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Home Motorcycle Home Triumph Home Export Home Norton Info Home Special Parts Updated 10/24/25 Master Switch Bracket Updated 02/28/25 MKIII Rebuild Updated 10/10/25 Combat 5 Updated 12/16/25 High Mileage Combat Updated 12/16/25 Roadster 850 Updated 09/21/24 Customer Combat Partial Rebuild July 24 Delivered 03/22/25 850 Commando Recommission Delivered 09/20/24 Customer Combat Build Oct 23 Shipped 7/13/24 1975 Norton Wiring Delivered 06/07/24 Blue 69S Delivered 05/17/24 High Mileage 850 Delivered 03/26/24 Mk3 Engine & Gearbox Delivered 03/07/23 1973 Customer BasketCase Build Delivered 07/15/22 1974 Norton 850 Commando Rebuild Sold 01/12/21 Updated 06/10/21 Customer Combat Delivered 09/07/20 First Place Norton 05/18/2025 1972 Norton 750 Commando Rebuild Completed 05/15/19 First Place Norton 05/16/19 Sold 01/01/20 1972 Norton Wiring Completed 07/19/18 1974 Norton Wiring Completed 07/27/20 Customer Combat and 69S Builds Closed 10/18/23		Wednesday, December 17, 2025
	November 24, 2025 Originally, I wasn't going to document this as I've documented engine/gearbox rebuilds before. But the owner's story tells me that this one might be interesting. Especially since this will be the highest mileage Norton I've ever worked on. As a part of his introduction, the owner said: "I recently acquired my old college roommate's 72 Norton 750 Interstate with a Combat Engine. It has over 78K miles on it and supposedly has never been opened up except to replace a cracked piston skirt early on in its life. He was stationed in Germany in the 70s and bought and had shipped back this bike from England so he is the original owner. I have known him for over 50 years and his recent bad health has had him put the bike up in 2021 until this August when he gave me the bike. I have gotten it running but there is knocking noise coming from the cylinder head I believe and it pops out of first gear. So I would like to get the engine and transmission rebuilt." He is planned to bring me the engine and gearbox this weekend. I'm hard at work on Combat 5 and two more heads and MKIII Rebuild but I'm always stuck waiting for parts so this should fit in just fine. The goal it for him to have it back to ride in the spring. Of course, that will be much easier if I don't do any hospital stays! Today, I looked around for a clear flat spot to put his engine on - found none - so I spent a lot of time straightening, putting away, and cleaning and now there's a place! This will be it's home at least while taking it apart and figuring out what it needs. Then it can go in bins until ready to be assembled and the gearbox can be worked on here. I considered building another of my mobile work tables as it would be more comfortable than working at a Workmate but I need to get some of these projects done! BTW, the black thing is a heavy duty "Lazy Susan" and the engine stand is a modified version of the stand Andover Norton makes. I have sent them the plans and hopefully once they've sold their current stock they will start making my improved version. With mine, you can get at the bottom bolts and screws and you can get to the sump plug(s). Also, when I ship engines, I mount them in this stand, screw the stand down to wood and that becomes the bottom of the crate - of course, insisting that the receiver take the stand apart and send it back. December 5, 2025 New plan - he's bringing the engine this Sunday. Issue: leave a flat spot untouched around here and it gets touched! I'll need to do some cleanup to get it back to the picture above :-) Also, guys are coming out of the woodwork - there may be another guy coming tomorrow or Sunday with an engine to rebuild and there's a guy out west considering sending a seized engine to be fixed. December 7, 2025 The brothers are back! Bike builds run into each other but I knew the owner of this one was the brother of the owner of another documented bike. That bike was the previous highest mileage bike! High Mileage 850. That bike is doing well. I meant to take a picture before doing anything, but we got to talking and I enforced my rule: "Visit me and you have to work!" It's hard for me, especially with the engine up high, to get the head loose so the brothers and I did it. The bike has at least 78k miles and it's only been apart once when it was almost new for a "broken piston skirt" which probably really was the top of the piston came off - those original Combat pistons had a bad habit of that and this a VERY low serial number Combat. One bore looks excellent and the other has some marks but you can still see the cross hatching in both! It currently has +0.020" pistons and since they were replaced early-on, they are likely the bad kind. The owner said that it has a top end noise and I took a cursory look at the head and didn't see anything. He wants my full treatment so we'll see when I get the head apart. It may be a while before I do much other than get the cylinders off and determine if they need bored as Combat 5 is the priority right now. December 10, 2025 Had some time today between coats of pain on Combat 5's cradle. Took the cylinders off, did some inspecting, and found some surprises. All the base nuts were only slightly more than finger tight! It's like this is two engines in one. Notice the timing-side piston in the first two pictures (left in the first, right in the second). That piston is in bad shape. The other piston, is in great shape! So, I measure the taper in the two bores: Drive side is only 0.002" - 0.004" is the max so that side could go a long time more. Timing side is 0.005" so past allowable On top of that, the pistons are the original type that tended to lose their tops so they need to be changed anyway. Of course, the only piston size I'm out of is +.040 for 750 :-( The third picture shows the shocking part! Those tappets look better than any I've seen in an engine rebuild and the are very smooth in the tunnels. That's good, because they are VERY expensive new