KPX Down Shift clunk ???

[Bill Hilly]

I have been racking up the miles on the KPX, and now have well over 200 on the odometer. I went to Point Pleasant, and Gallopolis yesterday, and Gallopolis in particular had a lot of traffic lights on it's main drag along the river. I have noticed is since I got the bike, but if you know that you're going to be stopping, and pull in the clutch, and just coasting, braking ,and down shifting while keeping the clutch pulled, the shift into first is a harsh like clunk, unless you are nearly stopped. I'm not talking about fast speed, I'm talking about just normal common sense, just like I have always ridden my TBR7, Hawk, and Brozz that I have had. There is no over travel below first on the KPX, but other than that,the bike shifts just like the other bikes. My idle is always around 1500, clutch properly adjusted, and neutral is easy to find. I have started treating 1st in the bike as a gear that I don't shift into till I am almost stopped, and I can deal with that, but I also am curious if it's normal for the KPX. If my bike has issues,I would like to have them took care of while under warranty. Thanks

[JerryHawk250]

I get a slight clunk but all my bikes do that. Even my Vulcan S. It's less when I adjusted the clutch lever with minimal play. It also does it less with synthetic oil.

[Bill Hilly]

Originally Posted by JerryHawk250

I get a slight clunk but all my bikes do that. Even my Vulcan S. It's less when I adjusted the clutch lever with minimal play. It also does it less with synthetic oil.

Maybe I notice it more on this bike because it's quite, and first is pretty low. It may improve after break in, and I switch to synthetic. My clutch is adjusted with minimal play. I was also wanting to ask if you can recommend a feeler gauge well suited to adjusting the valves? I took my tank fairing off yesterday, before firing the bike up, I intended to only check the exhaust valve clearance, because I didn't want to strip all the plastic, tank, seat, and rack off the bike yet. I took the little cover off, and was surprised at how difficult it seems to get a feeler gauge in there. I took the 0.10 mm blade off my set, and tried to bend the end to get enough angle on it to go in the opening, and between the valve stem, and set screw. It was just thick enough that it cracked , and I couldn't chance loosing it in the hole, so I didn't adjust the exhaust valve. I did verify that I have some play, so I just put everything back together. I plan on sending the ECU to Lifan after the upcoming warmer weather that we are supposed to get next week, and I want to do a though valve adjustment then.

[JerryHawk250]

Originally Posted by Bill Hilly

Maybe I notice it more on this bike because it's quite, and first is pretty low. It may improve after break in, and I switch to synthetic. My clutch is adjusted with minimal play. I was also wanting to ask if you can recommend a feeler gauge well suited to adjusting the valves? I took my tank fairing off yesterday, before firing the bike up, I intended to only check the exhaust valve clearance, because I didn't want to strip all the plastic, tank, seat, and rack off the bike yet. I took the little cover off, and was surprised at how difficult it seems to get a feeler gauge in there. I took the 0.10 mm blade off my set, and tried to bend the end to get enough angle on it to go in the opening, and between the valve stem, and set screw. It was just thick enough that it cracked , and I couldn't chance loosing it in the hole, so I didn't adjust the exhaust valve. I did verify that I have some play, so I just put everything back together. I plan on sending the ECU to Lifan after the upcoming warmer weather that we are supposed to get next week, and I want to do a though valve adjustment then.

I used a regular feeler gauge set and bent the ends on a slight angle.

[Thumper]

The transmission should be tight on a new motorycle. It will get looser and not clunk as loudly over time. But no reason to shock the engine with early downshifts while it is still breaking in. Just wait until you are going real slow for now or try to match engine approximate rpm to the gear you want when you shift to that gear (at idle). The dogs won't shock the transmission so much when they slide in.

[Bill Hilly]

Originally Posted by Thumper

The transmission should be tight on a new motorycle. It will get looser and not clunk as loudly over time. But no reason to shock the engine with early downshifts while it is still breaking in. Just wait until you are going real slow for now or try to match engine approximate rpm to the gear you want when you shift to that gear (at idle). The dogs won't shock the transmission so much when they slide in.

I wouldn't dream of mistreating the motor. I'm not talking about "engine braking". I was referring to shifting down through the gears with the clutch in, and in a normal manner. For instance your in a city, in an area with about a 35 mph speed limit, and your see the light ahead turn yellow, and you may be in 3rd, or 4th, and you pull the clutch, and start dragging the brakes, and gradually slow, while tapping the shifter down, so you don't end up stopped in a higher gear. The KPX needs to be almost at a stop before shifting into 1st , or it seems clunky. I will switch to full synthetic after break in, but I just wanted to know if others had noticed it on their bikes.

