odd cam question: 1st gen

Ok, this is going to sound a bit strange. I have an '84 vf750f with pitted camshafts. I'd love to harden the pitted cams and run a bit more aggressive profile like Megacycle or Dave Dodge offers. HOWEVER, my bank account can't exactly handle that right now. I found a set of cams off an '84 vf700f for pretty cheap and was wondering if they could be used temporarily in my 750? Any expert knowledge or opinions?

btw... I am going to install an oiling kit and replace the tensioners

 

cams

Call up the fishe and see if they are the same part number. Some dealerships can punch in the part number and the computer will list where that part number is used, every model and year.

Honda being Honda, I doubt they interchange, but it's worth looking into.

 

My understanding was that the 750 and 700 had different profiles. I doubt many have experience with this, maybe going the other way 750 cams in a 700. Just guessing, I'd assume the 700 has less lift and comparable duration. If anyone has some actual numbers that would be great. I just don't won't to make a bone-headed mistake.

 

The 700's and 750's have different cams, ignition curves, different carbs, and a different stroke.

1982: the 70 x 48.6mm (748)

1984: the 70 x 45.4mm 700 (699)

My best guess...
In answer to your question, if you use the 700 cams, I would use the 700 spark units. Otherwise, I don't think you'll see any improvement - and could actually reduce your performance.

 

Not expecting an improvement. My 750cc cams are very pitted and the engine cannot be run as it is now. One of the cams wore down and is making a loud clicking sound. I just need something to get by until I can raise the dough for a regrind and hardening. Do you think it will run "ok" with the 700cc cams?

 

They will more than likely work. Although I don't know what your performance will be.

The guy to ask if they will work is Dave Dodge: info@drp123.com

 

Hmmm sounds sketchy to me. they'll no doubt swap, but man I'd be weary of what might happen running wise, as close as they where, they are two different animals. So go ahead give it a try then we'll know. Good luck.

 

Ask and ye shall recieve. Here are the Honda part #s. You can see that the #s are similar, but not the same.
750...04101-MB2-000
........04102-MB2-000
........04103-MB2-000
........04104-MB2-000
700...04101-MB2-690
........14121-MB2-691
........04103-MB2-690
........04104-MB2-690

 

Have you had the cam lobes checked by a professional mechanic( tested for wear tolerances)?
The loud clicking you are hearing is more than likely not the cams but the cam chain tensioners have gone bad.. I had 3 different VF750F models and they all did the same thing between 15,000 and 25,000 miles.. Cam chain tensioner goes bad letting the cam chain have just enough slack to make the motor rattle and it can drive you nuts...

Hint: if you dont replace the tensioners and it gets worse the cam chains will slowly eat at the cam chain guides , experience talking ...

The 700 cams will not work in the 750 , I checked into that back in 1987 and the 700 cams would not work due to differences in lift ,timing , ..I used to have plenty of VF750F parts until 3 yrs ago , sold it all and bought the 99 VFR800 ( No cam chains or tensioners to mess with)...

 

Nailer,
Just to satisfy my curiosity, what about the 700cc cams won't work? Will the valves strike the piston or something like that?

 

I haven't taken the bike to a certified mechanic. But a visual inspection of the cams shows pitting on all lobes, and a significant amount of wear on the left front intake lobe especially: it looks like someone took a grinder to it.

 

http://pages.cs.wisc.edu/~john/vfr/specs/84-85-vf700f.html

says different cams/ignition/etc