YS 91 ST runing hot on the High end
08-22-2010, 09:13 PM
#1
Junior Member
Thread Starter
Join Date: Oct 2007
Location: Miami, FL
Posts: 12
Likes: 0
Received 0 Likes
on
0 Posts
YS 91 ST runing hot on the High end
I went to a couple sets of cylinders before I realized that my engine goes lean on the high end. Thanks to the CarbSmart, I found that My engine goes from rich in hover to lean ones you pas the half of the throttle. Initially started as the manual ask in the rich side but I went up 1.75 on the hover and 2 (two) turns on the high needle and still goes lean in the high RPM. Ordered some new O rings for the needle valves and checked the carb for restrictions but can figure out what could be the problem?
[
]
[
]
08-24-2010, 02:36 AM
#2
RE: YS 91 ST runing hot on the High end
I've been thinking about this, have you pulled the HS needle and spun the engine with the starter to flush out the passage? Also, have you cleaned out your fuek fliters? What about the check valve? Maybe a pinhole in the pressure line? Certainly sounds like a restriction somewhere in the fuel system or lack of pressure.
08-28-2010, 07:59 PM
#4
Junior Member
Thread Starter
Join Date: Oct 2007
Location: Miami, FL
Posts: 12
Likes: 0
Received 0 Likes
on
0 Posts
RE: YS 91 ST runing hot on the High end
Well, here are the final results. I had purchased O ring set for needle valves, and the seal fro the throttle barrel. I also replaced the regulator membrane and replaced all fuel lines including the filter as well as the check valve.The engine was still running hot in the high end. Finally I decided to bypass the header tank and believed or not that fixed the problem. I have not looked in to the header tank to find out what was causing the fuel restriction, but if I find out I'll post the results. Now the engine runes great and thanks to the CarbSmart, I was able to identify the problem and save my engine. Thanks again to all of you that tried to help.
