400 Penton Exhaust Modifications

[Daniel P. McEntee]

I'm working on the exhaust on the '75 Penton 400 project I have been putting together. This is a bike I have mentioned before that I think was built up from parts as a qualifier bike. One of the unusual features of the bike was the exhaust. It looks to be standard Penton/KTM from the header all the way back to the end of the rear cone. They cut off the sheet metal where the original silencer/spark arrestor was, and grafted on a unit from some other source that I want to try and identify. I have two questions:
  1) The spark arrestor in question is a straight, round tubular affair. It is 2 1/2" in diameter and about 17 or 18 inches long. It has the following stamped on it " J&R Krizman Spark Arrestor Pat.No 3407575 Model KS-650 Approved US Forrest Service." this is stamped cross ways around the can at the rear end. I think Krizman units were used on LOTS of bikes in the late 70's, which is when I think this bike was assembled. It might even be from a Japanese bike, like an IT or PE series bike. Does this sound familiar to any one. If I can find one like it, I will just replace it and not worry about repairing the spark arrestor.
  2) The spark arrestor in question was welded in place over the opening of the last cone in the pipe, and it is about a 2 1/8" opening. Can anyone tell me if this is the "normal" opening for the last cone of a Penton 400 GS pipe?
   I'm trying to rebuild this bike to look just like my brother found it. My guess is that figuring in the area my brother found the bike (Atlanta,GA) it may have been built by or at Barry Higgens' shop back in the late 70's.
   Thanks a lot in advance for any help, long shot that it may be. Lots of knowledge and experience out there and it has come through for me before!
   Type at you later,
   Dan McEntee

[Kip Kern]

Just saw the Penton movie in Indy and loved every minute of it:)  Outstanding job to all involved!  The wife really enjoyed it too and now understands the love behind the Penton marque and wonderful family!

[KJDonovan]

Dan,

I am presently finishing a 75 Penton 400 pipe, so I can answer one of your questions;  

"The spark arrestor in question was welded in place over the opening of the last cone in the pipe, and it is about a 2 1/8" opening. Can anyone tell me if this is the "normal" opening for the last cone of a Penton 400 GS pipe?"  

The ID of the "megaphone" end of the 400 where the chrome tail piece attaches is about 3.8"  (97MM).

Thanks,

Kevin


Kevin J. Donovan
Foster, Rhode Island
72 Jack Piner (My Ride)
72 Six Day (Wifes Ride)
71 Suzuki TS125
72 Montesa Cota 123
72 Montesa Cota 123T (Another Project)

[Daniel P. McEntee]

Hi Kevin;
   The "megaphone" at the end of the GS pipe is welded over the end of the last cone of the expansion chamber part of the pipe, where a "stinger" would normally be attached. I believe all Penton pipe expansion chambers stopped at that point, and had no "stinger". A sheet metal shape of some sort, a tube or as in the case of '74/'75 bikes, the "megaphone." The previous owner/builder of the bike cut off the megaphone, and replaced that with this unknown commercially available silencer/spark arrestor. It's actually kind of neat looking, or probably was when it was built. All banged up and some internal parts missing. I have a Super Trapp that I may do a similar adaptation with if I can't figure out this mystery. I just have a slight concern that the cone diameter at that last convergence point may not be the correct size for the engine to run like it should. There isn't a lot of diameter changes in the expansion chamber sections of the 400 pipe apparently.
  Thanks for the reply,
  Dan McEntee

[KJDonovan]

Dan,

I just went out and measured the pipe I have and it is about 2.9" OD where the last tube in the expansion chamber attaches to the megaphone end.  I say "about" 2.9 because it is not even close to being perfectly round in that area.  But it sounds like yours is close to the same diameter.

Thanks,

Kevin




Kevin J. Donovan
Foster, Rhode Island
72 Jack Piner (My Ride)
72 Six Day (Wifes Ride)
71 Suzuki TS125
72 Montesa Cota 123
72 Montesa Cota 123T (Another Project)

[brian kirby]

J&R was a popular aftermarket company in the '70s, they made clamp on silencers and spark arrestors. I have a clamp on J&R silencer on my 100.

