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- Jul 2, 2011
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Restoring a 1972 750. I know good place to start is cam upgrade but which and where to buy; i don't know. while it's a part what other upgrades would be great??
thanks!!
thanks!!
Bang-4-Buck upgrades for 72 750
- Thread starter redFireNorton
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- Oct 19, 2005
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I did some accidental experiments to find best single hop up on a Combat is just switch to standard factory small port head and keep the 2S cam and re-up CR sans base gasket and flame ring or even mill head a bit. Then got to re do the push rod length for rocker centering. 2-1 exhaust seems to help across the power band and sheds some mass. Costs to build crank and valve train to take much if any red line for long. Some electro ignitions are not as spunky as the points so look into that too.
For brake get stiff new hose even factory kind and poke red hot nail through the factory tiny restrictor hole in master cylinder rubber valve boot.
For forks get Greg Fauth's Roadholder kit and use supplied spring spacer for added corner lean or weaker one for factory sag stance.
Oh yeah look up the pcv breather threads for cheap to exotica options.
Beyond this its gets rather expensive for each incremental step up the power curve ball.
For brake get stiff new hose even factory kind and poke red hot nail through the factory tiny restrictor hole in master cylinder rubber valve boot.
For forks get Greg Fauth's Roadholder kit and use supplied spring spacer for added corner lean or weaker one for factory sag stance.
Oh yeah look up the pcv breather threads for cheap to exotica options.
Beyond this its gets rather expensive for each incremental step up the power curve ball.
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- Jul 25, 2010
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- 5,947
Who makes a decent fuel injection for them ?
Unless you take the time to see that its all within spec and crucial parts A1 , youre more likely to induce problems .
Though Cam , valve springs ( you get what you pay for , unless you find something else , and aftermarket carbs , would start it moveing .
A lot of time goes into carefully dismantleing and inspecting the whole cabbodle .First priority is the correct tools .
Overhauling the cradle / suspension / iso's would keep you occupied whilst you study the engine / Trans and get to know it.
And see something achieved so as not to get discouraged.
Inspection may well dictate primary disposal of funds . :shock: :cry:
Though if its all sweet and you dont wreck anything youll be doing well .
If the primary set up was chewed to bits the loot'd be beter spent on the belt drive conversion .
Id regard stock carbs , shocks , & valve springs as scrap metal , W.F.T.O.M.
The use itll be put to and the roads in youre area would have a bearing on how you looked at ' improveing ' it .
Seeing the design is of more leared chaps than our humble selves , it pays to see that it will actually improve the device,
within the constraints that it was a production machine and therefore economics prevented excess hours spent polishing and perfecting internals .
Needle rollers replaceing bushes is a csase in point . A collection of small gains will likely se beter results than dramatic alterations . :| :mrgreen:
Unless you take the time to see that its all within spec and crucial parts A1 , youre more likely to induce problems .
Though Cam , valve springs ( you get what you pay for , unless you find something else , and aftermarket carbs , would start it moveing .
A lot of time goes into carefully dismantleing and inspecting the whole cabbodle .First priority is the correct tools .
Overhauling the cradle / suspension / iso's would keep you occupied whilst you study the engine / Trans and get to know it.
And see something achieved so as not to get discouraged.
Inspection may well dictate primary disposal of funds . :shock: :cry:
Though if its all sweet and you dont wreck anything youll be doing well .If the primary set up was chewed to bits the loot'd be beter spent on the belt drive conversion .
Id regard stock carbs , shocks , & valve springs as scrap metal , W.F.T.O.M.
The use itll be put to and the roads in youre area would have a bearing on how you looked at ' improveing ' it .
Seeing the design is of more leared chaps than our humble selves , it pays to see that it will actually improve the device,
within the constraints that it was a production machine and therefore economics prevented excess hours spent polishing and perfecting internals .
