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My 336, cc upgrade, dual plug, light clutch tranny, project is a steller success! I fired it up and took it for the first ride last night. 30 miles of twisty Chuckanut drive to give her a nice initial break in.
I'm sure there are adjustments that can be made to tune, but whatever they are, this bike is everything I hoped for and more. Runs amazingly smooth, even at idle (I haven't even balanced the carbs yet), and there's loads of extra seat of the pants power from lower RPMs all the way up the rev range! I love the quick revs produced by the combination of post 81 clutch and tranny, light balanced Siebenrock pistons, and lightened valve gear. Night and Day over the old heavy flywheel etc.
This cam is nice. I guess the valve timing (6 degrees advanced) is just what I needed. I see no downside (except maybe law inforcement issues and MPG if I can't keep off the throttle.)
I've got no hesitation off idle, and it powers out of even steep up hill turns like a dream. No pinging, even with my tall 32/11 gears.
The sound through the 2 into 1 is reminiscant of racing in the it's hay day. An extra deep growl even at idle. Love this motor... I'll post pictures as soon as I clean the dust off this machine (and fix the shattered tach lens ).
It's going to be a fun summer .

Sounds really good, when you get run in, let's see some figures.

That sounds great.

The amount of planning and care you put into this has payed off with the bike you want.

It proves an old sailboat saying, "Don't start vast projects with half vast ideas!"

Well done, I'd like to see some pictures!

It's nice to hear when someone is satisfied with their project. Am I remembering correctly that you went from a R90/6 to a 1000cc set of jugs? Also, I don't remember which carbs you used. It sounds like the extra CCs gave torque that you would have given up if you had just added the cam. That is, if I understand correctly that it gives better top end with a slight drop in lower end grunt. If so, you now have the best of both worlds.

Chuey

Chuey wrote:It's nice to hear when someone is satisfied with their project. Am I remembering correctly that you went from a R90/6 to a 1000cc set of jugs? Also, I don't remember which carbs you used. It sounds like the extra CCs gave torque that you would have given up if you had just added the cam. That is, if I understand correctly that it gives better top end with a slight drop in lower end grunt. If so, you now have the best of both worlds.

Chuey

No power loss anywhere....really. I gained at every level. I gave up nothing, no compromise....that is compared to a stock R90/6.
Amazing throttle response, better low end than stock, great mid range (I'm still not given her all she's got) and R's over 5000 are a real rush. The slightly modified bike was fun and was a good match for any R90S or stock R100, but now we've gone to a whole new level.
Bike: 1975 R90/6
List of Mods (drive train only) performed over the last 20+ years:
38mm Dellorto's with Velocity stacks and dual K&N out board filters. Mild porting on intakes
32/11 rear drive
Mac 2 into 1 exhaust http://www.macperformance.com/store/cat ... tLevel=top
Recent mods:
Motoren Israel/Siebenrock 1000cc kit for pre 1975 airheads http://www.motoren-israel.com/product_i ... -1975.html, Nikasil barrels included (purchased during the Christmas sale thanks to Garnet ). Stock 42/40 head retained. The intake pockets on the pistons were deepened by .7mm. 9.5+ :1 compression ratio. Intervalve valves http://www.motobins.co.uk/displayfinal. ... lves&go=GO
Later model rockers with hardened tips.
Later model push rods (15g lighter (each) than 1975 push rods).
Later R100 connecting rods (also lighter than 1975 R90 rods)
Pistons and rods balanced end to end and side to side to with in 1/2g (by me)
Titanium valve retainers
1983 transmission, clutch and "clutch carrier" (no more flywheel)
Dual plug heads (performed by yours truly with a specially welded up jig)
2 dual Dyna Grey coils with 2.2 ohm resistance
post 1978 336 "no nose" cam with 6 degrees advance (maybe that saved the bottom end), dual row chain and sprockets retained, points hole blocked off.
Omega crank mounted ignition set at 4 degrees advance at idle with 28 degrees full advance.
I did it all except the valve pockets.

As a matter of course, I still need to play with timing, reset the valves after break in, and carb adjustments and jetting which I left as they were before all the recent mods. They seem to be amazingly close to perfect at R90S specs. I did check the Dellorto pumpers and set them both at around 1 1/2 turns out until they both produced equal volumes of fuel after 10 pumps.
I bought the recent parts over a span of 4 years, mostly at big bargain prices. I still have lots of parts to sell to get my money back with.
At this point I'm absolutely satisfied. None of the lumpy idle, poor low end punch, flat spots and added vibration that I had read about...instead I got the total opposite. Some of the improvements could be attributed to slop in my old timing chain and the increase in compression and cc's, but most of the "zing" (in my humble opinion) is coming from the cam and the light components.
I followed a lot of the information from this article http://mailer.fsu.edu/~jroche/road_rod.html
and of course http://moragafalconers.org/BMW_336_cam/
....and, of course, I've been listening to the experts on this sight and gleaning all I could. Thanks to all of you on Boxerworks Phorum for all the facts, opinions, information, misinformation, encouragement, discouragement, and general thread degradation. And thanks to GSPD and Fun Holliday where ever they may be.

What was the condition of R90 before you did the work? If it was tired, then you are not doing a fair comparison, and don't try to tell me you remember what it was like before it got tired - our brains just don't work that way. The long slow gradual loss of power is something we just don't notice.

If it was running at full stock power before the work, that's different, but the fact is, people VERY seldom do such hop-ups on a fresh motor - at least, in the Airhead world. The Duc people are all crazy: they throw out fresh stock parts all the time

Well done Matt, Sounds like a fun ride!

Major Softie wrote: The long slow gradual loss of power is something we just don't notice.

I notice not being able to get out of bed as easy as I used to.

ME 109 wrote:

Major Softie wrote: The long slow gradual loss of power is something we just don't notice.

I notice not being able to get out of bed as easy as I used to.

Ain't that the truth! Getting back in is much easier though.

Sounds like Matt now has exactly what he wants. Can't do much better than that!