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The 2-Stroke Garage => General Chatter => Topic started by: vinyas on June 05, 2021, 07:02:35 AM

Title: Acceptable Compression values - RD350
Post by: vinyas on June 05, 2021, 07:02:35 AM
Did a fresh top end with cast Pistons , Vforce intake work and dg pipes for RD350

Measured the compression - shows 110 PSI on both Cylinders  before a cold start.

Is that a acceptable number for compression or something is missing?
Title: Re: Acceptable Compression values - RD350
Post by: Yamaha 179 on June 05, 2021, 07:28:04 AM
Was it done on a cold engine with the throttle wide open?  Five or six kicks?  That is how a compression test should be done.  It might be a little weak but the rings haven't seated yet.  I would think 120psi would be more normal. 
Lyn Garland
Title: Re: Acceptable Compression values - RD350
Post by: vinyas on June 05, 2021, 08:41:39 AM
Quote from: Yamaha 179 on June 05, 2021, 07:28:04 AM
Was it done on a cold engine with the throttle wide open?  Five or six kicks?  That is how a compression test should be done.  It might be a little weak but the rings haven't seated yet.  I would think 120psi would be more normal. 
Lyn Garland

Yes Lyn that's right

Does opening up the intakes to accomodate the Vforce has a impact with compression drop ?

Did a leak down test, no issues found
Title: Re: Acceptable Compression values - RD350
Post by: m in sc on June 05, 2021, 09:39:47 AM
no effect.

let the ring seat see where it lands after a few runs, then retest when cold.. also, verify accuracy of compression tester. i've been burned by that before.
Title: Re: Acceptable Compression values - RD350
Post by: Striker1423 on June 05, 2021, 11:30:55 PM
What Mark said. I bought a good used snap on tester cause cheap ones never read right.