[mevocgt]

The engine on the bike ace is talking about in his post above, with the ace head installed,  is actually putting out over 40 engine horsepower at the crankshaft.

Ace or Otto once said it was about a 1.3% loss if I remember correctly.  So that would mean that we are running 42.3 at the crank.  Roughly......So yes, and it pulls like a train...?

[ace.cafe]

There might be some quibbling about exactly how much crank hp is available since we have no crank hp test data, but I think the estimates are in the ballpark.

However, what really impresses me is getting that kind of peak hp at barely over 5000 rpm. This indicates the kind of train pulling torque curve that MeVoCGT mentions.
Very broad torque curve with over 36 ft-lbs peak gives excellent power available at any riding speed, with impressive ability to roll on the acceleration power in any gear for passing traffic or just plain fun, and all on tap at rpms below the stock rev limiter speed.
I consider that aspect to be one of the most successful attributes of the head. I was very happy about that.
 

[Farmer_John]

So you don't need to unlock the PCV rev limiter?

[mevocgt]

We didn't change redline on the bike.  It's still at 5500...

[Aus.GT]

So you don't need to unlock the PCV rev limiter?

Not until Cams are added, He He

[ace.cafe]

Correct.
All the power gains are within the limits of the stock rev limiter under 5500 rpm.

Note that in the attached dyno chart, ALL parts of the Ace billet GT head curves, both torque and hp, are higher everywhere . There is no power sacrificed anywhere in the rpm range with this head. And it all happens below the rev limiter cut off rpm.

However,  as Aus.GT points out, there is room to go higher in power and rpm with the use of cams and other mods.At that point, the rev limit on the Power Commander would be increased to 6000 or 6500 rpm, depending on application.

[Good Vibes]

I was thinking of my favourite British single being my 1956 Norton ES2 when I wrote this comparison.  My Norton was bought in 1968 and had a capacity of 490cc with a bore and stroke of 79mm x 100mm compared to the CGT's 87 x 90 and much lighter flywheels. I got clocked at 78mph by a Traffic Cop who said my mate (on a similar aged Norton Dominator 500 twin) left me standing. He was correct about my speed because I looked at the speedo on hearing his siren. Interestingly, he let us both off as he said we were riding well.  Imagine that happening today?

Anyway, whatever power my Norton had, it would do 90mph with me lying on the tank and with enough road length.  I was never able to get much above 90mph.  My CGT accelerates way quicker to 120kph but runs out of steam at 130kph (80mph).  It will go faster but as with the Norton ES2, it needs a lot of road or a race track with a long straight. So really, not much different.

The final Norton Manx's (early 1960's) had a square configuration with overhead cams and were tuned to 50bhp.  Their top speed was over 100mph.  They wouldn't idle as way too cammy for that but non-the-less were fast beautiful bikes and not dissimilar in look to our little CGT's. Handling of both is probably comparable.

[ace.cafe]

My CGT will do 5000 rpm in top, which is 90mph according to rpm and gearing. I don't rely on the speedo, although in this case the speedo agrees.

It's current configuration is Sports silencer, PCV, and Ace/Derottone airbox with stack.

[Rattlebattle]

I was thinking of my favourite British single being my 1956 Norton ES2 when I wrote this comparison.  My Norton was bought in 1968 and had a capacity of 490cc with a bore and stroke of 79mm x 100mm compared to the CGT's 87 x 90 and much lighter flywheels. I got clocked at 78mph by a Traffic Cop who said my mate (on a similar aged Norton Dominator 500 twin) left me standing. He was correct about my speed because I looked at the speedo on hearing his siren. Interestingly, he let us both off as he said we were riding well.  Imagine that happening today?

Anyway, whatever power my Norton had, it would do 90mph with me lying on the tank and with enough road length.  I was never able to get much above 90mph.  My CGT accelerates way quicker to 120kph but runs out of steam at 130kph (80mph).  It will go faster but as with the Norton ES2, it needs a lot of road or a race track with a long straight. So really, not much different.

