[CSRoad]

Due to hot weather baking my shed and family stuff my "two day" project dragged on for a month.
But now it is finally up and running with valve springs and cams from a NT650 Hawk GT.
It now finally feels like a 750 did when I was a kid, it feels like a different engine.

I have not swapped out the exhaust yet, but I'm sure it is a bottleneck in the performance at this point.
I put Uni pods on the carbs, and followed along with stretched and heat treated slide springs to stop the slide flutter and fuel spray that is usually the nightmare of such installations. Slow jets are 42, main jets are 140 front and 145 rear and the Dynojet jet needle is on the second notch. The plugs look OK, but I'm going to have to go richer still with an exhaust change. My rev limiter is set to 6800 rpm that it hits readily in second and third gear, didn't want to cover ground faster than that while sorting it out.

Things I have learned:
I changed the valve springs without pulling the heads, making your own valve spring compressor is a pain, making 3 for different locations is worse.
I would probably pull the heads if I was doing it again even though I had good compression, despite what the manual says it can be done without pulling the engine.
Just for entertainment, stock intake springs you can remove with your thumbs, just grab the keepers with a magnet!

I almost forgot the most important thing: If you use a 4mm wrench when setting your valves tie a couple of feet of string to it. Those things are tiny and if they have a long tail it is harder for them to disappear. "Ah ha I've got you", is way better than "WTF did you go".

NT650 valve covers fit the VT750 although you lose the place for the secondary air cleaner and the crankcase vent is just a hose connection of the rear one and is noisy.
As the bike is now it only takes unplugging the spark plugs and four bolts to remove the covers to check the valve clearances.

I have attached a picture of how it looks with no added trim.

 

[CSRoad]

Just a bit of an update, since I had it out for a couple of hours of backroad riding today after some in city holiday stop and go.

All has turned out as I hoped. The jetting isn't quite right, it almost looks like I should swap the front and rear mains, but nothing too drastic plug colorwise and I will leave it as it is 'til I change the exhaust and to less restrictive carb boots, hopefully this week.

The downside to this mod other than needing an aftermarket ignition box to take advantage of it, is the loss of some low end flexibility, more like a motorcycle and less like a tractor. It cares more which more about the gear it is in when you roll on the throttle and it requires more throttle when you are starting out, I don't have a tach on it yet, but I would guess the engine likes it above 3000rpm and comes on strong where the stock setup is switching to running out of breath mode above 5500 rpm.

I'm still running with the previous 6800 rev limit, I'm not too worried about pushing it to a 7500 red line and will probably set the limiter to 8000 rpm. The valve train can keep up, the NT650 redlines at 8500 and is rev limited to 9300 rpm. The other more sporting versions of this engine design all seem to be able to routinely make it past 100,000 miles with routine maintenance despite considerable higher rev. limits than the 52 degree VT750. The other versions all have offset cranks though and also have shorter strokes and therefore less piston speed. The pistons are what I fear are the weak link in VT750 abuse.

If/when I finally blow it up I'll let you all know. (-;

 

[CSRoad]

I'm using stock carbs, the 750 ACE and some Spirits up until a running change sometime in 2001 used 36mm Keihins, then switched to 34 mm carbs. Luckily my 1999 CD3 has 36mm carbs. So while I would not turn away a set of Hawk GT carbs if they landed in my lap, given the price of them these days, it didn't seem to make much sense for a small margin of improvement.

AFAIK Megacam and WebCam still weld and regrind both street and race cams for the NT650. If you are going that way you would save a chunk of expense by using your existing KW0 cams as the basis if they are in good condition.
They've done it before.

I've been running an Ignitech TCIP4 ignition on it for the past four or five years, the capabilities are pretty amazing.

I like the look of your exhaust, I don't know about the difference between the Aero vs the ACE exhaust under the skin.
The ACE only has 32mm primary pipes inside the chrome tubes, IMO they actually work surprisingly well as designed.

The Hawk GT and the 650 Africa Twin which both used 1 5/8 pipes with the MS8 camshaft aftermarket pipes for the Hawk GT are usuallly 1 3/4.

