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Old 08-16-2013, 10:54 PM
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mapbike mapbike is offline
Motorized Bicycle Elite Member
Join Date: Mar 2010
Location: Central Texas
Posts: 5,379
Default Re: what did you do to your motor bike today?

Pulled the NT carb off my latest Dax engine, the main jet had been soldered and redrilled with a #73 wire gauge bit which works excellent on all my other engines, but this engine breathes so much better from all the port work and open exhaust that it was running way lean as you will see in the pix I included of the spark plug, I re-drilled the main jet with #71 bit and now its running rich, acting extremely rich actually and had to screw the idle screw a long ways in just to get it to idle and it's still trying to load up so before I make the jet smaller I will look into making sure the float isn't heavy from a hole or just adjusted to high, I just grabbed an extra NT carb out of a box of extra carbs & parts, it looked clean and all seemed good so I put the re-drilled jet in it and stuck in on the engine but, it may have float or needle/seat issues, been so long since I chunked it in that box I don't remember why I quit running it...LOL!

I thought that I had blown the head gasket because of the lean condition overheating but after closer inspection, what had happend is that the head nuts had loosened and that's what caused the squealing noise, the head gasket was leaking but still in good shape, this was the first time I had ever had a head gasket leaking issue and the first time I had actually used my in/lbs torque wrench on one of these little engines, being a grease monkey and small engine tinkerer all my life I just used the criss cross tightening technique on all my engines in the past with flawless results, this time I torqued the nuts down to 120in/lbs used loctite and actually double nutted them with solid stainless steel acorn nuts over the other torqued nuts and still they backed off, 120in/lbs just isn't tight enough in my opinion for the 8mm studs, so as I've always done I just left the torque wrench in its case and tightened the nuts down the way I always have before and again double nutted them, pretty sure that is gonna be problem solved now.

I went to local hardware store and bought 3ft of 3/4 soft copper tubing and a handful of fittings, 90's 45's and collars, maybe next week or later on this weekend I'll have time to work on the exhaust, really no need to try to get a fine tune on the carb until I get the exhaust built and get the Puch head drilled and installed, but I dont plan to run the NT carb long anyway so I just wanted to get it running fairly good so I could put a few break in miles on the engine. got a few goodies in the mail that I had ordered, and finally convinced an Ebay vendor to send me a new wrist pin in place of the defective one I got with the piston set I had ordered from them a week or so ago.

The spark plug in these pix is brand new and has about 25 miles on it, the engine got so dang hot that it caused the whitish blue chalky discoloring, the plug was nice and shiny when I left home on the bike, a testament again to how well the Opti2 protected my engine even though it was running way lean form bad carb tune and leaking head gasket, not sure this engine would have survived this on a conventional 2 smoker oil....

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File Type: jpg Rattle snake I caught down form house2.jpg (379.0 KB, 34 views)
I dont always ride WOT, but when I do..I do my best to keep the rubber side down..Ride safely my friends!
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