Honda CB750 Sandcast
General Category => General Discussion => Topic started by: BenelliSEI on February 15, 2021, 04:56:28 pm
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As noted in my “Introduction”, I recently went on a bit of a road trip to buy an interesting 1975 Amen/CB750 “Chopper”, late in January. Not my typical bike, I’m currently working on a ‘75 Rickman Honda CR and most recent project was an early, diecast K0. Also in my shop is my regular ride, a very clean K1, sitting with a K3 my son rides, my wife’s “flake orange” K4, and a K6. My son and I also have two more fully restored K7 and K8, that have been parked for the past few years. The chopper was reasonably priced and the original owner sweetened the deal with a “parts bike” that he had picked up +35 years ago. When I got there, I spotted the horn on the “wrong side” of the parts bike....... I loaded up and brought every thing home. I’ll attach a few pictures here.
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I’ve spent a few days, slowly pulling the motorcycle apart. Interestingly, nothing seized, stripped or destroyed. Today I removed the swing arm and the bolt undid easily, and just slid out! Clearly this bike has never been left outdoors. Basically have it down to the bare frame, oil tank still attached. Carbs, handle bars and both switches were missing, but essentially complete. The horrific luggage rack and crash bars have been binned. I have a set of carbs (non 28) that I’m cleaning up. The engine is free, turns over easily on the kicker, and I can find all the gears. I have the bores soaking in oil that I fed in through plug holes and intake runners. The exhaust is very original and despite a few marks and small holes, is saveable. Thinking I might built a basic wire loom (power a solenoid with a remote start button and coil feed) to spin it up? Check for noises and decent oil pressure. If that all works, do a “3,00 mile tune up”, install the fresh set of carbs, new plugs and fire it up?
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Earlier one of the forum members here asked about case marks on the engine. Today I found a couple, just to the right of the drainage slot in the top case. They look like my sketch here. What do they mean?
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A few pictures of my K0, to offset the Chopper photo!
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Yesterday I hung a solenoid, start button and a few cables on the frame. Been “oiling” the bores and turning it over on the kick lever, all week. Top end is oiled, valve clearances checked...... installed an oil pressure gauge. This bike has been parked for +35 years.
Spun it up and within seconds, 70-75 psi oil pressure on the starter (plugs out). Next will drain the oil and have a look at the filter element. Currently rebuilding a set of carbs. Tempted to blow the cobwebs out of the original pipes, before I pull the motor. I’m thinking this one will only get a top end checkover! Quick hone, new rings and cleanup the head. 17,600 original miles.
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That's a good outcome. My #28 had been sitting for many many years and was stuck solid when I took delivery. After 6 months with aero kroil in the cylinders and ratchet strap on the rear wheel it wouldn't move, so I decided to pull the engine. I pushed it of the centre stand forgetting I still had it in third gear. As it came down the rear wheel bit the tarmac and would you believe it the engine freed. I pulled the engine to check the bores but couldn't recover them due to the long term seizure. Ended up with .25 over, head renovated and a complete change of gaskets and seals. While the engine was out I did a thorough clean and fix up of anything needing attention. Due to the very poor condition of the paint, a full repaint with crack repairs was the only major cosmetic work done. I also re-anodised the switchgear, re-clearcoated the alloy and machine polished the chrome.Once it was all reassembled it started first go, the only issues being an oil leak which turned out being the neutral switch and 2 floats needing replacement. Here are before and after photos.
Good luck
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More fun today, installed a set of carbs I just freshened up, checked valve clearances, set points gap, static timing and opened the remote fuel tank valve. #2 carb had a tiny split, right up one side of the over flow tube (all inside the bowl). Heard of this, but never seen one. Frozen condensation? Soldered it up.
I’d installed an old truck solenoid and starter button, with a power feed to the coils. Pushed the button and she started almost instantly. No smoke, rattles or issues. 70-75 psi oil pressure (screwed a gauge in the main cross feed gallery). Primary and Cam chains absolutely quiet. Smooth idle, clicks through all the gears effortlessly. What a BONUS day. This engine has a small head gasket leak, “top end” work only
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Hi,
When it happens like that, it's a smile :D and a good motivation for the future, happy for you!
