I can't find a new top end.

[Hangar One-Four]

Hello everyone,

I have been searching for a piston and cylider set for my Ambo. I looked at the Cycle Garden big bore kit but it is 8 to 1 compression and that is pointless, I may as well stay 750. I would buy Gilardoni's if I could find them, bt everyone is out of them, even a shop I checked with in Mandello.

The tops of my pistons have seen better days and they have some wear on them. One of my cylinders has a broken fin, but it is repairable. If I could find suitable pistons I would fix my broken fin and send the cylinders off to Millenuim for nigasil.

It has been a long time since I have been "into" my Guzzi. For the last 15 years or so I have been a Ducati tech and have mostly worked on and ridden modern Duc's and late model off road bikes. I have had my Ambo since I was 18 (1988) and used it as a daily driver from '88 to about '98 or so, and then rode it ocassionally until about 2004. Since then it has pretty much sat.

So far on my restoration rebuild I have powder coated the frame and all the black stuff. Cleaned and bead blasted all of the engine parts, washed and poilished everything else. I have some time this winter to put the bike back together but am having trouble finding what I need.

I have inquired with all the US Guzzi parts places, no luck. I seem to remember back in the day, there was anther piston that had the right height to it, in 88 mm that would work well in Ambo's. Any ideas? Anyone know of a shop that has a Gilardoni kit in stock?

David
Hangar One-Four
Chelan WA (s10)

 

[kinkajou]

You should try Cycle garden (even with lower copression, you will have 15% gain in power and torque....)those guys are artists...they know what they do and do it well.
or maybe
MG Cycle, harper's guzzi , guzzi classics

all of them on the west coast except MG cycle.....

I also heard of people fitting VW beattle pistons in their bike but the result was less power but way cheaper....

Im myself going with the big bore kit and a hot cam from cycle garden....I seen their bikes on race tracks and its impressive what they do with those old mills....way more powerfull than my souped up V7 cafe 2010....

good luck

 

[Hangar One-Four]

You should try Cycle garden (even with lower copression, you will have 15% gain in power and torque....)those guys are artists...they know what they do and do it well.
or maybe
MG Cycle, harper's guzzi , guzzi classics

all of them on the west coast except MG cycle.....

I also heard of people fitting VW beattle pistons in their bike but the result was less power but way cheaper....

Im myself going with the big bore kit and a hot cam from cycle garden....I seen their bikes on race tracks and its impressive what they do with those old mills....way more powerfull than my souped up V7 cafe 2010....

good luck

The cycle garden kit is 8 to 1 compression. There is no way that a point and a half less compression, plus a 100 CC increase in bore size could equal a 15% increase in power.

I have tried Harpers, MG Cycle, Moto I, none have a Gilardoni in stock.
I talked to Mo at cycle Garden. He is working on a higher compression piston for his kits since the ones he used now are not availible anymore. It will be a few months before he gets them. He said the cost will be around $1300 for a set with exchanged cylinders. I will talk to him again after x-mass and see where he is at on it. The pistons will have uncut tops. He was planning on cutting them to about 9.5 to 1. That would be perfect. I may see if he will sell me some and I will CC my combustion chambers and cut them for 10 to 1 since I have access to excellent fuel here in Eastern WA, and even with the ocassional tank of E-10, I should be ok with 10 to 1.

With my 30 mm pumper carbs, and adding a high lift, longer duration cam, I really would be hesitant to run 8 to 1 compression. It would be a waste of time and money.

 

[Chris R]

Re Gilardoni's: this may be a temporary drought - it may be permanent. I would give Agostini's in Mandello a call and ask them if they know whether a new run is likely - they will probably know as they are just down the road. They also speak english, have the best prices and will ship worldwide. I am a bit amazed the OEM pistons are still not available - again check agostini's or Stucchi - they don't speak english but do respond to emails.



If you can't find anything then it is custom piston and nikisil plate time. Nikisil does not like steel or moly rings - good old cast iron is fine.

There are quite a few people who do nikisil plating nowadays - ask the two stroke/snowmobile brigade -like mongoose racing or millennium.

 

[Amboman]

About a year ago, Moto International had aftermarket, oversized pistons sets on Ebay for around $125/pr. IIRC. It would be worth calling them to check and see if they still have any. I need to do the same - tried emailing them several times and have yet to get an answer.

