The standard rear tire for a Six Day is 3.50 x 18. My question is how much power is lost when a bigger tire is used like a 4.00 or 4.60? [?][?]
Rod Whitman
Omaha, Nebraska
1972 Six Day (Rider)
1972 Six Day (Project)
The modern 400 series tires like Kenda or Cheng Shin are about the same size as the old 3.50 tires.
Tony
The 400:18 was the tire of choice on all CMF models 72 + clearance through the swing arm was more of a factor than the power loss. If you don't have traction, what difference does HP mean. Sprockets can be changed to keep you on the pipe.
Have Fun!
Rod, I jsut put a 4.00 x18 trie on my Six Days and it may have lost a little power(very little) but the extra traction is well worth it. Like Doug says HP doesn't matter if the bike won't hook up.
All of the "experts" on Six Days told me to run a 4.00,I make sure to listen to them!! It might rub the chain gaurd a bit but it works.
Plus it makes the bike look badder!
Conrad
Conrad Pfeifer
1972 Penton Six Days
I put a 4.00 X 18 on my bike just before the ISDTRR, the tire I took off was a 4.50 X 18. I used to always run 4.50 X 18 in the really muddy slop, it takes a little bit to get it to turn freely but it really pays off in ugly conditions. It is best to have your carb adjusted properly if you plan to lug around a 125cc machine with a 450 X 18 on it in the muck, if you are rich at the bottom it might make for a long day.
Paul
Quotequote:Originally posted by cubfan1968
The standard rear tire for a Six Day is 3.50 x 18. My question is how much power is lost when a bigger tire is used like a 4.00 or 4.60? [?][?]
Rod Whitman
Omaha, Nebraska
1972 Six Day (Rider)
1972 Six Day (Project)
Oversized tires dont bring anything.
I use a 410 on my 250 + 350
Helmut Clasen KTM
162 Hillcrest Ave
L9H 4Y3
Dundas Ontario Canada
Ph.905-627-5349
[email protected]http://speedy_c.tripod.com
Sachs MC-GS 250-7A reeds
Hercules 350-7A 77
Hercules 250-7A 76
Hercules 250 GS 7A 77
Zuendapp 125 GS
KTM 200 EXC 2003
KTM DUKE 96 Spec.
Ah Speedy, the soils are different in Mars:) I hope you were able to get your travel trailer back after the ISDTRR.
Paul
For what it's worth; I have used a Michelin trials tire in every AHRMA cross country event I competed in (7 or 8) this year except Barber and the ISDTRR. I have had zero traction issues with the trials tire. At the Qualifier Warm Ups in Arkansas there were times where the trials tire gave me too much traction as I needed to climb up on the tank or cut the throttle to keep from looping out while climbing a first gear hill covered with roots and rocks. The trials tires cost more but wears great. I also use them on my KTM 300X/C-W when racing Hare Scrambles here in Arkansas. While others go through 2,3 or 4 tires in a season, I still have life on the trials tire.
With that said, I tossed the 'Piner's chain guard (for tire clearance) and put on a new Michelin S12 for the Barber and ISDTRR events. I theorized that I would rather give up a pinch of power to pull the bigger tire than get stuck because of lack of traction. Plus you get addional rim protection with the wider tire. I'm glad I switched for those two races, especially the ISDTRR, where no matter how deep the mud, ruts or sand that S12 pulled me through with no problem. I probably don't think I could have said that with the trials tires!
BTW, Dirt Rider magazine just gave trials tires the runner up spot for product of the year. Try it you'll like it.
Pete Petrick
'01 KTM EXC 520, '74 YZ 250, '86 Honda XR 250, '71 Hodaka 100, '74 SUZUKI TM 400, '73 Penton Jackpiner
My current 6 days race bike has had the same modern 100/90-19...yes 19" Excel rim. Has never failed pulling holeshots in 125 classic class.
I put a veneer on it and it reads 4.70 outside. Keep that compression around 150-155 psi and she will pull it easy.
We always ran 4.50 tires on our 125s to float through the deep sand of a Florida winter series with great success.
Tom Benolkin
Quotequote:Originally posted by wfopete
For what it's worth; I have used a Michelin trials tire in every AHRMA cross country event I competed in (7 or 8) this year except Barber and the ISDTRR. I have had zero traction issues with the trials tire. At the Qualifier Warm Ups in Arkansas there were times where the trials tire gave me too much traction as I needed to climb up on the tank or cut the throttle to keep from looping out while climbing a first gear hill covered with roots and rocks. The trials tires cost more but wears great. I also use them on my KTM 300X/C-W when racing Hare Scrambles here in Arkansas. While others go through 2,3 or 4 tires in a season, I still have life on the trials tire.