I think with a lot of skill you will be able to straighten the bent cylinder block fins ... I had a cylinder head fin fully seated on top of the one below and managed to reassemble it fully and also to straighten a lot of twist fins on the cylinders ...
I take small oak wedges and I strike with a not too heavy hammer but the cylinder or the cylinder head must be free to move when one strikes to absorb the shocks of the hammer ... But it is important not that there is a crack start ... And do not count the time spent!
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Thanks for the encouragement! Dumped the oil and filter after a good warm up. Plan to run some clean oil through before pulling it out. The top end will come off and I will work on that damage when all the parts are separate and clean. I’ll take some pictures today.
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Ran it on Fresh oil/filter. Sync’d the carbs and really smooth and quiet. Repaired float bowl cured the drip. The two hole rear fender arrived. Beautiful, original, so no more missing parts. Need to strip it all down, and start some serious renovations.
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Nice to see you making headway John. Did I see on FB you’re looking for rims? Yours pooched? If the rear is a rolled rim I think they’re a tough find.
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Thanks! Not me, rims are fine. Including the correct rear. These parts will be replated.
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More progress today.
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Good stuff John. I’ll be watching as the project progresses.
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Repaired small holes in the rear foot bracket tubes, where a P.O. had welded stays for the luggage rack. Found a local “Hot Rodder”with a large media blast cabinet. He also has a small spray both and excellent paint skills..... going to head over there and see if we can clean up parts and do some priming and black paint on the frame, swing arm etc.
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Back from the painter today and the results are VERY satisfactory.
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Sounds good! Keep up us posted!
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Nice work. Frame and bits looks great!
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Fenders, instrument backing plates and rims are at Cambridge Chrome. Nice set of spokes/nipples arrived today. Dismantled the front forks today and ordered seals and boots. Not really working on this project at the moment, but lining everything up for a Winter 2021/22 build. Went through the “chopper” end to end and planning a test ride soon. Carbs are on the bench for a good cleaning. The engine is a very early (Jan ‘70) diecast, built up by Hensley Performance in Dearborn Mich. Alloy rods, big pistons and a FUBAR straight exhaust. Good fun!
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Nice! I love that old school scooter!
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Wayne..... thanks! It’s got me totally intrigued and sure is fun. I just have to finish the carbs and a “test ride” is next.
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Just for fun..... The chopper is finished and really is a hoot. The engine came from Hensley Performance in Dearborn Michigan. Described (by the original owner) as having “big pistons, alloy rods and a cam” it runs on KZ1000 Mikuni carbs. Pulls like a freight train and is very loud on the period FUBAR pipes!
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Chrome came back from Cambridge! Very nice work..... frame is painted and I was not going to start, but a rainy day got me clearing a few holes and test fitting a few bits......
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Chrome came back from Cambridge! Very nice work..... frame is painted and I was not going to start, but a rainy day got me clearing a few holes and test fitting a few bits......
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Love watching another sandcast resto underway. So far looks great. Waiting for the next update.
PS: did the chopper ever sell? I saw you had it on eBay.
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Chopper sold, going to Indiana! Instruments are back!
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Thinking about the original tank. Looking for a paintless dent remover wizard. It has no cracks in the original paint and the inside is good. Pop the dents, rub it down and fresh clear coat?
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Ive had great luck with paintless dent repair. The dents in this tank look shallow with no creases, so I expect you will have a great result.
I would not clearcoat original paint. It's only original once.
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Check with John at Connery Custom Paint in Scarborough. I’m pretty sure he told me he has a guy that will do tanks. Not all will.
http://www.connerycustompaint.com/
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Wayne..... Never thought of him. He painted my Benelli SEI and cb750F. Fantastic work.
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Nice. John and his late brother Dave did these custom Dyna tins for me. They turned out amazing.
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Winter and getting back on this project. Spotted this on the underside of my tank. What does it mean?
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One more photo......
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You have a 1st series 17litre triple (some say double) wrinkle tank. Has wrinkles in the tunnel and on both walls of the tunnel. Not a common tank and looks to be in good condition. Nice
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Thanks. The plan is to find a really good dent removal guy (it has a couple, with unbroken paint), then give it a good clean and polish. I have the original bodywork and plan to use it.
