technical quandry
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technical quandry
I am having an issue, of all things with my bike. I have a built 110 and run 650 lift cams with roller rockers, and up to this week end Jims lifters, the real good ones! And they have always been real noisy! I have lived with it, assuming that the high lift cams and roller rockers were just the problem. Bike runs great, and oil temps have always been right around 210* I have done a lot to help keep it to this temp. Baker oil pan (+1.5) great tune, oil cooler with a low temp thermo. This temp has been verified with a digital pyrometer.
I finally had to change the lifters, they got noisy at start up. bought a set of the new S&S premium lifters. with the H2R feature. I adjusted them to full collapse, and them 1/2 turn loose, (manufactures spec). Bike styill runs good, very quiet, all the noise gone. My problem is now the oil temp is a constant 230* and I am noticing a bit of spark knock on hard acceleration. Nothing was changed but the lifters. I can assume that I change some valve timing a bit, by reducing the play in valve train. but that shouldn't account for a 25* difference in temps, and realistically even the spark knock. any input would be appreciated. I'm kinda baffled here.
I finally had to change the lifters, they got noisy at start up. bought a set of the new S&S premium lifters. with the H2R feature. I adjusted them to full collapse, and them 1/2 turn loose, (manufactures spec). Bike styill runs good, very quiet, all the noise gone. My problem is now the oil temp is a constant 230* and I am noticing a bit of spark knock on hard acceleration. Nothing was changed but the lifters. I can assume that I change some valve timing a bit, by reducing the play in valve train. but that shouldn't account for a 25* difference in temps, and realistically even the spark knock. any input would be appreciated. I'm kinda baffled here.
Last edited by harleycharlie1992; Aug 26, 2014 at 09:28 PM.
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From: Central California
Although not very well versed in HD performance, I am in automotive performance and the principles are the same. It is very likely that the change in actual valve timing has altered the actual cylinder pressure at a certain rpm/load. This will increase temps. I've been through this same scenario with high performance air cooled VW motors. Sometimes a drop in compression ratio is necessary
You can try baking off the ignition timing a bit, use a higher octane fuel, or perhaps a larger header tube diameter. It may also be that a change in the way you run the motor might help, by avoiding those parameters where the ping is noticeable. Maybe.
You can try baking off the ignition timing a bit, use a higher octane fuel, or perhaps a larger header tube diameter. It may also be that a change in the way you run the motor might help, by avoiding those parameters where the ping is noticeable. Maybe.
Last edited by Mike Lawless; Aug 26, 2014 at 09:38 PM.
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couldn't be more than a couple degrees max, I would imagine, just enough to take the clatter out. Ping is only on hard accel. not that I won't try to back timing down a bit. It never pinged with the other lifters though.
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From: Central California
Hydraulic lifters can be a funny thing. If the other lifters were bleeding down in mid lift, then it will affect the actual valve timing. In essence, you've "changed cams" as the motor is likely seeing increased lift and increased duration at mid lift or "under the curve".
So now, as a result, cylinder filling is increased. More pressure equals more heat, and the two combined could cause pre ignition/detonation.
At any rate backing the ignition timing down a little at a time might get you where you need to be.
So now, as a result, cylinder filling is increased. More pressure equals more heat, and the two combined could cause pre ignition/detonation.
At any rate backing the ignition timing down a little at a time might get you where you need to be.
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