jetting for break in

[jerryblaster96]

I just finished rebuilding a blaster I bought that had cracked an intake boot and leaned out. The weather probably won't get above 40 for a while but summers will be around 90 degrees. I'm at an elevation of 810 ft.

The cylinder is bored. 80 over and it's ported with an fmf power core exhaust. Stock compression. I do not.know what air filter is.in it at the momen.

I can't really do plug chops yet and the rpms hang a little after blipping the throttle so I'm sure it's lean on the low end.

What size jets should I run for the break in? Or what range of jet sizes should I have on hand and I'll just break in with the largest as long as it doesn't bog?

 

[tbrooks]

I'd get 270-310, but that kinda depends on the filter setup. 310 will be a safe bet, but it shouldn't make much difference as long as you stay below 3/4 throttle until you can plug chop it

 

[Herpderplol]

I'd get 270-310, but that kinda depends on the filter setup. 310 will be a safe bet, but it shouldn't make much difference as long as you stay below 3/4 throttle until you can plug chop it

Like he said, dont be hammering it until you get warm enough weather to plug chop.

i suggest start with the 310 until it warms up. if it runs like crap maybe go alittle smaller if it shows the right symptoms

 

[Larry's Shee]

Best jetting advice in the world won't do much good if you haven't leak tested your new build. Hanging revs could also be air leak.

Be sure to re-torque head and cylinder after heat cycles.

 

[Awk08]

I can't really do plug chops yet and the rpms hang a little after blipping the throttle so I'm sure it's lean on the low end.

What size jets should I run for the break in?

in this order..........

leakdown test
correctly cleaned carb:http://www.blasterforum.com/threads/how-to-clean-your-carbureutor.254/
32.5 pilot/310 main/stock needle with clip in middle position.
tune the airscrew to correct the hanging rpms:
http://www.blasterforum.com/threads/adjusting-your-airscrew-pilot-jet.51060/
at least 3 heat cycles
re-torque head and cylinder nuts
leakdown test again
break-in: no long full throttle runs for a tank or 2 of fuel
then with the jets listed above, start large and plug chop down

 

[jerryblaster96]

Well after trying and trying I couldn't get the hang to go away and once an air leak was mentioned I realized that was my issue. I ran the leak down and it failed.base gasket is leaking. I knew.I shouldn't have used that paper gasket but I did it anyways and now I have to.redo it. Is the oem blaster base gasket metal? If not what's the best option for non paper gasket?

 

[Awk08]

Well after trying and trying I couldn't get the hang to go away and once an air leak was mentioned I realized that was my issue. I ran the leak down and it failed.base gasket is leaking. I knew.I shouldn't have used that paper gasket but I did it anyways and now I have to.redo it. Is the oem blaster base gasket metal? If not what's the best option for non paper gasket?

OEM or Cometic base gaskets only !
both are metal/coated gaskets

 

[jerryblaster96]

How about a cometic top end gasket kit? Good kit?

 

[Awk08]

How about a cometic top end gasket kit? Good kit?

yep !

 

[jerryblaster96]

That's what I'll get then. Seems like a good deal. Guess I'll update in a week or so. Hopefully that was my only issue. Im just glad I didn't appear to have any air coming out of my case vent.