I saw Garrett post this in the thread about PV bikes:
"There is a bolt on the side of the motor that you csn switch and change the motor from a 5 speed motorcross model to the 6 speed enduro model."
I am not familiar with this feature, how does it work and what engines have it? Do the 5 speed MC5s like the '77 400 have this feature too?
Brian
'72 Berkshire
Phil K. filled me on this info. Its on page 29 of the ktm's user manuel. I'll try to copy it and post it. Basically, you take out and exchange 1 bolt with the other. I'll also try to copy the difference between the gear ratio's. I just leave it in the 6 speed mode, since that's the bolt I have.
G
72 six-day
(http://i811.photobucket.com/albums/zz38/garrettccovington/KTM5to6speedconversion.jpg)
(http://i811.photobucket.com/albums/zz38/garrettccovington/KTMgearratios.jpg)
Sorry about the poor quality. But its the lower left bolt thats part of the Clutch arm housing
72 six-day
I have wondered about the 5 speed/6 speed conversion too. I have been building up a couple of spare motors and one of them had the pointed bolt. What I have found out is the shift drum has to have a pin sticking out to block out 1st gear. I only have come across one shift drum like that and it was not in the motor with the pointed bolt. I have a paper with some information about how you remove a pin from the drum so it can not engage 1st gear, paper is dated in the year 81 or 82, not sure without going to the garage to look. From what I can see and measured, the pointed bolt will not hit anything unless you have a shift drum with a pin sticking out.
Rocket
I have a 79 175 motor and it does have the pin sticking out the end of the shift drum and if it had the longer bolt with the point on it you can see where it would block the drum from turning past the point that would engage first gear. The bolt is the one that goes though the bearing cover ( clutch actuator housing) at the lowest part of it to the rear of the housing. As far as I can see if you have a 5 speed you can remove that bolt and simply put a shorter one in and it will be a six speed. The primary gearing on the 79 motor is also much lower than on my 73 motor. I asume that is done to facilitate turning 2nd gear into 1st if it is used as a 5 speed. If the shift drum does not have the pin sticking out the end of it, it can't be made into a 5 speed.
At least that is what it looks like to me.
Doug Bridges
73 Jackpiner
74 Jackpiner/FrankenPenton
project
82 XR200R
I guess what I am asking is, is the '77 MC5 400s really a 5 speed transmission or are they blocked out 6 speeders? I've been toying with the thought of acquiring a 6 speed transmission, drum, and shift forks/shafts to convert even before I heard of this.
Brian
'72 Berkshire
Brian
As far as I know, it should be a six speed. On your clutch actuator, the lower left hand bolt, remove it and measure how long it is. If it is 30mm long, that is probably blocking out the first gear.
Rod
(http://i52.photobucket.com/albums/g8/BobWardlow/Scan.jpg)
Keep in mind When reinstalling the longer bolt, The instructions warn about NOT having the transmisions in 1st or nuetral.
When racing last weekend, I was thinking about starting in 2nd, and trying that 5/6 speed theory that 2 is a 5 speeds 1st. but I'm not good enough and I felt that 2nd was to tall. In the tight hairpins 2nd was definitly to tall for my skill level.
G
72 six-day
Quotequote:Originally posted by Rocket
Brian
As far as I know, it should be a six speed. On your clutch actuator, the lower left hand bolt, remove it and measure how long it is. If it is 30mm long, that is probably blocking out the first gear.
Rod
That is very odd. Why would they block out a gear? I understand making a transmission with one less ratio so you can remove the gears to save weight or make the remaining gears bigger and stronger, but why just block it off? It makes no sense. That would be a pleasant surprise if that is all there was to converting to a 6 speed.
Brian
'72 Berkshire
Brian look at the gear rations between the mc/gs 250's and 400's and top speeds it even gets stranger.
G
72 six-day
I've had 2 MC5 250s and an MC5 400, all in mx setup from out of the crate from all I could see or per original owner in the case of the 400. All had 6 speeds. Haven't run into a blocked out 1st, 2nd-6th gear only bike yet. Purpose was to avoid mistaken shift to 1st granny gear coming into mx corners when 2nd+ would do the job everywhere on most mx tracks, but to leave 1st gear option in there for woods work when needed.
The 400 I'm riding is definitely a 5 speed. The weird thing is, its got 14/52 gearing which is from what I can tell 1+ on the countershaft from stock, yet first gear is so short its almost unusable. I cant imagine having another even lower gear than the current first. I'm tempted to go to the tallest gearing I can get just so 1st is usable.
On second thought, I never actually shifted it through all the gears to verify how many it had, it may be set up with 6 and I just assumed it had 5.
Brian
'72 Berkshire
I have a (very late "76)'77 250 MC5 and it is definitely a 6 speed. I try to never use first, it is too low, even for the tight turns. Unfortunately, sometimes going into a tight turn I actually down shift all the way to first, and you can probably hear me cursing at myself all the way to the pits.
