Fork setup

[wfopete]

Any guidance on oil amount and type for stock 32mm forks on a 73 Jackpiner? I saw the post on the mods for this front end but I'm not ready to start drilling and brazing dampner rods right now.

Peter Petrick

'01 KTM EXC 520, '74 YZ 250, '86 Honda XR 250, '71 Hodaka 100, '74 SUZUKI TM 400, '73 Penton Jackpiner

[DKWRACER]

Hi Peter!!!! You can try this...remove the springs and collapse the forks to full compression, add oil till the level comes to 5 or 6 inches measured to the top of the tube to the surface of the oil, tape measure etc. dipped into the tube...130 cc may get you close, ....move the tube up/down several times to fill all the cavities, then take your final measurment when the oil "settles", make sure you send me a photo or two of that unit, would like to see how the new fiberglass looks...Thanks, and welcome Home!! Tom....(Bel-Ray 10 to 30w depending on the dampening needed)

[wfopete]

Tom,

Thanks for the info. I'll be pulling the forks off and going through them later this week, but for today I'm working on getting the swingarm off and checked out. Any Penton "maintenance tips/tricks" out there let me in on them!

Peter Petrick

'01 KTM EXC 520, '74 YZ 250, '86 Honda XR 250, '71 Hodaka 100, '74 SUZUKI TM 400, '73 Penton Jackpiner

[tomale]

Peter, Tom is right. This is the only method that I use on my forks. I have tried using heavier oil and did not like the results. Believe it or not I went back to using ATF in the forks.(And I ride all big bikes)  I want the front end to be supple. If the forks seem to be too soft, try adding oil. What this does is in effect stiffen the springs to keep them from bottoming out. but will not effect the suppleness over the little bumps. We use to use air caps and such and they make the forks too stiff and hard to handle. You will see this especially in tight flat corners.... What is happening is the front end is not setting up to allow you to corner the way that you should. Better to stay with a lighter oil and more of it. It is important to make sure that both sides of the forks have the same amount of oil because it will mess up the effect when you hit a big bump and in effect acts like the forks have two different fork springs in them. Good luck on your project. let us know how it is going.

Thom Green,Still crazy after all these years!
76' 250 MC5 (orginal owner)
78' 400 MC5

[Mick Milakovic]

Thom - does ATF come in different weights, or does the rating make a difference?

[bentrims]

Mick,

ATF is time tested in my set-ups, and believe me my forks get abused. Last week my 32mm forks ran at 5 1/4 inches of oil (ATF) from the top with the springs out and the tubes fully compressed. I run helper springs to slightly stiffen up the preload. When you only have 6" of travel you best not lose any travel at resting.

I figure as in the E F Hutton commercials of the 70's...when Doug Wilford gives advice...I listen. Dane advice was mixed in also on my forks.

Dont tell the master I use ATF in my tranny too.

[bentrims]

PS...ATF only comes in one weight to the best of my knowledge. It does have different (Types)additives in it that manufacturers coin to try to manipulate their market share. For our purposes it all does the same thing regardless the type you buy.
Tom B

[Lew Mayer]

That's why you fly sooo high. Your springs are so tight they're bouncing you that high.

Lew Mayer

[Merlin]

deleted

[wfopete]

OK, forks are done and back on. Old fluid looked nice and clear/clean. Probably went a little stiff with ATF fluid at 5.5" from the top plus I dropped in a .75" preload spacer. I ended up with closer to 150cc's of ATF in each leg.  The tires that came on this thing were Trelleborgs "Red Stripe"; a Super Grip 344 in front & a Ten Masters Motocross 744 rear. Don't know how old they were but the previous owner had Moose Super Tubes in them. I replaced them with Michilin S12s front and rear. Hope it all works in Jefferson TX!

Peter Petrick

'01 KTM EXC 520, '74 YZ 250, '86 Honda XR 250, '71 Hodaka 100, '74 SUZUKI TM 400, '73 Penton Jackpiner

[Lew Mayer]

Now that we have the hot set-up on 32's, any measurements on the 35's from the top. Any tricks and tips from Mr. Doug? If it's 90% the rider and 10% the bike,my bike needs all the help I can get for it. Has to compensate for the rider.

Lew Mayer

[bentrims]

Well Lew atleast you picked up a sponsor for this race.

[Lew Mayer]

Gas card hasn't arrived.
Gotta be back 4/3 for the York swap meet,though.

Lew Mayer

[wfopete]

Tom,

Thanks for the info. I'll be pulling the forks off and going through them later this week, but for today I'm working on getting the swingarm off and checked out. Any Penton "maintenance tips/tricks" out there let me in on them!

Peter Petrick

'01 KTM EXC 520, '74 YZ 250, '86 Honda XR 250, '71 Hodaka 100, '74 SUZUKI TM 400, '73 Penton Jackpiner

[tomale]

Peter, Tom is right. This is the only method that I use on my forks. I have tried using heavier oil and did not like the results. Believe it or not I went back to using ATF in the forks.(And I ride all big bikes)  I want the front end to be supple. If the forks seem to be too soft, try adding oil. What this does is in effect stiffen the springs to keep them from bottoming out. but will not effect the suppleness over the little bumps. We use to use air caps and such and they make the forks too stiff and hard to handle. You will see this especially in tight flat corners.... What is happening is the front end is not setting up to allow you to corner the way that you should. Better to stay with a lighter oil and more of it. It is important to make sure that both sides of the forks have the same amount of oil because it will mess up the effect when you hit a big bump and in effect acts like the forks have two different fork springs in them. Good luck on your project. let us know how it is going.

Thom Green,Still crazy after all these years!
76' 250 MC5 (orginal owner)
78' 400 MC5