Topic: 650 cam into a 550

[paulages]

I know I would have to replace the cam sprocket from a 650 with the one from a 500/550K, but would it be necessary to oval out the sprocket mounting holes so the sprocket could be adjusted?

hym

yes. i don't have a mill, so i was planning on making a tool to slot them appropriately--i'll let you know if that happens and i'll hook you up if need be. if the sprocket had a center it would be really easy, but it doesn't. i'm thinking of clamping a couple pieces of flat bar across the sprocket and finding center in these. then the sprocket can be rotated on axis using an appropriately sized grinding burr (poor man's mill bit) to slot the holes.

[squirley]

Alright guys, my engine is in it's final build stages, and I am in need of some tuning advice.  With this 650 cam installed, what are the steps that I need to go through to get this thing timed and ready to make sure that it is firing in the right sequence. 
I have done most of it already, but am looking for a heads up or check list to make sure I have all my basis covered.
For all the other guys out there that were doing the same install, how did it work out?

[paulages]

Alright guys, my engine is in it's final build stages, and I am in need of some tuning advice.  With this 650 cam installed, what are the steps that I need to go through to get this thing timed and ready to make sure that it is firing in the right sequence. 
I have done most of it already, but am looking for a heads up or check list to make sure I have all my basis covered.
For all the other guys out there that were doing the same install, how did it work out?

the timing mark on the 650 cam is identical to the 550. without degreeing the cam, i think you might be hard pressed to find a simple answer, but i think you could at least start at the manual specs, with the notch set level with the top of the head at TDC. i would subsequently turn the motor through and check that everything clears, then run it as is. i can send you the degree specs megacycle gave me with my cam i got from them if you'd like. i'm certainly no expert, but that is what i would do in your place. i'm guessing mike rieck will give you a better answer.

[squirley]

Yep, I just set it up like a regular 550 cam.  Just wanted to make sure that I wasn't forgetting to do anything important.

[squirley]

Bringing this back up to the top.  I have wire my bike as simple as possible.  However, I cannot get the bike to fire.  Everything is working fine, have spark on all plugs...
If the cam is 180* out, what do I need to change in the wiring harness to get it to fire correctly?

[scunny]

wouldn't swapping the feeds to the coils do that

[paulages]

both cam profiles are almost identical. the locating pin for the ignition on the crank is in fact 180 degrees different on the 650, but i'm almost 100% positive the timing mark on the cams are still the same, making it irrelevant if you are using your 550 crank. if it is firing 180 out, swapping the coil low voltage wires would work though.

[paulages]

Bringing this back up to the top.  I have wire my bike as simple as possible.  However, I cannot get the bike to fire.  Everything is working fine, have spark on all plugs...
If the cam is 180* out, what do I need to change in the wiring harness to get it to fire correctly?

are you sure you have fuel to the cylinders?

[kayaker43]

The 650 does have a different firing order and I haven't thought it through but hoped if anything a simple swap between the yellow and blue coil wires would do it???

The 650 cam should give a solid boost, I'm still surprised its not a common mod?

Squirley,.. let us know when it runs,.. and how it runs. I'm ready to do this soon too.

[squirley]

That is what I did, just swapped yellow to blue and vis versa.  I still havent gotten it to fire yet.  I have spark and fuel getting to the plugs.  I am going to have to do a compression test to see if it has low compression after the rebuild.

[paulages]

The 650 does have a different firing order and I haven't thought it through but hoped if anything a simple swap between the yellow and blue coil wires would do it???

The 650 cam should give a solid boost, I'm still surprised its not a common mod?

Squirley,.. let us know when it runs,.. and how it runs. I'm ready to do this soon too.

no matter what 1 and 4 travel together as do 2 and 3, so no matter what the firing order of according to the crank it can only be 180 degrees off with the wasted spark setup. the 550 and 650 cam look identical to the naked eye and have the same number stamped in them as blanks. the only problem i could possibly see when timing the cam, is if the timing notch on the end is different, in which case one would only have to time the cam to the left side of the cam case instead of the top or swap the coil wires. i will check tomorrow, but i'm pretty sure i verified the characteristics of bot cams before sending my 650 cam in to megacycle instead of the 550. i'm almost positive the only substantial difference i found (besides the extra lift and duration) was the tach ratio.

[anparkinson]

What about these www.webcamshafts.com

They do a fast road and race cam for the 550 and 500.

[paulages]

What about these www.webcamshafts.com

They do a fast road and race cam for the 550 and 500.

there's also megacycle camshafts, but i believe this point of this thread is to explore using a 650 cam in a 550 engine to gain a little extra performance without the high cost of a regrind or hardface.

[hymodyne]

I'm buying a new set of pistons, rings & sleeves in the morning. I'm thinking about putting the 650 cam I have in since the head is off, but would like to hear what issues there are with this modification. I have already widened the spaces around the cam lobes to accommodate the  larger lobes of the 650 shaft, but don't know if I will need to slot the sprocket bolt holes to get the timing right (or, for that matter how to adjust the sprocket if I have to slot it). also, I was already having issues with oil consumption, in part because of one piece oil ring end gap issues  with this 605 overbore kit; am I asking for more trouble by replacing the old pistons with new ones that also have a one piece oil ring and putting the 650 camshaft in?

hym

[paulages]

hey guys- sorry it took so long to get back with more info. the 550 and 650 cams have identical timing notches, and identical lobe patterns except for the increase left and duration. the 550 and 650 cranks have the same orientation as well, but of course provide different stroke lengths. in other words, it is only the locating hole for the ignition assembly on the crank that affects the 1-4/ 2-3 firing order. if you are simply dropping the 650 cam into an otherwise stock 550, the firing order will not change. i would degree the cam to be absolutely sure that the valves are opening at the right time, but the two cam blanks started out the same.

