OK, most of you know I have been struggling trying to get the '77 MC5 400 handling sorted out. The bike just would not turn, I mean it was the worst turning bike I had ever ridden. So I decided to go all out to fix it and I bought '78 38mm forks rebuilt the 'Zokes shocks with one of Rocket Rod's kits and put fresh tires on it. The bike now handles like a dream, before where I would have to tip-toe riding like I was on ice so as not to lose the front end, I can now charge the corner and not even have to think about the bike. If I did not know better I would swear it was not the same bike I have been struggling with, truly a night and day difference. I am a little upset with myself for not doing the mods one at a time so I knew what fixed it, or it could have been the combination of them all. Normally I dont make wholesale changes like that, but I was desperate and one way or another, its fixed.
Thats the good news. The bad news is I think the shift forks are bent or the gear dogs are damaged. The bike will not stay in gear, especially 3rd, but 2nd is bad too. I moved the shifter so far up it was above horizontal so I know my foot was not hitting it, it is something internal. I also got faster as the day went along and corners that I had been going through in 3rd and it would pop out of gear EVERY lap in the same place, I started to use 4th and it would stay in gear. Because of that I am almost 100% certain its not a shift lever issue.
When it pops out of gear, its very odd, it is usually on landing from a big jump or hitting a big whoop in the middle of a corner, left handers are worse but it can happen either direction. I simply cant be my foot hitting the shifter because its worse in left handers where my foot is not even on the peg. Its almost like the shift pawl spring that returns the shift lever to the middle of the throw is not strong enough to keep the shifter from flopping around and kicking the transmission out of gear. The missed shifts are also much less common, when I'm riding cross country though they do still happen. Is it possible that the shift return spring could be bad? Moving the shifter by hand it feels normal. Also I've seen in the adds for JP Morgens 400 in the for sale section and he mentions "shift drum mod to fix false neutrals" or something like that. Anybody have any idea what that is? I guess I need to get in touch with JP.
Anyway, I know this is a long post, but I want to thank everyone that has helped me in this long battle to fix my handling problems. Guys like Larry Perkins, Mike Winters, Rocket Rod, Big Mac and everyone else that gave me ideas are a wealth of knowledge and I appreciate it.
Brian
'72 Berkshire
Brian,
Do you think you changed the rake angle on the bike? Are you telling us you did not have the neutrals before? Thanks for the update.
Ron Carbaugh
Perhaps there's a slight bind in clutch cable not letting the core wire return fully? The fact that you now have suspension that is getting compressed in the turns will help the bike turn better, along with new rubber. One other thing is to shorten the wheelbase slightly by removing a link.
1973 Penton Jackpiner
1982 Yamaha XT200
1982 Yamaha XJ650J Maxim
1987 Yamaha YZ490
2005 Honda CRF450R
Brain give me a call, I think I can help you. Later Gary
Uncle Ron,
I think the shocks I was using before were too short. They measure 13.5 eye-to-eye but the bike sat visibly higher in the rear end when I put the rebuilt Zokes back on. That alone could be the cause of the poor turning before.
I have had problems with false neutrals on several KTM engined bikes. Its strange, some do it and some dont. I rode Ernie's '74.5 250 that came from Chicago Jerry and it did the same thing, land from a big jump or really slam a berm hard and it would pop out of gear, but Ernie's other '73 250 I rode at Barber never once did it. This 400 has always popped out of gear. The most common condition for it to happen is 3rd gear flat left corner (no berm) hit a bump mid corner really hard and it pops into neutral, usually between 3rd and 4th. My foot is not on the peg or anywhere near the shift lever. If I take that same corner in 4th even faster and hit that bump harder, it stays in 4th. I am thinking of taping my helmet camera to the frame somewhere that I can see what my foot is doing just to eliminate that.
David, I did put on new chain and sprockets so the axle was full forward, where before it was almost at the back of its adjustment. That surely helped.
Gary, give me a call some time after 8:30AM tomorrow, I was out in the shop working on bikes when you called.
Brian
'72 Berkshire
Check your side cover. You must have a Sachs engine in your frame....
Brian
What type of oil, weight and amount of oil did you use in your forks? Did you get the forks off the guy on e-bay that was selling MC40(?) stuff.
g
72 six-day
G,
I set up all damper rod forks the same, from 6" travel vintage all the way to 12" travel PV. I use ATF 6" from the top, springs out fork collapsed.
Brian
'72 Berkshire
Brian-are you running your forks higher in the clamps (ie taking advantage of an attribute of the 78 clamps)?
Also, just want to confirm-no damper rod mods (ie RaceTech emulators) and stock/OE springs?
Finally-your comment about shock length. Are you saying that the re-build restored shocks to original length (13.5 or longer)?
