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Helping a friend to rebuild 1989 GSX750F Katana. The original camshafts are worn and looking for replacement. My friend got set of camshaft which should have been from same model but it does not look like that. The number of teeth on the sprockets are the same like the original, 34, but the lobe dimensions are different. According to lobe dimensions it seems that replacement camshafts are from GSX1100F.

There are letters stamped on the right side of the cams where the alignment markings are. The original cams have letters "S" on the inlet camshaft and "C" on the exhaust camshaft. The replacement camshafts have letters "B" on the inlet and "G" on the exhaust.
Can the camshafts be identified by these markings and are there camshafts from other models that can fit on 89 GSX750F
 

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you are correct in identifying the markings to their respective models, although some Kat 750's had "S" stamped on both cams. I've got a set of '89 750 cams both marked with "S" if you want to trade? :) they are in almost new shape
 

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You can use any of the oil cooled 4 lobe cams in an oil cooled head with forked followers/rockers - 1100f cams will just up the top end a bit - if the 1100 cams look healthy use them - or swap them, but the cams will work fine.
 

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You can use any of the oil cooled 4 lobe cams in an oil cooled head with forked followers/rockers - 1100f cams will just up the top end a bit - if the 1100 cams look healthy use them - or swap them, but the cams will work fine.
To be honest I already did that. I've put the cams from 1100F (If they are from 1100F after all) and started to turn the engine by hand. At some point I felt resistance and I think that piston and exhaust valves on second cylinder collided. I double checked everything and I can't find anything wrong in the assembly process. I followed the Haynes manual, even I left the valve adjusting screws all the way loose. These cams definitely have bigger lift but is it that big that can make piston and valves interfere. I will try to compare the angle of the lobes if they match with the old ones.

Without the cams installed the engine turns without problem. I used dial gauge to check when pistons are at TDC and compared with the TDC mark on the ignition to check if it points correctly. No issue there.

This is how I positioned the cams during assembly. Cylinder 1 and 4 at TDC, exhaust cam positioned with number arrow "1" marking on the sprocket towards the front of the engine and flush with the cylinder head, notches on the right side of the cams pointing to each other, positioned the timing chain with 21 pin between number "2" arrow marking on the exhaust cam and arrow number "3" marking on the inlet cam. When cams are positioned like this the cylinder number 4 is at TDC and cylinder number 1 is at overlap.

Am I doing something wrong here or these cams are not match for 750F?
 

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you mentioned it in the original post, but could be a possibility you've got the incorrect cam gears on there, IIRC the short stroke 748 motors used larger cam gears. can't remember teeth count, but those cams should work, only you'll lack bottom-end. the '88-'89 GSXR 750 used the same cam profiles, you don't need to degree them
 
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