[hymodyne]

this is helpful information. how does one degree the cam? does it entail slotting the mounting holes on the sprocket?

hym

[paulages]

this is helpful information. how does one degree the cam? does it entail slotting the mounting holes on the sprocket?

hym

it does if you need to move it.   

[kayaker43]

Very interesting, I confirmed what Paulages said and the cams are identical except for lift and duration. Should be a drop in swap with no changes in firing order needed. Just install with 550 sprocket and remove plastic tach gear because it won't mesh right with the 650 cam.

No need to slot the cam sprocket or degree the cam unless you want to blueprint it or run non standard timing. Just drop it in remove tach driven gear and ride. The specs are similar to an average "stage 1" street cam and should give a solid boost without losing drivability.

Likewise for running an aftermarket 550 cam in a 650,.. should work fine.

If the crank is in fact cut from the same blank with same orientation and the ignition is just 180 off, then it would be fun to drill another hole and set the advancer to run a 550 on 650 firing order. Honda didn't change the firing order for no reason,.. I wonder what the reason was. I never rode a 650, do they feel the same as far as smoothness? Do they have the same exhaust sound?

So potentially there are two low buck upgrades for the 500/550. Stick in a 650 cam, and change the firing order. This is a big deal and I'm surprised its not common knowledge by now. I'm still anxiously waiting for someone to report back with the cam swap results.

[Muk]

i am anxios to see to as i have a 650 cam sittin in my dresser drawer waiting for winter to put it in, and don't want to make a running bike into a paperweight

[squirley]

Well, if i could get my damn bike to fire, I would let you guys know...but...

[kayaker43]

Put the ignition wires back to stock and look for something else like fuel delivery problems?? Did you set the cam timing correctly?

What else have you changed besides the cam,.. did it run before the cam swap?

[paulages]

Very interesting, I confirmed what Paulages said and the cams are identical except for lift and duration. Should be a drop in swap with no changes in firing order needed. Just install with 550 sprocket and remove plastic tach gear because it won't mesh right with the 650 cam.

No need to slot the cam sprocket or degree the cam unless you want to blueprint it or run non standard timing. Just drop it in remove tach driven gear and ride. The specs are similar to an average "stage 1" street cam and should give a solid boost without losing drivability.

Likewise for running an aftermarket 550 cam in a 650,.. should work fine.

If the crank is in fact cut from the same blank with same orientation and the ignition is just 180 off, then it would be fun to drill another hole and set the advancer to run a 550 on 650 firing order. Honda didn't change the firing order for no reason,.. I wonder what the reason was. I never rode a 650, do they feel the same as far as smoothness? Do they have the same exhaust sound?

So potentially there are two low buck upgrades for the 500/550. Stick in a 650 cam, and change the firing order. This is a big deal and I'm surprised its not common knowledge by now. I'm still anxiously waiting for someone to report back with the cam swap results.

you won't need to change the firing order unless you actually use a 650 crank. in my case i am, so i'll just switch the wires. the entire 650 ignition changed to electronic, so i imagine they just moved the locating pin along with everything else that changed, such as the mounting stud which is a smaller diameter bolt on the 550.

i think it not being common knowledge is due to the fact that this breed was on its way out by the time the 650 came around. i've talked to local race builders from the time period who knew a lot about 550/650 compatibility.

[squirley]

Ya, I took the head apart to check to see if I had installed the cam correctly and decided that no wires needed to be swapped to get it to fire correctly.
As for the bike, I got it up and running when I first bought it, but it was a pile.  I have since torn down the engine and done a rebuild with a ported head, and a 4 into 1 yoshi header.  The bike is getting spark and fuel, but no fire?
Hopefully will be able to spend some quality time with it this weekend.

[kayaker43]

Keep us posted squirely...

I stopped racing in 79 so I missed out on the 650 parts. Now I look at it and say WOW!! the bigger valves and ports look way better than the Yosh ported head I have. Boy I could have had fun mixing up parts but they came too late.

I'm still surprised how people ignore this and spend crazy money on the old motors. There's nothing you can do to the 550 head to make it flow as good as the stock 650. Its also a great source for low buck hop up parts like cam, valve springs, stroker crank etc. They didn't make as many 650's, and they weren't popular so they're cheap and plentiful now.

[paulages]

Ya, I took the head apart to check to see if I had installed the cam correctly and decided that no wires needed to be swapped to get it to fire correctly.
As for the bike, I got it up and running when I first bought it, but it was a pile.  I have since torn down the engine and done a rebuild with a ported head, and a 4 into 1 yoshi header.  The bike is getting spark and fuel, but no fire?
Hopefully will be able to spend some quality time with it this weekend.

it's always hard to diagnose over the internet, but i'd go over all of your timing again. find TDC crudely with a screwdriver in the plughole, and if you can take the cam cover back off verify that you have the mark on the cam located right in relation to the crank. i doubt that's your problem, or you'd likely have clearance issues. given that, i'd double and triple check your ignition timing, and then finally try some starting fluid. lord knows i've thought i was getting fuel before only to have it start with starting fluid. in any case, there are only so many factors at work here... getting fuel and spark and doing so at the right time. get methodical enough and you can work through them all and find the culprit.