+7 mph by fixxing poor quality on 66cc

410 is fine if you don't have a 415 motor gear and what most kits come with, just use an HD Z-chain, the BMX style, they are pretty tough.

Cavi Mike said:

The leaking carb/manifold is a common and well-known issue and it's easily remedied by a simple o-ring placed inside the manifold.

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You must be referring to NT carbs not having an O ring as CNS carbs come with one, it is just too darn short to do the job so you need to seal them up at the groove on top.

I have started using this Permatx Ultra Copper High Temp RTV silicone gasket maker, it is gas resistant and remains slightly pliable.



It likes like this when applied on a CNS.



I have a topic here about it, 'Inside the CNS Carb'.

Personally I've never had an air leak issue on an NT carb with no sealing at all, but I can sure see an O ring in there being worth the extra buck.

My 2cents would be with kcv regarding splitting the cases of a new engine just for basic inspection.

From the many, many threads and posts I have reviewed here on the forum, and my limited experience with this flavor of engine, there have been a very limited number of problems with the crank and rod assembly.
SO, the odds are in your favor, in that respect. lol

There are a number of probs reported regarding the crank seals.
However, I would NOT advise pulling the pinion, or the rotor, on the opposite side of the crank, just to inspect the seal. If there is a problem with running too lean, that might be the second, or third thing I would inspect, though.

Good idea to inspect the clutch disk bearings, though...

...With a new kit MAB, IMO, the rag joint and chain idler are the most treacherous items requiring close attention.
For the power unit, the carb will require the most attention.

And I'll voice my opinion again, since I've hopped up on the soapbox; a coaster brake has NO PLACE on a motor assisted bicycle !

Best
rc

Motorbikermark said:

I think I'm going towards the Dax RT carb. And I am currently running a coaster brake but only til I am able to weld on some brake bosses and change over to avid mechanical disc.

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Way to go if you really want braking POWER ! an instead of welding on bosses look into bicycle designer they make a adaptor for that its well made an worth it .
Gary

Smiles at RC ;-}
'And I'll voice my opinion again, since I've hopped up on the soapbox; a coaster brake has NO PLACE on a motor assisted bicycle !'

Well, a coaster brake does have one place, as a 3rd 'emergency brake' on top of your front and rear dual-pull brakes.
This is what I like to use as my baseline 'Good and Safe' build.



That particular build has added shocks with a V-brake in front and I added a side pull brake on back on top of the coaster brake so it stops in a hurry.

I also like to swap out the rear wheels 18 tooth sprocket for a 19T on bikes like this.
I have a pictorial of that and a little more pedal side stuff HERE.

This is mindlessly easy to do and like $10, but you get a double bonus with a 19T rear wheel coaster brake sprocket...

Not only does the reduced gear ratio make it possible to lay down a nice 'J' skid with just the coaster brake, it also makes it easier and faster to get your bike moving to 'bump start'.

Motorbikermark said:

I am currently running (just?) a coaster brake but only til I am able to weld on some brake bosses and change over to avid mechanical disc.

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I am still up in the air on bicycle disc brakes...

They look cool and will stop you (in my tests) a tiny bit sooner, but for the hassle and cost to maintain even when the mount is already there, I really can't justify going out of my way to try to mod one in when there are other options that are much less expensive and far easier to maintain like V brakes, or even side pull rim brakes.

Front wheels are easy, they have a fixed mount point so it is just a matter of pulling the wheel and replacing disc pads, back wheels are another story if the bike doesn't have vertical dropout's but even then still a hassle.

All I really have to say about brakes, again, is don't skimp here!
If you can't bring your bike to a complete stop from YOUR top speed in about 25' or less you need to ride slower or get better brakes ;-}

KCvale said:

Smiles at RC ;-}
'And I'll voice my opinion again, since I've hopped up on the soapbox; a coaster brake has NO PLACE on a motor assisted bicycle !'


They look cool and will stop you (in my tests) a tiny bit sooner, but for the hassle and cost to maintain even when the mount is already there, I really can't justify going out of my way to try to mod one in when there are other options that are much less expensive and far easier to maintain like V brakes, or even side pull rim brakes.

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DONT take me wrong here just listen to my opinion an thats all .
is the difference between stoping sooner worth your life if ever in that situation ? at least consider the upgrade at a later date , many others here run coaster brakes an I have heard no complaints .
Gary

maintenancenazi said:

^^ This. The reports of all kinds of nasty stuff found in these engines (including my own) are too many to list. I consider it MANDATORY to do a full tear down, and inspection of every motor that you receive, before ever putting it into service. It's just cheap insurance.

Even still, after tearing down and cleaning, fixing threads, ect. I still had my first one go south after only 5 minutes of running! Turns out the main bearings completely self destructed, ( one side even spun in the case! )

I'm still going to try and rebuild this engine, so hopefully I'll at least have a spare when this new one expires. It truly S@#ks when....

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Ya know, (bit off-topic here) I wonder if my buddy could have made his Yugo last longer by doing the above. Of course, first you must WANT the Yugo to last longer...