Author Topic: ACE Is Assisting With Bulldog Customs Twin - PROJECT ABORTED  (Read 68947 times)

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High On Octane

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Reply #210 on: November 08, 2014, 08:23:57 pm
Ace, I'm curious.  I was already planning on having custom 12:1 pistons made for this motor.  How much compression can I run with the basic head job we spoke about last month?  I'm thinking of still making it a mild race motor and just take my time building it.
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ace.cafe

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Reply #211 on: November 08, 2014, 08:46:30 pm
Ace, I'm curious.  I was already planning on having custom 12:1 pistons made for this motor.  How much compression can I run with the basic head job we spoke about last month?  I'm thinking of still making it a mild race motor and just take my time building it.

It depends on the cam specs, primarily the intake closing timing.
On the Intereceptor R cams which are similar to our Ace Magnum cams for timing, I would think that about 9:1 to 9.5:1 would be okay in that small hemi chamber. Maybe even a little higher, depending on the cams. It should handle a little more compression than the 500 because of the smaller chamber volume.
If I had the specs of the cam with the intake closing timing at the .050" lift spec, I could run the numbers in my calculator program, and tell you what it would be.
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ace.cafe

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Reply #212 on: August 12, 2015, 03:33:15 pm
Hi Guys!
Got a very nice ride report on the progress of the Ace equipped 700 Trailblazer Twin with Ace Gemini heads yesterday. These are the heads that are described in this thread, made originally for Scotty's project, but ended up on Dapunds' 700 Trailblazer. I am not certain, but I think this is running a single carb/manifold at this time.

The bike has been undergoing some break-in rides for a while now, and apparently it was decided to try some high speed action!
I had to do some "reading between the lines" in the email, but it seems that there was some revving to 7000 rpm involved, and some speeds that referred to the fact that he "only has a 120 mph speedometer"!
:)
Not wanting to write any "incriminating evidence" in his email, probably to keep any plods from giving him a visit about it.

Ha!
So, it all sounds good to me! I think it is doing stunningly well as a road bike, and the sorting out and break-in procedures seem to be progressing. There were a few "teething" issues that came up, but nothing insurmountable.

Thought you all would be interested in how that machine is doing. I know I was very happy to hear the news!

Tom
« Last Edit: August 12, 2015, 03:44:11 pm by ace.cafe »
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Blltrdr

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Reply #213 on: August 12, 2015, 09:00:51 pm
Sounds great, but would love to see a vid. Surely one is in the making.
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High On Octane

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Reply #214 on: August 18, 2015, 01:33:11 am
So happy those heads went to a good home.  :)  And I too really want to see a ride video.  ;D
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da punds

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Reply #215 on: August 19, 2015, 04:52:25 pm
Video will follow, just waiting for a couple of pushrods, Tom mentioned a few teething problems. Two of the rods jumped off the rockers at highish rpm. I have had a bit more clearance made in the pushrod tunnels now I know what happens when the engine gets hot.
But what I can say is that from about 2000 rpm it really starts to go, and by 6000 I am glad I have the rev limiter set at 7K, in 1st and 2nd it just feels like I can't change gear quick enough. In very good conditions I have hit the rev limiter in every gear, this is really amazing for an engine designed so long ago. In theory the engine should make power unto about 9K, but until I have the pushrod clearance issue sorted, I am staying clear.
Crankcase decompression is a problem, I have replaced the factory vent with a crank vent and I am in the process of modifying the later crankshaft vent to fit. At high rpm I am chuffing oil and smoking quite a lot.
My biggest problem at the moment is time, I have just had a revamp of the business and both children are at University now. I am typing this in Edinburgh where I am fixing some stuff for my son, then later tonight meeting my daughter at the airport, and off to Inverness to sort her out in the morning. Planning to hit the charity shops in Inverness big time tomorrow, her flat is unfurnished.
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ace.cafe

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Reply #216 on: August 19, 2015, 05:44:29 pm
Video will follow, just waiting for a couple of pushrods, Tom mentioned a few teething problems. Two of the rods jumped off the rockers at highish rpm. I have had a bit more clearance made in the pushrod tunnels now I know what happens when the engine gets hot.
But what I can say is that from about 2000 rpm it really starts to go, and by 6000 I am glad I have the rev limiter set at 7K, in 1st and 2nd it just feels like I can't change gear quick enough. In very good conditions I have hit the rev limiter in every gear, this is really amazing for an engine designed so long ago. In theory the engine should make power unto about 9K, but until I have the pushrod clearance issue sorted, I am staying clear.
Crankcase decompression is a problem, I have replaced the factory vent with a crank vent and I am in the process of modifying the later crankshaft vent to fit. At high rpm I am chuffing oil and smoking quite a lot.
My biggest problem at the moment is time, I have just had a revamp of the business and both children are at University now. I am typing this in Edinburgh where I am fixing some stuff for my son, then later tonight meeting my daughter at the airport, and off to Inverness to sort her out in the morning. Planning to hit the charity shops in Inverness big time tomorrow, her flat is unfurnished.
Waiting for those pushrods, Kevin.

Regarding 9k rpm, don't do it with those alloy con rods!
They will not last at those rpms, and they will also stretch,  and pistons may hit the valves or heads, and when they finally do let go, it will be more than exciting! Absolutely, custom steel con rods will be required for getting anywhere near 9k rpm. Actually, the port size is set for about 8250 rpm in normally aspirated form(higher with supercharger or turbo), but it will be able to rev higher for a few hundred rpms more. With a 3.54" stroke in this sort of format, that's probably as high rpm as you really want to go unless you are racing for money or some kind of record. The piston speeds are dramatic at that rpm.

For the breathing problem at high rpm, get a KrankVent for that engine size. We have found nothing better than that. It's a bit pricey, but it works on all the racers like magic.

Edited to add:
I happen to know the holder of the 650cc pushrod gas land speed record in the East Coast Timing Association(ECTA) which runs the Ohio Mile, and his Triumph 650 race bike runs 128.2 mph, which is the current record for that class.

I calculate that with a 19T sprocket at 7000 rpm, your bike should be doing around 126 mph on the street!
 ;D 8)
« Last Edit: August 19, 2015, 06:07:33 pm by ace.cafe »
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Reply #217 on: August 20, 2015, 07:48:22 pm
Kevin,

once family and business priorities are sorted, would a 5 speed gear box (right-foot shift converted) be a good idea on this bike? I did hear the mainshafts for the twins and singles are different lengths, if so you'd need a custom 5 speed mainshaft. However, I have seen a picture of a Redditch twin with the Indian 5 speed box fitted, so it must be possible. Hitchcock's claim their own (ludicrously expensive) 5 speed box is for twins as well as singles.

A. 
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High On Octane

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Reply #218 on: August 21, 2015, 03:41:08 pm
My goal in naked form was to hit about 140mph at around 8000 rpms, which would be good for the M-PF or M-PG record currently at about 138mph for BUB speed trials. 

Definitely keep us posted Kevin and Tom as progress is made.  :)
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