Picco .28 Questions in savage XL

[KaPlow23]

Well I did it, I got my RR gears and slipper installed. Along with the new Picco .28 Boost. I did 3 tanks of heat cycle and 3 tanks of light/medium ovals around the street to break her in. I got a full tank in of normal driving with harder, almost full acceleration. Now I'm tuning on tank 8 (stock 160cc tank)...but something weird is happening. Very rich one pass, very lean with wheelies another pass and above 270 degrees! (I'm adjusting 1 "hour" at a time). It will idle fine for minutes after some passes and then idle VERY low for 3-5 seconds and then idle normal again after some more passes... After I was done I noticed the header to (block?) seal had good amount of oil below it, on the tank and roto box also. So it looks like I have a decent exhaust leak. Would this cause my problems? If so what header do you recommend to run with a ERCM pipe I have coming in next week? Looks like ERCM to header will be rubber coupling type also. I guess I'm in the market because I would like nice stug fit all around.
P.S. These drastic changes were happening after NO adjustment to carb.

 

[olds97_lss]

From what I recall, the Picco 28's were pretty known for carb air leaks. Some folks were pretty adamant that the carbs leaked bad around the slide and where the composite/aluminum was bonded on the HSN side. Usually once the engine got up to operating temp. People would use JB weld around the seam there and use Racers Edge sealant (which is supposedly 3 Bond Silicone ) around the boot and HSN around the banjo fitting. I usually use Permatex Sensor Safe Copper Sealant to seal up my carbs, but I don't usually put anything on the boot. Just the HSN banjo fitting, carb neck and back plate.

This is someones sealing job using jb-weld and the racers edge stuff on a picco carb:



A leaky exhaust seal isn't going to help you much either. I'm not sure what header your using, but what I'd try is buy a few different header gaskets from different manufacturers. They vary in thickness. Might want to try an old HPI purple gasket, unless that's what your using. If you are, try an OFNA, associated, losi... might cost a few bucks to get a few, but you should be able to find one that seals ok.

I've had a picco 28 NIB sitting in a drawer that I bought off a forum for $150 many years ago. I had LRP28's at the time and am still running those, so never bothered installing the picco and giving it a go. Supposedly, it outguns the LRP28S3 in torque and RPM's by a decent amount. I honestly have as much power as my rigs can handle with the LRP's. I bought this one just as a knee jerk due to the price. At the time, they were selling new for over $200.

 

[KaPlow23]

Thank you very much! Since reading this I have took the motor apart and sealed everything. from the rotostart all the way to the HSN and everything in between. I actually found a rip in the boot that was a decent size. When you go full throttle the rip would open up. So I hope I have found everything that can be a problem and I can get around to enjoying the motor again. I'm going to let it sit over night and have 16 hours before I get around to driving it. Thank for for the post!

 

[olds97_lss]

Post up your results once you get a few more tanks run through it.

 

[KaPlow23]

Sure will, thanks guys.