The final Norton Manx's (early 1960's) had a square configuration with overhead cams and were tuned to 50bhp.  Their top speed was over 100mph.  They wouldn't idle as way too cammy for that but non-the-less were fast beautiful bikes and not dissimilar in look to our little CGT's. Handling of both is probably comparable.

I had a Norton 19S a few years ago. It had the longest stroke of any English single (though it might have shared that honour with the Panther). Being a 600cc it had loads of torque - they were mainly used as sidecar tugs in their day. A lovely bike that wasn't much quicker than an ES2. Both of course can be tuned to produce considerably more power. Pushrod Performance is the main man for this in the UK.

A Manx will do a lot more than the ton; even 350 Goldies did 105mph. Are you sure the Norton had a lighter flywheel than the CGT - I doubt it. My brother weighed the flywheels in his iron barrel Enfield - it weighed less than that in his B33 BSA - a rough equivalent to the ES2. To me the current RE bikes don't slog like they used to...

[Otto_Ing]

Ton on the 350 Goldie sounds a bit optimistic to me though.

[SSdriver]

My CGT will do 5000 rpm in top, which is 90mph according to rpm and gearing. I don't rely on the speedo, although in this case the speedo agrees.

It's current configuration is Sports silencer, PCV, and Ace/Derottone airbox with stack.

Same here...Motad silencer, Pcv, k&N... 90 mph with gps... and not lying on tank.
I'm happy with the GT performance...think it's underrated for a big single.
Cheers...Jimmy

[Good Vibes]

Hi Rattlebattle

My composition was wanting, as I was referring to the CGT having the lighter flywheels.  The Manx's, that were purpose built for the Isle of Mann that is a 264 mile race so reliability was also an attribute built into the engine design.  They had double overhead cams and could do 140mph, pretty good for a 498cc single.  Some post production tuners got 60hp from them and slightly more top speed.

I too am very happy with my CGT that has the standard Keihin ECU although mine was re-mapped by the Chennai factory to prevent the stalling I had, and it came fitted with the sports muffler that is very loud.   I did stuff some chicken wire into the tail end to create a little back pressure that stopped the popping on deceleration, and it ran smoother and a little quieter.  I removed it a couple of weeks ago and it is noticeably noisier so will probably re-stuff it again.  It doesn't take much to make a difference and the mesh can be inserted about 50mm into the visible internal tail pipe with the rest twisted up and curled around the cavity behind the end of the tail pipe and the muffler back end to hold it in place.

What is the CGT's 0 to 100kph (60mph) time?  anyone know?

[Rattlebattle]

Ton on the 350 Goldie sounds a bit optimistic to me though.

I think not. The 350cc Goldie was at least as successful as the 500cc version. It was the 350 DB32 that used to win all the races, to the extent that races became a procession of 350 Goldies, rather like Yamahas a few years later. They were competitive in most branches of M/c sport too; the owners handbook had loads of data on cam timing, cams and carb settings. In road racing form with a GP carb fitted BSA claimed 105 mph top speed. I'm sure that this is realistic. It was almost a racer for the road - the reason why rockets wanted one, preferably a 500cc admittedly, though the 350cc was more civilised. Few rockers lusted after a Bullet; by the time the big head one arrived the world had moved on...

[Otto_Ing]

I think not. The 350cc Goldie was at least as successful as the 500cc version. It was the 350 DB32 that used to win all the races, to the extent that races became a procession of 350 Goldies, rather like Yamahas a few years later. They were competitive in most branches of M/c sport too; the owners handbook had loads of data on cam timing, cams and carb settings. In road racing form with a GP carb fitted BSA claimed 105 mph top speed. I'm sure that this is realistic. It was almost a racer for the road - the reason why rockets wanted one, preferably a 500cc admittedly, though the 350cc was more civilised. Few rockers lusted after a Bullet; by the time the big head one arrived the world had moved on...

Ok it was a racing Goldie 350.

[Rattlebattle]

Well, not really. You could specify what you wanted from the factory. Young men being what they are most specified clubman's trim i.e. clipons, GP carb, rearsets and RRT2 close ratio gearbox. They were fast in that format without tuning for racing.