T3 mods

[fossilrider]

OK guys,I figure there must be folks here that have gone down this path before and know the answers I'm looking for.I'm building a cafe racer from a '76 850 T3 and have just a few things I need answered.Basically it boils down to this:as far as power increase (useable power,as in bottom-mid range) is concerned,what gives the best bang for the buck? I know you have cams,big bore kits,carbs,ignitions,exhaust.And I know none of it is cheap.I'm 62,have ridden and raced dirt bikes for most of the last 40 years and ride street a lot at what I'd call a "crisp" pace.My preferred mount right now is a '07 Griso (LOVE that bike!).So,all that said,I'm looking to add more oomph without breaking the bank to this likeable old hunk that I'm building.I found out years ago that trial and error "fishing" for the right parts to get the effect you're looking for can get very expensive,and it's better to ask the people who have already been there.If a cam change is an important step,which one would you suggest ? Big bore kit,which one.Will the 1000 guzzi jugs,like the SP,fit without machine work or is aftermarket the way to go?Carbs,what brand/size? Which electronic ignition is best? I realize a lot of this is subjective and I might get just enough input to really confuse me,but tell me what you think,what your experiences have taught you.I know I could go crazy and do most or all these mods and spend a few thousand dollars (what am I saying,no I couldn't,I don't have that much to spend),but like I said what is going to be the best dollar spent to get the best results? All help will be greatly appreciated.Regards,Steve C. aka Fossil

 

[guzzibob]

I have a 78 T3FB I bought new in '78, currently has over 160k & counting on it. It also runs, handles, brakes & shifts substantially better than when it was new. It is by no means a cafe racer, nor was that ever my intent. By far the biggest bang for the buck, your stated goal, came from tossing the 30 VHB square slide Dell Orto carbs & replacing with 32 PHF's also Dell Orto. It's actually easier to go to 36's & much more commonly done, but the 32's fell in to my lap for a song. Little to no difference from stock down low, up to about 4200 RPM or so. From there on up to 6800-7000 RPM way, way more willing than stock. Of course these RPM figures are still way too low to cause reliability issues. It just feels so much more free, so much more willing to go when I really want to go. And yet no loss down low. It's also been bored/sleeved to 1000 or so, & twin plugged (really over pinging issues, not for HP). Also went to Dyna ignition-really not for performance, but because I regard fooling with points as a pain. None of these other things made anywhere near as big a performance gain as the carbs. Use the search function to find the details explained elsewhere here. If you go with the 32's I know what jetting is needed, also detailed elsewhere here, & can save you a lot of time sorting that out.

 

[fossilrider]

Guzzibob,this is exactly the kind of input I'm looking for!Thanks for the reply.Yes,I've seen quite a few mentions of the carb change and it seems everyone who does it is very happy with the results.I'll certainly be on the lookout for a set.A couple more questions,since you mentioned the bore mod and dual plug mod.How expensive were each,who does each and was boring/sleeving less expensive than just going with a kit?Also what brand ignition did you choose?Again,thanks much.Regards Steve

 

[Chris R]

I agree with everything Bob says, fitting 36's is the cheapest performance mod on these bikes. Methodically sorting them will give you the greatest improvement at virtually zero cost. Most people don't spend enough time sorting out their carburetion - get the dellorto tuning guide and a handful of jets and start by sorting one circuit at a time.

Nicasils (also known as the 'Gilardoni' kit) are the single best mod you can make - there is much less blowby, the bike runs cooler, they last for a very long time. Forget boring out the iron bores - the cost is virtually the same for a much inferior result. The 1000 bores will not produce much more power than 850 and most of the power increase comes from increased compression. Set the squish as tight as possible and that will help with pinging. The kits can be hard to get of late so if you see them snap them up.

Twin plugging as Bob says doesn't really increase the performance but does stop your bike from pinging which... actually increases performance - on the roundhead it can be done quite cheaply.
Gas quality is only going to go down so I would do it - you have to recurve the distributor by about 6 degrees. The fact that you can reduce the advance that much tells me that it is effective.

Lighten the flywheel as much as possible. This will transform the bike. Todd and his merry men do it at what I think is a reasonable price given that it will require balancing and the metal can be a bear to machine.

I wouldn't be tempted by timing gears - they are expensive, offer no measurable performance improvement and can, if you are unlucky, self-destruct. The aftermarket tensioner (sometimes knowns as the Valtek or Agostini tensioner) is fine.

Cams tend to just move where the power comes in - this and playing with exhaust tuning is the last thing you should start playing with. The megacycle is the only one to get IMO at the moment as it is made from a billet piece of steel - they used to do weldups and have learned the hard way. Again Todd sells them and can point you to the best one for your application. It is critical to replace the followers and use moly paste on them. Breaking in the cam is the hardest thing to break in on any engine.

All other mods to the valve train - titanium valve collars, steel pushrods etc - are marginal improvements at best.

By the way I have never met Todd, just appreciate his passion for Guzzi, his workmanship and knowledge and why not support the site when you can?

Ta,
Chris R

 

[fossilrider]

Thanks to you also Chris.I'm filing all this away and will be acting on at least some of this in the near future.I picked up my T3 a couple of years ago and started on it but got side tracked and am finishing a few other projects and selling some others so I'm about ready to get back on the T3 and wrap it up.When I bought it the previous owner had replaced the rings,most of the seals in the engine,installed a RAM clutch (so I hope I don't need the lightened flywheel),installed new IKON shocks and new Macadam tires.Since I've had it I have delinked the brakes using braided ss lines,picked up a "Tank Shop" aluminum tank,installed clubman bars,and am currently considering my options as far as tail sections/seats/rear fenders.I like the classic look of the stock fenders with a bum stop/gunfighter style seat but I also like the bobbed fender style.Anyway hopefully I'll have it on the road by spring and all this info will certainly help as I look for the pieces to finish the project.Again,thanks for the info.Regards,steve