[Thumper]

During downshift coming to a stop, even with the clutch pulled, if the part of the transmission connected to the spinning crankshaft which is idling (the input shaftcounter shaft-counterspinning shaft, or main shaft in the transmission) is spinning much slower than the forward spinning side (connected to the rear sprocket/wheel), the dogs on the side of the gear has to abruptly change the speed of the input shaft to go into the next gear as you downshift. This is the situation when the engine is idling, and the motorcycle is rolling to a stop. This shocks the transmission bearings, seals, dogs, and even the contact between the gears and the shafts. The input shaft spins even with the clutch pulled, and it is spinning slowly at idle.

It is not possible to precisely match the rpm of the engine to exactly the speed of the output shaft for a given gear every time, but the farther away it is, the more shock the transmission experiences. OK, you say it is worst going down to first, but that is the lowest gear so it makes some sense.

Ever seen someone rev the engine, pull the clutch, then slam it into first without waiting for it to return to idle. Yeah. LOUD crack. This is because even with the clutch pulled, the main shaft (counter spinning shaft) is spinning FAST since the clutch has some friction even with the clutch pulled, turning the main shaft/counter shaft, and the output shaft is NOT TURNING at all since it is connected to the rear sprocket and the wheel is not turning. Putting it in gear instantly stops the input shaft (breaks the clutch loose). That is a major shock to the transmission. Downshifting at speed with the clutch pulled is the same thing, but with reversed forces.

You have to shift! I know

But try to wait until the difference in the countershaft and output shaft (for the gear you will shift into) is as close as possible. It WILL get better as the transmission is broken in, or worse if the transmission is subjected to repetitive shock. The quieter the shift, the closer you came to matching the speed of these two shafts, for a given transition.

I usually put the engine in first gear, pull the clutch and break loose the clutch (rolling forward/back) BEFORE I start the bike (after warm up). Yes, I will actually turn it off after warm up and do this. So my transmission experiences NO shock at all when I do that. It is much gentler on the entire transmission. When you pull the clutch, the input shaft (main shaft/coutershaft) keeps spinning! Putting it in gear stops it from spinning, abruptly!

[IdahoRider]

I'm over 9250 miles on my KPX and I've experienced the "clunk" up until just a week ago when I did my 9th valve adjustment and replaced the spark plug. My exhaust valve was a little tight and I think I did the best adjustment I've ever done on the valves (intake did not need any adjustment) and the bike now seems to be running and shifting better than it ever has. I can even tell a difference in how it sounds. I changed the plug because it was getting pretty gray but thing adjusting the exhaust valve spot on is what really made the difference. I'm not getting quite the clunk and it seems to be shifting better over all. I've been using Rotella T4 for most of the miles and thought about changing to synthetic but didn't think that would make much difference since I've been changing the oil and filter between 1200 and 1500 miles. I have plans to do a 200 mile loop through the mountains tomorrow and have a goal to hit 10,000 miles by next month.

[Bruces]

You are not downshifting properly if you are actually doing it like you claim in post #6 above ,you are going to hurt yourself and your bike if you continue slowing down while riding the brakes with the clutch pulled .I would imagine there is probably a basic motorcycle riders instruction somewhere on the net ,but any manual transmission instruction for cars and trucks would be just as good to learn basic clutch and shifting skills .

[Bill Hilly]

Originally Posted by Bruces

You are not downshifting properly if you are actually doing it like you claim in post #6 above ,you are going to hurt yourself and your bike if you continue slowing down while riding the brakes with the clutch pulled .I would imagine there is probably a basic motorcycle riders instruction somewhere on the net ,but any manual transmission instruction for cars and trucks would be just as good to learn basic clutch and shifting skills .

