A previous owner has spent a lot of money on stainless exhausts, braided brake lines, new front brake master cylinder, various stainless fasteners, new tyres and so on. Oh yes, the biggest Motobatt battery I’ve ever seen, 30Ah!! But mechanically it was in need of a bit of TLC! I have certainly been kept quiet for a month and have been in a steep learning curve. The biggest problem was a copious oil leak from each cylinder base gasket. It turned out that the O-rings sealing all 4 pushrod tunnels had become rock hard and were not sealing anything. Easily fixed as it turned out and gave me an opportunity to have a look inside the engine and find it to be in great shape. I had heard horror stories about the chrome flaking off the plated bores, but mine are fine, with no signs of wear or degradation. Similarly the pistons and rings were excellent with not the smallest sign of blow-by. Maybe someone can tell me if that O-ring failure is a common problem?
Both exhaust valves (tiny valves!) had very pitted seats and one in particular needed a lot of grinding to be satisfactory, but it’s working well at the moment.
There was also a lot of oil leaking from the airbox/breather assembly. I’ve carefully reassembled that with a new filter, but I’m not optimistic about it remaining oil tight and I’ve been advised to replace it with K&N filters and a separate breather box - again any comments or other ideas gratefully accepted!
I have also attended to a host of small issues, including cleaning and re-building the carbs, overhauling the starter and replacing quite a lot of dodgy wiring. BUT, none of these things are particularly unusual for a 40 year old bike and I think there is an awful lot to like about it! I am well impressed by its handling, I find the engine very willing and against my expectations I find I like the linked brakes. I think I shall get on well with this bike. Now there must be something I don’t like, hmm - oh yes, I don’t like the side stand very much.
By the way, does anyone know if that red is/was a standard colour, or has it been re-sprayed?
Thanks for the reply. I had looked on Google images and I could see red ones with and without the lining. I could also see different styles of lining, so I still wasn’t sure. The paint quality is “pretty good” - i.e. not perfect but certainly a professional job. I’m not sure how good Guzzi factory paintwork was in 1980 but I could easily believe it’s original. The bike has 14,000 miles on the clock and I have enough old MOTs to make me think it’s genuine, of course I could be wrong.
I am riding it! I put about 40 miles on it yesterday and re-torqued the head nuts today. I got almost a quarter turn on each nut so I guess I’ll do another 50 miles or so and check it again. No problems though - except a big question mark over ignition timing, I’ll post another topic on that subject though! No oil leaks, yippee!
Stick with the standard airbox if you can. I don’t know about the 500’s, but I have an older 750 that the previous owner put K&N’s on, you could easily lose the will to live ! A good tip is to put a K&N replacement filter in the airbox.
Glad you’re enjoying it.
Thank you, I would be most interested to see those did you intend to post them? if you need my email, PM me. I’m sure the black & white photos are very er, artistic! Actually, even back in the '70s it must have been a bit weird to photograph motorcycles in black and white.
Thanks for your comment, an interesting different slant on this. What was the problem with the K&Ns? My current plan, having bought a new air filter element, is to see how it goes for a while. The main problem was that the rather complicated contraption on the end of the airbox for breather oil recovery is very prone to leaking all over the place. The rubber parts are also pretty perished in places. I’ve temporarily patched it up with bits of old inner tube and rubber solution (not pretty, but it has worked better than I expected). If that continues to work satisfactorily, I may buy a new assembly, though they are not cheap.
Another problem with the airbox is that the conical-shaped filter element is under a bit of end to end pressure and tends to bow outwards, choking itself against the sides of the plastic airbox. Here’s a photo, but I warn you, it’s not pretty and not for the faint hearted!
Quite different from the 750, that has a flat tray shaped element. I don’t want to bore you with all the details, but the 750 I have (750T) has seemingly gained a reputation for poor or erratic running if separate K&N pod filters are used. The chap (Paul ?) at Corsa Italiana told me that he’d seen several of them over and over again, brought in by different customers who’d got the bike cheap but could not get them to run well. I re-jetted mine and if it was a race bike it would be fantastic, wide open throttle it goes like a bat out of hell. At low to mid range when poottling along it’s like a hesitant dog and most horrible to ride.
I now have the proper airbox from a member who has owned several of this model and he told me that one problem with the pods is the blanked off end being so close to the carb. Possibly fitting an extended tube before the pod would be better. As you probably know, modern bikes have large airboxes that supply still air that is more efficient.
Look, now I just bored you with all the details !
I can’t honestly say what the advice should be for the 500, there are others on here with years of experience that will help you out
The separate pod filters can be a problem. There are a lot of posts on here about removing the air box, carburettor and engine breathing problems. I fitted a K&N in the original housing. Had to slightly modify to accept a parallel filter. The K&N has a wire cage that doesn’t get crushed.
K&N No. MG0200
I’ve not heard of the O rings perishing before, though mine have probably been replaced every 20-40k miles anyway.
The airbox will leak oil. That air filter is a bit of a pain to change. But stick with it.
The bore lining is not chrome it is nikusil or nigusil – I’m not sure which or whether there is any difference. It’s not known for flaking and is very hardwearing. However I did have that issue on one of my pots which I found whilst looking for a different issue, probably at around 20k miles.
The valves on these have some reputation for weakness and dropping (no folks, I’m not mixing this up with the 4V Lario heads). They were originally 2 part swaged. You might want to think about replacing them around 40 – 45k miles, unless you are back in there earlier for some reason.
Around 1980/81 they came either in red or a rather fetching light silver/blue colour, and with pin stripes. The plastic side panels were very prone to flaking so given how good yours are I would suspect a respray.
Lastly – you don’t have to treat these bikes gently; change the oil every 2k miles, warm up gently from cold … then run it as hard as you like. A really great little bike.
Many thanks for all the replies and information. I put another 40 odd miles on the bike today and so far I am seeing no oil leaks from either the cylinder base gaskets or the airbox. So far so good. Although it was cold, the roads were dry and mostly clean, so I was able to push on a bit more and I’m pretty happy with the way it goes. I am aware of some fuelling issues, but it’s routine stuff and I won’t bore you with it here.
Thanks for the warnings that ditching the standard airbox in favour of separate K&N filters may not be trouble-free. I’ll do nothing on that for now, the plan is to see how the standard setup works out and leave any decision for later.
I find the gearchange can make a bit of a clang sometimes, once it’s warmed up, other times it’s pretty slick, I don’t know if that’s typical. The clutch is nice and smooth and doesn’t drag or slip - a good clutch really. And I still like the linked brakes - strange, I thought I’d hate them.
I recently bought a V50 II and one of the first jobs i did was extend the length of the side stand by 3/4 of an inch,its so much more stable now.I did this by cutting it in half and using a piece of tubing which slid over the stand and had it welded.Hope this is some use to you.
Thanks Robert, I must have a proper look at the side stand, up to now it’s been irritating but well down on the priority list! I have the impression that it meets the ground too close to the bike, so anything other than dead level ground makes it want to lean too far to the left or fall over to the right. I certainly wouldn’t leave it unattended on the side stand. When (if) I get around to looking at it, I’ll report back here.