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how to you plan to protect all those metal surfaces from salt?
750cc Norton Commando Salt Flats Build
- Thread starter Zachary Brown
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Looking good.
Have fun getting the front two 3/8 stud nuts on fastening the head to the barrels. A couple of strips of 1/4" or 5/16" material slid in the front and back under the fins outside the gasket surface to hold the head up so you can start the nuts might help. Then again those barrels might have a different casting than the Molnar barrels I have and will be easy to fasten.
Zachary Brown
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Alright everyone. Did everything I could with the time I had this weekend. Sadly I didn't get pictures of all the steps but hit some of the highlights. As previously shown, got the head back to the house late Friday evening, and first thing Saturday morning I set into getting pushrod length set for proper rocker arm geometry (long story short, rocker arm adjuster stem being parallel/colinear with the valve stem and approx. 90 to the rocker arm axis at half gross lift). Luckily after tedious checking and rechecking, the pushrods provided in the JS4 cam kit measured out perfectly without modification.
There was one change made to the rotating assembly (made on the recommendation of Leo Goff after an in person visit to see the bike), a set of Omega Pistons were swapped for the JS Hi-Comp set for stock rods. Don't worry Jim, there is another hot 750 street/race build that these will be slotted for! The balance factor was only changed by about 3% after weighing the new units and running the numbers(you're balance factor may vary).
And before I get any further in this, I know there have been questions about ports on this head so here are a few shots of the intake and exhaust. Unfortunately I don't have the numbers in front of me for the port sizes but I will get those tomorrow when I go to the shop. However, I can say that after the port/polish and flow work Leo Goff has said "the head will flow enough for 90-95HP". Sadly no actual CFM numbers for those interested.
Here's the intake(w/ CNW manifold matched to ports):
And here's the exhaust (I know Schwany was looking for the but I don't know how to tag here)
After many hours of test fitting, checking, re-checking, and hair pulling we finally ended up with the head torqued onto the barrels. And the headers fitted for added effect.
There was one change made to the rotating assembly (made on the recommendation of Leo Goff after an in person visit to see the bike), a set of Omega Pistons were swapped for the JS Hi-Comp set for stock rods. Don't worry Jim, there is another hot 750 street/race build that these will be slotted for! The balance factor was only changed by about 3% after weighing the new units and running the numbers(you're balance factor may vary).
And before I get any further in this, I know there have been questions about ports on this head so here are a few shots of the intake and exhaust. Unfortunately I don't have the numbers in front of me for the port sizes but I will get those tomorrow when I go to the shop. However, I can say that after the port/polish and flow work Leo Goff has said "the head will flow enough for 90-95HP". Sadly no actual CFM numbers for those interested.
Here's the intake(w/ CNW manifold matched to ports):
And here's the exhaust (I know Schwany was looking for the but I don't know how to tag here)
After many hours of test fitting, checking, re-checking, and hair pulling we finally ended up with the head torqued onto the barrels. And the headers fitted for added effect.
Zachary Brown
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Thanks! It's a temporary piece. The final one will be made alot better. Also had to be bent to clear the old cable mount on the swing arm when activating the brake.
grandpaul
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A bent rod will produce a "spongy" pedal...
...then again, you don't use brakes on the salt very much!
The one time I did (in the pits, when some fool pulled out from between two trucks without looking), I was instantly doing a very close-up inspection of the salt in the pit lane...
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Taking pics of a build is really difficult. Who really likes to stop and take pics other than influencer types or people selling product. I personally have to stay focused and on task or I'll forget something important I meant to check.
Thanks for the pics of the entrance and exit sides of the STS head. 90-95HP out of a Norton 750 would be really impressive. He must have meant with a larger displacement engine???
Those pistons are something else.
Beautiful work.
Zachary Brown
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Yea its a pain to stop and take pictures when you're mid workflow haha.
And he said the CFM for the head is enough to handle up to 90-95 but the motor won't be making that level of power. Would love it if it managed to pull that off though!
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Zachary,
Life getting in the way lately or what? 2 months and no sneak peeks on your progress.
I'm just ribbing you. Any info would be good. I've never tuned for sustained high RPM. Plus if you have time it would interesting to know how all the engine mods are working out for land speed record chasing.
Life getting in the way lately or what? 2 months and no sneak peeks on your progress.
I'm just ribbing you. Any info would be good. I've never tuned for sustained high RPM. Plus if you have time it would interesting to know how all the engine mods are working out for land speed record chasing.
