[kip51035]

The one I got here in Canada has a squarish black head and a 2 3/4" head pipe. The one I picked up off Ebay has a round dark brown head and came with a 7 3/4" head pipe. Are they different inside, like different timing or compression? What percent nitro fuel do I use? I have a tuned pipe to go on it, what RPM should I shoot for? The long head pipe has had an extension welded on it 3" long. I suspect the original pipe was 4 3/8" long. How does it run in midrange? Does it lean out when the pipe cuts in? Is it sensitive to the heat range of the glow plug? If someone has had some experience running one of these, please talk to me!!! I have been running two cycle engines for sixty years now.
KIP

[navav2002]

edit

[kip51035]

Wow I did not know there was such a lot of models! What I have is a "YS 61-R and a YS 60 FR". The FR has the round head and the crank case is one fin shorter than the -R. I would like to know: what RPM to shoot for, if they will run right without the pipe and if the mixture changes drastically when the pipe cuts in? I also would like to know, what fuel to use? KIP

[navav2002]

edit