|
Post by lc on Sept 25, 2011 19:20:16 GMT -5
As I said, a normal transmission can be easily shifted up through all gears at VERY high rpms while racing without releasing the clutch simply by applying pressure to the shift lever, momentarily rolling off the throttle (or killing the engine with a momentary kill switch). You can down shift with no load too, but it IS harsh on the trans.
It almost sounds like one of the forks is hanging up on the shift drum in one of its commanded directions. Before you get too deep have a look to see if the hooked arm part (that rotates the drum, located on the back side of the large primary gear) is adjusted so the drum pawl pin is centered evenly between the two hooks when the shift shaft is at rest..
Also have a look at the plate that retains the drum in the case to be sure it is secure (not allowing the drum to migrate) but not restricting the drum rotation. Check to see if there is anything else that would prevent the shift drum from rotating, such as the spring/ratchet mechanism also located at the end of the drum.
If you have to go back in there (splitting the case) the cylinders can be left on.
J
|
|
|
Post by ballvo on Sept 25, 2011 23:42:15 GMT -5
Thanks, Scott. It was shifting up and down through the gears with no clutch, but only at low rpm, like I said. And easily from 1st to 2nd at "normal" rpm. It feels like the shifter just bumps up against a stop of some sort. I guess I'll be tearing a bit deeper into that side and check out what you've suggested. It'd be a real bonus if I could figure out and fix the problem without pulling the motor. It's funny, I was just thinking of getting an H1 motor on my bench and opened up, as a start on a winter project. I definately wasn't planning on it being this one, though. Of course, today was one of the nicest riding days we've seen lately. Even worse news - it's supposed to be beautiful for the rest of the week Cheers, Neil
|
|
|
Post by lc on Sept 25, 2011 23:54:17 GMT -5
From what you're saying it almost sounds like there is something interfering with the shift shaft/hook mechanism etc. that rotates the shifter drum. You can check this out when you remove the clutch/basket. Also try turning the shift drum through each gear selection to see if it binds up in the problem areas you have reported. (You may have to remove the chain and turn the sprocket a bit for the dogs to mesh) Be sure your rear set/linkage is not banging up against something and the linkage levers are at a good angle too.
J
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Sept 26, 2011 8:19:12 GMT -5
I had that same problem when I bought my first 500, at least it sounds exactly the same. I had a bent fork and the side of the gear was carved and rough. Was the tranny shimmed? No shimming is better than an incorrectly shimmed tranny. Worn circlips, when replaced make a huge diference in shifting. A worn circlip destroyed an MX tranny on my kids YZ. Take a good sniff of new oil in a bottle, then smell your used oil for burnt smell
|
|
|
Post by ballvo on Sept 26, 2011 9:23:20 GMT -5
I hope to get the clutch side opened up sometime this week to have a look. Rearset linkage is free and clear and seems to be operating as it should. Donnie, I bought a used, good condition, tranny from JessBikes when I was building this motor. I used my old tranny to practice disassembly and assembly, as well as measuring clearances, several times before I shimmed the "new" one with all new shims and circlips. The new tranny included shift drum and forks. The forks didn't show any sign of overheating (like the old ones) when I installed them but I don't recall checking for straightness. Oil is nice and clean cause I changed it when I swapped the clutch pushers. I'll still take a whiff though, just for you. ;D The thing is the tranny was shifting and working flawlessly for the first 600 mi and now, quite suddenly, gone south. Definately keep you posted as things evolve. Cheers, N.
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Sept 27, 2011 11:28:31 GMT -5
As I said, a normal transmission can be easily shifted up through all gears at VERY high rpms while racing without releasing the clutch simply by applying pressure to the shift lever, momentarily rolling off the throttle J this makes me nervous. Pressure should never be applied while under any load. This will cause shift fork issues faster than anything. Racers kill the engine, then the shift is made and power restored. MX'rs never use a clutch, and the transmissions pay the price, been there and seen it first hand. Good luck Neil
|
|
|
Post by zambia on Sept 27, 2011 11:42:54 GMT -5
As I said, a normal transmission can be easily shifted up through all gears at VERY high rpms while racing without releasing the clutch simply by applying pressure to the shift lever, momentarily rolling off the throttle J this makes me nervous. Pressure should never be applied while under any load. This will cause shift fork issues faster than anything. Racers kill the engine, then the shift is made and power restored. MX'rs never use a clutch, and the transmissions pay the price, been there and seen it first hand. Good luck Neil Haha, I raced a CZ 175 MX in the mid '70s. It (and me) was slow so I raced in 125 class against the RMs and YZs and Elsinores (usually got lapped, but at least I had the loudest bike). For quite some time I didn't even have a clutch cable, we just red-lined it and when the gate dropped, bang it into gear!! Lucky those old Czech bikes had tank transmissions in them!