Thanks..love the details BTW. It's what makes this site such a great resource when you go "search" for help for your bike. Actually- on that note, you might want to add "gearbox" or "shifting" to your subject line. : - )
When I set up the forks I took the springs out, then set the bike down on the ground with the triple clamps loose. I moved the forks up until the tire hit the four bolts that hold the fender on. I then jacked the bike back up on the stand and moved the forks down just enough, maybe 1/8th inch, so the tire no longer hit the fender bolts. The forks are dropped as far down as they can go. For now the springs are stock and no emulators, but I did use a spacer to limit travel to the Historic class limit of 9".
As for the shocks, I only rode the bike once with the blown Zokes and put on some Progressive gas shocks I had laying around. The Progressives measured the same length, 13.5, but I think the rubber bushing in the Progressives allowed the shock to in effect be 12.5" once the bike bottomed a few times. The Zokes did not change length after a rebuild, but with the spherical bearing in its eyelets it stays at 13.5 when mounted. I'm actually pretty impressed with the action of those Zokes after I rebuilt them, they work very well.
I got an email from JP Morgen about his shift drum mod, what he does is eliminate the extra neutral between 2nd and 3rd which is there for when you block out 1st and make it a 5 speed. He confirmed my suspicion that there is something wrong internally, probably a bent shift fork, he has never see one of these KTMs pop out of gear unless something was wrong.
Brian
'72 Berkshire
Just for reference, do the silver engines share shift components from the 175-400 or will I have to get 400 parts if I need a shift fork? I think the black engines had a different shift drum than the silver engines right?
Brian
'72 Berkshire
Hi Brian, just a sidebar, moons ago I send both the gears/shaft asslys to Murdock Racing in Florida, they were able to re-face the dogs, probably the best gearbox I have experienced, it was expensive...
Adios, Tom Brosius
How far down did you drop the forks. Mine is currently at the 2nd ring and I feel like i have to tippy toe thru the corners too. Next race I'm gonna drop it another ring.
g
72 six-day
I dropped them all the way. My forks dont have rings on them so I took the springs out and set the bike on the ground, then moved the forks until the tire hit the underside of the triple clamp. I then put the bike back on the stand and moved the forks 1/8", just enough for the underside of triple clamp to clear the tire at full compression. The tubes stick up roughly 1.5" above the top clamp measured to the top of the steel tube not the cap.
Brian
'72 Berkshire
Brian, I had some trouble like this on my 78 400. Big Mac and I split the cases and what we found was and I am not sure what you call it..on the end of the shift shaft there is a sort of a hook and claw looking thing. this actually turns the shifting drum... there a few things that you need to be concerned about, if it is bent then shifting will be difficult at best.. and how far the claw is from the hook is important too because it determines how far you must move the shift lever to get it to shift..check your book for the correct distance.. Of course if anything is cracked or what ever then that too must be address as well..
To give credit where credit is due.... I would have been sunk with out my buddy Mac...In my case the claw part of the shifter was cracked and we had to replace it... Mac had one sitting on the bench... thanks Mac....
Thom Green,Still crazy after all these years!
76' 250 MC5 (orginal owner)74'
250 hare scrambler (project bike)
Thom,
After talking to a few people about my shifting problem I am pretty sure its that "claw" thing on the shift shaft. Apparently that is a fairly common problem, it seems more so on the 400 than the 250 or 175. I am going to split the cases to inspect everything in there just to make sure there is not also a bent shift fork or a damaged gear.
Brian
'72 Berkshire
Brian, the transmission gears and shift mechanisms will interchange between the '74-'77 250 and 400 motors. Not sure about the 175s. Black '73 motor had an old style, not so good shift drum. Somewhere around '75-'76 (Larry Perkins knows for sure) the side dogs on the gears were back-cut, ie they "locked" in after shifted together with the angle on the dogs. These gears in good shape shift together better and stick, much less popping out. Suspect you have worn side dogs with no back cut.
Good news is there are lots of good transmissions around, out of water-damaged cases. And splitting cases is real easy, and not much to jiggling gears in and out. I've bent a couple of the shift pawl arms back to the spec'd gap and they've worked fine. Get a decent set of gears out of a '76 or '77 and a spare center case gasket, and you can swap it out in a couple hours.
My old '73 Harescrambler was a shifting nightmare, but when I swapped in a complete '77 drum and tranny, it was sharp, snappy and perfect no-miss shifts...best shifting vintage bike I ever owned. Good luck with it.
Brian, Good luck.. I am sure Mac thinks its an easy thing. but then He would...Mac is quite the KTM Guru.. we are blessed to have him in the Northwest...
Thom Green,Still crazy after all these years!
