Starting a 400 Penton

[Daniel P. McEntee]

I had my first Pentons, a 69 or 70 Berkshire 100 steeltanker and a '72 125 Sixdays, back in the early 70's. I wanted to move up to a 250 Penton in 1975, but Dave Mungenast told me he just couldn't lay his hands on any of them at that time, so he talked me into buying a '75 250 Husky WR. It was a decision that I did not regret, and still own that bike to this day. (It would be almost 40 years before I could finally find my elusive 250 Penton!) It was during a riding and hang gliding outing at what is now St. Joe State Park in Park Hills, MO ( the site of three ISDT Reunion Rides) that I witnessed the awesome power of the mighty white Penton Mint 400. There was a steep, steep, chat hill that we used to ride down and fly the hang glider off of, but none of the bikes we had could pull up that steep grade in the sand like chat. I had heard about the 400 coming out, and this was the first one I ever saw. The guy didn't even need to make a run at the hill, he just idled up to the base of it and rolled the gas on and up he went! I just couldn't imagine handling a bike with that much power!
  When I started to collect vintage bikes 17 years ago, I was always looking for Penton projects and had a secret hope of finding one of each size Penton, including the 400. I finally achieved that desire a few years ago ( which in itself is an interesting story) and the 400 that I acquired was from the Kansas City, MO area with the help of Jeff DeBell. It's a '77 MC-5 that I have slowly been trying to make look like GS model. The bike was in pieces, and Jeff assembled it into a roller. I got the bike from him and decided to finish assembling the bike and replace what was really needed to get it running and riding before doing any cosmetic work. The engine seemed in good shape, had great spark, and really good compression. Even though it is an MC-5, the bike had Petty enduro rear fender and head light on it with Missouri license inspection stickers on the fork tubes. I think the bike was used on a farm and only ridden there and on farm roads, or the engine had been over hauled at some point. It came equipped with a Lectron carb and that was my introduction to those. I got a set of Progressive shocks for it, checked out all the other controls and proceeded to try to start it.
   I had been warned by several of you guys out there to beware of the thing kicking back on starting, and that they tended to have a light switch type power band. I have to use a milk carton or something to get high enough to start the damn thing, but managed to get it to fire and start with in a half dozen kicks, most of the problem being dealing with the engine compression. I rode the bike up and down the street and was amazed at how smooth and torquey it was, more like a big bore Husky. I have owned the bike for several years now, and for lots of reason I never did get a chance to get the bike out to really ride it and experience it.
   Well opportunity finally presented itself a couple of weekends ago to go ride on a guy's property that my nephew knows, and he had some open fields and a vintage style MX track. The 400 was one of the bikes I took with me. In the previous few years, I had rebuilt the Lectron with a new slide and needle, and this helped make it "easier" to start with in a few kicks, but those few kicks were killers dealing with the compression the bike has, as me and my right leg are now several years older! I got to wring out the throttle a bit on some level ground and get it above third gear for the first time. It's more like a modern bike, like you sit on top of the thing and the seat positioning is different, and before I ever ride the bike in the woods, I need to be able to more comfortably start the damn thing! The power it puts out is amazing! I probably have no business riding something like this!
   The engine has a place in the back of the head for a compression release that I had heard that some 400 Pentons had. If I shine a light in the opening, I can see a hex socket head like a set screw or some kind of plug. How does the compression release mechanism work of these things that were equipped with one? I'm assuming in isn't like anything that you would see on an OSSA or Bultaco! Would this be something that would be a benefit to me if I can find and acquire the necessary parts? If not I just may have to re-evaluate things, sell the bike and get a Jackpiner instead! I would appreciate hearing from some of you experienced 400 owners.
   Type at you later,
    Dan McEntee

[ALB]

HI Dan,

The hex head screw that you are seeing on the side of the cylinder is a sealing bolt. The stock compression release for this will be difficult to find.
You have too much compression.
You will be better off doing one or both of the following:
1) reset the deck height of the cylinder to the GS specs for less compression by adding thicker base gasket(s).
2) contact Chicago Jerry to see about enlarging the dome in the cylinder

Having less compression on a 400 will make it easier to kick over give you strong usable (not scary) power.

Alan Buehner

[KJDonovan]

Daniel,

Another option is to attach a piece of 1/8" fuel line to the overflow on the carb and run that tube under the tank all the way up to the cross bar on your handle bars and zip tie it off there.  Then just before you are ready to start it, blow into the tube to 2 seconds.  This pushes fuel vapors into the cylinder which are more combustible than fuel resulting in one kick starts.  I saw this little trick online and ended up using it on a mid-80's KTM 250 I had that was always a bear to start.  Low-tech, but it works.

Thanks,

Kevin

[checkcrew]

Dan,

Jerry Berkie did the head mod on a 400 i had, it started as easy as a 250 but ran as good as a 400 does, these 400 make crazy power but what good is it if you can't use it [8D]
my .02 here,

regards,

Mike Gallagher, NJ.
[email protected]

[SouthRider]

Make sure someone hasn't advanced the timing. Those bikes actually run better with it slightly retarded from stock. Think tractor like power.

_____________________________________________________________________________________

"We the willing, led by the unknowing, are doing the impossible, for the ungrateful. We have done so much, for so long, with so little, that we are now qualified to do almost anything, with nothing."

1972 Penton Berkshire 100
1983 Husqvarna 250 XC
2011 Jayco 31.5 RLDS
2009 Chevy 2500 HD Duramax

[Kip Kern]

2.4mm BTDC is timing (Motoplat), find/try a Motoplat trials ignition (huge and heavy), calms the beast right down.  I have a 76 GS and starts on the first kick, put it in 3rd and ride it like an automatic. 38mm Bing all stock bike no compression release.  Love mine

[Daniel P. McEntee]

Thanks to all for the replies. I think I'm looking at having the head work done as mentioned. I had read about that here on the list before but have forgotten about it. The bike does not kick back when starting, just hard for these old short legs to get any leverage and follow through to kick it through the compression.Once running, it seems to run very smooth and even, just with gargantuan amounts of power! I'm not sure if I can get comfortable with  the seat position on the bike, but if I can get the work done and it starts easier, then I could ride it more and get used to how I sit on it. Time will tell and I'll look into getting the head work done.
   Thanks a lot,
   Dan McEntee

[chicagojerry]

hi dan. get that head mod done... it makes them start SO much easier.
i hardly ever do a 400 motor that doesn't get that treatment..     chi jer