a fix that not only improves reliability but also gives a modest power gain - win, win situation.

In the early days i started from scratch with regards to diagnosing these problems; having very little knowledge about these small 2-stroke bicycle engines.
With current knowledge, my engine is past the 8,000 kilometer mark; only a set of piston rings replaced at 4,000 kilometers.

It must also be noted that the big end connecting rod bearing has been improved, now using a crowded roller design - today, virtually all engines come with this arrangement, but the bearings (in my opinion) were never the main problem, in fact the mechanicals are surprisingly good if the engine has the above mentioned modifications and operated at sensible rpm.

 

[2stroker]

That's right, i'm on my 8th engine now. I have explained why the engines failed, and it was not because of the mechanical components, but incorrect carburetor jetting and standard CDI ignition timing, both of which are an easy fix, being a $5 item and an $80 item. It's a fix that not only improves reliability but also gives a modest power gain - win, win situation.

In the early days i started from scratch with regards to diagnosing these problems; having very little knowledge about these small 2-stroke bicycle engines.
With current knowledge, my engine is past the 8,000 kilometer mark; only a set of piston rings replaced at 4,000 kilometers.

It must also be noted that the big end connecting rod bearing has been improved, now using a crowded roller design - today, virtually all engines come with this arrangement, but the bearings (in my opinion) were never the main problem, in fact the mechanicals are surprisingly good if the engine has the above mentioned modifications and operated at sensible rpm.

My kit is tested on a test bike and the carbs are tuned by the manufactor and as long as you keep it clean you dont have to touch it. So you dont blow it up from bad carb settings. I go full throttle every where i go. No problems. Your 8th engine. holly cow take it easy on those poor things.lol