commando 750 head
- Thread starter nortones7
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I've tried various approaches, chemical & mechanical to brighten up and semi smooth up 750 heads on and off barrels but found out that the head alloy is innately grayer-darker than the cases and covers so as mentioned may leave cleaner but duller than ya started with. Also once a small area smoothed over enough to notice then sticks out like a clean thumb on dirty hand. Best to spend most effort on the valve covers and fasteners - before sending off to vibe media polish.
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Chemical cleaning nice aluminum castings is bad and discolors the aluminum. Wire brushes or metal scrapers make a mess of the aluminum.
Soda or walnut shell blasting is good. I’ve done both. Is the motor still in the bike frame? Could even soda blast in the frame. There are commercial shops around here that would do that. Trailer the bike over, blast it right on the trailer. Take the carbs off and plug the ports. Take off other parts that would be in the way. Be sure to plug any holes, including tapped holes.
A really good way to blast that I have done also is dry ice blasting. Fantastic process. We have commercial guys around here that do that too. A little expensive, but they will come to you. Not worth it with a bike for that. The abrasive is dry ice, which evaporates leaving only fine and dry dust. I’ve used this on small precision parts (to deburr nylon gears for experimental electronic steering systems) and large parts (cleaning inboard boat engines in the boat).
Check Craigslist or your local Yellow Pages for soda blasting or dry ice blasting. Lots of places here in southeast Michigan. Or just google for your town and soda blasting.
Soda or walnut shell blasting is good. I’ve done both. Is the motor still in the bike frame? Could even soda blast in the frame. There are commercial shops around here that would do that. Trailer the bike over, blast it right on the trailer. Take the carbs off and plug the ports. Take off other parts that would be in the way. Be sure to plug any holes, including tapped holes.
A really good way to blast that I have done also is dry ice blasting. Fantastic process. We have commercial guys around here that do that too. A little expensive, but they will come to you. Not worth it with a bike for that. The abrasive is dry ice, which evaporates leaving only fine and dry dust. I’ve used this on small precision parts (to deburr nylon gears for experimental electronic steering systems) and large parts (cleaning inboard boat engines in the boat).
Check Craigslist or your local Yellow Pages for soda blasting or dry ice blasting. Lots of places here in southeast Michigan. Or just google for your town and soda blasting.
N0rt0nelectr@
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I had the head off my project 750 Norton hell it was a total basket case with few parts together. The head was a mess so I sent it to Vapor Blast Solutions in Santa Fe. The finish was amazing when it was done.
If you don't want to remove the head and I can understand why look at soda blasting. Harbor Freight has a blaster with a hopper that works quite well and they sell 50# bags of soda too.
If you don't want to remove the head and I can understand why look at soda blasting. Harbor Freight has a blaster with a hopper that works quite well and they sell 50# bags of soda too.
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From a conceptual standpoint just remember there are three types of cleaning/blasting results: open, closed and neutral. If a part is really bad you usually have to use something like sand blasting or similar. This leaves an 'open' structure, ie the microscopic pores in the casting are opened up. This has two problems, it makes it much more susceptible to new oxidation and holding onto grime. Using bead, either glass. metal or whatever beats down and 'closes' those pores which leads to a better looking and more durable finish. Of course some kinds of cleaning don't directly affect the pore structure and so are neutral.
As to soda blasting, etc, I don't know enough about it to know if it opens, closes or is neutral. Perhaps someone here can say.
So you use whatever is appropriate to get it clean but then if it is a process that opens the casting you need to follow with a closer.
On a practical level, I use a well worn stainless steel brush just for this purpose. When there's nothing else to do, I just pull up a chair, turn on some tunes and lightly, repeatedly start brushing.
As to soda blasting, etc, I don't know enough about it to know if it opens, closes or is neutral. Perhaps someone here can say.
So you use whatever is appropriate to get it clean but then if it is a process that opens the casting you need to follow with a closer.
