Ys 91 sr

[choppertastic]

I'm thinking of getting a t-rex 700 and was wondering if anyone is using a YS 91 engine in one.

Has anyone run this combination or got any comments about this engine? It will prob be on a hatori muffler.

[mark Taylor]

seen people using the 91 sr and hatori pipes with great effect mate,
make sure you get the hatori for the ys as they do one for os engines as well
cheers

[Arwel]

I use the YS SR in my 700. Make sure you get the SB19 Hatori pipe, maybe even the Kasama header for it

[Steve]

I've had a SR with dedicated Hatori pipe for 18 months or so now in my Vibe and it's great. Just don't try running it in freezing cold weather (i.e. snow on the ground) because the check valve is likely to seize up and that is a pain. Peak power of this engine is at about 15400 rpm I think, which might give you a lower-than-expected head speed, but then it's a long-stroke design, so don't be put off by this 'cos it makes up for it with loads of torques.

[choppertastic]

I'm not looking for mad head speed as I'm not looking at 3D so I dont think the low RPM will be any issue. I do wonder about the cold tho as I tend to enjoy flying in cold temps.... weird I know.