Vito's stroker crank question

[blaster7]

I bought a Vito's stuffer crank from a member and its supposed to be a 3mil stroker crank and the funny thing is I had my 240 cylinderhead cut for this and I did a compression test on it and its only at 132psi? sooo I then put a standard stock cylinder and head on it and the piston did not make contact with the head,then I did a compression test it came out too 160psi plus,any ideas? is there anyway I can meager with my micromiter to see,today I did meager from the top of the cylinder to the top edge of the piston and that came too 59.40mm let me know what you guys think.Thanks

 

[darealblaster]

I would start with contacting the person who did your cylinder head. Good thing is that at 132psi, you know your piston and rings are doing there job. Problem is at the cylinder head.

 

[blaster7]

yeah I thought the same thing bud the head or the crank but I still would like to know if this crank is a stroker you know,and actually the guy who I bought the crank from is the same guy that cut the head.

 

[Larry's Shee]

Did you get a cylinder spacer plate with the crank? Did you use it with either cyl? Does the piston stick out of the cyl (at the edge) when at TDC? What compression were you looking for?

 

[blaster7]

OK Larry yes the piston does come just above the cylinder,as far a compression on the Vito's 240 I have it came up as 132 psi also remember that the exhaust port is raised 2mm so that will drop compression,now when I put the stock cylinder set up on compression jumped up to 160 plus psi.as for your other question no I do not run the cylinder spacers I had the cylinder head cut.Thanks for the help.

 

[blaster7]

oh and no I did not get the spacers with it and no I did not put have any spacers on the stock cylinder nor a cut cylinder head bud.

 

[Awk08]

stroke of a stock crank is 57mm
stroke of vito's +3 is 60mm
should be able to measure with the head off
vito's makes both lengths with the same blue plastic stuffer blocks

 

[Larry's Shee]

At first I couldn't figure how the piston wouldn't hit the head on stock cyl/head combo. I'm in the process of doing a 3mil, so I measured the spacer+ 1 gasket and measured the head recess right at the edge. Theroredically it would clear but not enough to run, lol.
If you measured 59.4mm of stroke I'd call that 60mm.
Best thing to do now would be to measure the squish. Also be aware that when the ex is raised the distance you have to compress is less so cranking pressure is less.

What compression numbers were you shooting for?

 

[Larry's Shee]

Ha Ha , I forgot to allow for the head gasket also, extra .032" guess it wouldn't hit

 

[blaster7]

as far as compression go's with the ported 240 cylinder on there it was 132psi with the stock cylinder it was 160 plus,so maybe it is a stroker huh? seeing that the stock compression is suppose to be right at 130psi so at 160psi it would have to be a stroker crank shaft right? Thanks for all the help guys.oh and how do you measure squish.

 

[Blaaster]

http://www.sacoriver.net/~red/squish.html

 

[blaster7]

Thank you blaaster your like a book of knowledge my friend,OK when I get the chance I will make a pit stop by radioshack and pick up some solder and check the squish.anain thanks guys.

 

[Blaaster]

It is not that I retain much knowledge, but I have a special keyboard on my iPad with the letters "Google".

I know and understand the processes but sometimes I allow someone else to explain them for me.

 

[tfaith08]

That exhaust being raised 2mm makes a difference. If you used a thicker head gasket and thicker base gasket than the previous guy used, you're going to have even lower compression. I'd see what he used with the setup. If he can't help, get a thinner head gasket. If you need more, get a thinner base gasket.

IIRC, the Vito's thin HG gives you about 10 more psi.

 

[blaster7]

@tfaith08 thanks for the info buddy but the thing is that I'm the guy who is building this one lol,I just didn't cut the head I sent it to a guy that did it for me and I gave him the info on what I'd be running and he went from there.also the guy I sent my head to is the guy that I bought the 3mm Vito's stroker crank from and the reason he did not give me the crank with the cylinder spacers is because he was cutting the head so he knew I didn't need them,as far as compression go's I do agree 2mm is very aggressive and 132psi isn't too low so I thank I will try the thinner head gasket first and if I feel not enough I will then popped for a thinner cylinder base gasket.again thanks to everyone that has commented and helped me out god bless.

 

[tfaith08]

Ahh, didn't know you were building it. I read after having been up for 20 hours.

Have either of the cylinders been decked? What is the exhaust port height of the stock cylinder? What's your deck height measurement on both cylinders? What is the distance from flat area to flat area on the edges of your squish band? 2mm on a stock bore is worth 6.8cc (bore x bore x height x .0007854). That's almost enough to offset the compression to the extent that you're experiencing.

 

[Larry's Shee]

2mm sounds like a lot, but the piston starts 1.5mm higher. No stroker plate.

Did you check the rod/case clearance? Right about mid stroke the rod gets rea lclose to cases by bottom of cyl.
Paul @ Vito's said minimum .020". I ground mine to .040, only had to do it one side. It's a PIA process because you put cyl/piston on one case half. Then, if you have to grind either remove brg or tape everything off.

If you don't have proper clearance the rod will hit the case at speed, sending bits of alum in engine.

 

[blaster7]

@Larry's Shee yes bud all clearances have been performed and the case half's have been matched to the transfer ports on the cylinder. @tfaith08 no none of the cylinders have been decked.on the standard cylinder its all brand new and what I mean by that is I bought the straight from my dealer,now as far as the Vito's 240 its been ported the exhaust has been raised 2mm and the intake lowered 1mm other then that the rest of the ports were just cleaned up.I did not want to run those junk spacers you know so I went ahead and had the head cut and rechambered.I thank what I'm experiencing is the norm for what's been done also 132psi isn't to bad considering its not even broken into yet,Thanks for all of your help guy's.

 

[tfaith08]

Did you ever get the squish clearance? Also, what intake was lowered by 1mm? Do you mean the piston ports or the cutouts on the piston by chance?

Also, to hell with buying a new Blaster cylinder. At my cost, it was still $470. But... that's better than a Banshee set at over $1000, $740 my cost.

 

[blaster7]

@tfaith08 no bud I have not got the measurement yet but I did pick up the soldier.I'm going to have to locate that darn head gasket I put to the side because it was used ha lol just go's to show should put things up,but yeah I'm looking to get you that measurement tomorrow bud and yeah those cylinder was pretty pricey but man $470 wow I guess I'll stick with my friend that works at a cycle shop he let my have it for $360 it was new old stock and the ports on it stink so I will be cleaning them up.Thanks for all the help bud.