Brian

[Daniel P. McEntee]

Hey Brian;
  Thanks for pointing that out. I was think J&R was just Krizman's first initials! So they were a brand. That is the kind of info I was hoping to hear. You say you have one on your Berkshire? Do you plan to repack it in the near future? I have been working on and looking at the one I have, and if I can find out what all it had for parts and what they looked like, I may be able to rebuild the guts and use this silencer again. There is a spring in the middle of the inside that I haven't figured out what it's for because I think I'm missing an end cap. I think I have you email address and I'll send you some pictures I took tonight of what I got, and if yours is a model 650 could you take some pictures and the internals and send them to me?
  Another question I was pondering is that this silencer may be too restrictive? I'm just going to keep working on the pipe while I gather more information.
   Thanks again for the information,
   Dan McEntee

[Wesley Plunkett]

Hi Dan,
I have seen the name Krizman on many spark arrestors, mostly Honda. I googled it and came up with this link.

http://www.fs.usda.gov/Internet/FSE_DOCUMENTS/stelprdb5319644.pdf

As for the opening of the last cone, I think for the pipe to work properly it needs to reduce down to around 1" and end in a short "stinger" before the spark arrestor/muffler. I have a pipe similar to yours that came on a 250 HS, it had pretty flat power. I put on an Ace pipe that ends in a 1" ID stinger and adapted an FMF turbine core muffler to fit, wow what a difference! The muffler is not period correct but it's relatively quiet.

Wes      

[Daniel P. McEntee]

Hi Wesley;
     I have also noticed the name Krizman on just about every Japanese exhaust I have ever seen. I think Mr Krizman had patent rights to a very good spark arrestor/silencer design at the time, and all the manufacturers found it easier and cheaper to pay him a royalty than to come up with their own. I think Brian Kirby is correct in that this is an after market clamp on silencer that had the clamp end cut off, and welded on in place the the stock, heavy megaphone and silencer. It was just the right length to do that with, and makes for a pretty clean, trim exhaust. I got into the exhaust on my '75 Husky and discovered that it didn't have a tradition "stinger" at the end of the last cone, just a wire mesh spark arrestor, and the can for the rest of the silencer was welded to the last cone. On an engine like a 400 KTM, it might not be necessary for the traditional stinger to create the back pressure  to boost power. I have a complete, in tact GS 400 exhaust, but can not see past the bend in the megaphone to see if it is the same as this other one. This bike isn't your typical, stock  75 Penton 400. It has an engine that was built up using what looks to me like a 250 bottom end with 1973 dates on the casting clocks, and a 400 top end. It had leading axle Marzzochi or Ceriani forks that weren't available until the '76 or later MC-5 models. It has some a pair of the first generation Works shocks on it, along with a Hi-Point aluminum gas tank. Preston Petty enduro fenders and head light, and lots of other little serious enduro type tricks that guys did back then like the back side of the levers had a thick layer of silicone, and cables between the rear brake pedal and gear shift, and  GEM reed valve kit. Someone went through a lot of time and trouble to put this thing together. I want to rebuild it just like it was found as an example of what was done back in the day. If the exhaust doesn't work out, I have the other stock GS pipe to put on it. From what I have read about the 400 Penton, and my own brief experience with my '77 MC-5, I don't think I'm going to be hurting for power! Anything that will even out the power band on it I think will be an advantage for a rider of my meager skills! Gary Ellis has the engine going through it right now, and by the time I get it back from him, I hope to have the rest of the bike ready for it and we'll see how it all works together. I want to get some pictures of it out circulation around, and with the knowledge that it was found in the Atlanta area, maybe some one will recognize it and know more of it's history.
   Thanks a lot for the input,
   Dan McEntee

[Wesley Plunkett]

Hey Dan,

I race mx on that 250 HS with the Ace pipe so I'm looking for a good midrange to top end hit to keep up with the CZ's Hooskas and Maicos. If I was riding in the woods the pipe with the flat, mellow power would be a better choice, especially with the added power of a 400.
 