and even though I buy used sets whenever I can, the best set if have would take me 3-4 hours to flatten where these only need a 30 minute touch-up. I haven't checked the cam yet but as good as the tappets are, there's a chance that it will run again. (1 Hr Today) December 13, 2025 Was working on getting the rest of the engine apart when the owner called to see if he could bring the gearbox by. When he got here, I invoked my shop rule - visit and you work! We got it all apart except for splitting the crank - very helpful! There continues to be amazing things: Many things loose but some tighter than expected. The intermediate gear shaft in the timing chest does not wiggle but easily pulls out of the crankcase. It should be OK as is, but once the cases and timing cover are clean, I will put it in with some shaft mount Locktite and I'll put the timing cover on and leave it overnight. The oil pump appears to have never been serviced, or at least the screws never staked. When I turned it and looked in the return port, it looked like the gear was not turning. Took the pump apart and it turned out that the was a broken piece of metal in the return port that did not come out of the pump. The port was no completely blocked so the pump worked. I'm almost positive it left the factory that way! Once of the return gears was slightly hitting that piece of metal so I'll change that gear.. It's mate looks fine. The inner race on one main bearing is not tight on the crank. It's a easy slip fit and should be a much tighter fit. When I put it back together, if that's still the case I'll use bearing set Locktite on it. It's not bad enough to need anything more. The big end shells look great - very hard to believe 78k+ miles. Of course I'll install a new set. The big end journals have light marks that cannot be felt. I have not checked them with a micrometer yet , but I'm guessing they only need a quick polish. The conrods look fine. A little polish and a slight nick or two to remove. (6 Hours today, but had help so only counting 3. Running total, 4 Hours) December 14, 2025 This engine keeps amazing me! Measured the big-end journals today. Both measure 1.7500 in all directions. The factory size is 1.7504-1.7509 and if ovality or scoring is over .0015" then it must be ground. These have 0" ovality and are well within .0015" of original. So, this crank does not need to be ground. I used some 1000 grit paper and WD40 to polish up the journals - they are good. Then I inspected the cam. The lobes look great. There is some minor scoring on the timing side journal that runs in the bushing and I need to study that more but off hand - I think this cam can go back in. I always change the timing-side bushings to the MK3 style - especially on 73/73 engines because the inner thrust washer tab can break off and run through the engine and there is no outer thrust washer. The MK3 type corrects both issues. Once I have those bushings in, I'll recheck the cam journal. Inside a Command crankshaft is a sludge trap. Prior to having oil filters, a lot of sludge would be caught in there. Often there is little to none if an oil filter is installed and the oil is kept changed. Of course, there's no way to know withut splitting the crankshaft. The pre-MK3 crankshafts, have a big location pin that goes through the flywheel and both cheeks, and it has two bolts at the top that are a tight fit - between them the crankshaft is aligned side-to-side. There are four more bolts or studs that simply provide clamping force. Once all the nuts are off, wiggle, wiggle wiggle and the crank comes apart - usually. Sometimes the top two bolts/studs are too tight and need to be drifted out. On this crank, one of those was hard to drift out, and the other was almost impossible! I never had so much trouble getting a Commando crankshaft apart. Once out, I could see a slight bend in that bolt and a burr on the cheek. Originally the top two and middle two were bolts and the bottom two were studs. They will all be replaced with the later studs. In the first picture you can see no sludge. The only thing I did at that point was spray some WD40 and wipe them out - shockingly clean! Then I checked the oil holes in the journals as I often find issues there. On the timing side, one hole was not fully drilled so there was only a pinhole to the inside - the right size drill was used but they didn't go deep enough. The other hole in that journal, thankfully, was done properly. The other journal had one not fully drilled but not as bad. Anyway, they are properly open now. Then I looked into the main bearing inner race on the drive side - the one that was loose. It would pull off 1/8" but no more os I setup the puller in the second picture and it came off easily. I can't tell for sure why it was able to turn on the crank, but I'm sure the new on will be good with bearing set Locktite. I pulled the race form the timing said and it came off with a lot of heat and difficulty as it normal. (5 Hours today. Running total, 9 Hours) December 16, 2025 See the first picture - the crankshaft is clean and back together. Had one issue. A while back, I bought all the individual studs and nuts from RGM Norton as they cost about half of the kit from Andover Norton. Everything seems high quality and correct. However, the two bolts for the top which are longer than the other four and slightly larger diameter were wrong. The length is correct but they are the same diameter as the other four so they were a loose fit in the top holes. Fortunately, I had two from Andover Norton that were correct! After the crank was back together I started on the crankcases. They need the sealing compound removed, the bearings removed, a good washing, and then the beautification process. The second picture shows the goop that was last used to seal the cases and the third shows it mostly removed. Still have to do the other side - took forever! (3 Hours today. Running total, 12 Hours)

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