EVO All Evo Model Discussion

Cam question

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Old Dec 29, 2021 | 03:14 PM
  #11  
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By the looks of it I would say it's an old school cam with lots of duration but not a fast ramping cam. Which is good for Evo's. If you have a pair of vernier calipers, measure the base circle and then the entire Lobe and post.. That will give me the info I need to calculate lift.. Seeing it's a custom built bike there might be more to the motor but by taking it apart before doing a compression test, we really cannot advise on a suitable cam for an upgrade..
 
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Old Dec 30, 2021 | 11:19 PM
  #12  
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Default Cam question

Originally Posted by 98hotrodfatboy
By the looks of it I would say it's an old school cam with lots of duration but not a fast ramping cam. Which is good for Evo's. If you have a pair of vernier calipers, measure the base circle and then the entire Lobe and post.. That will give me the info I need to calculate lift.. Seeing it's a custom built bike there might be more to the motor but by taking it apart before doing a compression test, we really cannot advise on a suitable cam for an upgrade..
I got the bike apart .and just so I know a fast ramping cam is not got for Evo or it is
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Old Dec 31, 2021 | 06:55 AM
  #13  
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The second picture showing the lobes indicate pretty square lobe which would indicate a fast ramp, definitely.. The fourth picture of the lobes it looks a little different I don't know if it's a shadowing or not. But faster ramp cams will bring the power band in sooner.. It's allowing for earlier cylinder fill and that's one of the elements to making better bottom end torque.. Do you have the rocker covers off? I'd be curious to see what type of springs are being used.. Also did you do a cold compression test before you took it apart? It's always good to get a baseline before making any changes.. I tried looking up the numbers posted and couldn't find anything.. Is this a bottom or a top breather motor? It would help to know that to narrow down the year or you can post up the serial number on the left side case.. And again measure up the lobes, total height and width and post up the numbers... Seeing it's a custom build there might be a lot more to the motor that can't be seen.. but a compression test will help.. If you know some one that has a stock cam N grind cam, install it to do a compression test.. it will give a great indication to where the motor is, making it easier to recommend a cam...
 
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Old Dec 31, 2021 | 12:23 PM
  #14  
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Default Cam question

Originally Posted by 98hotrodfatboy
The second picture showing the lobes indicate pretty square lobe which would indicate a fast ramp, definitely.. The fourth picture of the lobes it looks a little different I don't know if it's a shadowing or not. But faster ramp cams will bring the power band in sooner.. It's allowing for earlier cylinder fill and that's one of the elements to making better bottom end torque.. Do you have the rocker covers off? I'd be curious to see what type of springs are being used.. Also did you do a cold compression test before you took it apart? It's always good to get a baseline before making any changes.. I tried looking up the numbers posted and couldn't find anything.. Is this a bottom or a top breather motor? It would help to know that to narrow down the year or you can post up the serial number on the left side case.. And again measure up the lobes, total height and width and post up the numbers... Seeing it's a custom build there might be a lot more to the motor that can't be seen.. but a compression test will help.. If you know some one that has a stock cam N grind cam, install it to do a compression test.. it will give a great indication to where the motor is, making it easier to recommend a cam...
I got the bike it was taken apart already he said he was going to change the cam and cam bearing never finished I just want to make sure I put the right cam in I want the motor to be right would like to find the same thing that's how he ran it I'm learning a lot so far I just don't want to buy something that's not going to work for my application.
 
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Old Dec 31, 2021 | 12:37 PM
  #15  
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If the motor is apart then show pics of the cylinder heads n springs and combustion Chambers and the tops of the Pistons if possible.. Then maybe we can make a better education decision.. Just because that was the cam that was in it doesn't not guarantee that it suits the build..
 

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Old Dec 31, 2021 | 12:49 PM
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Default Cam question

Originally Posted by 98hotrodfatboy
If the motor is apart then show pics of the cylinder heads n springs and combustion Chambers and the tops of the Pistons if possible.. Then maybe we can make a better education decision..


This is how I got it with the cam out
 
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Old Dec 31, 2021 | 01:14 PM
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I would believe that it's a 93 or later Evo motor being a top breather and with the CV carb on there it might have some minor upgrades but nothing real major, I doubt without tearing into it.. You won't know exactly what's in it..
 
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Old Dec 31, 2021 | 01:17 PM
  #18  
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Other than identifying it as a later production top breather, not a lot to go on there.

How hard are you willing to work with this. Probably the "right" thing to do is to pull the heads so you can identify if the valves have been worked over, and also if the pistons have been replaced.

Or you can put a basic cam in it and take your chances. It will run, but maybe not up to snuff relative to the rest of the motor.

What was the guy's story? Why did he think he needed to replace the cam?
 
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Old Dec 31, 2021 | 07:16 PM
  #19  
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Default Cam question

Originally Posted by 0maha
Other than identifying it as a later production top breather, not a lot to go on there.

How hard are you willing to work with this. Probably the "right" thing to do is to pull the heads so you can identify if the valves have been worked over, and also if the pistons have been replaced.

Or you can put a basic cam in it and take your chances. It will run, but maybe not up to snuff relative to the rest of the motor.

What was the guy's story? Why did he think he needed to replace the cam?
The cam has a spot on one of the lobes and it is rough on the end that goes in the bearing I can see why it needs to be changed I just like to put in the same thing that's how it was running rather not have to go any deeper than I have to
 
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Old Dec 31, 2021 | 07:21 PM
  #20  
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Then throw an ev 27 in it and go from there... Really can't go wrong with it unless your compression is higher than 10:1.. Most of the time it's a safe bet..
 
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