xXxCellARatOr

hey guys, i just recently bought an XR80 and im having a little trouble figuring out how the engine is runing. I have personally tuned 4 other engines. F4.6 from my Savage X (4 gallons through it and running like new), .15FE from my RS4 which I also bought an O.S.18CV-R and an HPI T-15 . So ive had quite a little experience with tuning, but i have never had to mess arround with a mid-range. The XR80 has 3 tunning needles (+ idle) and the mid-range was fiddle with it before. Knowing that, how do i tune this engine? Do i start with the High speed, then the low speed, and then the mid-range? Also, the cars seems to realy take alot of fuel off the line when i give it full throttle, but gets it going much faster if i slowly increase throttle. And at full speed, there lots of smoke untill it reaches peak RPMs and then it just suddenly bogs and goes quite, then restarts. Too lean on the high end and too rich on the low end?

P.S. im only running in first gear since the tranny isnt adjusted yet. And i can probably listen to the engine easier.

hpi apollo

in most cases you dont even need to tune the mid range needle, if you do, tune the hsn, then lsn, then play with the msn if you want to, also you said it takes alot of fuel off the line...how do you know how much fuel it is using, if your engine is running then quickly bogs and dies, its too lean, if it takes a while to get up to speed and theres alot of smoke thats a clear indicator of running too rich, your description was kind of confusing

xXxCellARatOr

yeah sorry about the confusion, i tryed to be specific but theres a few things to take into account. Ill go from the start. so.... when taking off, i notice its sluggish to begin with, so that gave me the sensation that its running rich on the low. but thats mostly when i full throttle it. if i give it less gas it wont be so sluggish. so im thinking its definetly rich on the low. and then it seriously picks up with lots of smoke till it gets to top speed and just as it gets to the top of the RPM the smoke cuts out and it bogs and just stops (it basically seems to run lean, but i might be wrong i dunno). also i was only running it in the first speed only, so could it be reaching TOO HIGH RPM? is that possible? so i richened the HSN and leaned the LSN. and it kinda stopped cutting out so much at the end but then i noticed that after getting to top speed when slowing down, it made a sort of boging noise. i remember this was the same noise my savage made when it was running lean on the LSN. but i dont think its the LSN that was causing the problem cause as i said the LSN was running rich. and even after leaning it, it was still sluggish after i let it idle for 10 seconds and full throttled it. So im thinking this is what i need to do: Richen HSN, Lean LSN, Richen MRN. correct me if im wrong and if u have any other suggestions. thanks!

hpi apollo

have you sealed it to prevent air leaks? it can make tuning tricky, if it quickly bogs and dies, its lean, if you floor it and it bogs, making weird noises, the low speed is lean, just make the top end work good, and then work on the lsn, dont tune both at the same time

xXxCellARatOr

just got back from playing arround with it some more. what happens is, off the line, especially if i give it full throttle, its really sluggish and it seems to chocke on the fuel. however if i go slowly it takes off much faster and it sounds much better. so its giving me the impression that the LSN is still a little too rich. but im worried that i might be going too far since im only 1.5 turns out from all the way in. but im still quite convinced that its rich because even when i bring it in and let it sit for a while, the rpm starts to drop after about 5-10seconds, so it prolly means its rich. right? and for some reason it still seems to make weired noises when i slow down from a high speed run, as if its running too lean on the mid. im going to play arround with the settings some more tomorrow, but im just hoping im not leaning it out too much while thinking its rich.

P.S. also if i let it sit for too long (say 20 seconds or more) and give it full throttle, itll just die on me. again that makes me thing its way too rich.

hpi apollo

lean it out