RCU Forums - View Single Post - thunder tiger .91 4 stroke issues

09-29-2008 | 11:30 PM

#20

DarZeelon

Senior Member

Joined: Apr 2003

Posts: 8,913

Likes: 0

Received 6 Likes on 6 Posts

From: Rosh-HaAyin, ISRAEL

RE: thunder tiger .91 4 stroke issues

Quote:

ORIGINAL: chashint

Here is a link to the manual.
http://www.thundertiger4u.com/pdf/f_91s.pdf
Page 9 has the valve adjustment information.

Charlie,

There is one thing on page 9 I cannot subscribe to and this goes for all four-stroke engines...

It reads to turn the prop to a location where "both lifters/followers are 'somewhere' on the cam's base-circle"...
The machining accuracy of the cams may be such, that the base-circle is not perfectly concentric with the camshaft...

Each valve must be regarded as an individual adjustment item; and that means it must be adjusted 'alone', with the very middle of its cam's base-circle on its lifter/follower, without any regard to the position of any other valve...

This is very easy to find...

Select one valve.
Look at the rocker of that valve and rotate the prop find its 'point of maximum lift'.
From there, rotate the prop exactly one complete turn, 360º (this will rotate the camshaft exactly 180º; one-half of a turn, to the point opposite the cam's peak) and adjust that valve's lash only.
Repeat this procedure for the other valve.

Also the adjustment should target the minimum value (to maximize total lift and duration)...
The go/no-go procedure described is just too crude and could result in a power loss and more valve-train noise/wear.

Reply Like