I was going to get my local header bender to twist up some pipe for a 2 into 1 for me to glob together, but I've gotten lazy, impatient and will put a set of Cobra pipes on it for now.

 

[CSRoad]

I'm running UNI pods, the left fit right in, the right one is deformed sideways to clear the backbone, ugly but it appears to work and carbs can come off quite quickly now. (-:

Previously with the stock cams and exhaust I was running a K&N filter with my Bean Box inspired air box and after much messing around with several WOT runs and plug cuts at various speeds the carbs ended up with (Keihin size) 40 pilots, 132 main front and 135 rear with a Dynojet Stage 1 needle on the second notch. The stock exhaust probably cost me some top end and may have affected the main jet choice.

I've heard of people running Dynojet sized 134 & 138 with similar setups, but for me jets that size it were way too rich at WOT , gave sluggish mid-range and gave horrendous fuel mileage.

FWIW I'm 800 feet above sea level here.

There is always some mix of science, luck and magic in jetting.
It seems every bike is different and nothing replaces trial and error.

"Put it back as it was, if you can remember how and leave the damn thing alone, Honda got it right to start with!"

 

[CSRoad]

Well I thought I'd update since I've now run 4 tanks of gas through it, 91 Octane, no ethanol.

So far no surprises, I did swap the exhaust with a set of Cobra Boulevard Classic slash cuts, they are loud when you get on it.
I put new Hawk GT carb boots on it to give an unrestricted shot at the intake port, I used Norma 40-60 x 9mm Euro-type hose clamps to make it all leak free.
The jets are, mains 138 front, 140 rear, with 42 slows, needles are the ones that came with a Dynojet "Phase 1" kit on the third notch, stock slide springs are stretched to 8" and then toasted in the oven for 2 hours at 325 F and then let cool in the oven. My altitude here is ~800' ASL, current temperatures running about 55 to 80 F.
Filters are single layer 3" UNI street pods.
My ignition is still setup as here other than a 8000 rpm oops limit: https://www.hondashadow.net/threads...grade.140733/page-11#lg=thread-140733&slide=4

The bike can still chug along cruiser style as long as it is in the right gear, but going full throttle it has a whole lot more get up and go.
I have not done any timed 0 to 60 runs yet, but it feels like a good improvement.
Pulls well through the gears, seems to be happy from 3000 rpm and really comes alive from 5000 rpm, I'm using 7,500 as max. shift point.
Top speed is anybody's guess, I saw 7000 rpm in fourth gear and shifted to fifth and it was pulling, but I had enough of that foolishness.
Above about 6800 rpm there is strong buzzing in the handlebars and I can't think anybody would want to cruise there although it is easily tolerated to blast past somebody.
Unlike the lower speed harmonic vibration that people often gear around, when this sets in it does not seem to go away as revs rise.

All in all it is a fun around town street surprise.
On the highway it can easily handle any traffic.

I have had the gas tank off so many times and the trip odometer unplugged that I really have no idea what the fuel mileage is going to be like.
I pretty sure like most bikes it will get worse when one turns up the wick a lot for grins.

Anyway, four tanks of gas, plenty of fun and testing it is still together.

 

[CSRoad]

It is still going well although I've only had it out for 5 rides so far this year due to life and weather.
I don't have a detailed parts list, the pieces I used came from a various NT650 Hawk GT that were being salvaged/parted out.
Luckily I found the complete heads with cams, valve springs and rockers off a wrecked low mileage 1990 model that ran in a supplied video before parting out.
I stripped the heads for cams and gears, inner and outer valve springs, retainers, and spring seats.
I used new valve collets.
The valve covers came off a 1988 model, but I could have used the ACE covers.

The unrestricted versions of the 650 Deauville or Revere heads have a slightly milder camshaft, but way hotter than the 750 ACE, the rest is the same as the Hawk GT and might be better suited to a cruiser application.
These should be easy to find in Europe and considerably cheaper on the used market, just look for low mileage and good condition.

The Stock 750 ACE uses the KW0 camshaft number.
The 650 Hawk GT used the MS8 camshaft number.
The 650 Deauville and Revere use the MN8 camshaft number.
See attached chart for the timings of each part number:

All those cam models will fit, the ones from the XRV750 Africa Twin are even hotter, but crazy priced on the used market due to the cult following the bike has.

