YS-91SR Engine Problem
 

I am running a YS 91SR engine with an SB19 pipe installed in a T-Rex 700 heli. On first start, the engine turner over fine and I was only able to get it to idle. When the throttle was advance, no matter how slowly, the engine would die. There was plenty of smoke. I finally figured out that I had not installed the one way valve between the engine and the tank vent, so no pressure in the tank. I installed the filter but now the engine turns over too hard for the starter. I can turn it by hand. I have two batteries and charged both to make sure they were charged. I pull the glow plug and the engine turns over smoothly and fast with no strange noises. I also disconnected the fuel line from the tank vent and from the engine thinking too much pressure was causing a problem. No difference.

Any ideas?????[:o]

*** I have a T-Rex 450 and T-Rex 600, both electric. This is my first nitro, so I have no experience in this area.

RE: YS-91SR Engine Problem
 

So originally you had neither the check valve nor a filter?

YS engines don't like crud in the fuel and a filter is MUST or the regulator will get junk in it and will not operate properly. This can and will cause the engine to hydro-lock with fuel which is what I think might be happening since the starter cannot turn it over until the plug is removed.

First thigs first though....where are the high, low and hover needles set? If they are in the running range of the engine as noted in the manual then you might want to make sure the regulator is clean.

If you don't feel comfortable working on the engine then box it up and send it Richard at YS, if you feel confident then you might want to pull the regulater body off the engine and flush it out fresh fuel to make sure it is clean. If you look at the exploded view in the instruction manual this would parts 35-39. The screw on the side of the regulator right under the fuel nipples is FACTORY SET...do not mess with it unless you are careful to make note of exactly where it is set.

RE: YS-91SR Engine Problem
 

I do have a filter installed. Finally, because of your message talking about a hydro/vapor lock, I disconnected the fuel lines from the carb and after about 15 minutes of trying, finally the engine turned over normal. Now with the one way valve installed the engine ran normal. I had not set the rev limiter, so I did not hover, but the engine ran fine at high power.

Thanks for the help. Now to setup the 611 better and set the rev limiter in the 7100R and she will be ready to fly.

RE: YS-91SR Engine Problem
 

Cool. I'm glad you got it running.