Inner primary

brewcrew

brewcrew

Member
Well i have a question , my buddys inner primary is cracked , i was wondering how to determine if its stock, or if it has an offset, he has a 240 on the back of it and a 100 inch rev tech on it , i dont know if that helps , but i guess i was wonderin if there was a place to measure from. Any help would be great


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ground pounder

ground pounder

Active Member
its offset. the 300 tires are 0 degree offset. Its probably 1/2 inch offset. You have to measure the lip on the back of the primary when you get it off.
 
Marky-Marc

Marky-Marc

Well-Known Member
Definition: the amount or distance by which something is out of line.
"these wheels have an offset of four inches" :D

Measure from the back part of the primary to the center line/seal on the primary. When looking at it, measure the left side/small derby/forward cover side from the back of the primary, where it bolts to the bike, if it's 'offset' it will be greater than 2 inches.

I have one that's 1/2" offset that I'm currently cleaning up. Which means when I measure it from the back side by the front on the forward side, it measures 2.5".

My Ridgeback with a 300 tire measures 2".
 
Marky-Marc

Marky-Marc

Well-Known Member
Since I'm in the garage today...the first pic is my Ridgeback 300 tire 0" offset inner primary which measures 2", the second one is the one I just got that I'm cleaning up with a 1/2" offset.....so it measures 2.5" on the forward side of the primary.

:cheers:
Marky
 

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BadDawg Bill

BadDawg Bill

Well-Known Member
The word offset and the way it's talked about is misleading and confusing. Every bike inner primary has an offset because without one there would be no inner primary or a space to hold the gears and clutch.

If we take a Harley for example, a stock fatboy has a zero offset but the primary cover is 1 1/2 inch thick from the inner lip to the outer lip. So if we put a 250 tire on a fatboy frame we need to bring the belt out 1 1/2 inches so you would need a 1 1/2 inch offset spacer to do that.

Now take my 2004 BD chopper with a 250 tire. Stock inner primary width is 3" so the offset compared to a Fatboy is 1 1/2 inches but it's zero offset for a stock 2004 BD. Confused yet?

If you have one frame say a Daytech the offset is 1 7/16 compared to a FB but if you have a RT frame it's 1 1/2. (talking now about the LHD bikes)

The only way to get the primary you need is to measure the overall width of the inner primary from where it meets the motor to the outer lip where the cover bolts on then find one that is the same. All HD type motors and trans have the same bolt pattern so there is no difference there. (again LHD)
 
Marky-Marc

Marky-Marc

Well-Known Member
BadDawg Bill said:
The word offset and the way it's talked about is misleading and confusing. Every bike inner primary has an offset because without one there would be no inner primary or a space to hold the gears and clutch.

If we take a Harley for example, a stock fatboy has a zero offset but the primary cover is 1 1/2 inch thick from the inner lip to the outer lip. So if we put a 250 tire on a fatboy frame we need to bring the belt out 1 1/2 inches so you would need a 1 1/2 inch offset spacer to do that.

Now take my 2004 BD chopper with a 250 tire. Stock inner primary width is 3" so the offset compared to a Fatboy is 1 1/2 inches but it's zero offset for a stock 2004 BD. Confused yet?

If you have one frame say a Daytech the offset is 1 7/16 compared to a FB but if you have a RT frame it's 1 1/2. (talking now about the LHD bikes)

The only way to get the primary you need is to measure the overall width of the inner primary from where it meets the motor to the outer lip where the cover bolts on then find one that is the same. All HD type motors and trans have the same bolt pattern so there is no difference there. (again LHD)
Click to expand...
I confuse myself as well when I try and describe offset.....LOL...it's really hard to explain, that's why I tried a bit with the photos and the tape measure.....measuring it is the BEST bet to get the correct one.......and every frame is a bit different.....

:cheers:
 
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