Tire Pressure? I can't believe it!

[garrettccovington]

Its funny how I think a problem I might have is caused by one thing and actually ends up being something completly different.

I've been having problems going thru corners and over jumps on my 79 KTM.  I figured it was my clutch pull was too stiff.  Well walking thru thew pits this morning and checking out the clutch levers on another KTM and other bikes, I felt mine was actually easier.  So I was bummed.  Going over the bike before practice,  I was checking the tire pressure and noticed I had ONLY 28 pounds in both tires.  I useally like to run anywhere between 38 and 42 lbs.

My buddie, starts laughing at me,  (A Young Man) "Dude, you should be only running 8-14 lbs."  (In my Scoobie Doo Voice) HUH?   Anyways,  I lowered the tire pressure to 12 and the difference was unbelievable.

I actually felt in control of the bike as opposed to My patented Mr. Magoo riding style.

Everything worked great.  It turned,  Went over jumps perfect,  I actually passed somebody in a race and I raced the whole race, as opposed to getting pooped out, by the 3rd lap.

Unbelievable!

G

72 six-day
79 KTM MC80 250

[cdb50mx]

Magoo ,
  I've been racing vintage for 16 years and still come across tricks that allow us to go faster . At least your bike rolled easily when you have to load it .

Mike  11.5 psi

[tomale]

Magoo, maybe I am mistaken but are you using the clutch on the race course? The only time you should be using the clutch is either you are in a corner too tight to allow you to pull out of the corner without slipping the clutch or you purposely entering a corner a gear too tall and are using the clutch to keep the Revs high. These motors are not car transmissions but are constant mesh and you do not need to use the clutch to move from one gear to another. All you need to do is back off on the throttle and shift to the next gear. the same is true down shifting too, back off on the throttle and downshift.

Thom Green,Still crazy after all these years!
76' 250 MC5 (orginal owner)
74'250 hare scrambler (project)
74' 1/2 440 maico
78' 440 maico
72' cr125 Husky (project)
74' TM125 suzuki
93' RMx 250 suzuki

[joe novak]

Garrett,  How can that be?   38-42 lbs. in each tire!   That would make your KTM weigh about 60 pounds more than all the other KTM's and other bikes you are racing.   No wonder it was a challenge to handle.   Joe

[garrettccovington]

LOL!!!  Mike,,, Yeah it's pretty easy to push around.  I got to get a low pressure tire gauge, thanks for the info.

Joe,,Thats why I bought one of those Harbor frieght lift stands.  I couldn't pick the pick up!:D

Thom.  As a Matter of Fact, I do use the clutch for all shifting until around the 3rd lap.  Then my left forearm would be so tired, I would save it for upshifting only.  

I guess you can teach an old dog new tricks

g

72 six-day
79 KTM MC80 250

[Larry Perkins]

Yes, Yes.  With the KTM motor and most the rest clutch only to start, stop, or if a shift was missed.  The rest of the time shiftee shiftee.  

Man, I remember coming off the Sachs Penton 100 & 125 to an Elsinore 125 and sleeved 100 and you could no-clutch shift under power without letting off the gas.  Wow that was great for saving seconds in a race and so far from even the KOBA shift kitted Sachs bikes I had raced.  It was eventually hard on particularily 3rd gear if I remember right but that was down the road a ways and parts were cheap.  Good thing.  I rode a DG kitted EC Birt sleeved 100 Elsie that had to have a ring every race and piston and rings every third race.

Larry P

[brian kirby]

For everything but a Sachs, the clutch is for starts and to prevent stalling in tight corners only, not for shifting.

Brian

[joe novak]

It works with the Sachs engines, too.   I just wonder how many shift without clutching.  Joe

[Lloyd Boland]

Larry, I had an EC Birt motor on a 1972 400CZ in the early-mid 70s.  Reed valve, 38mm Bing, completely redone cumbustion chamber on the head, porting, etc, etc.  The thing was the most powerful CZ I ever rode.  I wish I had the specs on what he did back in the day.  I have 3 CZ400s now, all with reeds, porting, etc, they are fast but none of the bikes I have today compare to the EC Birt motor.  Anyone have any contacts that might have this info?
Lloyd

[Larry Perkins]

EC knew his stuff.

Larry P

[checkcrew]

Lloyd,

go to //www.superhunky.com

EC has a forum on his site, it is titled "Just Ask EC" [something like that],
you can contact him there,

hope this helps,

regards,

quote:Originally posted by Lloyd Boland

Larry, I had an EC Birt motor on a 1972 400CZ in the early-mid 70s.  Reed valve, 38mm Bing, completely redone cumbustion chamber on the head, porting, etc, etc.  The thing was the most powerful CZ I ever rode.  I wish I had the specs on what he did back in the day.  I have 3 CZ400s now, all with reeds, porting, etc, they are fast but none of the bikes I have today compare to the EC Birt motor.  Anyone have any contacts that might have this info?
Lloyd

Mike Gallagher, NJ.

[Lloyd Boland]

Thanks Mike.  I did send an email there, but this goes to EC Distributing, the company that EC Birt started, but sold a few years back. I am hoping he still gets these emails or they will forward my email to him.  Back in the day, so many people crossed paths.  I understand Donny Emler of FMF fame may have actually got his start with EC Birt.

Back in the day he was one of the best tuners/fabricators.
Lloyd

[rob w]

I remember one time EC Birt wrote some magazine article about modifying the Jackpiner engine.
Just after that John Cobb wrote an article in Keeping Track that said, 'DO NOT do what EC Birt had specified about modifiying the 175, unless you want to destroy your engine'.  Don't know all the details of that at the moment, but I would have believed John Cobb over EC Birt when it came to Pentons.

[Doug Bridges]

I use to race against a guy who had an E.C. Birt tuned Penton Berkshire 100cc at Oak Creek Ranch Near Tehachapi CA. He was always first to the turn and the first part of the course was all up hill. The bike did nothing but pull away from everyone in the field. The guy was also a very good rider, So nobody else had a chance.

Doug Bridges
73 Jackpiner
74 Rickman Zundapp
78 Suzuki PE175
82 XR200R

[checkcrew]

Lloyd,
there are 6 posts in his forum, i think the 3rd one down has a corrected email addy to use for direct contact to EC,
check that out !!

regards,

quote:Originally posted by Lloyd Boland

Thanks Mike.  I did send an email there, but this goes to EC Distributing, the company that EC Birt started, but sold a few years back. I am hoping he still gets these emails or they will forward my email to him.  Back in the day, so many people crossed paths.  I understand Donny Emler of FMF fame may have actually got his start with EC Birt.

Back in the day he was one of the best tuners/fabricators.
Lloyd

Mike Gallagher, NJ.