Hope this helps.

 

[CSRoad]

Hey can you please send me a picture with a line on the exhaist where you cur it to remove the main part of the baffling/ restriction? I would really appreciate it. I am transforming my 2001 Honda Shadow Ace to an apocalyptic design. Hopefully it all goes well. I bought it for $500, less then 39k on it. It had set in a barn for about 5 years and collected dust and hay.

Sorry for the slow response I just saw this.
The 2 into 2 pipes currently on my bike are Cobra Boulevard Classics with baffles, the original 2 into 1 pipes, I kept untouched and now sit in the corner of my shed.

 

[CSRoad]

There is no six speed that will work.

It was pointed out to me, by a fellow member here that it would be possible to mix and match the fifth gear from the later shaft drive 750's to the cluster for less crazy cruising.
That is beyond the depth I'm willing to go with this project.
I currently use a programmable Ignitech TCIP4 for ignition to match things up.
I went from the 17 x 41 final drive to a 16 x 44 to regain bottom end punch, it is like losing 5th gear, hence the suggestion of the later 5th gear ratio for highway.
As it is I doesn't bother me for my purposes 5th gear 7,500 rpm is 120 mph and that's stupid fast for what it is.
Don't forget t is not exactly vibration free either.

Another complete engine or a spare bike is a good thing to have as any day tuned this way it could blow up. When? I don't know Honda wasn't planning this, so sometime, not yesterday, not this afternoon, but maybe tomorrow.
Doing it does not make a lot of sense, other than the sleeper fun effect there is not much to be gained. Would I do it again? Good question, maybe because it is still fun.
A Kawasaki Vulcan S 650 offers similar performance, is more civilized, better handling, is known reliable and has a 6th gear and all OEM and aftermarket parts, but it does not have the looks or the V-twin sound. (-;

PS I thought it was a Spanish flag in your sig hence the Euro references.

 

[CSRoad]

I am happy to answer questions here.
I keep my email private and I don't do Facebook.

 

[CSRoad]

This pdf chart shows the 650 Deauville timing.
The inner valve springs are necessary, the rest can be reused if in good shape as they are mostly the same, the spring seats on the 750 ACE are all ready for double springs and I would imagine the 750DC is the same, but better check all the part #'s.
There is no point in changing the cams unless you are willing to spin the engine beyond the factory limit and you need the valve pressure increase to do that and of course the ignition box with the higher limit.

I have no video of my 750 ACE running, but it does run well or at least did 3 weeks ago when I last had it out, it feels like a completely different engine character compared to stock.
Most of my limited riding lately is restricted to short runs on my Versys as I'm trying to break it in and the rest of my traveling seems to be stuck with people in the car. )-;
One of these days I should get a GoPro and rig it up, but it isn't high on my list.

 

[CSRoad]

Also, I just did a cross reference, it turns out the valve spring part numbers for VLX 600 are the same.

That makes sense the VT600C until 1998 wasn't rev. limited until 8000 rpm, the power was all done at 6500 or so, but Honda let them spin.

 

[CSRoad]

There is lots of mixing and matching doable but some may not work easily and most are not worth it when one equates the dollars/time vs. benefit.

The VT600 has an external hard oil line to the top end complete with banjos, where as the 750 uses an internal passage in the cylinder casting.
The rear exhaust port is reduced diameter on the VT600, Honda did this to balance the cylinder flow, I think.
The VT750 has ports the same size and the cylinders are balanced by carb jetting instead.

I'd stay clear of the single carb VT600 heads, I understand they have reduced intake flow as does obviously, the intake manifold and then things are topped off with the KW0
The '99 and later VT600 lost a bunch of power compared with the earlier engines, I think Honda claimed about -2 hp, but the performance figures would indicate a loss of around 7 or 8 hp.

The last year NT650 ('91 only) has internal oiling to the heads and they should/maybe bolt up to the VT 750.
I wanted a pair as my first choice, but could not find any without a bike attached.
I don't know when the Deauville changed to internal oiling, but figure they must have as the Africa Twin and TransAlp made the change.

