Question about longevity

[Dave H.]

Has anybody determined the life expectancy of a 125 Sachs motor used in a racing environment? How many miles can you expect the weakest part to last? What is the weakest part? the rings? bearings?  My Penton six day is being used as a road racer. I laced a Bridgestone 7 inch dual leading shoe drum to an 18 inch rim with Avon racing tires front and rear, installed Ciriani road racing forks, and I run a 15 tooth front and 48 tooth rear sprocket, which is the highest ratio that will fit. I finished second place, and 6th in my last two races in the vintage 250 class, against a gaggle of Honda CB 160's. My fastest laps were 2:13 on a 2.25 mile 10 turn track. I love the comments I hear in the pits when people stop to look at the bike, and even the race announcer always has something to say about it, because it's so unique. I've only met one other person road racing  a Sachs powered bike, in Holland through the internet. I hope someone can provide some info on the life ecpectancy of the rings, and connecting rod bearings...I don't want any broken bits at 80 miles per hour :-)
Thank you,
Dave H.


 

[OUCWBOY]

Dave
Years ago when I raced a Penton, I would always tear it down and inspect everything after every race.  This always assured me that things were "right" when I hit the track.  Had to replace the clutch a couple of times and had to bore the cylinder 2 times in 2 years.  Went through a piston and rings about every 4 to 5 races. Never had to repalce any bearings the whole time.

Donny

San Diego Area Penton Owner.

[Dave H.]

Are there any other 125 owners that care to comment? If what Donny says is what I should be doing, then I've been racing a time bomb!...
Donny, how did you know when the piston needed replacing?

 

[metalkfab]

I had a 100cc Berkshire,rode it every day and raced every weekend.I went a whole year before I needed to replace the rings,after another half a year I wanted to bore the cylinder to 1st over and had to argue with Cobb Engineering to bore it.Cobb stated that it didn't need a bore 'cause the cylinder still showed cross-hatching.I guess with proper maintence to air filter,clean gas and proper running conditions the longevity should be good.Maybe Kip Kearns should really answer this one.(or maybe Doug Wilford)

[Heinz Raidel]

OK... you are taking a 25-30 year old 125 two stroke out on pavement with the intent of seeing how fast it can go?  And all you're worried about is the life expectancy of the MOTORCYCLE ENGINE?  Thanks for making me feel a little more sane.  

However, any day spent beating up on Hondas can't be a total waste of time. Keep us posted on how you're doing!  HR

[Doug Wilford]

Dave;
There are some good answers to your questions.  Road racing should provide you with lots of time on the Sachs Motor, clean air and a good pre-mix and tranny oil you should be good for a season.  Then I would check the piston and ring wear for sure.   You can go to a lower ratio 15- 54 to high will slow you down as the engine can't get up to revs.    Before I rode Penton I had a CB 160 converted for enduro, when I lowered the gearing on that it was a rocket ship. 17 seconds in a quarter mile, with stock gearing the thing wouldn't hardly get past 60 mph.   I think with the right gearing you should get pretty close to 85.   The early ISDTs' had a final special test that was always on a road racing course, the Penton with knobbys and enduro gearing would do 75-80.  Tried a Wisco piston once and smoked it on the road race, HE! HE! Fun tho, Good  Luck and hope to see you at Mid-OHio
Doug



Edited by - doug wilford on 06/04/2001  9:40:40 PM

[Dave H.]

I think I originally did run a 15:54 but found that I reached the top speed too soon on the straight section of our local track (Seattle International Raceway). But this little motor seems to love the mix I use though: 40:1 VP-C12 (110 octane race fuel) and Golden Spectro! It's a rocket ship! I easily pull away from the hondas out of the corners, and my starts are pretty fast for a 52 year old rider on a 30 year old motor I even get a little light headed from the rush! (maybe my helmet is a little tight)
I didn't know the ISDT's had a road race test too. I bet the corners were exciting, to say the least, with knobby tires!
Dave H.