With that said, I tossed the 'Piner's chain guard (for tire clearance) and put on a new Michelin S12 for the Barber and ISDTRR events. I theorized that I would rather give up a pinch of power to pull the bigger tire than get stuck because of lack of traction. Plus you get addional rim protection with the wider tire. I'm glad I switched for those two races, especially the ISDTRR, where no matter how deep the mud, ruts or sand that S12 pulled me through with no problem. I probably don't think I could have said that with the trials tires!
BTW, Dirt Rider magazine just gave trials tires the runner up spot for product of the year. Try it you'll like it.
Pete Petrick
'01 KTM EXC 520, '74 YZ 250, '86 Honda XR 250, '71 Hodaka 100, '74 SUZUKI TM 400, '73 Penton Jackpiner
I tried 2 Dunlop trials tires. Destroyed both in 65 miles. Good traction on hard pack , rocks and roots. Mud is marginal. Suprising good traction on sand. Braking is HORRIBLE. I tried to slide through every fast turn. I went back to Pirelli MT16 tires. OH, By the way I use the Cheng Shin C183A on all my small bore bikes. I use the 350X18 on my Hodaka and do not lack for traction. A 410X18 is similar in width to a 350 but with a lower profile. If you are putting a 400X18 on your Six Day 125, I suggest the C183A. It is a Barum copy and isn't quite as aggressive as a C755 Cheng Shin and lasts longer. Really hooks up in the rocks and roots. If you have a Jackpiner I highly suggest a 110/100X18 ( 400X18 ) Pirelli MT16. It uses a older tread pattern and although it resembles a Metzler MX Enduro or a Pirelli MT08, it is made with a modern carcass and rubber compound. I use them ( 120/100X18, 450X18 ) on my 525EXC KTM. A modern tire like a Michelin S12 has no place on a vintage bike. Too much traction. Modern tread designs look wrong on a vintage bike. Michelins didn't even make knobbies till about 1986.
IMHO,
Dwight
Dwight Rudder
7 time ISDT / E medalist
8 time National Enduro Class Champion.
Quotequote:Originally posted by bentrims
My current 6 days race bike has had the same modern 100/90-19...yes 19" Excel rim. Has never failed pulling holeshots in 125 classic class.
I put a veneer on it and it reads 4.70 outside. Keep that compression around 150-155 psi and she will pull it easy.
We always ran 4.50 tires on our 125s to float through the deep sand of a Florida winter series with great success.
Tom Benolkin
First of all a 19" rim is wrong on a vintage bike made in the 70's. I seriously doubt also that the tire would stay on the rim with 150 PSI!
Also a 450 Metzler MX Enduro was about the same size as the 400 Pirelli MT16. The 450 Multicross was a HUGE tire meant only for open class bikes. A 18" tire is better to prevent flats as you have more sidewall cushion. A 19" rim is marginally better on a hard pack blue groove track like in SoCal. Or a SX track.
IMHO,
Dwight
Dwight Rudder
7 time ISDT / E medalist
8 time National Enduro Class Champion.
Quotequote:Originally posted by Dwight Rudder
Quotequote:Originally posted by bentrims
My current 6 days race bike has had the same modern 100/90-19...yes 19" Excel rim. Has never failed pulling holeshots in 125 classic class.
Keep that compression around 150-155 psi and she will pull it easy.
We always ran 4.50 tires on our 125s to float through the deep sand of a Florida winter series with great success.
Tom Benolkin
I seriously doubt also that the tire would stay on the rim with 150 PSI!
Dwight,
I think (hope) Tom was talking about the compression in his motor. You destroyed 2 trials tires in 65 miles? What the hell were they on, your 525? Don’t tell me you did it on your Hodaka! I have not used a Dunlop trials tire, so I can't speak for it's durability.
Pete Petrick
Rod,
I see that everybody is giving you their take on what size of tires to use, but I don't see anybody answering your question. I don't know I can give you an accurate answer, but I can let you know the actual effect of different size tires.
First off, when you go to a larger tire, you have to take in effect the diameter of the tire as well as the width. A wider tire with a lower cross section, can end up with the same effect, depending on the actual dimensions.
During the steel tank/cast iron cylinder days, the 125s used a 3.50 rear tire, but when the aluminum cylinders and eventually the CMF frames came around the horsepower levels of the bike rose, and they would work well with the 4.00 tires.
