crank longer for daytona??

[jjsaez]

miniriders hello, I am Jesus, from Spain, I need help please!
I want to mount a rod in my daytona 150. Sent me a OORACING, sold Monstermoto.
is off-center, increasing Race 2 mm. Who has set this in Daytona 150?
I have to do to mount? that height of cylinder?
my head is 4 valves. I appreciate any help eser
thank you very much
I want to buy 2 motors daytona, whom I will send them to Spain?

 

[sean01]

lol man your hard to understand, but im gona give it a shot..

you got a +2 offset stroker pin right?

to fit it you will need 1 of the following to make it work.
2mm shorter conrod to accept the standard piston.
or a piston with the pin height 2mm higher..

you will need to the crank professionally assembled..

 

[grnman]

i am getting this done to my engine as we speak. yes you will need to get the crank professionally assembled. the kit should work. it comes with a bigger base gasket so all it does when you install the original piston back on is bump the compression up to 14:1. but with the 4 valve daytona head and the stroker i think the compression is lower as the head has more volume. i think its 12.5:1 from memory with the 4 valve head

 

[sean01]

hmm, so how far down the bore is the piston at TDC in standard form?

and thicker base gasket would put your cam timing out a bit

 

[grnman]

checkout this thread where i went through the compressions of daytona's
http://www.miniriders.com.au/tech-talk/18528-150cc-t-rex-daytona-motor-photos-15.html

 

[sean01]

is it a lumpy top, flat top?
how far down the bore at tdc is it...
all these things come into play when working out compression..not just bore,stroke and head volume...

 

[grnman]

well the daytona 150 as stock comes with a flat piston that i think is .25mm below the cylinder at TDC as stated on the daytona specs that runs 12.5:1. the high dome piston you get after market makes it 14:1 but you carnt use the high dome in the stroker kit as the compression will be insane.

so with the 2mm stroker, the head volume of 12cc would be reduced by (28.5 x 28.5 x 3.14 x 2mm) = 5.1cc. that would make a head volume of 7cc. so the compression would be 22:1. so the base gasket compensates for this and makes it 14:1 with the flat piston in 160cc form.

first lets go with what we know. the daytona 2v head must be 12cc because 150cc div 12cc = 12.5:1
daytona say it goes to 14:1 in 160 form.
and Hackmunch has said the 4v head is 13.63cc

so 160cc div 11.4cc combust = 14:1 for the daytona 160 2v setup. that means with the extra stroke and bigger base gasket the head volume is reduced by .6cc.

now lets take that data and translate it for the 4v head setup.

we have already established 150cc div 13.63cc = 11:1

so less .6cc volume from the head and work out for the 160
160cc div 13.03 = 12.3:1

 

[Hillz]

Jesus has returned!

 

[themountain]

so with the 2mm stroker, the head volume of 12cc would be reduced by (28.5 x 28.5 x 3.14 x 2mm) = 5.1cc. that would make a head volume of 7cc. so the compression would be 22:1. so the base gasket compensates for this and makes it 14:1 with the flat piston in 160cc form.

...since when does a stroker reduce head volume..??

first lets go with what we know. the daytona 2v head must be 12cc because 150cc div 12cc = 12.5:1
daytona say it goes to 14:1 in 160 form.

...of course...same headvolume but more cc

so 160cc div 11.4cc combust = 14:1 for the daytona 160 2v setup. that means with the extra stroke and bigger base gasket the head volume is reduced by .6cc.
now lets take that data and translate it for the 4v head setup.
we have already established 150cc div 13.63cc = 11:1
so less .6cc volume from the head and work out for the 160
160cc div 13.03 = 12.3:1

I don´t think so ...you better check all that jibberish again...something is not adding up , my friend !

 

[grnman]

...since when does a stroker reduce head volume..??

well where does the extra 2mm in hight go? it adds 4mm to the entire stroke from 58.7mm to 62.7mm so there has to be 2mm extra pushing up. if the cylinder does not change and is original, then the 2mm on top will have to be taking up the compression area. wouldnt you say?

im open to suggestions, but in the meantime im sticking by my calcs.

 

[sean01]

nah grnman... it sounds like your very lost. or youve confused the hell out of everyone..
and the way you work out compression is very strange too.
mountain is correct..
but yeah i see wat your saying about the extra 2mm having to go somewhere.. but its not going to go in the head cause the combustion camber probly wouldnt allow it...

you want my advise...(probly not lol)

fit the stroker pin
use a standard base gasket(to retain proper cam setup)
machine down the piston and make it just under zero deck height.(providing the crown of the piston allows it)

now to work out compression..

cc the head (not every head will be the same but should be similar..)
measure the head gasket bore size and thickness
cc the piston (valve reliefs) add it to the head cc's

ok, heres what i got for standard 150 comp ratio working off the following

bore 57mm
stroke 58.7mm
piston deck height (you said) 0.25mm
head 12cc
head gasket 57.5mm bore by 0.5mm thickness (i only guessed this)

now i get a figure of 11.74 comp
now also i see hackmunch said his standard piston was had a 1mm deck height not .25mm
so with 1mm comp is only 10.45
and with his valve relief cc's added to the combustion camber volume (13.63) that makes comp 9.56.

take into account i havent got one of these engines to do all the sizing.. so im only going off what information is available here on the forum which is mostly hackmunchs info..

also iv never heard anyone work out compression the way hackmunch says.. to many variables.

**work out what the head gasket measurements are and let me know**

 

[grnman]

yeah cool i understand. but if you run off what the manufacture says. like daytona, 12.5:1 comp than you dont have to work out all that nitty gritty stuff and you can just do one simple calc to find the total comp volume is 12cc. and if your adding a 2mm stroke to the engine when eveything being the head, cylinder and piston are comstant to the original, then it has to be a bigger base gasket that makes the 150 go to 160 and go from 12.5:1 to 14:1.

(p.s what are we talking about here again?)

 

[sean01]

lol, man you never run off manufacturer specs there always wrong
and wat nitty gritty stuff.. if your not prepared to do some simple measuring then you shouldnt be modifying engines.

look do wat ya want, i dont really care.

but i thought you might of wanted to know how very wrong you and daytona's specs are.
its not rocket science to see it..

 

[grnman]

yeah well thanks for your help sean. i think my approach was way to simple. my bike is getting the stroker put in it next week and also full ceramic bearings if the cost is decent. a shop is doing all the work so i cant measure anything any way. i will have to post up a vid of how it goes when i get it.

 

[Cactus Jack]

...since when does a stroker reduce head volume..??
...of course...same headvolume but more cc

I don´t think so ...you better check all that jibberish again...something is not adding up , my friend !

He means the volume above the piston at TDC is reduced IF the piston moves higher up the bore with a stroke increase ...

 

[grnman]

yeah thats is what i meant. sorry guys i prob wasnt very good at portraying my thoughts.

 

[jjsaez]

problem longer

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[jjsaez]

more problem

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[grnman]

hello jjsaez,

how long is the pin offset?
it looks like a big difference to stock.

you should be able to fit a 2mm offset pin in so how long is yours?

what will the total stroke be of your engine? bore 57mm x stroke ??mm

 

[sean01]

you need the cases machined... no other way around it.

but it will end up being paper thin