I have drove manual transmission since I was a kid way before I was old enough to have a license. I know the difference between how to shift a gated transmission like in a car, or truck, and a motorcycle type transmission. I know that you don't want to come to a stop in a higher gear on a motorcycle type, and I don't see any point, nor is there always time to release the clutch, and engine brake on each down shift on a motorcycle. So what is the correct way ? I do down shift, and let the engine brake at times, but in a situation of running in traffic with cars in front of you at a normal distance you have to stop at least at the same rate as they do. I'm not talking like city blocks were there is a stop sign at every corner. I'm talking about pretty heavy traffic that in this case was in Gallopolis Ohio, and is basically a strip along the river were the traffic runs around 35 mph , and the lights are just here, and there. The point of my post was to basically ask if anyone else has noticed the first gear downshift being clunkier than expected? I know not to be going along at 35 mph, and just start fast tapping the gears down to first. I don't go into first at a speed that I wouldn't use first to pull away from if the traffic was moving. I honestly don't know how you think a person can get by without slowing with their brakes, as they downshift. Maybe it's just a mis understanding, but I don't know any other way. In any case even if I were just in a parking lot , and running in second, and slowed down, and shifted to 1st, the clunk that I mention would be the same. Unless you are all but completely stopped the shift into first is clunkier than I have ever noticed on any other bike I have ever had. It has been like that since day one. It's no worse after me riding it over 200 miles. I think that the fact that it's not broken in yet, in combination that 1st is pretty low with it being a 6 speed just makes it the clunk a little more noticeable. I have pretty much just figured out that it's probably best to not shift into first unless almost stopped.

[Thumper]

When I begin slowing down, I do periodically pull the clutch and blip the throttle, down shift and drop the clutch to engine brake. But I try to match RPM so the it is minimally shocking. But I only do this maybe once or not at all. I let it engine brake, then when I reach idle in gear, I pull the clutch and gently downshift at idle while still rolling. One by one, back to first. Sometimes only to second if traffic is still crawling. Engine braking is fine. It is the shifting that needs to be smooth!

It sounds like you are doing something like this, downshifting at low speed. Engine braking is no problem, but wait until you are near idle before pulling the clutch and gently downshift while still rolling. You should be able to get into first without shock sometimes, when RPM matches input/output in the transmission.

I often allow it to pause in neutral at idle, low rolling speed on my way to first. It can help avoid the thunk.

[Bill Hilly]

Originally Posted by Thumper

When I begin slowing down, I do periodically pull the clutch and blip the throttle, down shift and drop the clutch to engine brake. But I try to match RPM so the it is minimally shocking. But I only do this maybe once or not at all. I let it engine brake, then when I reach idle in gear, I pull the clutch and gently downshift at idle while still rolling. One by one, back to first. Sometimes only to second if traffic is still crawling. Engine braking is fine. It is the shifting that needs to be smooth!

It sounds like you are doing something like this, downshifting at low speed. But engine braking is no problem, and wait until you are near idle before pulling the clutch and gently downshift while still rolling. You should be able to get into first without shock sometimes, when RPM matches input/output in the transmission.

I often allow it to pause in neutral at idle, low rolling speed on my way to first. It can help avoid the thunk.

This is pretty much how I do it. When I engine brake I do momentary apply enough throttle to closely match rpm, and When I do down shift while rolling to a stop with the clutch in , it's just as you describe. The throttle is closed, and really the only difference is the way we word our statements. You say gently down shift one by one while rolling. I said slowly down shift. I said slowly , but what I meant is the same thing. I was trying to make it clear that I was slowing down to an appropriate speed before each down shift.

[Bruces]

What was written above was that you were pulling in the clutch lever ,and holding it while riding the brakes to a stop .At least that is what I was reading .Now you are saying you are using the engine braking to slow you down ,but I certainly didn’t read anything about that in post #6 ,above .

[Bill Hilly]

Originally Posted by Bruces

What was written above was that you were pulling in the clutch lever ,and holding it while riding the brakes to a stop .At least that is what I was reading .Now you are saying you are using the engine braking to slow you down ,but I certainly didn’t read anything about that in post #6 ,above .

You are not reading it correctly. I said that I do engine brake at times, and on my last post , I was saying that WHEN I engine brake, I do rev match. If I'm going along in 3rd gear, and the cars in front of me are slowing, and getting prepared to stop, then yes. I let off the throttle, pull the clutch, and start braking, and when slow enough shift to 2nd, while keeping the clutch in, and when almost stopped shift to first . If I would have initially engine braked, and then shifted to 1st while rolling at the same almost stopped speed, then the clunk would be no different. It's the way you arrogantly , basically stated that I should learn to drive a manual transmission ,that rubbed me the wrong way. The bike is new to me, and I was just curious if others with the bike noticed the first gear downshift as being a little clunkier than expected.