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Happy New Year! Back at it.
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New tubes.
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From Canadian Bearings. $10.67 for 100.
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Snow tires arrived today!
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Tree is sorted. New balls and fresh grease.....
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Cleaned the back end of the engine, before setting it up for the stand. It ran so well, I only plan on doing the top end.
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Rims have been rechromed. Prepping parts for fresh front wheel.....
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Great progress! 👍
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Thanks Wayne! Determined to do a little at a time, but totally finish each step. I’ve built 7-8 cb750’s from a bare frame before this. Thought I was done, but this one has my full attention. No plans to rush and easily distracted. Just finished this little project for my grandson.....
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Progress.....
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Next step....
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Cleaning before top end “refresh”. Aargh.....
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Great progress!
Looks like you have a later oil filter cover. Yours should be a round cover I believe (not sure exactly when the cutoff for the round cover was).
Also, the oil lines should be secured by bolts and a not screws.
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Sam....... engine #581, you are probably correct. That oil filter cover was on the bike for many years. Note the large, aftermarket, 17 mm head locating bolt. I suspect it was “upgraded”. Any ideas were I might find an original? The screw are just to keep the crud out.
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Original round oil filters are very hard to find. Many people take a later cover and turn it down on a lathe. Yamiya sells a replica. It is a bit beefier than the original:
https://www.yamiya750.com/index.php?main_page=product_info&cPath=246_21_250_62&products_id=88
If you get a that yamiya replica, i suggest turning it down on a lathe to match an original.
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Thanks Sam..... there will be a Yamiya order at one point. I’ll send you a request for the correct O.D. then.
John D.
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Straight and true.
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Thanks Sam..... there will be a Yamiya order at one point. I’ll send you a request for the correct O.D. then.
John D.
I believe this is where I got mine. It was nicely done. He’s probably sold out but who knows.
http://cb750sandcastonly.com/smf_forum/index.php/topic,921.msg15449.html#msg15449
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Wayne..... Thank you. I will enquire. J.
Wayne.... He had one left! Got it. Thanks.
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Checked balance on the total assembly. Heavy spot was a bit off the valve, so set the “yellow dot” there.
Will be nice to get the bike securely clamped to the lift table.
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Some progress today.
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Rear wheel is next. Old bearings all came nicely, for a change!
Wonder what “4 6” means?
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Casting date.
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Some progress today.
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Looking good! Take video of you getting the motor in. I’m always curious to see how people do it!
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Will do. Usually two of us and lots of used grips and pipe insulation!
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Front end coming together. Building rear wheel.
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Looking very nice! Perhaps its me, is the headlight bucket a bit faded? Cant remember if this is an original paint bike or freshly painted.
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Sam..... I just touched up a few chips, polished and waxed. The other side of the headlight is almost faded grey, but I kind of like the look. I plan to ride this bike, so I may use all the bodywork “as found”.
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Love it. I have an original paint daily driver sandcast...happy to know there is another lunatic out there! :)
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Sam..... +2 to that! There is a guy in S.W. Ontario I have run into two or three times. He is riding a blue Sandcast, that he bought new in 1969. Very clean, unrestored.
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Built up the rear wheel today. With the band and tube in place, marked the heaviest spot (7-8 spokes away from the valve hole). The “yellow dot” is opposed. Last time I took this extra step, so little weight was required, I skipped it.
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Back end is pretty much together.
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Same amount of progress at the front.
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Rear sprocket was in excellent shape, so I left it. Chain guard cleaned up well!
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Looking more like a bike. When I’m done refinishing the rear foot pegs, the “roller” is pretty much done.
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This arrived today. Thanks to those that sent me looking, and many thanks to Joerg!
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This is not the correct decal for my project. Does anyone make the correct, early style for my side cover?
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Following along here John. She’s coming along nicely. Remember the early oil filter bolt had 14 mm hex head. Your later finned cover was probably fitted with a 12 mm. Made guys less likely to torque the bejesus out of em. I think KP sourced some side cover and other decals. He’ll chime in I’m sure.
