Motorcycle Forum / General / Yamaha / July 2008

Hi all,

I saw some good answers to XV535 questions, so maybe you can help me
out. First up is some background, but if your not interested, you can
skip this next paragraph. It’s important to note that I have not owned
a 535 up to now (or any twin this small), so I don’t know how
normal/abnormal the below is.

I got the bike very, very cheap as it was not running, but nearly
perfect in looks and put it aside as a project. Lately, I started
repairing it and rebuilt the carbs, pumped out the tanks, and verified
the spark. I got it running but very poorly. Turned out the front
cylinder was dead due to a vacume leak at the boot. (btw, getting
these carbs out is great fun  :evil: , but on the second go, I found
the trick to do it relatively easy). Replacing the boots and O-rings
corrected it, but the thing is still kinda doggy and lacks power.
Adjusting the carbs with a hand-held digi-tach helped, but even still,
it is virtually unrideable for the first 5-mins. After about 15mins of
riding, the bike seems to finally wake up and rides fine, idles fine.
Till its warm, you have to run it full choke, and even then it seems
to idle grudgingly from 5-10mins, stalling being fairly common unless
you actively rev it time to time. At this point, I have noticed the
front cylinder heats up at about twice the speed of the rear.

On to the question. Finally, I did something I probably should have
done earlier: whipped out the compression gauge and checked the thing
out. The front is about 150 lbs, the rear about 123, which is out of
spec according to the manual. My question is: granted it is not up to
par, but 123 is not terribly bad either, yet I have no perfectly
running 535 to judge it against. Could this compression cause it to
run this poorly? (or to put it another way: are they this sensitive to
compression?)

-mike