Author Topic: 1977 Benelli 750 SEI (Read 4699 times)

BenelliSEI · « **on:** March 07, 2019, 05:13:20 PM »

18 months ago I heard about a lady selling her husband’s project motorcycles. None were complete and the list included two 1970 cb750K0’s. I was building one for my self and though5 I should have a look....... long story made short: I bought 7 bikes in various states, and lot’s of NOS parts he had been collecting for 40 years. Kept all the “gold” and sold the mortorcyles as I got them finished up.

Except for the Benelli 750 SEi! The engine looks a lot like a cb550 with two extra cylinders. 3 X Dellorto carbs feed thru’ wishbone manifolds. Exhaust is a BUSSO 6-6 with almost no baffles or restrictions. Twin Brembo front discs, Borrani wire wheels, and some funky all steel body work. Even the fenders and master cylinder are sculpted to match the design theme. It’s actually smaller than a CB750 whenon board and cleverly hiding the alternator up above the clutch pack keeps it relatively narrow.

When I first fired it up, it was like having a 1970’s V12 Ferrari F1 car in the shop. Despite only collecting Hondas, I still have it and plan on adding to the 1000 miles I put on it, late last Fall. Compared to my Hondas, it’s a pain to work on it, but I’m keeping this one...... The CB750 turn signals in the photo just got replaced with the correct CEV units, but there are a few Honda parts hidden away.

MoMo · « **Reply #1 on:** March 07, 2019, 05:17:47 PM »

very nice. Larry

HondaMan · « **Reply #2 on:** March 07, 2019, 06:30:41 PM »

You've done a beautiful job of putting it back together! They are a very flashy ride, loved their look.

They were said to have mediocre handling, due to 'chassis issues', which I suspect are all in the pivot for the swingarm. If you get to the point of wanting to rebuild that sometime, I might like to take a crack at it?

BenelliSEI · « **Reply #3 on:** March 07, 2019, 08:44:15 PM »

Mark....... thank you! I made new bushings and it’s good at the back. Building a second set of forks now. They have a weird cartridge shock absorber built in, that needs some attention, but other than that it’s all working well. The main winter project is building a degree wheel mount for the LHS end of the crank. I installed an Electronik Sasche ignition system that entails removing the original advancer...... I want to be able to check idle and full advance with a strobe light, to ensure the settings are spot on. It’s only run 7500 miles and all seems spot on. Pretty cool ride and totally unique here.........

nvr2old · « **Reply #4 on:** March 11, 2019, 05:18:32 PM »

I've always wanted to do a Benelli and make it look as much like a Honda as possible and have special graphics for the side covers that say..wait for it..SeiBX..

HondaMan · « **Reply #5 on:** March 11, 2019, 06:27:28 PM »

Quote from: BenelliSEI on March 07, 2019, 08:44:15 PM

Mark....... thank you! I made new bushings and it’s good at the back. Building a second set of forks now. They have a weird cartridge shock absorber built in, that needs some attention, but other than that it’s all working well. The main winter project is building a degree wheel mount for the LHS end of the crank. I installed an Electronik Sasche ignition system that entails removing the original advancer...... I want to be able to check idle and full advance with a strobe light, to ensure the settings are spot on. It’s only run 7500 miles and all seems spot on. Pretty cool ride and totally unique here.........

Nice work!
What is a "Electronik Sasche" ignition? Was it especially made for this unique bike?

BenelliSEI · « **Reply #6 on:** March 14, 2019, 11:54:08 AM »

German Company...... they make programmable ignition systems for older Moto Guzzi, Ducati, and Benelli. Very nice stuff! Check out their web site.......

Don R · « **Reply #7 on:** March 16, 2019, 07:10:18 AM »

My brother became a Benelli dealer when these came out. He never got one to sell, ordering was tied to selling the smaller bikes to qualify for the right to order one. He couldn't move enough small bikes around here to get the bigger ones.

BenelliSEI · « **Reply #8 on:** March 20, 2019, 02:19:27 PM »

My Benelli came with a spare set of forks and two NOS fork bottoms, still in the bags. They had some shelf wear, so I refinished them and took apart the spares. Tubes are clean and straight. Weirdest thing, they actually have a small set of shock absorbers (sealed) inside! Identical to same vintage Moto Guzzi (A. DeTomaso owned both firms at the time) so parts ordered from MGCycle in the USA.
Here’s what they look like. That “screen door closer” is the shock absorber.......

BenelliSEI · « **Reply #9 on:** March 21, 2019, 09:35:00 AM »

Pressed in new seal sets, still waiting for parts to complete. My K0 and F0 and the Benelli are going to the Toronto Spring Motorcycle Show. Hoping to get these installed before that......