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Wayne..... thanks. I gather “early bikes” didn’t have the US pints indicated. Will be interesting to hear what defines and “early bike”? I will check my oil canister bolt.
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Wayne..... thanks. I gather “early bikes” didn’t have the US pints indicated. Will be interesting to hear what defines and “early bike”? I will check my oil canister bolt.
http://cb750sandcastonly.com/smf_forum/index.php/topic,2211.msg15948.html#msg15948
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Interesting details! Thanks Wayne. Where can I purchase the “early” oil decal (6.0pints)? My existing oil filter bolt takes a 17mm wrench and definitely looks “aftermarket”. Sources for a 14mm headed bolt?
Today I finished re plating some engine mounting hardware and building up a clean set of passenger foot pegs. I still need to decide how I am restoring my seat, but the roller is done. Engine top end work is next.
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Heading out to our first 8 Hour Endurance Race at Mosport (Canadian Tire Motorsport Park) this weekend, so this project is on hold for a while......,
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So it’s been awhile! The race season was a hoot. The LEXUS was new to our Team. It was built for the American Grand Am Series by a group of Lexus factory engineers. It had not been raced in several years, so took us a while to sort. The tired race motor finally let go mid season and we swapped over the “tuned” head to a very low mileage, stock motor. After that it ran like a train. It’s a big six, and has lots of HP and even more torque. We added a 20 gallon fuel cell so each of us could stay in the car for a full 2 hours (the races are 8 hour enduros). Power steering and brakes make it easier for long sessions, and the brute is fun to drive. Not as fast as some of the Porsches and newer imports, but very satisfying....
Took the Benelli 750 SIE to the Cobble Beach Concours, late Fall. No prizes, but a fellow from Florida took a real shine to it, so it’s headed there now. Also, sold the 1970 cb750K0 to a local guy who put +1000 miles on it. Completely stalled out on the Sandcast and Rickman CR projects, but getting back to it now.
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Back to work on #582. I had this engine running nicely in the frame, before tearing down the bike. Great oil pressure, no chain noises, all good. Pulled the head and then got stumped..... the bore portion was solidly stuck to the cases. An I mean STUCK. Built a lifting frame and hung it from the rafters. Despite a ton of soaking, penetrating muck, etc., it would not come apart.
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Today I added a pair of threaded rods sticking up from the angle iron bolted to the barrels. Built a bridging platform across the top of the head studs and pulled up with the threaded rods. Despite a tremendous amount of preload nothing budged UNTIL I super heated the base of each front stud where the dowel tubes are located. Several huge , scary hits with a brass drift and a 2.5 lbs. hammer and it finally “popped”. So pleased, I forgot to take a photo. Will take a few next shop day.
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Here’s a photo of the “lifting rig”.
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Moving forward again. Stripped the head today. “Homemade” valve spring compressor works well!
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Chatted with Brian at Rocket Performance today. They are close to me, in Whitby, Ontario. The two major components pictured above will get my first test with “vapour blasting”. I’ve seen other stuff he has done, it looks like new when completed, with no alterations to base material.
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Repairing a few bent fins will be the next order of business when the parts return from vapour blasting. The top end will get a light hone, rings and all new gaskets and seals.
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Very successful repairs completed!
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Pistons in, light hone, new rings. All well within specs. The oil rings in my RK set were too tight in the grove. The originals were not 1/2 way to the wear limit. Back in.
Guess who managed to fire a piston pin clip into the crankcase, years ago?
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Started assembly today. Side covers and paint when the weather warms up......
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A few wet days led to some shop time. Determined to do more riding than work, this summer. Buttoned up the top end. After this photo, rockers went in, valve clearances set.
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It’s been a while! A few projects got in the way and I’m still busy endurance racing an ex Grand Am LEXUS IS300 a Team of friends. Last week I received an invitation to the Cobble Beach Concours. A few years ago, I won best in show with my 1970 cb750. Took my Benelli SEI there most recently and this September I want to take the Sandcast. I typically don’t attend shows, but this is a spectacular event. Back on it, with a deadline!
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The Benelli didn’t win a prize, but still my favourite.