I recently bought a '74 400 that was set up for the Nevada desert with   Marzocci leading axle forks and early finned Works shocks. It also has the early 400 motor with the light crankshaft, fine for the desert but hopefully your motor has the weights on the crank to slow down the revs a bit for the woods. The pipe appears to be stock but the stock "megaphone" removed and a Super Trapp muffler welded on.

Sounds like a cool bike, I'm looking forward to the photos of the finished product!

Wes

[slvrbrdfxr]

Dan,
I was just looking at the pictures of your pipe posted on Vinduro. That muffler/spark arrestor looks identical to the one I recently welded on the rear of a 77 400 GS6 pipe which was missing the rear cone. Hoping to have this GS6 done and on display at Mid Ohio this year. I can email some pics of my completed pipe if you drop me a line.
Dave McC

[Daniel P. McEntee]

Hi Dave;
   Thanks for the reply. I will most certainly drop you a line later today with new pictures of what I have done with the silencer so far. I made new baffle and spark arrestor cores. I still would like to find out what the end cap looked like, and when I reassemble it, I'll leave the anchor wire for the spring and add the end cap later if I have to. A friend of mine who just closed up his motorcycle parts business after 40 plus years thinks this particular silencer may have been offered through Hi-Point, but we can't find it in any old catalogs. He remembers a customer with one on a bike, and that it did have the rear flapper, and the length of the thing also. It's 18 inches long as it sits, and I don't know how much was cut off. That's a lot for a clamp on device to hold, and he thinks it may have been designed do be used in just this manor. I'll take anothe couple ofo pictures and send them your way today.
  Thanks a lot,
  Dan McEntee

[slvrbrdfxr]

Dan,
My silencer/spark arrestor is approx. 18" long and came with a 1974.5 Mint 400 that I bought locally many years ago and think it could be a Skyway brand. Looks just like the one in the link below. I think someone had cut it off the original header pipe and then used the header on a homemade go-cart or etc was what the seller told me. Fortunately I was able to buy a 2nd 74.5 Mint 400 which had a good original exhaust and used that pipe when I built my 74.5. My 77 400 GS6 had a an old beat up Super Trapp attached to the end of the pipe which was completely trashed and no way to salvage it. I removed the Super Trapp and installed the Skyway unit and the pipe turned out pretty good.
Dave McC

http://www.ebay.com/itm/Skyway-SPARK-ARRESTOR-SILENCER-TUBE-exhaust-3-X-17-Husqvarna-WR400-AHRMA-/160889755033?pt=Motorcycles_Parts_Accessories&hash=item2575c6d599&vxp=mtr

[Daniel P. McEntee]

Hi Dave;
    I saw that eBay auction on a search of any J&R silencers. Unfortunately, that is just the outer can, no inner core or guts. I have a shorter Skyway that I was considering rolling a new tube for and replacing what was on the pipe originally, but repairing the pipe and silencer hasn't been to difficult. I wonder if the guts in my Skyway would fit the eBay item? Too much of a gamble I think but I may dig it out and check it out. I just sent you some pics in a couple of emails. Check them out and will be looking for pics of yours.
   Thanks a lot,
   Dan McEntee

[SouthRider]

Dan,

If you are going to replace the Krizman - the vast majority of riders in the late 70's used the super trapp. It afforded the best range of performance vs. silencing, and it was an obvious spark arrestor to any inspector.

Back then people wanted the least obstruction possible as long as they could pass the sound test. The trapp was the easiest to use as they could carry a few extra disks in their tool box & put them in or take them out as needed. They were literally tuning each weekend depending on how strict the club was at each race. The amount of tightening on the nut provided additional tuning (some rattled pretty bad...).

The biggest negative of the trapp was the rattling, and also the yucky black 2 stroke oil stain on the side of the rear fender. I can't remember any serious 400 riders in the south who weren't using one.

The reason that it is so hard to find an intact OEM exhaust from that time is that they were extremely restrictive to meet New England sound standards so the vast majority of them were cut up to add a trapp.

Clark

_____________________________________________________________________________________

"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