General tuning issue with my LRP28S3.

[olds97_lss]

Well, I've noticed that if I tune for good temps (around 225F) that I end up with a bog area from 1/8-1/2 throttle. It idles fine and runs wide open fine, but I have this bit of bog down low if I let it sit and idle for more than a few seconds.

I want to say I had tried leaning out the LSN, but it made my temps climb higher than I'd like (over 250F). I leaned it out a hair today and richened the HSN considerably which then kept my temps in the 235-240F range, but I still have a bog if I let it idle for literally more than 3-4 seconds.

Any tips or anything I should take a look at on the engine to help this issue?

Engine specifics:
4+ gallons
In an aftershock w/+1 CB, trans gear flip mod, maxx sized tires
Compression feels good
Glowplug OS #8
Fuel 25% byrons

Power is still outstanding pretty much throughout the entire RPM range. Starts easy, runs around 220F-250F.

 

[Scrogg]

Check the carb O-rings closely. 4 gallon mark is where the LRP carb O-rings seem to give out. The idle screw O-ring in particular. That engine should be run on long McCoy plugs. MC59 is what Rick at RB Mods said to run in it. That was all I used in mine.

 

[olds97_lss]

Thanks for the info. I'll get a gasket set (hopefully if available) and maybe buy a few extra MC59's on my next tower purchase.

Any idea what temp the MC59's are? Hot? Medium? I think the OS #8's are medium-hot.

 

[Scrogg]

McCoy lists them as hot but remember there is no industry standard for heat ratings. I know a MC8 would work too, that is the medium heat version.
I run a MC8 in my Picco .21 with Byron's 25%, works nicely.

 

[olds97_lss]

I know this is an old thread, that I started... but figured posting my results may help someone else. Since this thread, I've had 4 LRP28's. Pretty much all of them had similar issues like the first one.

These are my findings:

- fuel with more than 20% nitro
-- will run on 20%, but runs and tunes much easier on 25% nitro and < 12% oil

- plugs that are medium temp work best
-- odonnel purple work well for me

- a pipe that is a bit constrictive
-- the HPI polished pipe made it run like crap everywhere in the middle of the RPM range. Could not tune out the burble in the mid-range no matter how hard I tried. I run an LST2 HT pipe on my savage (and at the time, got one for my aftershock) and a THS BB revo pipe on my revo, and whatever OFNA's stock pipe is on their 10 year old buggies. For a while, I even ran a Losi HT pipe on my revo as a side pipe. Still ran great. I just got tired of the side pipe on a revo and got the THS BB revo pipe, which worked nearly as well.

- a gallon of fuel has been through it
-- after about 3/4-1 gallon, the power really comes on and tune stabilizes very well. Up to 3/4 gallon, I chase tune pretty bad, so by the time I bought the 3rd one, I just tuned it to keep the temps between 220-250 and lived with the periodic stalling, blubbery low end, high off throttle idle... It's really like the engine fights itself and if your constantly adjusting the tune, your just irritating it and you.