Another issue that must be taken in account, is the bike's gearing. The effect of a larger rear tire, can be countered by adding a couple of teeth to the rear sprocket. By going this direction, you can retain the acceleration rate, but of course, you'll lose a little top speed.
When Metzler came out with the 4.10 rear tire, we pretty much went to that tire, because it had the footprint that we wanted, but because it was a little lower in aspect than the 4.00. Later on the metric type measurements came out, they began to make even lower profile tires with wider foot prints, which gave us even more options.
As for the actual horsepower loss, that actually isn't going to happen, because you aren't actually affecting the engine. But larger tires, width or diameter, will affect the bike's acceleration. By changing the gearing, you can adjust that effect.
Personally, I liked the low profile tires with a wider footprint, providing it clears the chainguard and swing arm. One thing you have to keep in mind regarding the low profile tires, is that they don't protect the rims as well when you're riding in rocks.
I hope this information helps you out a little.
Dane
Dane,
Don't you mean subtracting a few teeth? "The effect of a larger rear tire, can be countered by adding a couple of teeth to the rear sprocket. By going this direction, you can retain the acceleration rate, but of course, you'll lose a little top speed."
Teddy
No, Teddy. When you add teeth, you lower the gear ratio (higher number/lower ratio) and retain the acceleration rate. The larger tire, is harder for the engine to turn, so by adding teeth to the rear sprocket, you counter that effect.
Dane
Dwight,
I think (hope) Tom was talking about the compression in his motor. You destroyed 2 trials tires in 65 miles? What the hell were they on, your 525? Don’t tell me you did it on your Hodaka! I have not used a Dunlop trials tire, so I can't speak for it's durability.
Pete Petrick
[/quote]
Yes, they were on my 525EXC. I short shift and use engine torque a lot. I didn't hammer them or spin them much.
Dwight
Dwight Rudder
7 time ISDT / E medalist
8 time National Enduro Class Champion.
Yep- I was talking motor compression and making the point that if my 125 Six Days will pull a 19" modern tire that mics out at 4.70 there should be no problem with most any 4.50 - 18 incher. BECAUSE the taller circumference adds to a taller gear ratio.
The standard tire being 3.50x18 was likely a good match to stock compression, carburetion and gearing.
TB
I like the 19" rim for the simple reason of tire selection and availability.
I like testing new things on my race bike whenever possible. It currently runs an 87 KX 125 wrist pin, 79 CR125 stinger, 75 Elsinore 125 fork springs. May soon test a made to fit 175 yamaha pipe.
Clearly-This is not my fathers Six Days. But as Uncle Ron insists I will keep a Penton tank on it.
TB
PS- Tire selection is ultimately a personal thing because the great equalizer is how skillful the rider can fan or slip the clutch and when he slips it.
And you DO know when to fan it.:)
Lew Mayer
Quotequote:Originally posted by bentrims
PS- Tire selection is ultimately a personal thing because the great equalizer is how skillful the rider can fan or slip the clutch and when he slips it.
That is funny. The Sachs clutch is so small that even a little bit of clutch slipping is hard on it. Not to say that you can't do it a bit but you better not do it a lot. Too big a rear tire will cause the clutch to fail sooner as you need a bit of wheel spin to properly exit corners.
IMO,
Dwight
Dwight Rudder
7 time ISDT / E medalist
8 time National Enduro Class Champion.
Quotequote:Originally posted by bentrims
I like the 19" rim for the simple reason of tire selection and availability.
I like testing new things on my race bike whenever possible. It currently runs an 87 KX 125 wrist pin, 79 CR125 stinger, 75 Elsinore 125 fork springs. May soon test a made to fit 175 yamaha pipe.
Clearly-This is not my fathers Six Days. But as Uncle Ron insists I will keep a Penton tank on it.
TB
Testing new things on a bike that was designed to be raced 35 years ago tends to be a bit wasteful doesn't it ?
Also there are more 18" tires available for your bike than 19" . What does a 1987 Kaw wrist pin do for it ? Why a CR125 stinger ?
I would think that listening to the likes of Dane Leimbach and Doug Wilford and Paul Danik would give enough tips on how they made them go when they were new.
Just an Opinion,
Dwight
Dwight Rudder
7 time ISDT / E medalist
8 time National Enduro Class Champion.
Dwight,
It seems you are irritated by the entire discussion so I will choose to end it here. Go to an MX sometime and just see.