I've seen a lot of different mushroom adjusters fail (the kind with screwdriver slots to adjust them.) The mushroom is very close to the rocker arm and a lot of thread is sticking out the top, that is not what I want to end up with. How did the cam degree in , What are the lobe centers?
Zachary Brown
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I was meaning to get back and post an update, but unfortunately its not good news. Salt is out of the running this year.
Zachary Brown
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Degreed in at 3 degrees advance to hit the correct lobe center per JSM instructions.
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That is unfortunate. Anything to do with the Norton build?
Personal stuff can put a halt to just about anything. Getting older and arthritis is a good example
Zachary Brown
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Turned into a combination of both. Had problem with the build and budgetary issues just made it impossible to run this year.
Here's what happened with the build. Got it all put together and gotta say, I like how it's turned out. The exhaust is gonna be ceramic coated once tuning gets done and the chain guard will be painted/coated. Here she is minutes before a fatal error occured.
During startup it built oil pressure and would start. However, it wasn't quite right and didn't stay running for more than a second or two at a time as you can see here:
After about 5-6 attempts to start accompanied by checking, re-checking, and adjusting everything we could think of, decided to roll it back on the lift and dig into it in the comfort of air conditioning. Cam timing, ignition timing, valve clearance, ect. All the items on my list came up good. Until I looked into the cylinders..... Scoring of the nikasil lining from piston rings. Its hard to tell how bad it is in the photo but the bore gauge showed that it was at minimum .002" deep in just the few times we tried to get it running.
The problem turned out to be the rings. In the swap between the JSM pistons to Omega, I failed to double check the coating of the rings provided like an absolute idiot. The rings provided were chrome, which as alot of you I'm sure know is NOT what you use in nikasil cylinders. So now I have to get the cylinders re-lined by Millennium Technologies which blows my budget for the remaining things needed to make the salt flats this year. Pair that with ordering a set of domed pistons and rings from Jim to fit the stock rods for nikasil cylinders with piston skirt coating. Since my attempts at finding a set of nikasil compatible rings for the Omega pistons turned out to be a bust. They may be out there somewhere but I spent a week looking and turned up nothing.
Not the update I wanted to give, but sh*t happens and I've now got alot more time to work things out for next year.
Fast Eddie
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I feel your pain Zach. But, on the bright side, you found it now, and not when it decided to ‘let you know’ at 8,000 rpm !
BTW it’s not just the ring material you need to consider, it’s also the coefficient of expansion of the pistons and barrels. Nickasil kit tends to run minimal clearances, which is fine when it’s fine, but you’ve much less margin for error.
BTW it’s not just the ring material you need to consider, it’s also the coefficient of expansion of the pistons and barrels. Nickasil kit tends to run minimal clearances, which is fine when it’s fine, but you’ve much less margin for error.
Zachary Brown
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That's the one thing I keep telling myself. Way less pain that if it was a 8k with me on it lol
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The following not very community friendly thoughts will sound awful, but whatever.
Might not really have been the piston rings causing the quick stall, but they were slowing the pistons down some, so one step in the right direction installing the right pistons and rings in the future.
How familiar are you with FCRs? If you disabled the accelerator pump and are using one of the popular overly lean tunes members here swear by, you are going to have a hard time making that race engine with longer intake manifolds run when stone cold. The SUDCO jetting for the FCRs would be closer than the lean tunes. And disabling the accelerator pump is is a solution looking for a problem that does not exist for a race motor unless you have to do it for whatever class you are in.
Might not really have been the piston rings causing the quick stall, but they were slowing the pistons down some, so one step in the right direction installing the right pistons and rings in the future.
How familiar are you with FCRs? If you disabled the accelerator pump and are using one of the popular overly lean tunes members here swear by, you are going to have a hard time making that race engine with longer intake manifolds run when stone cold. The SUDCO jetting for the FCRs would be closer than the lean tunes. And disabling the accelerator pump is is a solution looking for a problem that does not exist for a race motor unless you have to do it for whatever class you are in.
Zachary Brown
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I'm open to all insight when it comes to this build since it's my first attempt at something like this. So "community friendly" or not I'll take it.
As for the rings and pistons being the root cause, I don't think thats the case but definitely a contributing factor for sure. Hindsight being what it is I do remember the original setup having less rotating friction. My experience with FCR carbs is limited. I've rebuilt them before but never done alot of tuning. I don't have the current jetting in front of me but Im open to suggestions. And the accelerator pump has not been disabled. No regulation for class to do so.
