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1999 Shadow 750 ACE VT750CD3 Modified
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Discussion Starter · #1 ·
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.


282334
 

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Very cool, sucks that I don't have a cycle wreckers near by...
 

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1999 Shadow 750 ACE VT750CD3 Modified
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Discussion Starter · #3 ·
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. (-;
 

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2007 VT750DC Spirit “chopper”
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Are you using the 36.5mm Hawk GT carbs? Also what ignition module do you have that allows changing the stock redline? Looking to do something like this down the line, there are companies that still re-grind even more aggressive hawk GT cams.


For the record, you can fully open up that Aero exhaust if you're handy, I cut 12" out of the can on mine(cut right behind the mounting bolt holes) and punched out the remaining front most baffle section then reassembled the cut down stock cover with the stock tip, flows great - stock cams and such but it runs perfect on 132F and 135R jets with an open intake and still gets 50mpg+ with no popping. That stock Aero exhaust is a huge flow bottleneck, gotta change that!
282415
 
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1999 Shadow 750 ACE VT750CD3 Modified
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Discussion Starter · #5 · (Edited)
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.
 

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Are you using the 36.5mm Hawk GT carbs? Also what ignition module do you have that allows changing the stock redline? Looking to do something like this down the line, there are companies that still re-grind even more aggressive hawk GT cams.


For the record, you can fully open up that Aero exhaust if you're handy, I cut 12" out of the can on mine(cut right behind the mounting bolt holes) and punched out the remaining front most baffle section then reassembled the cut down stock cover with the stock tip, flows great - stock cams and such but it runs perfect on 132F and 135R jets with an open intake and still gets 50mpg+ with no popping. That stock Aero exhaust is a huge flow bottleneck, gotta change that! View attachment 282415

Just curious, what did you do to the air intake?

I gutted my exhaust fully, put in a 22" 3" pipe and just dump right into it, it's capped to remove the tin pang.

I'm running 122/125. Based on your post and a few others I've seen, I think I'm still shy. I have Jets on hand all the way up to 135.

My airbix is gutted, no snorkel, and I'm running a UNI foam filter.
 
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1999 Shadow 750 ACE VT750CD3 Modified
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Discussion Starter · #7 ·
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!"
 

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2007 VT750DC Spirit “chopper”
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Just curious, what did you do to the air intake?

I gutted my exhaust fully, put in a 22" 3" pipe and just dump right into it, it's capped to remove the tin pang.

I'm running 122/125. Based on your post and a few others I've seen, I think I'm still shy. I have Jets on hand all the way up to 135.

My airbix is gutted, no snorkel, and I'm running a UNI foam filter.
Full bean box mod, snorkel removed and the intake inlet is opened to match the back of the filter, I'm using a HifloFiltro replacement, not a fan of K&N style elements(personal preference).

My full mods would be:
4° timing mod
Bean box intake mod
15% upgraded clutch springs (EBC CSK28 kit)
Factory Pro jet kit, Factory pro needles on 3rd clip setting
132F, 135R jets, 42 Pilots.
Mixture screws three turns out
Fully opened stock Aero exhaust(Very loud)

Runs flawlessly, even with me beating on it I routinely get 50-55mpg or more, plugs are perfect. Have to be honest that my timing is probably a bit more advanced than 4°if I'm honest and I ONLY run 91 octane ethanol free fuel, next time I have the side cover off I plan to print out a degree wheel to figure out just how much advance I can run, I ground down the factory bolt head on the top side so I could advance further than the bolt bottoming out against the pickup(Heh, the things I do with no programmable ignition module...) 134/138 jetting was too rich, couldn't get it to stop rich popping on decel no matter where I put the air fuel screws and the MPG never got over 45, plugs were black. REALLY happy with 132/135, pulls really hard to 80mph in 3rd with no flat spots at all, the closer to redline the harder it pulls.

Edit: Should definitely mention I'm 2,000 feet above sea level where I ride.
 
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I'm thinking of running velocity stacks next year. I'll pop off the carbs (I can get it out, rejetted and back on in 20 mins now lol) and slap in some 130s. But first I'll pull the plugs (ngk iridiums) and see what I got.

I have the ebc springs, just too busy to put them in. Next year before I do my oil change I might pop them in.
Thanks for the replies guys, always nice to know where everyone sits. The stock areo/ace pipes are damn loud when the junk is removed, but not loud enough to be a pain on long rides.
 

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1999 Shadow 750 ACE VT750CD3 Modified
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Discussion Starter · #10 ·
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.
 

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Are you using the 36.5mm Hawk GT carbs? Also what ignition module do you have that allows changing the stock redline? Looking to do something like this down the line, there are companies that still re-grind even more aggressive hawk GT cams.


For the record, you can fully open up that Aero exhaust if you're handy, I cut 12" out of the can on mine(cut right behind the mounting bolt holes) and punched out the remaining front most baffle section then reassembled the cut down stock cover with the stock tip, flows great - stock cams and such but it runs perfect on 132F and 135R jets with an open intake and still gets 50mpg+ with no popping. That stock Aero exhaust is a huge flow bottleneck, gotta change that! View attachment 282415
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.
 

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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.


View attachment 282334
Super interested in doing this to my 2k ace 750. Do you have a parts / mods list per chance? I’d like to see what all it entails
 

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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. (-;
So how’s she doing? :))
 

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1999 Shadow 750 ACE VT750CD3 Modified
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Discussion Starter · #14 ·
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:
Font Slope Pattern Number Parallel


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.
 

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1999 Shadow 750 ACE VT750CD3 Modified
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Discussion Starter · #15 ·
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.
 

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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:
View attachment 301511

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.
Thanks! I’m stateside but all very interesting info. I ride like a banshee so the hotter the better. Haha I’m thinking of getting another complete motor and just building it to install. What about the case- any ideas on getting a 6th gear?
 

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1999 Shadow 750 ACE VT750CD3 Modified
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Discussion Starter · #17 · (Edited)
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.
 

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I am happy to answer questions here.
I keep my email private and I don't do Facebook.
completely understandable, so you wrote that the Deauville NT650 camshaft are “hot” and “milder” than the Hawk GT NT650 but the specs are same, so what’s the difference? Better or worse? I seen some on eBay and wanted to pull the trigger and grab the Deauville version.

The Hawk GT version are at $80 a piece vs $80 for a pair of the UK Deauville version.

Also, Are the valve spring necessary or can I do without?

lastly, I also have IGNITECH CDI but uninstalled and will be running it on my 07 Shadow Sprit 750DC.
 
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