TB
Dwight,
Shoot me an email and we can talk about my anti-Elsinore/pro-Penton project. Lets do our absolute best to not be like the other sites. By doing this the kid on the other side of the room will be willing to raise his hand and ask how far to gap a spark plug.
Tom Benolkin
[email protected]
Tom,
Thanks for sharing some of your secrets. I think many of us enjoy hearing what you do to out run ALL the other branks 125, 250 and Open Class bikes.
Dwight,
I think you should understand that Doug built the this engine and I think when Tom won 6 Motos back in April at the Texas AHRMA race that was a mile stone for any brand of bike. I was PROUD he did it on a Penton.
Ron Carbaugh
Kerrville, Texas
My feeling is that a vintage bike should be good representation of how the bike was raced during it's day. To modify a bike to what it was not is a shame. I am against butchering good OE exhaustpipes. Modifying the frame and swingarm or changing things to achieve a more "MODERN" look or feel. There were NO racers in the 70s using 19" rear wheels although some of the British bikes in the 50's and 60s did. Just my personal opinion. By the way I have won motos in the classic 125 Exp. class against super modified CZ and Husqvarnas on my "STOCK" Hodaka Combat Wombat ( it even had the lighting kit on it. ). USD Shocks were not even used till about 1977 and I hate to see them used today. As Dick Mann said at the ISDTR banquet. Vintage bike racing is about showing everyone what riding the old "crappy" bikes was about. Even today we can get the stock forks working better than they ever did back then and we can use much better shocks, although I feel they should look similar to those used during the day. Like I said this is only my opinion and I admit I am a bit of a purist. When I asked about a couple of the mods ( ie. Wrist pin and stinger ) I was serious and wanted to know why you went this route. I could care less about a wrist pin change. (or fork spring change )If it isn't seen, I feel it is allowed if it is a improvement. I just want to know why you feel it was a improvement. Also why are you running a Classic class bike against Elsinores ?
Cher'o,
Dwight
Dwight Rudder
7 time ISDT / E medalist
8 time National Enduro Class Champion.
Quotequote:Originally posted by bentrims
Dwight,
It seems you are irritated by the entire discussion so I will choose to end it here. Go to an MX sometime and just see.
TB
Not sure what you mean. I have been to MX events. I have raced Vintage MX events.
Dwight
Dwight Rudder
7 time ISDT / E medalist
8 time National Enduro Class Champion.
Quotequote:Originally posted by bentrims
Dwight,
Shoot me an email and we can talk about my anti-Elsinore/pro-Penton project. Lets do our absolute best to not be like the other sites. By doing this the kid on the other side of the room will be willing to raise his hand and ask how far to gap a spark plug.
Tom Benolkin
[email protected]
What do you mean about the Kid on other side of room ?
What is Anti-Elsinore ? The Penton is a Classic Class bike.
You do what you feel is right. I am only expressing my feelings and opinion on the subject.
Cher'o,
Dwight
Dwight Rudder
7 time ISDT / E medalist
8 time National Enduro Class Champion.
Dwight,
As long as you are expressing your feelings so am I. Your ideas and thoughts don't always match others as well as what I think doesn't always match what others think. I hope all of the Hodakas you are racing now are stock.
Ron Carbaugh
Kerrville, Texas
Thanks guys for all the great answers / responces to my question. I really thought I'd get about 2 or 3 posts with an answer back like "yeah, you gain 20% more traction with a larger tire but you sacrifice 18.5% quickness" something like that.
I have learned alot from your feedback. Thanks
By the way I have a 4.60 on the rear of my Six Day. (the previous owner chopped off the chain guard) I ride alot of sand and feel it gives me more traction. The main detriment to speed on my mount is the 240 lb joker at the controls.
Rod Whitman
Omaha, Nebraska
1972 Six Day (Rider)
1972 Six Day (Project)
OH YEAH!!!! We were out to answer a question weren't we?:)
Rod,
I feel your pain. Outfitted with gear I may be just a little over that, so my choice of motivation is a 250, but I hope with a little working out over the winter, I can gravitate to a 175 77 MC5 and move out of post vintage open class once I get the bike built. Mike
Michael R. Winter
I enjoy rebuilding and appreciating Pentons!
1974 250 HS Pentons-1980 KTM 250'S
Maybe the question should have been Bigger bodies = Less power?
Rod Whitman
Omaha, Nebraska
1972 Six Day (Rider)
1972 Six Day (Project)
Dwight,
I wish you had sent me an e-mail when I asked a few days ago because I cannot seem to master exportin a photo on the POG board. I wanted to show you phots of my bike being the ONLY 125 to do double jumps (that were not even meant to be double jumps per AHRMA).
