Topic: New project- Guzzi NTX650

[BenelliSEI]

Did he suggest why the valve failed?

[simon#42]

Two piece valves do this , the joint can crystallise over time and the head falls off . Have seen this on the bigger guzzis but have never had much to do with the small ones .

[Tim2005]

I suspect the cause will never be known for sure. I wondered if it is to do with the bike sitting a long time, I think it must have been parked up for 15+ years, maybe corrosion could have got into the valve stem joint. 

All the bits have arrived so I now have a small jigsaw to sort out over the next few days.

I notice the exhaust headers are quite pitted, see photo. I've cleaned them up and treated them with rust killer prior to painting them black, but can anyone suggest anything that could be used to fill in the pitting? I'm not keen on grinding it out as they aren't all that thick & would be very hard to replace

[MRieck]

It's not good. As I figured a strip down was essential, it was even no longer possible to remove the right pot's spark plug, that one undid perfectly well last week & was suddenly stuck. Draining the oil didn't reveal much at all though, no glitter, so that is positive. Anyway, off came the exhaust (easy enough) and the carb (awkward but ok) and then the top end. It is very simple to dismantle this, it's a pushrod motor with overhead valves so very straightforward.

Well, it used to have overhead valves. As you'll see from the photos it now only has 1, the top of the other had dropped off & wrecked the piston & head. The cylinder survived ok luckily. I'm currently on the hunt for parts. Secondhand cylinder heads are reasonably available, but it is at times like this I realise how good we have it in the Honda world, if this was a Honda I could call up David Silver's, or others, and get a choice of new pistons in various sizes. For a vintage Guzzi there are no new pistons available, nobody supports them, so I'm actually having to buy a used piston for it...

That chamber can be salvaged. I've repaired worse than that with more complex shapes. That being said....it very well may be cheaper to find a good used one. The ones I have done had a lot of porting etc in them.

[BenelliSEI]

I once had a set of pitted pipes “ceramic coated”. They were the original pipes on a 1957 Lotus Eleven I raced for many years. It improved their appearance 100% and the coating lasted forever. It was ages ago, so this may have changed, but I recall it was pretty expensive.

[simon#42]

There is a firm that ceramic coat parts in warrington tim .i had some piston crowns done but when i collected them they had exhausts that they had done and they looked good .

[Tim2005]

I'd be surprised if it is salveageable but it'd be worth having a spare around as parts are so rare. There's one big gouge next to the inlet in particular that seems to have actually moved the valve seat in the head, it chewed up the spark plug thread too. I'll see if I can get a photo later.

Thanks for the ceramic coating idea, I'll look into that. I'll just paint them for now to keep the weather away, my plan is to get it back on the road shortly (should only be a few days now as all the have bits arrived) and use it until spring so i can make sure the rest of it is aok. It always was intended to be a winter bike. In the summer I want to repaint the whole thing, with an idea of doing something along the lines of Fabrizio Meoni's Gauloise colourscheme, I can send the pipes off for ceramic coating while I'm doing that.

[MRieck]

I'd be surprised if it is salveageable but it'd be worth having a spare around as parts are so rare. There's one big gouge next to the inlet in particular that seems to have actually moved the valve seat in the head, it chewed up the spark plug thread too. I'll see if I can get a photo later.

Thanks for the ceramic coating idea, I'll look into that. I'll just paint them for now to keep the weather away, my plan is to get it back on the road shortly (should only be a few days now as all the have bits arrived) and use it until spring so i can make sure the rest of it is aok. It always was intended to be a winter bike. In the summer I want to repaint the whole thing, with an idea of doing something along the lines of Fabrizio Meoni's Gauloise colourscheme, I can send the pipes off for ceramic coating while I'm doing that.

That's not a problem to fix with aluminum....may need an insert for the plug hole.

[Tim2005]

Quick update- the engine rebuild is progressing well, with a slight delay as the top end gasket kit does not include the gasket for the inlet manifold, so I've had to order it separately - only £1.50 but another few days wait and £4 postage annoyingly.
Meanwhile... the replacement cylinder was actually freshly vapour blasted and cleaned and ready to use, so very smart looking (unlike the rest of the bike....) but I thought I'd give it an extra clean just in case. I let it soak in a tub of petrol/gas overnight, with a few shakes,  and there was definitely a little fine sediment in the bottom after. I've given it an extra cleaning through all the oilways etc too now. I don't generally like engine parts being blasted, I am now pretty confident this is clean but I think I'll give it an oilchange after it has run just a little.

[simon#42]

a bit late to add this after you have put it all back together but I would have changed the valves before I assembled it . The aftermarket ones are one piece and would prevent a repeat of your problem . Same for the other cylinder .

[Tim2005]

Yes that was my plan too, but neither of the UK specialists were able to supply valves, they both said that valve problems on the 2 valve small block engines aren't a known thing, it's the 4 valve ones that usually have the problem, so they haven't sourced them. 

I have since spotted that Stein Dinse in Germany list them, though 2 different types without explanation (one at €25 and one at €140), so I'll look into them. Getting the heads off is a very straightforward, I can do them when I have the motor out for the bike's paint job in the spring

[simon#42]

yes the joy of twin cylinder bikes whose cylinders stick out is top end repairs are easy .

