Hi, My Imola II is running but the rocker s are slightly offset from the valves and cause them to wear on one side, does anyone know why this is? as this engine has lots of issues with the 4 valve head does that mean that parts from the V65 4 valve may have been fitted in the past which may be slightly wider or was there a change thro the production run? any info on this greatly appreciated - lastly
can it be converted to 2 Valve? if so has anyone got any heads for sale?
Mark
Do you have a photo, it might help. I have lots of V65 Lario bits so could compare sizes etc if you provided measurements, although my guess wld be the rocker gear would be the same on both.
2 and 4 valve frames are similar enough to swap engines I have been told so you could probably put a 2 valve engine in, preferably with a matched gearbox. Anything else would, I think, be technically challenging
Cheers
I should add that they all do that. Due to design the rockers hit the valves off centre. I have heard it said this can mushroom the valves over time. Guzzi made lash caps to protect the ends as a retro mod and Guzzi Pui in Germany can supply them new.
The biggest problem with the valvegear in most people’s opinion is that the valve springs are much too strong and this can damage the cam lobes, shear them or snap valves. There are solutions centred around replacing the OEM springs with lighter ones. Suzuki GN250 one choice. Lario Brian on FB has a document that lists mods and part numbers for his fix he will send you or I can if you PM me.
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I think sometimes that the off centre rocker/valve thing is a design feature meant to rotate the valve during use and so distribute the wear. Certainly in some other makes.
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Funny, a similar thread came up on Facebook just the other day . Maybe this will help you
https://www.facebook.com/photo.php?fbid=1443888505723975&set=gm.1752336031465540&type=3&theater
I think you’re right Tony,good point and I did read that somewhere I’m sure - that would mean I suppose the problem is the soft metal of the valve mushrooming?
Cheers
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No way can I see the offset in the above photo turning the valve stem around. Made impossible by the pressure of the springs at least I would think.
Hi just got a V35 Imola and I’m after info about the 4 valve mods.
Can you help please
Hi
I have worked on a Lario to fix it but foget some of the detail, there used to be a FB page run by Lario Brian and that was a good resource.
The issue with Lario and probably the Imola 2 is the valve springs are too stiff; this places strain on the valves and can lead to them snapping, it also ruins the camshaft by wearing out tge lobes leading to poor performance.
The cure for a Lario is to fit a later camshaft (16mm lobes) to replace the earlier 13mm item if this is not fitted and fit new, weaker valve springs. I think some folk used springs from a 2V motor, I might have some if you are interested. The cams are hard to come by and expensive and they must be compatible as some are made for models with different ignition systems, all a bit of a minefield but I got one eventually.
The final thing is the valve tips get hit at an angle by the valve gear but you can get top hat shims that fit over and stop them wearing asymdtrically.
Often it is easier to put a different engine in from a 2V machine.
there is a German independent that sold bits but was very expensive, can’t remember the name, Guzzi Pui or something. TLM has some bits sometimes, you can get a parts book from Grdg Benders site and that might give you the correct cam number.
Not sure all of the above applies to imola 2 but the principles will be yge same - crap design, valve springs overspecified and soft cam faces a bad combo.
Cheers
When i got Pip Higham’s advice on my Lario (in the 90s) he thought that the 2 problems were (1) a weak valve design - apparently 2 part valves are very common and work well but these are a bad design. (2) single valve springs - a single spring can resonate and surge causing decreases and increases in spring pressure - causing valve ‘float’ and ‘hammer’.
Btw he agreed that the offset rockers are intended to slightly rotate the valves as they lift evening out wear.
Thanks very good, I’ll let you know about the springs
Thanks a lot