View Full Version : XR500 cam in a 350X

04-18-2007, 10:33 AM
I talked to a guy the other day and he was telling me that an XR500 cam will bolt into a 350x head. I said GREAT!! they are about $100 cheaper and provide more lift and duration.

Unfortunatly I cant find anyone els that has tried this or any info on it. So I figured Id check here to see if anyone here has tried it or has any info on it.


04-18-2007, 06:13 PM
Gunnar maybe My-mint ,Billy or Jason Hall will chime in to help ya out on that ,but I do know that the only thing in common with a 600 and and 350X cam are the honda name ,those guys can probably help ya out ..Good Luck and I will keep in touch on this..

04-18-2007, 09:10 PM
sandpuppy101 hopefully they will chime in on this. I did find a guy with 2 "like new" ones and they should be at the house tomorrow. So I should be able to see the differences in person. One is a stock cam and the other has been set up with needle bearings for a worn head. If anything comes of it Ill keep you all posted.

Liquid....if you look on the Megacycle cams site and compare the 350x with the xr500 you will see that their aftermarket offerings are exactly the same. If what they told me when I called them is true then the stock xr500 should fall somewhere in between stock 350x and the web cams bolt in cam.

Wish me luck

Billy Golightly
04-19-2007, 02:32 PM
Its been so long since i messed with a 4 stroke, I'm not exactly sure about the cams but I do know the cylinder heads are very, very similar and a XR/XL/FT500 head will bolt directly onto a 350x cylinder. The rocker covers differ between the two but I believe the actual arrangement of the rockers themselves are the same as the 500 head swaps I've heard of use the 350 cover to use the stock head stay mount.

I'd check the parts fiche's but it seems like I remember one of the two being shorter in length the other, but I'm not positive on that.

04-19-2007, 05:27 PM
Billy i have to dissagree with you, I have tryed to put the xr, ft and xl head on my 350x and none of them would line up, maby with some machineing it would work but it woudnt be easy or cost affective. The cams arnt interchangeable eather. Sorry to burst your bubble, but its just not going to happen without alot of work.

Billy Golightly
04-19-2007, 07:06 PM
You cannot use the 83-84 XR or XL500 cylinder heads. You have to use the earlier 79-82 ones. I know that it works because I had one sitting on a 350x cylinder at one time. I'd go take pictures of it right now but I got rid of all my XR500 stuff, Lomax has it. He could probably snap some pictures if need be.

Billy Golightly
04-19-2007, 09:16 PM
FWIW I talked to Will (Lomax), he doesn't have the 500 stuff anymore but just happened to be heading over to the guys place he sold it to. He measured the cams and he said they are exactly the same space wise on the lobes. He also checked the heads and he said they are extremely close (maybe exact) to being the same bolt pattern but that the timing chain area on the 500 was alot larger, would make a head gasket tricky.

04-19-2007, 10:07 PM
Search for greenhuman's post about the 500 head, I remember him talking about what the differences are and he knows his stuff. Heck, even pm him.

04-19-2007, 10:18 PM
The cams are the same. The stud pattern is the same between the FT and the ATC. The front smaller stud is in a different spot. a new hole and a little milling fixes this up. The FT head has the small front stud coming down from the head, so you drill a new hole in the cylinder and mill out a bit of alloy to let you tighten it down with a nut, just like on the FT cylinder.

04-19-2007, 10:43 PM
You cannot use the 83-84 XR or XL500 cylinder heads. You have to use the earlier 79-82 ones. I know that it works because I had one sitting on a 350x cylinder at one time. I'd go take pictures of it right now but I got rid of all my XR500 stuff, Lomax has it. He could probably snap some pictures if need be.

Well obviously i had the rong years, i must have had the ones that didnt line up. NOW, heres teh question how is the porting on them? Is it going to be better or worse than the 350? and what are the size of the valves because i want bigger valves on my X.

Billy Golightly
04-19-2007, 10:51 PM
All of them have bigger valves then the X heads to my knowledge. Now supposedly, the porting on the earlier ones (Haha, a few years even had a reed valve PLUS regular intake valves) was a little to be desired. The FT500 speedway/cafe racer bikes are suppose to have a redesigned head that does not have the reed valve setup. And they are suppose to be a major improvement.

04-19-2007, 11:24 PM
The valves are much bigger with a thicker stems as well. I used mine on a Powroll stroker crank and resleeved ATC cylinder with a 92mm FT Wiseco piston kit. I had Powroll shrink the rod and extra 3mm so I did not have to modify the top of the piston.

04-20-2007, 11:00 AM
Just figured Id add this to clear it up. Im using the 350x head and rocker cover, and just the cam from the xr500.

I had a chance to play with the different cams lastnight and billy is right they are about 1/4 in shorter to the outside of the head, everything els lines up perfectly. Im not sure if its stock but the ones that I have are set up with roller bearings. They catch the inside of the rocker cover by about 3/16 of an inch. Looks like it will work. Still have to play with it to see if the valves will clear the piston.

Took some measurements of the cam lobes if anyone is interested (smallest part of lobe and largest)----stock 350x,30.05 and 36.10mm xr500,27.06 and 34.81mm. That means that the xr500 has 1.7mm more lift and the lobe centers are closer but I dont know by how much. Any cam gurus know how this will effect the motor. I know more lift=more gas=faster. But where bottom,mid,top.

Questions.... the valve clearence on the xr500 is .002 intake and .004 exhaust while they are .003 for both on the 350x. So should I go .003 intake and .004 exhaust? Any suggestions.

Ill get back to you all when I know more.


04-21-2007, 05:55 PM
So far so good on the cam. I bolted it in today and rolled it over a few times. Nothing hit or bound up so it looks like it may just work. The valve springs are close to being fully compressed but there is still a visible gap between the coils. I still have bent valves in the head so Im hopeing that with new ones the springs come up a little. There is little valve clearence adjustment left with the smaller cam lobes. But other than that everything els looks good.

The only problem is that I wont know how much of an improvement this will be due to the motor not being in the best of shape before.

should have my valves by early next week


06-01-2007, 09:27 PM
Sorry it took so long to get back.

Just figured Id let you all know its a no go. I checked all over and couldnt find any specs on the cam . I also found out that mega cycle is very unreliable. But thats my opinion.

The valve too piston clearence was too close for comfort and didnt want to buy high comp piston racing valve springs etc. and not have it work then have to start all over again.

So I just shelled out the coin for a web bolt in cam.

Sorry guys thought it was a good idea