I wasn't aware that Cycle Garden's big-bore kits were only 8:1 c/r. Given that, it would still be possible to use them with some alternation to achieve the desired c/r - machining either the bottom or top of the cylinder casting would be one way. Of course that may effect rocker geometry, so it might be necessary to remove the same amount from the pushrods. Just a thought.

 

[geodoc]

Heh David,

I was in the middle of an engine mod project during a previous Gilardoni drought. What I ended up doing was taking a set of 850T barrels I found on eBay and had them bored to 86mm to maintain a reasonable cylinder spigot thickness. The pistons that I used were a set of custom-mades from JE with a 850 LeMans pattern dome / valve cut-outs. The compression ended up just shy of 10:1. (This was using a 1000SP bottom end BTW).

The pistons came from Mike Rich and I believe he may have ordered extras. Don't know if the cylinder spigot diameter is the same on the Eldo / 850T barrels as the Ambo barrels. The total price for plating, pistons, wrist pins and rings was just short of $1000 - a couple hundred more than Gilardonis when you can get them.

I have a pair of used Eldo barrels with peeled chrome if you need to get a set as cores.

Are the Ambo barrels shorter than the barrels on 78mm stroke engines? Are original Ambo barrels chrome plated? Little experience on the 750's myself.



George
Vancouver BC

 

[john zibell]

If you use 850 T or T-3 barrels, you will need to grind a relief at the top of the pushrod channels on the cylinder side. If you don't the pushrods will contact the top edge.

 

[Hangar One-Four]

Eldo barrels won't work. As to messing with cylinder height to get the CR higher, way too much trouble on a pushrod engine.

I am going to take another look at my pistons, maybe they will look better now that I know it's not easy to find replacements.

I know that cast iron rings are the only way to go when using nigasil cylinders, it seems there are a couple different options for those availible.

I have been waiting for Moto I to get back to me on a parts request. I will call them Monday (if they are open Mondays) and see whats up.

I have emails out to Agostini, no reply yet. I also emailed these guys http://www.valpolini.com/home-en/
They responded, but no Gilardoni sets in stock. They are also right down the street from the factory. I am suprised I didn't see this shop last time I was there.

 

[jr1967]

This company is one of the largest in Europe; give them a try, they have always been easy to deal with.

I found this, just don't know if the pistons would match the valves and small end diameter.

http://www.sd-tec.de/catalog/product_in ... 1514fa3de5

Over the years I found that most companies are swamped with questions by email. The staffing costs to answer them vs actual revenue ratio is probably way off, hence the unresponsiveness you might experience; calling them directly I found most companies are very helpful.

Cheers, JR

 

[Penis Rotor]

Problem will be the deck height. Ambo used 70mm throw crank rather than the 78mm throw crank of the 850. The rods were the same length but the deck height of the 750 pistons was 4mm higher. when I built my short stroke hot-rod I used 4mm overlength Carillos to get the deck height right but still had to modify the combustion chambers to get the CR up using 'LeMans Pattern' 90mm pistons and mid-valve heads. Not worth doing on an Ambo as you'll probably end up cracking the crankcase if you up the power very much.

Pete

 

[Amboman]

This company is one of the largest in Europe; give them a try, they have always been easy to deal with.

I found this, just don't know if the pistons would match the valves and small end diameter.

http://www.sd-tec.de/catalog/product_in ... 1514fa3de5

Over the years I found that most companies are swamped with questions by email. The staffing costs to answer them vs actual revenue ratio is probably way off, hence the unresponsiveness you might experience; calling them directly I found most companies are very helpful.

Cheers, JR

Yes, V7 Sport sets will work - I have a customer running them in his Ambo sidecar rig. C/R is 4 tenths higher (9.6:1 vs. 9.2:1) but that doesn't seem to make much difference, nor does the slight decrease in displacement (749cc vs. 757cc) due to the smaller 82.5mm bore.

I "have it on good authority" that the first of the new batch of Gilardonis will be here towards the end of January. However, the first to be produced will be 88mm round-fin (Convert/G5/SP/CX100), with Eldo/T/T3 after that and finally Ambo.