After that day I had to throw away my square rims and straighten out the forks unless I wanted the extra 3 inches of wheelbase[:p].
The modern rims are on my bike to keep me out of the hospital. I dont ride my Penton like most people and most of the mods are done to help keep me intersted by feeling that I am continually improving something on my bike (FOR ME). If I can't stay interested there is no reason to race. As cowboys say "The pay just aint that good".
If anyone ever protests my bike I may ask them for gas money home and they can keep the bike. "The pay just ain't that good"
TB:) Have a good weekend while we got em'.
GO PENTON!
Quotequote:Originally posted by firstturn
Dwight,
As long as you are expressing your feelings so am I. Your ideas and thoughts don't always match others as well as what I think doesn't always match what others think. I hope all of the Hodakas you are racing now are stock.
Ron Carbaugh
Kerrville, Texas
Ron, care to do a tear down ? I have raced completely stock Hodaka 100B bikes even down to the stock shocks. My MX Combat Wombat is STOCK except for the Progressive suspension shocks. My ISDT Combat Wombat is STOCK except for the added light kit and Works Performance Shocks and plastic front fender. OH, I added a Wombat luggage rack and Wombat tank. The engine is completely and painfully stock. Just carefully jetted. It has a whopping top speed of 55 mph.
I am going to stick the engine back into my Jackpiner right now. Back later.
Cher'o,
Dwight
Dwight Rudder
7 time ISDT / E medalist
8 time National Enduro Class Champion.
Dwight,
Thanks for the email, but I didn't attack you. I was just stating my thoughts just like you did when you wanted to make a point. I made my point and if ALL your engines are totally stock then you made your point. I like enhancing engines with what I feel makes them do what I want them to do in this day and time. Just my thoughts and since you made your thoughts public I felt like I was at least possible able to make mine public...maybe not? From now on I just won't post anything in the same post that you give opinion on since it might interfer with your higher thought pattern. That's it.
Ron Carbaugh
Kerrville, Texas
I am sorry if my comments have offended anyone and I pointed out that my comments were only of my personal opinion. I also said that anyone is free to do what they feel is right. But personal attacks have no place on this forum. Ron your comments are most welcome.
Cher'o,
Dwight
Dwight Rudder
7 time ISDT / E medalist
8 time National Enduro Class Champion.
Dwight,
I am sure you are a great person and have plenty of friends and followers. I know from experience that things can get twisted through on line chats because we miss out on the valuable face expressions and vocal tones of a normal conversation.
Suggesting I do not listen to Doug, Dane and the lot of excellent Penton people could be somewhat viewed as a personal attack as well as the fellow that misspelled vinyl.
Lets move on and let this thread get buried into the unseen archives where is belongs. I am going down to take my 6 Days down to the frame, full glass blast, paint and start over again for 2007.
PEACE
Tom B
Could you or Ron send me the Jetting specs for your 32mm Mikuni carb. I have some 28mm Mikuni carbs I want to put on my Six Day and my Zündapp GS125. Probably similar jetting. Both came with 27 Bings.
Pax,
Dwight
:D
Dwight Rudder
7 time ISDT / E medalist
8 time National Enduro Class Champion.
I will be tearing my 32mm Mik apart Sunday AM and will send it. Big UPS (as my son would say) to Donny Smith for the specs. Two seasons of race punishment without a failure.
In 2005 my friend saw me unload the bike after 1100 miles to Texas and it actually started 1st kick. Not the case with his Yammy.
Thanks again Donny.
PS- Funny part is Donny misplaced them in the move to Arkansas and e-mailed me for them last week.:) Donny..they are coming.
32 Mikuni:
3.0 slide
Needle Jet 159 8N
Jet Needle 6F4 center clip
45 Pilot
160 main...I plan to try 170 main for break in of new bore, then go back.
I remember having to read jets for my dad. Now I have to use a magnifying glass and get in the right light[xx(]
Tom B
Thanks Tom and Donny for the jetting specs. I have a magnifying glass too.[:p]
Ron Carbaugh
Kerrville, Texas
I think IRC makes a good tire that measures out about 4.00 they call it 102mm overall width, that's about 4.020in. The model is the M33 110/100x18 sounds fishy but that's what their web site says? Gavin p.s. My dear departed friend Kendall use to say "Bring what ya got, ride what ya brung" let's just have fun :D