Needle rollers replaceing bushes is a csase in point . A collection of small gains will likely se beter results than dramatic alterations . :| :mrgreen:
- Joined
- Oct 19, 2005
- Messages
- 18,978
Another rather big expense item is steel flywheel as ancient cast iron issue are shatter prone near red line and boy howdy are Combats and similar configurations eager to pull beyond that in a hurry in lower gears or even 4th. Lighter flywheels tried by racers just slowed their track times so stick close to stock but I loved my 4.5 lb ligher smaller flywheel in my Ms Peel special, beat all comners in rev up contests even spotting them buzz bomb in line 4's 4000 on tack or they lagged to match to even have a chance. Ms Peel was fully cyrogentic tempered then Tungsten dioxide dry friction coated engine to tranny so lower friction than most. Poor moderns all went vaarRRROOMMMM to 9000 rpm, Ms Peel would fling tack needle from 2000>7500 before I could snap to WOT> BLATT.
Almost all the 'hot' street-road race cams are just minor variation of basic 2S profile. After that you must remove engine metal to fit the radical cams.
State your pocket book size and we can find the parts or processing to fit.
Belt drive is good device for loss of spun and sprung mass and oil/clutch mess.
Best place to spend first for bang for the bux is the wheels. Put on Al rims and seal the spokes then run tubeless for significant kick and fling and brake increase.
Stick with narrow lighter tires for ice skater like aiming and less mass. Practice on half aired tires so you can handle the excess speeds and G's you can get a Comat to deliver.
When I first got a plain Jane well used but well maintained Combat in summer of '99 by fall I realized too leaky worn not to open to renew, so on eve of Y2K I tried to break it on my way back home near dusk. It felt like a 3rd piston kicked in at 6800 as front floated in 1st then again in 2nd as I held on to past 7500 while dicing a S shaped chicane. When front lifted in leaned state I didn't let off but did lift eyes back to road, so don't know how fast before next snick to 3rd leap. Look at my avatar taken first week on this stock Combat getting the jump on the 1200 cammy wheelie bar'd Sportster. Not the flashy stupid wheelie look at the rear tire buckle throwing out asphalt and rubber not spun to smoke just insane hook up grind out of there. It takes a hard heart to really run a Combat into full cam ram as w/o some bux its also using them right up.
But hey how long ya think ya got to enjoy this stuff so get on it.
Almost all the 'hot' street-road race cams are just minor variation of basic 2S profile. After that you must remove engine metal to fit the radical cams.
State your pocket book size and we can find the parts or processing to fit.
Belt drive is good device for loss of spun and sprung mass and oil/clutch mess.
Best place to spend first for bang for the bux is the wheels. Put on Al rims and seal the spokes then run tubeless for significant kick and fling and brake increase.
Stick with narrow lighter tires for ice skater like aiming and less mass. Practice on half aired tires so you can handle the excess speeds and G's you can get a Comat to deliver.
When I first got a plain Jane well used but well maintained Combat in summer of '99 by fall I realized too leaky worn not to open to renew, so on eve of Y2K I tried to break it on my way back home near dusk. It felt like a 3rd piston kicked in at 6800 as front floated in 1st then again in 2nd as I held on to past 7500 while dicing a S shaped chicane. When front lifted in leaned state I didn't let off but did lift eyes back to road, so don't know how fast before next snick to 3rd leap. Look at my avatar taken first week on this stock Combat getting the jump on the 1200 cammy wheelie bar'd Sportster. Not the flashy stupid wheelie look at the rear tire buckle throwing out asphalt and rubber not spun to smoke just insane hook up grind out of there. It takes a hard heart to really run a Combat into full cam ram as w/o some bux its also using them right up.
But hey how long ya think ya got to enjoy this stuff so get on it.
- Joined
- Aug 19, 2010
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- 1,967
For me, bang for buck, in 2011, these bikes are worthy of refinement, not total reformation.
