66cc engine tear down, setting it for high performance setup

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DanielMaia

DanielMaia

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[VIDEO INSIDE!]66cc engine tear down, setting it for high performance setup

Hi guys,

I'll tear down a 66cc engine, and need some advices.

What i thought to do in this engine:

- All new gaskets!
- New SKF 6202 roller bearings, 4x
- Intake port patched
- Exhaust polish and take 0.5 or 0.6mm, from the top.
- Polish and remove edges, courves in the crankcase.
- Remove 0.3 or 0.4mm in the cylinder head, to increase compression.

It has stock NT Carb with ADA racing air filter by SBP

SBP Expansion Chamber, angle head (45degrees) and BPR6HIX iridium spark plug

What do you recommend? Any advice?
 
Last edited:
Skarrd

Skarrd

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Oct 13, 2010
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i like what your thinking.


especially the roller bearings.

i've got the grubbe gt5 2010 66cc engine.

keep us posted. i'd like to see what you find.
 
earl.k

earl.k

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Jan 19, 2011
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are you thinking about a new carb to maybe up your performance? if you get a new style cns carb. the one with the bolt on red air filter. you can still use your sick bike parts air filter, and have your choke on your handle bars. plus i think its a better carb? anyway just a thought.
 
DanielMaia

DanielMaia

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Thank you Skarrd and earl.k.

Right now im worried about the crankshaft. I hope im wrong, but seems to me has a little clearance, at the roller bearing that connects rod to crankshaft. The situation is: this engine has broken 2x roller bearings piston/rod, dont know exactly why...

The carburetor, yes, maybe in the future a Dellorto SHA15, me and my friend are considering it.
 
Skarrd

Skarrd

Member
Oct 13, 2010
501
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Chandler, AZ
DanielMaia said:
Thank you Skarrd and earl.k.

Right now im worried about the crankshaft. I hope im wrong, but seems to me has a little clearance, at the roller bearing that connects rod to crankshaft. The situation is: this engine has broken 2x roller bearings piston/rod, dont know exactly why...

The carburetor, yes, maybe in the future a Dellorto SHA15, me and my friend are considering it.
Click to expand...
good thought on the dellorto. despite what people say, don't go for the CNS, it's crap.

they tried to build it like the dellorto and failed. mine wouldn't stay on without JB weld... and even then it still needed zip-ties to keep the darn thing from twisting...
 
GearNut

GearNut

Active Member
Aug 19, 2009
5,104
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San Diego, Kaliforgnia
DanielMaia said:
Thank you Skarrd and earl.k.

Right now im worried about the crankshaft. I hope im wrong, but seems to me has a little clearance, at the roller bearing that connects rod to crankshaft. The situation is: this engine has broken 2x roller bearings piston/rod, dont know exactly why...

The carburetor, yes, maybe in the future a Dellorto SHA15, me and my friend are considering it.
Click to expand...
From what I have learned concerning the roller type wrist pin bearings, the rollers themselves are made out of a material that is too soft for the application.
They tend to get longer and thinner over time, as if they are made from a malleable material. Also the space in the piston between the wrist pin bosses is to wide allowing the wrist pin bearing to drift from side to side thusly not allowing it to fully support the load against it squarely and evenly.

Many folks have tried to find a better replacement bearing and there is one out there, an INA Needle roller and cage assemblies K10X14X13-TV.

The killer is in the details though. The big end connecting rod bearing is an odd size, No one has been able to find a suitable bearing upgrade yet from a bearing supplier.
 
earl.k

earl.k

New Member
Jan 19, 2011
242
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DanielMaia said:
Thank you Skarrd and earl.k.

Right now im worried about the crankshaft. I hope im wrong, but seems to me has a little clearance, at the roller bearing that connects rod to crankshaft. The situation is: this engine has broken 2x roller bearings piston/rod, dont know exactly why...

The carburetor, yes, maybe in the future a Dellorto SHA15, me and my friend are considering it.
Click to expand...
can i get a link to a dellorto sha15? id like to check that out. and that is odd your roller bearings keep breaking. iv never had that happen to me and iv put my bike to the test a few times. i hope your new ones work out.
 
earl.k

earl.k

New Member
Jan 19, 2011
242
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PA! USA
Skarrd said:
good thought on the dellorto. despite what people say, don't go for the CNS, it's crap.

they tried to build it like the dellorto and failed. mine wouldn't stay on without JB weld... and even then it still needed zip-ties to keep the darn thing from twisting...
Click to expand...
lol. iv never have that happen either. i did not like my first cns carb. the one with the clamp on air filter. but the new style cns are fine buy me. im always looking for better parts. and if that delltoro is in fact better, id love to fun one on my bike.
 
GearNut

GearNut

Active Member
Aug 19, 2009
5,104
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38
San Diego, Kaliforgnia
Most any good bearing supplier can get it for you.
It is a bearing made by INA and it's number is K10X14X13-TV. Just tell them that and you should have the bearing in hand. The info I have says it should cost 5 or 6 dollars.
 
DanielMaia

DanielMaia

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Jun 24, 2009
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Do you guys want some fresh photos?! here you go guys!







Piston in top position:


Some damage, but i will polish all the surface:
 
DanielMaia

DanielMaia

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Jun 24, 2009
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Piston in down position:


Piston will be replaced:


The major tools needed to desassembly the engine:




Piston damaged by piston bearing:
 
GearNut

GearNut

Active Member
Aug 19, 2009
5,104
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San Diego, Kaliforgnia
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