Tohatsu pistons

[mattsaks]

Talk about projects getting out of control!!<br />Does anyone know the bore size and piston diameter for a 1993 tohatsu 90hp? Also what are the tolerances(if any) on these sizes?<br />Thanks, Matt

 

[rodbolt]

Re: Tohatsu pistons

mattsaks<br /> look in the service manual under engine specifications. wiesco makes after market pistons pins bearings and circlips. youcan check their web site as well. Ithink the standard bore size is listed there.<br /> good luck and keep posting

 

[45_red]

Re: Tohatsu pistons

As per Clymer;cylinder bore=3.86";piston clearance=.010-.016";piston ring end gap=.25-.40 mm.

 

[Dhadley]

Re: Tohatsu pistons

Wow! Thats a bigger bore than the 3.3 liter Evinrudes! If thats .010 to .016" skirt to wall, I'll bet its kinda noisy too.

 

[mattsaks]

Re: Tohatsu pistons

Cool. Thanks guys, i will have a measure up this weekend. I had also heard 86mm for the bore measurement?

 

[rodbolt]

Re: Tohatsu pistons

hahaha I am with DHadley. a skirt clearence of .01 to .016 is rather loose. piston slap would be a bit noisy.

 

[phatmanmike]

Re: Tohatsu pistons

maybe he is missing a zero....<br /><br />clearance=.0010-.0016

 

[Dhadley]

Re: Tohatsu pistons

86mm is what I see for the standard bore on an M90A. 3.860" is quite a bit bigger than that so be careful.

 

[TOHATSU GURU]

Re: Tohatsu pistons

Matt,<br /><br />Piston max diameter (measured 10mm above the lower edge of the skirt) is..... 85.93 +- 0.01mm.<br />Piston clearance is 0.08 - 0.13 mm

 

[45_red]

Re: Tohatsu pistons

Clymers' conversion is off, Marubeni manual shows max bore of 86.50 mm(3.43") ring gap .8 mm(.031"). Manuals do lie,I'm too lazy to break down a powerhead to check.Edit; can't blame Clymers for all of it, I read the bore #'s wrong, they have86mm(3.386") The inch conversion I believe is shifted over one column which would give a piston clearance of .0031-.0051 and a ring gap of .010-.016.Thanks to the web for peer review