 

[CSRoad]

Not something I would consider, but it might appeal to some folks as there are quite a few that have attempted single carb conversions with varying success and this sounds like a rather clean solution.
Thanks for posting it.

 

[CSRoad]

No real tips, you basically have the choice of pulling the heads and using a C-clamp style valve compressor or doing an overhead valve spring replacement and of course an automotive OH spring compressor won't fit at least not the one I had, likely Snapon has one that will work for $.

The is a video somewhere on the Web that I used for inspiration where the guy replaces valve seals on a Africa Twin or TransAlp with the engine in the frame without removing heads of course the frame is different. Sorry no link for that either.

Anyway I did it without pulling the heads it was a fair McIver hassle and I ended up making three pry-bar type spring compressors, with a bend and a hole to clear the keepers, more or less like a Stanley Wonder bar without the hook made out of 25mm x 8mm bar stock but a bit longer for leverage and they levered off a bracket I made that bolted to the side of the head using two of the fin bolts and caught the pry bar end as a fulcrum with a double nutted eyebolt. II used a flex magnet to scoop the keepers. I could push the intake retainers down with my thumbs originally they were a lot tougher on reassembly with the extra spring.

For the cylinder head I found top dead center backed it up a bit, put 3/16" rope/cord in the plug hole and brought it up again to top dead center to hold the valves closed.
Put shop towels everywhere, plug all holes you don't want valve keepers or other stuff in the crankcase

Follow the procedure in the Service Manual for camshaft removal and timing. I used a long screwdriver to push back the cam chain to loosen the tension on the adjuster and vice grips to hold the wedge. A 2mm bicycle spoke piece works for the locking pin.
Set the valve clearance like usual for the cam.

Now if I was going to do it again I think I'd consider pulling the heads and buying gaskets, it might be easier enough over all to make it worthwhile over the additional costs.
The Service Manual says you need to pull the engine to remove the rear had but you don't, you can double nut and remove the offending cylinder stud for tipping clearance to get it out.

There is other stuff I should remember but it is 3 years ago, I didn't take pics or video and my memory has had better days.
I allowed a weekend to do it, but domestic stuff happened and it took a month 'til completion. )-;

 

[CSRoad]

Idk pulling the heads and cleaning all the carbon and lapping the valves with some compound and a lapping tool might be worth it. Are the head bolts one time use? Btw I love this posti been keeping up on it and been thinking about a winter project

Pulling the heads does make sense especially if you have signs of excessive carbon build-up or the compression is a bit low.
The main head bolts are 10mm studs through the cylinder and things are clamped down by nuts they only require lubing and I think something like 35 ft/lbs so not really a lot of stretch and no where like throw away bolts in some cars.

The attached old magazine articles might prove interesting regarding technique, the hop up pieces are long gone of course, as are print mags, but it might be of value none the less.

 

[CSRoad]

Lot easier than I thought, I just bolted down the a 10mm wrench to both cam holder bolts.

used It it like a cross bar, then used 21” wrench and leveraging pressure on the 10mm as a cross bar as it puts pressure on the retainer, with help of my son it used a magnet to pull out the wedge keepers. Took total 10min each side.

That is thinking outside the box I created myself, thank you it is great what you can learn here.
I made my life far more difficult than it had to be, I think of the time and money I wasted.
Oh well it's not the first and will probably not be the last time. (-:

 

[CSRoad]

No the 750 Cams were put in sandwich bags in a box, never to be reused.
I pulled the gears from the chains before realizing they were the same damn part.
It was all done at one time, I had complete NT650 heads and I dissembled them using a C-clamp valve spring compressor, before diving in.

 

[CSRoad]

Without a helper or three hands those keepers are miserable.
I do like your tool set up, ingenious. It's one of those "Why didn't I think of that" things.

 

[CSRoad]

Not really, I changed to the NT650 idle spec which is 1200 +/- 100 rpm up 200 rpm from the 750 ACE setting, so it is pretty smooth.
Not lumpy like a vintage Pan Head with a 3/4 Race cam. (-;

 

[CSRoad]

I do have a programmable ignition box, but I just adjusted the throttle stop to match the NT650 manual figures.