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S-25 Low Speed Needle closed point and break in

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R

rossb

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Last night I was double-checking the factory settings before my initial startup so I screwed the High Side in unit it was fully seated. It went in about 5 turns without any problems. I backed it out 4.5 turns as per the break-in instructions.

I went to turn in the Low Side Needle and I found right off the bat that it had a lot more resistance than the HSN. It went in about 3 turns and then I started to feel even more resistance although it was still turning. I was able to get another two more turns until it felt like it was really seated, a total of 5 turns! I did not want to force it but I think I got 5 full turns until it felt really tight, that seems to be way off from the recommended initial setting of 3.5 turns. At this point I am not really sure if I went to far when screwing it in because I felt a decent amount of resistance throughout the entire range of the needle. I backed it out 3.5 turns from what I think was the fully seated point and I hope that I am not too lean for break-in. I may have turned it in too far when trying to seat it.

BTW – Has anyone tried the Fantom Racing method of break-in. They are recommending running WOT right away. This was discussed here:

https://www.rcnitrotalk.com/forum/showthread.php?t=17501
 
I wouldnt recommend running a brand new egine at WOT , You will mess it up big time. just do like the manual says first tank wheels off the ground at normal idle. and even though it says you're ready to go after 3 tanks. My LHS suggested running at least 8 full tanks before hard bashing. Worked for my .21 and I just did it all over again with my S.25 and all is good. just be patient and you will get a lot out of it in the long run..
 
Their break in method applies to their engines. Unless you want to F up your engine, I'd steer clear of that method.

As for the LSN issue, no telling if you damaged it, but the needle does tend to be a little more resistant to change. As for setting it properly, most LSN settings are best when the head of the LSN screw is flush with the collar that surrounds it. That is the guideline I use and it works. From there I tune it as necessary...guess what, haven't had to do much tuning with it.
 
Thanks for the replies and the tip about the LSN collar. This is what the LSN looked like right out of the box. It was not flush with the collar.

BTW - Does the angle of the carb body to the crankcase (rotation of carb) make a difference?

lsn.jpg
 
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Not particularly. You might want to verify their settings, but from what I know that looks to be just a bit too far in.
 
Now I think I know why my LSN went in so far. According to the forum on HPI's WWW site screwing in the LSN will cause the carb slide to open. I was probably opening the carb slide with the needle!

I will reset the LSN tonight before I start the motor by holding the slide closed while closing the LSN. After I find this fully closed point I'll back it off 3.5 turns and see if it fits flush with the collar.
 
I held the slide and I was easily able to find the fully closed position of the LSN. I then backed it off 3 turns to the factory spec.
 
Just use the factory specs as a guide but if it wont run right dont be afraid to adjust it to get it to run thru break in. When I broke in my New S.25 My LSN at factory spec had my engine at run away throttle like 30 seconds after starting. it turned out it was too lean at factory settings. It took me forever to get thru the first tank until I got it figured out.
 

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