76' 250 MC5 (orginal owner)74'
250 hare scrambler (project bike)
Trannys in the silver motors are all the same. Check claw, shift fork straightness to it's shaft and dog edges on gears and you will prob find problem. However, I have a 72 175 engine I built that is doing this and I tore it down and checked everything and can find nothing wrong??? Im wondering if something may have been welded wrong as the old ones have welded shift drums. Dont have that issue on silver motors. At least your half way there now with the handling straightened out. Good Luck
Mike,
That is good to know the silver engines are all the same transmissions. I am pretty confident I will find something obvious when I get it apart.
I also have to agree with you on the MC5s being competitive in classes that lump all 75-81 bikes together. After I got the handling fixed, that bike will absolutely RAIL corners. I am really without words to describe how much better it turns now and I would not be afraid to race it against any age bike on the right track.
Sunday I went to a new track that just open a few weeks ago to test my suspension upgrades. There was a long 3rd gear 180 degree left hand corner with a big sandy berm in it. After I got loosened up and got confident in the bikes newly improved handling I started railing this berm and kids were stopping to take pictures! I'd come in hot, downshift to 3rd, lay the thing over, slam the berm and buuuuurrrr-RRRAAAAAAPPPP! Front wheel in the air, it was awesome except for the times it would pop out of gear in that corner. I am so pumped about this bike now, I had just about given up on it and had serious doubts about spending the money on buying the 38mm forks and Zokes shock rebuild kits but I am glad I did now.
Brian
'72 Berkshire
Brian
I would look at the engagement dogs on the back side of the gears. The edges should not be worn or rounded off, if they are, that is probably your biggest problem with it slipping out of gear.
Rod G
I have been told that the shift drum from the silver motor fits right in on the black motor. I have a friend that was having trouble find parts for his black motor so he replaced the shift drum with a shift drum from the silver motor and it worked great...
Thom Green,Still crazy after all these years!
76' 250 MC5 (orginal owner)74'
250 hare scrambler (project bike)
I blew my seals on my 38's today, I ordered the ones listed in the book and Al carried the same part number last week and they came today. Thankfully they were a snap to pop out. My 38's had 2 seals in each leg and the book and Al's only list 1 per leg. My old ones were 7 mm thick each and the book list 1 and it measures 10mm thick. Is that what you experienced. Should I pop in the 1 10mm and call it a day?
I took my bike out today after moving the Bars father forward, (a la Victor Monz) my forks are now at 1/2 inch from the top clamp. I wish I read your post before I went riding. I'm gonna go another 1/2 inch for next week test. Definitly headed in the right direction. All I did was practice corners and berms. With the bars moved forward, the longer Clutch and front brake lever I felt pretty good.
72 six-day
Garrett, yes I went through the same thing when I replaced my fork seals. I do not think it is a good Idea to put another 10mm seal on top of the other 10mm seal. it would create too much stiction. besides I think a second seal will not fit all the way in. I think the problems stems from the fact that we are using new seals and not seals built as an exact replica of the orginals.. It would be too expensive.......
Thom Green,Still crazy after all these years!
76' 250 MC5 (orginal owner)74'
250 hare scrambler (project bike)
I ordered the 7mm seals from Al B this morning
G
72 six-day
I didn't know that the 7mm seals were even available. they were not the last time I ordered any... thats good to know...
Thom Green,Still crazy after all these years!
76' 250 MC5 (orginal owner)74'
250 hare scrambler (project bike)
Brian, Glad to hear you like your bike now. I love mine. You know Penton or KTM knew they were on to something in handling. Every frame fron 72 to 79 measures the same from the bottom of the steering head to the swingarm bolt, every frame except the 73 and pre long travel 74 250 engine frames...which I never liked back then...before I knew this fact! The steering head is extended out on those frames. I bet they thought they would need to do that for a bigger engined bike for stability...and later found out it was not a good idea to violate the golden measurement!
Got the seals in and added ATF per Brians recomendation. I dropped the forks to 1 inch (4 rings). Definitly cornered alot better. For right now I'm gonna call it a day and see how it works on the track this weekend.
Brian, thanks for the tip!
G
72 six-day
Brian, I am so glad that the bike handles so well for you, and I am excited to see how the bike handles now that I have copied what you have done... well as best as I could considering that I am using Fox gas shocks instead of the stock shocks....Had to try and use them, first because it is what I had and because I just had them rebuilt a few months ago and last because they have been on the bike since 77'
Thom Green,Still crazy after all these years!
76' 250 MC5 (orginal owner)74'
250 hare scrambler (project bike)
Brian
Lowering the front forks 1.5 inch's down (6) rings is definitly the hot set up. The bike cornered fantastic. Thanks.
G
72 six-day