As for chassis -
Ream the swing arm pin's tube to fit a new oversize swing arm pin and be sure to weld/install fixing bolts/ring to pin the new oversize pin in place and prevent it's rocking in the swing arm pin's tube. Then replace the shim style isolastics with vernier isolastics and while you're at it install an upgraded upper head steady. There are several fork mods/kits; getting rid of the bottoming and topping clashing and clanging is nice.
As for engine -
Lock down the auto advance to isolate/eliminate it from unstable idle/hard starting that you might otherwise attribute to carburetion, or, get a magneto or electronic ignition.
Assuming your carb bodies are worn, sleeve or replace them with a new set of carbs. If your carb bodies are not too far gone, you might get by with just some new anodized aluminum sleeves.
A crank case reed valve reduces oil leaks generally and if you get one that uptakes in the sump, instead of the timing chest, it will help evacuate wet sumped oil.
Generally -
Do these easy, less expensive things first. They involve very little down time. Wait until there is a reason to pull the head or to split the cases to go for the port job or the cam. Enjoy the bike now.
As for chassis -
Ream the swing arm pin's tube to fit a new oversize swing arm pin and be sure to weld/install fixing bolts/ring to pin the new oversize pin in place and prevent it's rocking in the swing arm pin's tube. Then replace the shim style isolastics with vernier isolastics and while you're at it install an upgraded upper head steady. There are several fork mods/kits; getting rid of the bottoming and topping clashing and clanging is nice.
As for engine -
Lock down the auto advance to isolate/eliminate it from unstable idle/hard starting that you might otherwise attribute to carburetion, or, get a magneto or electronic ignition.
Assuming your carb bodies are worn, sleeve or replace them with a new set of carbs. If your carb bodies are not too far gone, you might get by with just some new anodized aluminum sleeves.
A crank case reed valve reduces oil leaks generally and if you get one that uptakes in the sump, instead of the timing chest, it will help evacuate wet sumped oil.
Generally -
Do these easy, less expensive things first. They involve very little down time. Wait until there is a reason to pull the head or to split the cases to go for the port job or the cam. Enjoy the bike now.
My big bang upgrade are many but the biggest are the radius ground cam and BSA radius lifters. Add good main bearings, big bore exhaust and a solid carb upgrade and you will have the foundation for a hot street bike.
Lubrication curcuitry is good to study up on. Money spent here will help you sleep better.
The crank is the heart of these bikes but it's the head that makes it go. Anything you do in relation to the head will be money well spent. Fortify the gearbox and any drive related items to handle performance upgrades and the goosebumbs will rise when ever you take a good twist of the throttle. Everything else will be an add-on, like belt drive, oring chain (not necessary) fancy electrictronic and the like.
I didn't mention any dealers or manufacturers in an effort to keep your thread on point. Fell free to pm for details.
It all has to work together and one thing will lead to another. Think "system". Many assemblies make up a solid unit. This is one of the great things about a norton. You can address them all at once or one at a time depending on your money, time line and priority.
Hey man, Red is my color. Hows bout some pics.
Lubrication curcuitry is good to study up on. Money spent here will help you sleep better.
The crank is the heart of these bikes but it's the head that makes it go. Anything you do in relation to the head will be money well spent. Fortify the gearbox and any drive related items to handle performance upgrades and the goosebumbs will rise when ever you take a good twist of the throttle. Everything else will be an add-on, like belt drive, oring chain (not necessary) fancy electrictronic and the like.
I didn't mention any dealers or manufacturers in an effort to keep your thread on point. Fell free to pm for details.
It all has to work together and one thing will lead to another. Think "system". Many assemblies make up a solid unit. This is one of the great things about a norton. You can address them all at once or one at a time depending on your money, time line and priority.
Hey man, Red is my color. Hows bout some pics.
