High Map KPA after cam change.

[Harley Pilot]

So changed my cams in the 103 to the Rivas 574's and contacted Dynojet for a starter map but I'm now in the 40-45 KPA in the Map area, any ideas how I can get back to the 30-35 range??

Thanks,
Dan.

[KE5RBD]

I think you are talking idle area.  Pretty normal for a performance cam to go up to that area idling.  The higher the Kpa the less vacuum at idle.  This is because the cams are not as efficient at idle.  At cruise it should be about the same.  If you raised the compression and got better air flow it may help some. With the stock cams you had about 192 cranking compression.  With the Rivas around 185 with everything remaining the same.  Raising idle rpm's can raise it if idling too slow. If too rich leaning out can lower it a little.  Mostly just nature of drop in performance cams.

[1FSTRK]

I think you are talking idle area.  Pretty normal for a performance cam to go up to that area idling.  The higher the Kpa the less vacuum at idle.  This is because the cams are not as efficient at idle.  At cruise it should be about the same.  If you raised the compression and got better air flow it may help some. With the stock cams you had about 192 cranking compression.  With the Rivas around 185 with everything remaining the same.  Raising idle rpm's can raise it if idling too slow. If too rich leaning out can lower it a little.  Mostly just nature of drop in performance cams.

Are you say that just raising the static compression will raise the vacuum at idle?
Please explain.

[rigidthumper]

So changed my cams in the 103 to the Rivas 574's and contacted Dynojet for a starter map but I'm now in the 40-45 KPA in the Map area, any ideas how I can get back to the 30-35 range??

Thanks,
Dan.

Email Dynojet, and ask them if they will set the IVO and IVC table (there's hidden tables that DJ and tuners can use to adjust this) for your cam, explaining the difference in MAP reading at idle.
Also check the CCP, to verify cam timing.

[Harley Pilot]

KE5RBD, "If too rich leaning out can lower it a little"
        I did notice a drop in VE ( down from 65 to 53 )at idle after I ran a couple of auto tune sessions.

[Harley Pilot]

[/quote]
Email Dynojet, and ask them if they will set the IVO and IVC table (there's hidden tables that DJ and tuners can use to adjust this) for your cam, explaining the difference in MAP reading at idle.
Also check the CCP, to verify cam timing.
[/quote]
I'll email them on Monday,they are very quick to respond which is way cool. I did get a starter map from them but I did not include cam timing but I'll supply them that information on Monday.

Thank you,

[1FSTRK]

Email Dynojet, and ask them if they will set the IVO and IVC table (there's hidden tables that DJ and tuners can use to adjust this) for your cam, explaining the difference in MAP reading at idle.
Also check the CCP, to verify cam timing.
[/quote]
I'll email them on Monday,they are very quick to respond which is way cool. I did get a starter map from them but I did not include cam timing but I'll supply them that information on Monday.

Thank you,
[/quote]

Drop your idle down below 1000 as far as you can, do a couple runs and send DJ the log file.

[KE5RBD]

I think you are talking idle area.  Pretty normal for a performance cam to go up to that area idling.  The higher the Kpa the less vacuum at idle.  This is because the cams are not as efficient at idle.  At cruise it should be about the same.  If you raised the compression and got better air flow it may help some. With the stock cams you had about 192 cranking compression.  With the Rivas around 185 with everything remaining the same.  Raising idle rpm's can raise it if idling too slow. If too rich leaning out can lower it a little.  Mostly just nature of drop in performance cams.

Are you say that just raising the static compression will raise the vacuum at idle?
Please explain.

I should have said cranking compression and did say it may help some.  You have to raise the static compression or change cam timing to change cranking compression.  A typical drop in cam on stock compression and heads will run between 30 and 40+ Kpa at idle.  Too much duration and the Kpa at idle will go up to 45 to 50 depending on how high you go. Raise compression on the typical drop in and put cnc heads and it will drop 5 to 10 or more points. Have seen an Andrews 57 in stock compression 103 runs around 35 to 38.  Same bike raised compression to 10.5 and added CNC heads and it was idling at 25 Kpa. Also cruised about 10 Kpa lower around 25 to 40.  Cam chest wasn't touched.  Stayed at 103 and stock intake and injectors.  Ran surprisingly better than figured. Same bike now has S&S 110 drop in with 10.8 compression and S&S CNC super stock heads and S&S 635HO.  Kpa at idle is now 30 to 38Kpa.  Put that is stock motor if could handle lift and Kpa would be lot higher for sure, my guess would be 45 to 55 and run like a dog.