|
|
|
Post by lc on Sept 27, 2011 12:00:04 GMT -5
As I said, a normal transmission can be easily shifted up through all gears at VERY high rpms while racing without releasing the clutch simply by applying pressure to the shift lever, momentarily rolling off the throttle J this makes me nervous. Pressure should never be applied while under any load. This will cause shift fork issues faster than anything. Racers kill the engine, then the shift is made and power restored. MX'rs never use a clutch, and the transmissions pay the price, been there and seen it first hand. Good luck Neil I agree Donny, extended pressure on the shift lever will cause issues (sorta like resting your foot on the clutch pedal in a car). Let me re phrase this : Upon desire to shift pressure is applied to the shift lever a few milliseconds prior to killing the power. This equates to simple co-ordination between the foot lever and the roll off of throttle or use of the kill switch. Yes, it probably is harder on the trans than using a clutch, but for a balls on drag race it does shift faster. J
|
|
|
Post by Walms on Sept 27, 2011 12:00:29 GMT -5
Funny...I've never shifted without a clutch... Not unless I had to because of busted clutch cable or something like that... Never got the buzz because I always felt of the damage it was doing. (right or wrong) The finger flick pulls it in and releases it so quick, you'd be lucky to have it slammed into the next gear in time! I've shifted plenty of times without letting go of the throttle though! ;D ya just gotta be quick!
|
|
|
Post by lc on Sept 27, 2011 12:11:45 GMT -5
The point being was to clerify to Balvo that his trans should shift throughout the gear range easily, even with the clutch fully engaged (provided the load on the trans is off at time of shift). J
|
|
|
Post by Walms on Sept 27, 2011 12:55:37 GMT -5
No problemo... I was just pointing out that I'm not a big fan in clutchless shifts...
|
|
|
Post by lc on Sept 27, 2011 16:34:37 GMT -5
Me neither J
|
|
|
Post by JA-Moo on Sept 27, 2011 23:34:23 GMT -5
The majority of my shifting has been without a clutch since I started riding big street bikes. (1978) The only way you can damage your transmission is with a sloppy shifter, or sloppy shifting. With the shifter leverage ratio, you could never put enough pressure on a fork to cause any kind of burning or wear. Forks get bent and burned by missing shifts, compounded by bad shimming. The dogs get rounded and don't engauge deep enough, so they push apart loading the fork against the gear burning both. Plus the forks get bent from "popping" out of gear agravating the problem and burning/wearing the fork. If you think about it, engaging the clutch is just taking the load off the gear, for the gear change. Flicking the throttle off when shifting without the clutch is the exact same thing. This is the same process of the ignition cut out connected to the shifter. The ignition is killed, the load is off the gear and you change it. You get a quicker shift without the clutch, and it takes a lot less coordination, not having to deal with "timing" the clutch. It does take some practice, but when you can do it, it's sounds like shifting an automatic. If you get real good, you can downshift without a clutch also, but it is more difficult. One thing to prevent missed shifts, (with or without the clutch, no under cut) is to hold the shifter in the full up position when you shift until you are back on the gas. This way the fork is holding the gear in full engagment when the gas is back on. I get the weirdest looks when I am around another motorcyclist at a stop. I take off then rest my left arm on my hip and run through the gears...........
|
|
|
Post by Walms on Sept 28, 2011 7:07:42 GMT -5
I'll concede to the point that clutchless shifting isn't hard on the tranny but I still believe that keeping on the gas while blipping the clutch is quicker... Not necessarily measured in seconds but the revving state of the motor...
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Sept 28, 2011 7:23:01 GMT -5
I agree for the most part except with a clutch the engine is disconnected from the power source completely and you don't have a guy like me shifting it. Not using a clutch is the best way to prevent heating it up excessively. This is a big concern when all out racing, and to speed up the shifting process the smallest amount. Wear will occur because I couldn't hit the disengage perfectly every time and it would be "reefed out" of engage when I get all excited because a 400 is about to blow me off the road. The release of the clutch absorbs any shock to the drive line and makes it so anyone can shift correctly. The weakest link in an H1/2 engine are the POS forks, they were designed to bend. A racing MX has forks twice as thick/1/2 as long, you really have to try and bend them as they are tougher in a YZ125 than an H1 fork. Guys that race are good at racing an engine. Us peon's should use a clutch always. More so on an under engineered transmission. The rest of the motor is tough and can take a beating, but the forks are the weak link in our bikes. Oh, and never hold in your clutch in your car, or your triple at a light. Select N somehow and release the clutch.
|
|