BenelliSEI · « **Reply #10 on:** March 27, 2019, 11:41:19 AM »

Got the parts I was waiting for today. Listed for a Moto Guzzi of the same era, all identical, right down to the bolt sizes and pitches. Phew! Fair prices and fast delivery from MG Cycle in WI. I already had seals, so here are the bottom sealing washer, dust seals, top cap “0” ring, and shock absorbers.

BenelliSEI · « **Reply #11 on:** March 27, 2019, 11:42:17 AM »

Eat, Sleep and Repeat.......

Old Moe Toe · « **Reply #12 on:** March 28, 2019, 01:16:19 AM »

Saw this 900cc model just last weekend.

BenelliSEI · « **Reply #13 on:** March 28, 2019, 04:49:36 AM »

Moe...... I’ve yet to actually see a 900 SEI! There are a few 750’s, but not sure any 900’s ever made it to Canada. Cheers.

BenelliSEI · « **Reply #14 on:** March 28, 2019, 10:33:05 AM »

All done, ready to swap in. Good timing!

BenelliSEI · « **Reply #15 on:** March 29, 2019, 04:08:42 PM »

Got it all back together today and the front nd feels great. Too bad my road is 3”s deep in mud, gravel and frozen ice chunks.......

BenelliSEI · « **Reply #16 on:** April 24, 2019, 03:58:46 PM »

Installed the new fork set. Parts came from a USA Moto Guzzi Shop. The forks are dampened by a shock absorber on top of the spring. They supplied an upgraded unit, bolted right in. Fork legs (bottom half) were an NOS pair I had. New seals and oil, slipped right in. Ready to ride!

BenelliSEI · « **Reply #17 on:** July 29, 2019, 02:46:53 PM »

Discovered that a stock SOHC cb650 oil pan is a bolt on replacement for the Benelli part. It’s an inch deeper and has lovely internal baffles and cooling fins. Extended the Benelli oil pick up by the same amount and increased my oil capacity by almost 40%! It doesn’t hang below the pipes, so no clearance issues either. Delighted!

Bankerdanny · « **Reply #18 on:** July 30, 2019, 01:12:06 PM »

Quote from: BenelliSEI on July 29, 2019, 02:46:53 PM

Discovered that a stock SOHC cb650 oil pan is a bolt on replacement for the Benelli part. It’s an inch deeper and has lovely internal baffles and cooling fins. Extended the Benelli oil pick up by the same amount and increased my oil capacity by almost 40%! It doesn’t hang below the pipes, so no clearance issues either. Delighted!

Now that is very cool. I doubt I will ever need to use the info, but I will file it away all the same.

BenelliSEI · « **Reply #19 on:** July 30, 2019, 07:07:58 PM »

Discovered it on another website and I had a cb650 pan. Identical base section. No question Benelli copied lots of Honda parts. The engine looks just like a cb550 with two extra pots.I wonder if the 650 and 550 pan are the same???

MauiK3 · « **Reply #20 on:** August 04, 2019, 10:23:18 AM »

Weird how they squared off the fins on the head, seems to not fit with the other lines.
Very cool bike.
I don't know what I'd do if I stumbled across such a find as you did, dangerous stuff all that NOS K0 stock!!

BenelliSEI · « **Reply #21 on:** August 04, 2019, 04:36:36 PM »

MauiK3...... everything is sculpted on the bike. The instruments are in weird cube shaped plastic and even the master cylinder is machined from a cast alloy that looks like a pyramid with the top cut off. DeTomaso had just bought the company and he wanted a unique design!

BenelliSEI · « **Reply #22 on:** August 10, 2019, 04:25:33 PM »

First really good ride since building a degree wheel for the LHS of the crankshaft, to accurately check the electronic ignition setting at idle and full advance (with the engine running and timing light). The problem is the electronics trigger installation calls for removing the mechanical advancer (identical design as a SOHC-4) so all the timing reference marks are gone. It was off a bit, so I slotted the mounting holes for the ignition sensor base plates and nailed it.

What a difference, had to turn the idle down when hot and it ripped through the gears. The 6-6 pipes don’t have much baffling inside, so after an hour and a half, I’d had enough! Ear plugs next ride. What a great machine. Front end is really working well, brakes are fantastic. The rear shocks are NOS originals and marginal. Hagen makes a set but will check with IKON first.......

MauiK3 · « **Reply #23 on:** August 11, 2019, 10:13:26 AM »

I'm liking my Hagon's, good service, quick delivery all the way from UK to Maui!

BenelliSEI · « **Reply #24 on:** August 11, 2019, 06:00:11 PM »

Hagon will put one together that looks almost stock. Mmmmm.

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Author Topic: 1977 Benelli 750 SEI (Read 4699 times)