[Tim2005]

It is time I posted an update on the Guzzi. Well the engine is back together and running well, after an initial test run I gave it an extra oil change to pick up any leftover pieces of piston or valve, then took it for a good ride out one day last week for around 100 miles. The engine has an odd power curve, it is really lively up to about 3500 rpm then just flattens out when I expect it to keep building & get exciting. I do forget it's only a 650 though.  The rest of it works ok, though I want to try to improve the tickover/low down running as it has some issues there, I just needed some different vacuum gauge adaptors as the manifolds have M6 threads & my gauges have smaller ones, I've found some online & they've just arrived. Talking of threads, clutch adjustment has been awkward, the bar lever end was missing a locknut, which turns out to be the unusual size M8 x 1.0mm, I've bought a normal nut & slotted it for now but would like to get a proper round adjuster for it, meanwhile the pushrod adjuster & locknut is at the back of the engine & access to it is completely blocked by the swingarm. 
Meanwhile, I have also made progress with the wheels, I found a pair of old rims and had them anodised gold, got some new spokes from Italy and have have rebuilt the front wheel, which was the worse corroded rim.  I repainted the hub while it was stripped out too, it now makes the rest of the bike look rougher ...

[BenelliSEI]

Well done! Such an interesting motorcycle.

[Tim2005]

It’s been quite a while since my last update about the Guzzi, I haven’t made as much progress as I’d originally intended, though have at least got it running and riding well, mostly it’s the cosmetics/paint job remaining, plus getting the seat remade a bit higher to improve the riding position.
So, what’s happened meantime in this voyage of discovery..
Brakes- been through them, bled them etc, and fitted the new front pads, the most aggressive sintered ones I could find as the front brakes on it isn’t the most powerful ever, though with those pads it is fairly reasonable. Rear brake is good.
Sidestand/kickstand- this is a definite result. The original one sprung back like a rat-trap, the previous owner warned me about it and I still ended up with the bike on its side in the workshop.  So I have changed the mounting points and springs, it was definitely not easy to get the geometry right but so worth it as now the stand stays down under spring tension and stays up under tension.
Suspension- forks were easy, just fresh oil & what came out was actually pretty decent. Rear shocks, I’m still running the Chinese ones in the photos, with dodgy extenders, they actually work pretty well for the road but they are very short travel. I got a set of the original Marzocchi MX-580s from the previous owner but the damper rods were knackered, I looked into getting them rechromed but that was really expensive, then I found a supplier of new rods in Italy. Not the quickest guy to deal with though, each email reply seems to take around a month. 
The bike actually handles well, its light weight helping, it corners very nicely with unlimited ground clearance too and cruises very stably too. It has a weird feeling at low speeds- tight junctions etc. it steers oddly. It took me some time to figure out why it feels weird, it’s something I’ve never seen on any other bike and I’m not sure if it is a common Guzzi feature, maybe someone here can guess?
Right, I’ll leave this update here for now as it is getting late and I’m not sure of the max post size, anyway it’ll give everyone something to look forward to in upcoming tales of the voyage through electrics, clocks and engine stuff

[BenelliSEI]

Tim…. Following along, good to see an update. Add some pictures, all the old ones have disappeared !

[Tim2005]

It's a pity the photos have gone, here's the most recent one I can find of it complete with rebuilt front wheel, which reminds me that I still haven't got around to doing the rear. I'll dig out a few others tomorrow too

[BenelliSEI]

Interesting bike (I’ve never seen one). Looks like fun!

[seanbarney41]

My guess on your steering is either that it has tapered roller bearings with too much pre-load or there is a steering dampener that is malfunctioning or cranked up to max dampening.

[Tim2005]

My guess on your steering is either that it has tapered roller bearings with too much pre-load or there is a steering dampener that is malfunctioning or cranked up to max dampening.

Nope, neither of those, it's not something worn/broken/faulty, it's a very unusual design feature.   

Here are a couple more photos - before and after of the stand springs change - the whole stand has been added by someone in the past as these bikes didn't have one originally, and the original spring arrangement just tried to pull it up when it was down & didn't support it much when it was up. The stand is also very heavy & when up it is on the brink of overwhelming the springs I have used, so maybe a further redesign may be needed sometime

[spotty]

nice work.
i believe that auto retracting side stands were mandated by the italians for safety to stop people riding off with the sidestand down, i've seen a lot of pasta blasters over the years with them

and re the above comments about ceramic coating, i recently got a quote for a set of 4-2 drag pipes ( so no mufflers ) and they wanted $600aus, about $450US

[Tim2005]

Cheers, that explains the rat trap side stand, I'd never have guessed the reason.

I haven't pursued ceramic coating yet, it seems expensive here too - similarly a few hundred, but you buy aerosols of Cerakote much cheaper, maybe I'll look into that sometime, though BBQ paint seems sufficient for now.

Next update - fun with a speedo. It has a KM one, with no MPH markings, and with all the cameras around here that's pretty sketchy. So I got some little number stickers for the MPHs and mounted my phone onto a bar mount with a GPS speedo app running. I used that app lots when cycling.  I then spent what seemed like ages one day riding around on the Guzzi & trying to avoid enough traffic to hold it at steady speeds 30/40/50/60/etc etc, then temporarily marked/memorised the settings and later on attached the stickers appropriately. Job done I thought. A while later they updated that app and added lots of #$%*ty adverts, so I installed a different one.  I then discovered that my speed in the usual places when cycling was 5 mph different with that new app. I’ve no idea which one is right or if the number stickers are in the correct places.

[scottly]

 

Here are a couple more photos - before and after of the stand springs change - the whole stand has been added by someone in the past as these bikes didn't have one originally, and the original spring arrangement just tried to pull it up when it was down & didn't support it much when it was up. The stand is also very heavy & when up it is on the brink of overwhelming the springs I have used, so maybe a further redesign may be needed sometime

Tim, the stand spring is set up wrong; the upper anchor point needs to be to the left of the pivot bolt, so that when the stand is down, it's "over center", holding the stand down. Also, the lower anchor needs to be on the outside of the stand. I had to figure this out when I added a stand mount on my Seeley.