How to: SQUISHBAND your engine

[charge]

yo guys, how about shaving off 1mm of at the bottom of cylinder head besides removing the gasket? Is it the same as shaving off the upper portion of the block?

 

[haen]

hi chiglai.. gasket removal = 0.5 mm block / head shave.. 1 mm block shave + gasket removal = DAREDEVIL.. LoL... better use 0.5 mm cyl bottom + gasket removal

 

[phl6684]

i dun understand...hehe..is it feel the same if i remove the bottom gasket...n replace it wit only 3bond seal???

 

[charge]

hi chiglai.. gasket removal = 0.5 mm block / head shave.. 1 mm block shave + gasket removal = DAREDEVIL.. LoL... better use 0.5 mm cyl bottom + gasket removal

hehe, its me asking actually. I'll just go for 0.5mm cyl bottom first. If not enough only remove gasket, lol.
thanks !

 

[joel]

The T135 has lesser squish than the R15. U can further bump compression by phasing the piston size a bit to avoid the sqish, deepen the valve pockets by 0.5mm. You'll have easily 13.5:1. He he he
However u'll need to strictly use 96 octane.

 

[joel]

wow.. judging from the spark plug color.. PERFECT COMBUSTION..

But to me, it looks a bit on the richer side. Light biscuit brown is the right plug color. This is a shade darker. U'll have to lean by little to make it run even better.

 

[justkir]

what a brave mods traxxas..salute...

joel, if i plan to shave my bike head to 0.5mm, what is the new VC for my bike? care to share?

 

[joel]

Ur comp ratio with 0.5mm shave is 11.77:1

 

[traxxas-modifier]

Ur comp ratio with 0.5mm shave is 11.77:1

wow thats just a little above than yamaha R125 11.2 CR
go for it bro!

 

[traxxas-modifier]

wow.. judging from the spark plug color.. PERFECT COMBUSTION..

But to me, it looks a bit on the richer side. Light biscuit brown is the right plug color. This is a shade darker. U'll have to lean by little to make it run even better.

should i adjust it on AIR FUEL screw only
or on the mainjet/pilot jet?

my pj is from stock #20 to 22.5
my mj is from stock #103.8 to #107.5

 

[Mafiaflix]

@traxxas-modifier :
Have you check your compression ratio by compression gauge tester..?

 

[traxxas-modifier]

@traxxas-modifier :
Have you check your compression ratio by compression gauge tester..?

bro syd i wish i can but i dont have access to that king of tools here.
i couldnt find it here locally

 

[justkir]

wow..i better try this...but again, if my oem head also already shave..is it okay to do squishband?


thanks joel and traxxas

 

[Azzurri]

There's should be a detailed math formula to calculate compression before modify these squishband.
Basic math, calculating compression ratio is

1. Calculate the cylinder volume by measuring BDC Bottom Dead Center to TDC Top Dead Center.
2. Calculate the combustion chamber volume by measuring of cylinder head using "burret".

Compression Ratio : Cylinder volume/Combustion chamber volume

*This is only basic calculation, ignoring gasket thickness

Also everytime we change to much wider pistons or shorter/longer conrod, the compression ratio and performance also changed. Depend on experienced skills and by understanding in modifying bike. Compression ratio also could change by placing piston pin different from standard assembly.

so, by decreasing combustion chamber volume could increase compression ratio. traxass wat is ur exact compression now?

 

[haen]

100% correct mr. Paradox :

Let's refresh..
The static formula for computing compression ratio is :

CR = CV + CCV / CCV

CR = Compression Ratio
CCV = Combustion Chamber Volume --> the hardest part, any slight changes in the head / piston crown could make calculation harder so the best is using burette filled with liquid parafin

Assuming the pistons are flat top, formula for the volume above the piston is :

V= phi x D^2 x H / 4000

phi = 3.1416, D= diameter of the bore (mm), H= clearance between piston crown and block deck (mm)

Things to remember :

Higher comp = higher temps --> affecting valve durability
Higher comp = higher bearings load

road engine --> 9.5 - 10.5 : 1 ratio
racing engine --> 11 - 12.5 : 1 ratio

 

[joel]

wow.. judging from the spark plug color.. PERFECT COMBUSTION..

But to me, it looks a bit on the richer side. Light biscuit brown is the right plug color. This is a shade darker. U'll have to lean by little to make it run even better.

should i adjust it on AIR FUEL screw only
or on the mainjet/pilot jet?

my pj is from stock #20 to 22.5
my mj is from stock #103.8 to #107.5

If I were you, I'd for for a 105 instead. The Mains will matter the most.
Use a 105. Pilot is ok. It will improve your low end response.

 

[traxxas-modifier]

wow.. judging from the spark plug color.. PERFECT COMBUSTION..

But to me, it looks a bit on the richer side. Light biscuit brown is the right plug color. This is a shade darker. U'll have to lean by little to make it run even better.

should i adjust it on AIR FUEL screw only
or on the mainjet/pilot jet?

my pj is from stock #20 to 22.5
my mj is from stock #103.8 to #107.5

If I were you, I'd for for a 105 instead. The Mains will matter the most.
Use a 105. Pilot is ok. It will improve your low end response.

mj#105 is the stock jet of automatic version of t135 using stock carb and stock pipe..


i

 

[joel]

So what just use it. 105 should be fine. Have u richened the needle?

 

[traxxas-modifier]

So what just use it. 105 should be fine. Have u richened the needle?

ive tried once but it seems overfeed of fuel so i get it back to
middle (stock) setting of needle...

 

[charge]

Yesterday my squishband mod is finally done!!

I shave off 0.6mm on the cylinder head, using back the gasket and put some adhesive on it. Also got YYPang valvespring and use back stock camshaft.

However, the engine started to sound (knocking) on the 1st start even during idle rpm

We re-adjust the valve tapette (make it higher). On the 2nd start, the engine sounds fine during idle rpm! So, we warm up the engine and increase the rpm up to max. Once it backs down to idle, KNOCK again

Well, I dont know what is the problem right now. Anyone have this experience before. FYI, I am using RON97 petrol.