A good solid rebuild that includes proper head work and parts like ampco bronze guides, black diamond valves and springs set up properly, fix the 3 head studs NOW, a clean straight bore along with quality pistons and rings, superblend main bearings set with proper end play, a good oil pump and there is more to it than just laping the end cover and housing for end play,the CORRECT oil sump mods along the breather system, a proper seal on the tach drive, a good electronic ign system, I prefer trispark or pazon, if it is a combat stay with a combat grind if it is a standard than a stock grind, on a combat I like to machine the piston tops 20 30 thousand's to help with todays gasoline, a clutch push rod seal will be some of the best money spent to stop clutch issues, stay with the surflex plates, a belt drive is nice as the weight loss is easer on the gearbox, if you need new final drive do the 520 O'RING conversion = less maintenance, a good swingarm pin fix with the heinz collars. most of this is if you have the bike apart but you can pick and choose if it is still in one piece. do it once do it right and it will last a long time but skip a small item it can get costley. it is not just put it togather and ride it bike as it will need things like head retorques, valves reset and proper break in on a new motor.
bill said:
With you on nearly all that but for the 520 chain conversion. From my studies and from people who have done it, it appears the chain lasts longer but the sprockets wear quicker. I find it much easier to change chains on a Norton than sprockets. Also, if you fit a belt drive and use Barnett plates then the migration of gearbox oil onto the plates becomes a non-issue because the Barnett plates are made to run in oil. I've done about 20,000 miles now with Barnett plates with no clutch issues at all.
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- Dec 28, 2009
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Well said Windy , Couldn't have said it better myself !
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- Oct 19, 2005
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- 18,978
520 is on enconomy mod as indeed does eat the teeth rather faster, just fit 530 x-ring and let it eat itself a clear path if not clear path to begin wit.
My Combat just did 1000 mile trip getting on it in climbs on 87 octane no ethanol pump gas just fine and rushed to over 100 mph surprising faster that I expected.
Motorcycles and women are endless shopping spree's.
My Combat just did 1000 mile trip getting on it in climbs on 87 octane no ethanol pump gas just fine and rushed to over 100 mph surprising faster that I expected.
Motorcycles and women are endless shopping spree's.
I like the 21-watt halogen pilot light from Walridge--it's bright enough to satisfy the gendarmerie--and high beam looks like a flamethrower when I flash motorists making left turns or entrances from side streets
Tim Kraakevik
kraakevik@voyager.net
'72 Combat, '74 RH10 850
Tim Kraakevik
kraakevik@voyager.net
'72 Combat, '74 RH10 850
rvich
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- Jul 25, 2009
- Messages
- 3,189
Some basics...
Is your 750 a Combat? Change the oil pick up. Put a breather on the crankcase. Regardless of model, put a proper layshaft bearing in the gearbox! Build a custom wire harness or at least change out all the connectors on the stock harness and clean up that kill switch! Some of the stuff that will make the biggest difference doesn't cost very much but time.
Is your 750 a Combat? Change the oil pick up. Put a breather on the crankcase. Regardless of model, put a proper layshaft bearing in the gearbox! Build a custom wire harness or at least change out all the connectors on the stock harness and clean up that kill switch! Some of the stuff that will make the biggest difference doesn't cost very much but time.
- Joined
- Aug 11, 2009
- Messages
- 294
All this talk about going faster, how about stopping faster? If you have front disc brake, take it off and have it Blanchard ground or at least take a sander and some 30 grit paper to it and clean it up. Get a set of AP Racing brake pads (best ones I have had any experience with) and a stainless steel front brake hose. These modifications will yield a much better front brake performance and feel.
If your budget can stand it, have master cylinder resleeved to 13mm bore as well as having your brake rotor lightened by drilling, you can then have it coated to prevent rusting of rotor. I will be sending mine out this winter to have that done.
If your budget can stand it, have master cylinder resleeved to 13mm bore as well as having your brake rotor lightened by drilling, you can then have it coated to prevent rusting of rotor. I will be sending mine out this winter to have that done.
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