Lloyd
I am going to have to verify its only a 5 speed, it might have 6 and I didnt even bother to check. Ernie also has a '76 MC5 that is a 6 speed.
Brian
'72 Berkshire
Next Tues. I'm gonna get my hands on bolt and take it over to my friends shop and make the 30mm "Dog Leg Pointed bolt" I don't have and try it out. I have questions i.e. where is neutral, does the spacing gear ratio, between gears change, is it worth it, etc.?
G
72 six-day
I checked the bike when I got home and with some embarassment I announce that it has 6 speeds. I've been riding this bike for a year and had no idea it had a 6 speed transmission. [:o)]
Brian
'72 Berkshire
It just makes the transmission effectively a 2-6th gear transmission. It does not change the ratios. By selecting the appropriate sprocket combination, the effective 5 speeds can then be utilized for MX use. All of my KTM 250-400 engines have been 6 speeds, although the later versions, starting somewhere around 1977 or 1978-early 1980 can be limited to 5 speeds by the addition of the longer dog point bolt. The proceedure is also outlined in my 1980 MC250 Users Handbook.
Both are listed in the 1978 Engine Repair instruction Manual 0561-080203 m8x20 & 0561 080303 m8x30. Remember the transmission must not be in 1st gear or neutral when installing the longer screw, or the gear shift drum could be damaged.
There has always been what I refer to as a "false neutral" between 2nd and 3rd gear, which I am assuming would be the neutral in a 5 speed configuration. Mike
Michael R. Winter
I enjoy rebuilding and appreciating Pentons!
1974 250 HS Pentons-1980 KTM 175-400'S
I fail to see any reason why I would pass on the option of using every gear the transmission has to offer.
I agree, why not use all the gears available. I thought maybe it changed the gear ratio's between all the gears. I think I'm still gonna try it though.
G
72 six-day
I think the 5 speed thing is because in most MX situations if you gear for the start so you can use 1st then you never reach a speed to get in 6th and if you gear for topend to be right in 6th then first is too low. Personally I like the 6 speed geared that way and then do 2nd gear starts and have 1st for an off-road bailout gear. This gearing situation arose because the bikes were designed for enduro & Six Day type events and on a road section the high 6th gear was a blessing. Just not many 80 mph sections on an MX track.
Larry P
That is exactly what I was going to do Larry, gear it for 2nd gear starts and use 1st as an emergency bailout. Its too tall right now for 2nd gear starts.
Brian
'72 Berkshire
Hello, My daughter and son have a Suzuki JR-50. It is sold as a single speed, centrifugal clutch. The bike actually has a gear shifter which needs to be shifted into gear to engage. I have read and seen advertized on Ebay Suzuki JR-50's which have been converted to a two speed bike. I understand that the first gear is blocked out, and that only second is used. Some have unblocked first gear and have made a two speed bike out of it. Anybody know anything about this conversion? Thank you, joe
6-speeds give you lots of versatility: Enduro, Hare Scramble, MX, and Desert on one bike. The Penton designed machines excelled as a one-bike-that-can-do-it-all! However, when you look individually at specialized disciplines such as open class Moto Cross, the Maico's with their linear powerband and slick 4-speed gearboxes are legendary. While the riders of the peaky machines are jabbing the shift lever ... the Maico rider just pulls away. Back in the day as well as now, the '72-'74 open class Maico's allowed average riders to achieve better than average results by providing predictable power delivered via an optimized gear set. In the hands of experts; Ake, Adolf, Werner, Gerrit ... these guys cleaned house with 4 speeds in the early 70s Trans-AM events. If KTM would have had the time and resources, I believe the Mint MC-5 would have had a proper 5 speed (different ratios than the 6-speed). Of course then the name "Mint" would have to be changed to ... "Carlsbad"?
Ernie P.
Chattanooga, TN
A 4 speed transmission is lighter too which makes those Maicos easier to push back to the pits when the break down. I know this from experience. :D
Brian
'72 Berkshire
LOL, not much lighter, but a pound or two..I guess any amount helps when you are pushing[8D]
The maico 4 speed works fine for most MX races but two years ago I was wishing I had a 5 speed. I had the bike geared as tall as I could. It was so tall in first gear, it was like a 2nd gear start. There were places on the track that I had to slip the clutch in first gear to keep from stalling it in a tight hairpin, but there was a section that had a 75 yard straight followed by a sweeper and then another 75 yard straight.. I was passing everyone in the tight stuff but the bikes with the 5 speeds would leave me in the dust...on those long straights. I was wishing I had brought my MC5 but alas, there was no room.
Thom Green,Still crazy after all these years!
76' 250 MC5 (orginal owner)74'
250 hare scrambler (project bike)
In 78 they went to the drum with the pin sticking out farhter that could be blocked out to lock out first. It is easy to know if you have one of these engines because the bolt is 8mm(the threads), not 6mm like the old ones. Prior to 78 they blocked out first a different way (lack of a pin in the drum)so this bolt change thing wont work. I have made up a paper on how I have done this to the older engines. If interested email me at
[email protected].