07-10-2009, 05:38 PM #1
- Join Date
- May 2007
- Buzzards Bay, Massachusetts
just assembled 2 Lowell motors...haven't run them yet...compression question on 1390
I hit the starter with a compression checker in the machine for a cycle...got 158 to 160ish with all 3 cylinders on my Lowell ported 1300...
I hit the starter etc. on my 1390 Lowell machine and receive 125 on each cylinder. The 1390 was nikasil'd and bored through Lowell.
I haven't run either one of the machines but I was wondering if I have done something wrong or if the nikasil/rings need to set themselves on the "new" motor. The other engine I just changed the rings because I broke it all down, cleaned parts etc. I do know that on the bench the 1390 by hand was near impossible to turn for a cycle vs. 1300 which was slightly less "impossible"..
Let me know your thoughts...I'm holding off on the exhaust installation until I hear a thumbs up or down.
BTW there is a rebuilt T+W crank from crankworks in it, 4 degree keyway...Basically all the mods in my sig.
07-10-2009, 06:15 PM #2
IMO too many variables to diagnose your problem on here... cylinder bases cut, head size, # of head and base gasket layers, port height...
Call Lowell and he will get you on the right track
07-10-2009, 06:47 PM #3
I know group K's website talks about the compression not reading correctly on their 1390's due to the extra volume when they crank...
07-11-2009, 02:22 AM #4
- Join Date
- Apr 2008
- Lindenhurst, IL
When warm i am hitting, 130,130,125 (40cc,40cc,42cc).
I think the pipes have something to do with the reading, not sure.
Put em in you be fine.
07-11-2009, 02:25 AM #5
- Join Date
- Oct 2006
new builds dont read right when first assembled, they need to be run so the rings seat ....i freaked out with my first build when i cranked it over and it read way low.....after it was run it was up 20psi odd to 140psi
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