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Compression rating on a V Twin??


Jovee

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Anyone have a reference or know the compression rating for a Briggs 20hp V Twin (400000)? Its the only B/S book I dont have and 145 seems a little high. Thanks - Joe
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Hi, Sounds high to me, I would expect about 75 to 90. Wouldn't be surprised if your valve clearances aren't too wide. This in effect disables the compression relief. Does it crank hard and does the starter seem weak?? Al Eden
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Al, Its funny you used those two numbers. I have Intec twin 16 I'm also doing and one bank is 90 and the other is 75. The engine starts normal and easy. Nothing unordinary. I was under the impression that 120 was the norm for the opposed engines with a variance of 5 either way. I dont know if the V twins were different but that still seems up there. This is the engine I just went thru a tough time getting the drive pulley off the crank. It blew the crank seal out clean and whole. The new one went in way too easy. I fear the little bit of play in the shaft has opened that aluminum up a bit but correct me if I'm wrong on anything. The pcv filter was a bit ugly which I have made operable again. The engine ran smooth for about an hour yesterday with no doomsday simptoms but something just doesnt make sense about it all -Joe
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Mid range test went good today for 45 min. Still afraid that new seal is going to come out. Todays compression was 135 & 140. Worse for the 16 which dropped to 55 & 60 but nothing leaking down on either one. Not too worried about the 16. Its on its last leg and its been a challenge to get it to running condition. But the 20 is a different story. I wont give it back to my uncle until I completely trust it and that is yet to happen -Joe
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