Road Race Report Round 2 (long)

[Dave H.]

This past Memorial day weekend, May 24-25, 2003, the Washington Motorcycle Road Racing Association held round 2 of it's racing program at Spokane Raceway Park, near Spokane Washington. The weather on Saturday was in the high 80's which scorched the asphalt and made the Avon race compound tires stick right from the git-go. I am new to this track, having only put my Penton racer on this track once before, which resulted in a sobering crash two years ago.   My plan on Saturday was to bed in  some new front brake shoes I bought from Michael Morse at vintagebrake.com, and I am very pleased with the results. While mine are Bridgestone 175 brakes, he can do stock Penton brakes too. I was pleased with my starts, and began to memorize the track layout. Saturday night a major squal and thunderstorm rolled in and it rained horizontally for the rest of the night, scattering some folks's canopies across the pits. The following morning, only a light drizzle was falling, and the race program began in earnest. I did a quick practice in the morning to try a new line through one of the trickier sections, and then waited for the first heat.
  The 250 vintage class is dominated by two guys on Hondas, one on a CB160 and the other a CB175. Here is how it went down: I got a fantastic start...the Penton 125 pulls like a freight train down to the middle of the 1 mile straight-a-way then reaches the end of it's gearing and power...the first guy, Mike Bateman on the 160 rolls past me...I have to back off the throttle to keep the Sachs engine in the power (wierd, don't know why)  I'm losing ground to Bateman...but I own the racing line in second place, and keep the heat on through the first 5 turns...then I over cook turn six, a tight left hander with a late apex, and I run out of room...the foot peg stubs on my CMF frame drag on the ground, (I did not want to cut them off or change the stock frame in any way when I built my racer) and I have to straighten out the curve and go into the dirt...two guys blaze past me as a result of my mistake...another guy on a CB160 gets eager to follow them and crashes behind me in turn 7, riding beyond his traction limits. I reenter the track and chase the three leaders...I stay within 6 bike lengths of the third place guy, Mark Etheridge, but I can't reel him in. On the last lap, I get passed  by Cob Collins just at the entrance to turn 6 which I am entering conservatively...I'm down to 5th place, but there are 4 more corners till the checker...I draft him into the right turn 7 and he goes wide...I cut iside and pass him back, and keep 4th place to the finish.
  The second heat is almost exactly like the first, except Cobs blows the same corner! He goes  down, right in front of me, and sliding out of my line, I look over my shoulder to see him doing a graceful backwards swan dive, and I drive to the finish line 4th again!  Hoorah!
   I was met at the track by a fellow pogger...Dale Walter, from Idaho. It was a pleasure to meet you. Thanks for your support! Dale used to race Pentons in California on the dirt back in the 70s
Thanks for listening,
Dave Hussey
WMRRA#49
Penton-Fichtel-Sachs 125cc

 

[Dave H.]

Sponsors needed...
I would like to buy, beg, borrow or steal an internal rotor PVL ignition, and straight cut primary gears for my Penton-Fichtel-Sachs 125 road racer. Please feel free to email me at [email protected] with any leads. Thanks,
Dave Hussey,
WMRRA #49

 

[john durrill]

Dave,
 try going up one tooth in the back, at a time on that track. lots of engines will rev way past their peak power and acctualy go slower as you continue to rev out in the same gear.
 sounds like your power peak is  at some lower point in the rpm's your gearing will let the engine rev to.
 Make sense?
John D.

 

[Dave H.]

Thanks John,
yes it makes sense, but wouldn't that limit my top speed more than backing off of the throttle? I would rather do porting or pipe modifications to get a higher power peak if that were the case...I have been told that the Sachs engine has loads of power to be released by some careful metal removal...but that costs money, and I can't do it meself!
Dave H.

Dave,
 try going up one tooth in the back, at a time on that track. lots of engines will rev way past their peak power and acctualy go slower as you continue to rev out in the same gear.
 sounds like your power peak is  at some lower point in the rpm's your gearing will let the engine rev to.
 Make sense?
John D.

 
[/quote]

 

[john durrill]

Dave , yes it would. Man i appologize. i ment down a tooth at a time. i just woke up and must not be paying attention . chuckle chuckle
 Are you running stock porting? we have the hop up porting specs listed in the library for a 125 sachs.
 I can bump Martjin about it also. You can do all the porting with some handfiles , a degree wheel, sand paper and patience except the tops of the transfers. they are better done with a 90 degree tool like a dental drill.
John D.

