Hi there, I just aquired 2 1977 Benelli 750 Sei's.
Both were found in a barn in 1980 and kept in a garage till now. Both have good titles. Could not turn them down at the price I was offered them for :-)
1/ 1977 Red Complete bike except calipers and rear brakeplate removed to move it around. 8K miles engine stuck 6 into 1 exhaust.
2/ 1977 Green Complete bike but completely stripped down into parts except the engine. 6K miles engine stuck, 6 into 1 exhaust. All parts in very good restorable condition.
Question is with the stuck motors....I have started filling with oil/rust remover and will leave to soak for a while. If I get them unstuck what would be best way to go as they are both low mileage engines....just a complete strip/clean/replace bearings,circlips etc and hone with new rings. Or complete strip and crank inspection only...maybe rebuild (will be expensive). Were the cranks normally good on these?
I am used to working/restoring Kawa Triples but this is my first 4 stroke. Had one of these on my wall as a teenager so would love to get one at least up and running. Have got parts and workshop manuals on order...Thanks will try and post pics later.
Last edited by Orlando6; 07-13-2011 at 11:11 AM.
If the motor is "stuck" due to standing for 25 years I would not take any chances and would strip down and check everything. Once tha barrels are off check the bores & rings, if Ok and the engine will then turn over plus there is still the right level of oil you could be fine with just a top end strip down.
Also both tanks look good apart from where the badges fasten into the tank...anyone explain how they come off? Thanks
Hello ORLANDO, welcome !
Thankyou Georges,Droid etc, I am waiting for my 750 Sei workshop and parts manuals to turn up. Anyone stripped these engines down completely before?
My engine has 6K original miles but is stuck due to being in a barn/garage 30 years. I have taken rocker cover off/apart and everything inside is like new. Want to take the head off to work on stuck cylinders but do not have manual yet. Whats the best procedure for removing head (sorry am used to 2 strokes)? I have all fasteners off just cam chain holding cam to the head, what is correct way to move this? 2 bolts through top cam sprocket to cam lobe cannot be reached and engine is stuck remember so can't turn it. Sorry to go on but just love working on this beautiful engine so far.
My intentions if all go well is completely strip engine. Vapour blast all engine crankcases/head/cover and paint/polish as necessary. Hopefully just check crank/bearings, clean inspect all internals just replacing bearings/seals/circlips.
Hopefully get away with hone and maybe new rings if damage is not bad. Fit new type coils and electronic ignition and hopefully ready to go!
Last edited by Orlando6; 07-16-2011 at 05:28 AM.
If you don't as yet have a manual, let me have your email address and I will send you a copy of mine.
Take all the plugs out and spray down with WD40, leave for a week before trying to lift the barrels.
Hi Droid Thanks for that, have pm'd you my email.
I have stripped just about everything I can on this motor now. At the moment I have a very rusty boat anchor
Looks like the engine was left for a large amount of the 30 years in the barn without inlet and exhaust covered which means valves very corroded as well. One spark plug snapped off as it was corroded in, so can't get in to soak that cylinder. Will get a nice long easy out for that should do it.
My dilemma is...the 2 bolts holding the upper cam chain sprocket on the cam are visible but cannot get socket on them to get cam chain loose to remove the cam, then the head so I can work on the stuck cylinders. The bolts are below the top of the head. I can grind down a 10mm wrench to loosen them but they won't come out enough because they hit the head. I can't turn the engine to get them clear because it is stuck so.....the only way I think I can get the head off is grind down a 10mm wrench, undo the 2 bolts enough to get a gap between head of bolt and the sprocket and saw the head off the feckers
Then with the head off I can work on the stuck cylinders. I have experience with stuck cylinders from my Kawa Triple restorations so I,m hopeful to sort it sooner rather than later.
Still the complete bike (which is in the same condition) and the complete parts bike only cost me $100 each so I think I should be able to get at least one nice bike at least on the go eventually.......Laters....have found my camera so will try and get some pics.....
Last edited by Orlando6; 07-17-2011 at 03:48 AM.
Welcome Orlando and congrat. You have a nice, hard and long work with these beauties...
I´am also rebuilding a 1977 MK2 750 Sei, basically paint, electrical and rubber connections and looking for head lamp and front mudguard.
I have not open the engine (and hope to don´t need to do...).
Hope to see pictures from them!.