sparky 25

Took my savage out today for a second run since i installed the orion (picco) .28,

its been almost two weeks since i first ran it and it was running pretty good the first time,

today it runs good but just when i have the idle, lsn and hsn to where its running as it should, it starts to buzz like a bee,
no amount of adjustment on the hsn makes any difference,

but when i cut down the idle it stops buzzing, runs fine for about 10 seconds at idle then the revs drop and it stalls,

so i reset the idle and fire it up again, give it a minimal amount of throttle and it starts to buzz again,

this time i open up the lsn about a couple turns out from flush before the buzzing stops, but as i try to drive off it loads up and stalls,

if i set the lsn back to flush and restart the engine it will start usually fire up first or second pull and idle all day long,

until i squeeze the trigger a little again then it will buzz,

if i continue to drive the truck, as soon as i get past a high idle the engine runs great and revs out just fine, when the throttle is released after full rev the engine drops the revs instantly goes to idle then again will start to buzz,

sometimes a quick blip of the throttle will bring it out of the buzzing and back to idle but most of the time it continues to buzz

i have been trying everything i can think of to set this problem straight, the fuel lines are fine, my lrp30 runs great with them,

the engine backplate and carb body were freshly sealed just before i installed it,

also where the compostite and alloy meet on the carb i have run some CA glue round to prevent it from drawing air there,

the engine is bone dry all over with no signs of such a thing as a leaking bearing,

any help from the guys fimilar wih the picco engines would be greatly appreciated,

im all out of ideas[:@]

wolfie1

i had a the same thing, turned out to be a leaky front bearing

sparky 25

My lrp30 puts out a little amount of fuel on the front bearing, but it runs perfect,

this picco is bone dry i`d say its the driest engine i have ever ran

can a bearing be leaking without putting out residue?

sparky 25

Well i pulled the engine apart and the front bearing is a little damp just at the crankshaft,

but thats the small problem,

the bigger problem is the one way bearing is dozed with raised lips around the the slots that the crankpin sits into,

this has started to eat the conrod leaving very fine filings everywhere,

so i need a new front bearing and a one way bearing for it,

anyone know the part numbers for these two items or where i can buy them cheap?

the good news is that neither the piston or barrell are marked.

supertib

do you have the OFNA throttle mod ?

to me it sounds like your carb is not closing all the way at idle...

Also how large is your idle gap ? with carb restricter removed you should have a .5 -.7 mm idle gap............

that high idling your hearing is almost always caused by too much idle gap....wether its a bad linkage setup or a bad needle position...

sparky 25

I striped the engine and flushed out the crankcase with nitro fuel,

and washed the small filings off the other parts with fuel also,
i checked the front bearing by plugging the carb and center of the front bearing by my finger tips and filling the crankcase with nitro fuel and none leaked out after a good few mins,
after this i emptied the crankcase of fuel, i plugged the carb neck, centre of front bearing and top of crankcase with my fingers and blew into the exhaust port and held as much pressure as i could for around 10 seconds there was no sign of any air escaping from anywhere,

was able to save the oneway bearing by dremmel sanding the burrs of from around the elongated holes where the crank pin sits, then took a dremmel cutting disc and made another 2 new slots opposite each other for the crank pin to sit,

while i was taking previous idle gap measurements i was doing so with the venturi installed,
as you say to take the idle gap measurements with the restrictor removed this may explain the buzzing im hearing at idle,

im running a type of throttle mod, more of a diy setup from some linkages i had laying around as the stock setup is for nothing,
so its possible that the carb may not closing all the way i`ll check these two things and see how it runs then

thanks alot for your help tib.

supertib

Idle gap is your #1 thing when tuning...the idle gap must be between .5 and .7 mm.....then adjust the LSN so the engine idles decently...if it lean bogs on WOT acceleration from a dead stop you need to fatten the HSN....Most guys try tuning around a big idle gap, or a inconsistent idle gap...that makes tuning impossible

sparky 25

I`l keep those tips in mind for when i next run the engine, thanks,

just checked the new exhaust gasket i installed on the header when i first ran this engne and its torn already,

it was the wrong type with the rib around it,

so i just have made an order on ebay for the straight non rib picco type header gaskets,

could be a few days until these arrive so i wont get to try the motor again this week,

one more thing i noticed while i had this motor apart was that theres a little bit of slop on the conrod bushing that goes onto the crank pin, not alot but around 0.02mm - 0.03mm

are they at all designed like this to allow better bushing lube or is it worn?

very miniature amount of play but i have never seen this on any other nitro engines i had taken apart