 

[john durrill]

Dave ,
 sent Martijn a note on gearing and port mods. Lets see what he has to say.
John D.

 

[deek]

Hi John
Dave's maxed on the primary (17) and running the minimum (48) on the rear. Need to port that puppy, then it'll really bark. Would
the Monark GS port specs do the trick??

Dave, ya still did a great job against those 2 hole four strokers. Hope to see you in Spokane in August : )

Dale





Edited by - deek on 05/28/2003  12:41:07 PM

Edited by - deek on 05/28/2003  12:49:01 PM

[john durrill]

Dave,
 here is Martijn's reply.
 sounds like the porting is not hard to do.
Hi,
 
If you have a big carburettor cilinder(30mm)
Not much to win on the cilinder.
raise the exhaust 1-2 millimeter.
cut off 1-2 millimeter of the skirt.
 
More important:
Use a machined off head.(Squish 1mm)
Use a nice expansion type exhaust.
 
Martijn Stehouwer

 you need to bump the compression some. Anything over 160 psi cranking preasure would be chancy. I have an article on the Monarch mods that covers how to mill the head if you like. Check and make sure you have 1 mm clearance between piston and head when your done.
 deek , thanks for the gearing i sent that off to Martijn to get his feed back. Ill ask him which pipe he was running befor he went liquid cooled and rotary valve on his Sachs.
 The guy is  good. He builds small ( 50 cc and up ) RR bikes even the frames and sells them in the Netherlands.
John D.


 

[rob w]

John, How is that 1mm measured, is that from the top of the piston at the outside edge to the top edge of the cylinder, or how? I'd like to know that, thanks!
I think a road race pipe is made abit longer and thinner, w/ a longer, smaller stinger.
How about bolting on a 32mm Bing model 84, easily adaptable to a B cyl., would that be too big?
Excellent story Dave, please keep us updated through-out the year. If your foot peg mount scrapes the asphalt, that's pretty wild!


 

[john durrill]

Rob, we use electronic soldier. you can get it in .063 or .074 sizes. lay it across the piston crown  with the piston down about 1/4 inch from tdc. replace the head gasket, head and torque it. then rock the piston through tdc and down about 1/4 inch. remove the head and measure the thickness of the soldier with a mic. its the outside band thats closest to the piston you need the clearance on.
 You can go down as far as .030 but any expansion or clearance in any of the moving parts under high RPM can give you contact between head and piston. .040 is a safer bet.
  The One big exception we have found is the 72-75 175 head . it uses a double taper squish band and the deck height recommended is .028 at the outside edge of the piston.
 I still like more so we are running .035 on my engine and have a cranking pressure of 145 psi like that . thats plenty for my use and runs cooler

 

[rob w]

John, Oh yes, I see now what you're saying. The dimension I described is the deck heigth, which has nothing to do with the head.
The reason I'm asking is not for gaining compression, but that I have a Sachs head that is beat up pretty bad in that tapered squish band ring, if I was to take a cut in the lathe and clean it up (maybe .015-.020), then I would need to remove some off of the base (mill) to bring the volume or compression back in the range it was before. Once again, I may be able to salvage it, but with limited time available, the solution will most likely come from buying a new one. It's just good to know these things. What would we do without you John, thanks again.

 

[john durrill]

Rob,
 you could turn the squish area down just enough to remove the high spots. de-bur any sharp edges and use that head. you wont lose much in the way of compression and it should work fine.
 If you do that let me know how you made up the holding fixture for the head into the chuck. They are wide heads and i would like to do some reshaping on one if i can get it to clear the lathe bed i have.
John



Edited by - john durrill on 05/29/2003  12:17:46 PM

[john durrill]

Dave, here is martijn recomendation for a pipe.


Hi,
The old penton or hercules pipes are for
good midrange power.
Yes you could overrev these.
Try more modern pipes if you tune.
I use a Rotax kart pipe now,
peaky but powerful
 
Martijn Stehouwer

 

[deek]

John
You say "cut off 1-2 mm of the skirt", is that the piston (exhaust side)??

Dale

 

[john durrill]

Dale,
 no its 1 to 2 mm's off the intake side of the piston. it increases the duration the intake is open on a piston port engine.
 That was Martijn's recommendation . He Road races Sachs engine bikes in vintage classes in the Netherlands.
John D.



Edited by - john Durrill on 05/29/2003  9:51:28 PM