New 20 ounce tumblers available now! Forum donation credit with purchase. https://www.wildguzzi.com/Products/products.htm#Tumbler
This is interesting that someone is going to give this idea a shot. I have a feeling it is much more complex than a swap of a couple components. This is the "holy grail" for some owners, so if it works, you have done yourself a service for the community. Best of luck and keep us posted. Your rewards are ahead of you if it does! ;-T -Kevin
Yes, I saw the cutouts on your thread. Thanks for posting that BTW! Im digging into some parts books now, trying to determine if the V75 two valve engine ran a different part number piston than the V75 four valve. If they did, I figure I could try to get some factory pistons from a V75 four valve...I'm going to get bronze valve guides installed as well. MotoInternational in Seattle has six in stock. I've found two more in Germany, so gotta order them. Thinking about just ordering eight guides from Germany, and new circlips, and having Millenium Technologies install them.
I use Randy Long in Honey Brook, PA.New guides $15 each, insert, lap, clean, $65 a head.They come back looking like new. It's hard to beat.He does a great job of fixing broken cooling fins too.Mac
You will, at a minimum, need to make pistons. V75 have 22mm wrist pin, v65 lario are 20mm. The two valve and four valve pistons are completely different designs- the former is Heron head, latter is a pent roof. Using stock pistons will produce an abnormally low compression ratio. ~7:1 or so. You may be better off starting with a complete lario motor and doing a big bore kit. Smallblocks are very different animals from big blocks, especially when you start trying to mix and match. Ed Milich Guzzipower.com
Wow, this is a really cool idea Mike.I'm looking forward to how it turns out. ;-T
My thoughts, for what it's worth...Having pistons made or finding correct pistons is the best course of action IMO. I don't know how you would ever be able to use the stock V7C pistons - the dished crown is totally wrong for the 4 valve head. I don't think you could mill the heads or cylinders enough to bring the compression ratio up to where it should be either. Might be tough to find, but maybe V75 GT pistons? Same 80mm bore and 74mm stroke as the V7C, though I wonder if they have 20mm wrist pins like the Lario. Might be possible to enlarge the hole in the piston to 22mm if there's enough material in the casting.Lario pistons (80mm also) with custom-made connecting rods (to work with the longer stroke and 20mm pins) might be another possibility.Just throwing some ideas out there.
Have you sourced the flat top pistons yet? :+1 on the dyno runs before and after!
Doing some research on pistons, found some interesting info. The pertinent specs for each bike:V7C:Compression ratio 9.6:1Stroke 74mmBore 80 mmLario:Compression ratio 10.3:1Stroke 64mmBore 80 mmSo the V7Classic piston will travel 5 mm higher in the bore than the Lario piston in a Lario engine. I will have to cc the combustion chamber in the Lario heads when they come in, cc the combustion chamber in the top of the V7C piston, and then factor in the 5mm longer stroke of the V7C crank at the top of its travel.
The difference is made up in the barrels, not the heads.The heads are the same for the 750 and 650 cc engines.I have a set of barrels and pistons for a 750 4 valve I bought several years ago from Germany. The pistons are the standard 22mm wrist pin for a 750.I have a spare set of heads.CheersTrevor G
Thanks! That is kind of the allure of doing this, exploring new territory. With all of the recent advances in manufacturing, who knows? Maybe a company could reproduce four valve small block heads with a 3D printer. Heck, they are already printing AR15 rifles. I am really tempted to go whole hog on this, put on a Ed Milich 850 big bore kit, different cam, etc...But my goal at this point is to see just how stock I can keep everything, and see what difference a four valve head makes on a modern small block. To get to this point, I have had to change the ECU, and install an autotune and Power Commander. The nice thing with that swap complete, I can set the air fuel ratio I want with my laptop, based on a wideband O2 sensor, so compensating for the increased airflow through the heads becomes an easy five minute programming change. I gotta give a big shout out to Todd at Guzzitech for making that possible. Heck, two years ago it wouldn't have been. Once the heads are here I will post pictures of the work. Fun times indeed!
It will be fascinating to watch your latest project develop.I stopped in at a fellow Italian Motorcycle Club member's house two weeks ago. He has a lovely V35 Imola that is currently fitted with a V50 motor. On the bench was a beautifully restored V65 Lario motor that is destined for the Imola! He is running Suzuki GN250 valves & springs.Kurt
Why in the world didn't Guzzi develop a new set of 4-valve heads for the V7 series when they did this latest upgrade? Oh, we've already been through all of that ....
Has anyone else any experience of using GN250 valves in the Lario?
I was wondering about what happened to that project. Any movement on it ?
The four valve heads are very alluring on these sb's. Don't know if you heard, but myself/Ed are setting about taking a Lario to a new place never explored (to my knowledge). He is raising compression, adding larger valves, fitting bigger carbs, and reducing recip. weight. I have a stocker and love its pull. I think there's more refinement to be had hence the project. Keep at it with yours. Gonna be tough, but anything is possible.-Kevin
Thanks for that, I have been searching for a part number for the V75 GT pistons, but no luck so far. Arias will make me some, no problem, if I can't find some that will work from another source.
It is taking a lot of parts to get this conversion done.... 2 heads, 8 valve springs, 8 lower spring seats and 8 uppers, 16 valve keepers, 4 exhaust valves and 4 intakes, 2 pistons.....that's 50 parts so far.Also going into this are 2 valve covers, 2 rocker assemblies, 4 pushrods, 4 tappets, all the gaskets, and some outside service work, DLC coating on the tappets and cam, seat work on the heads, etc...The project is proceeding well however...just waiting for parts to come in at this point. Many thanks to IceBlue for all of his help on this...it would be much more difficult to make the conversion without his help, and this forum! ;DHere is a teaser pic...
You're going to have the hottest late-model Guzzi small block on the planet Mike. Congratulations!
He he..fun..getting this going. I'm planning to ride to see my parents in Prescott this summer, I'll have to swing by on the way and see you. I can check out the Racer!!!Cheers!
Some good questions here on converting the Imola II head to a Lario head. So far, all the information I have gathered leads me to believe that the intake and exhaust ports are the same dimension as the Lario head. The combustion chamber is the same as well. The only difference I am aware of at this time is the valve seats. However...comma.... :D I want to confirm this for sure. To that end I have ordered a stock Lario head from Martin at Guzzi PIU shop. (It was on sale)! When that head arrives next week or so I will be able to measure exactly all of the dimensions and compare them. So far I have measured the length of a stock Imola II exhaust valve and a stock Lario exhaust valve, and they are the same. The Imola II combustion chamber measures 22.5 cc's. With some stock V75 pistons, I will have a compression ratio of 10.2:1. Thanks to Brian, again, for posting the link for the V75 pistons and rings on ebay. The seller is shipping them tomorrow. I am having a lot of fun with this project already, and so far all I've done is parts research...LOL!http://www.ebay.com/itm/271133009688?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649
Page created in 0.026 seconds with 23 queries.