On a practical level, I use a well worn stainless steel brush just for this purpose. When there's nothing else to do, I just pull up a chair, turn on some tunes and lightly, repeatedly start brushing.
batrider
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You can still do a lot while it is on the bike. I used a cleaning then painting process although it was much easier than real painting. There are a lot of nooks and crannies and it will take some patience. Remove as much 'in the way' stuff as possible and have some good lighting. Clean/degrease the head before painting with toothbrushes and narrow "acid" brushes. Don't use steel tools on it or it can show up as rust dots later. Polish the smooth areas above the spark plugs with aluminum polish if they need it. Mask as needed (around top of black barrel, etc.).
Get some foam tipped swabs and a clean dry rag. Put rubber gloves on. Spray some hi temp aluminum header paint on the rag and rub it around on the rough cast areas of the head so it is not thick or wet looking. Afterwards, do the same with a foam tipped swab and use it in between the fins. Don't spray the head directly or it will look horrible. You don't want it to look coated or painted. The rag rubs the paint into the aluminum and it looks natural. Go over any polished areas again after the paint dries.
I learned this after taking a Norton head to an old-time local car engine builder (race and show) and asking his advice on cleaning. I was willing to have him do whatever process he used on his engines, but he just suggested the above method and said he wouldn't be able to do any better. I will be doing it again this Spring. It lasts maybe 5 years.
Russ
edit: Forgot to mention the paint smell for about the first 2-3 weeks
Get some foam tipped swabs and a clean dry rag. Put rubber gloves on. Spray some hi temp aluminum header paint on the rag and rub it around on the rough cast areas of the head so it is not thick or wet looking. Afterwards, do the same with a foam tipped swab and use it in between the fins. Don't spray the head directly or it will look horrible. You don't want it to look coated or painted. The rag rubs the paint into the aluminum and it looks natural. Go over any polished areas again after the paint dries.
I learned this after taking a Norton head to an old-time local car engine builder (race and show) and asking his advice on cleaning. I was willing to have him do whatever process he used on his engines, but he just suggested the above method and said he wouldn't be able to do any better. I will be doing it again this Spring. It lasts maybe 5 years.
Russ
edit: Forgot to mention the paint smell for about the first 2-3 weeks
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Air jet cleaning of left on solvents and metal etchers is my favorite way to fun and easy way to get nice looking where takes a light to see. Will have to set up for soda blast then water wash and blow dry head doo. Rally sites don't usually have much water taps let alone power washers for those Cdo's ridden far enough to road girme so hope to remove Peels evidence idling to power air station with hose long enough to share air.
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Dynodave wrote: "NHT heads are painted on the sand cast finish areas."
Not sure what that means exactly. I am guessing NHT means Norton Heavy Twin. So all Norton heavy twin heads were painted from the factory????
Stephen Hill
Not sure what that means exactly. I am guessing NHT means Norton Heavy Twin. So all Norton heavy twin heads were painted from the factory????
Stephen Hill
wot said:
Be careful with walnuts as a medium. The oil contained in the shells penetrates the surface of the substrate and distrubes a lot of follow-up processes like painting or anodizing. I learned that the hard way when a new supplier wanted to showcase his abilities - they had to redo the whole batch as the stuff couldn't be anodized properly anymore.
Just a little hairsplitting: Dry ice is considered as non-abrasive as it does not affect the substrate (as long as this is realtively solid, off course). It only removes stuff which adheres to the substrate and which is soft enough so that the dry ice particles acn actually penetrate the surface. As soon as the particles hit the dirt they evaporate immediately and that is the cleaning effect. It's perfect for dirt, oily deposits etc. but pretty useless on e.g. sound 2K paint already.
Tim
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Stephen Hill said:
No they are not all painted. I've never seen one that was painted from the factory. They may exist but I have never seen one.
I just use a stiff nylon brush and strong degreaser. It's laborious but I don't have access to any sort blast equipment.
Ian
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Nortoniggy said:
painted-cases-and-heads-late-commandos-t20800.html
you-paint-the-head-t9203.html
Yes the heads are painted...mostly commando... and you have probably seem many many painted heads...It is a testament of how good the paint job was done to fool so many people.
The ones I see definitely not painted often have evidence of a cleaning/blasting process.
It has taken some effort for me to find a formula to recreate the "invisible finish". Which also fools norton expurts (sic)
I WILL also be painting my fullauto head before installation.
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