[Cover Tune]

1983 Yamaha Maxim XS400

I'll be cruising along at highway speeds (100km/h-ish) in 5th, and when I let off the throttle to gradually slow down, the whole bike "lurches" or "jerks" over and over. It's not really violent, but enough that it's uncomfortable and I can even see it.

I've paid very close attention and I'm certain that I'm letting off slowly and smoothly.. and not even letting off all the way, even just easing up a fraction causes this.

Thoughts?

 

[Trondyne]

I've got one of the most lurching bikes in history...because of the jackshaft and secondary tranny this bike has... All I could suggest is that you work on micro movements of the throttle.. When I first started riding my current bike I was lurching like mad but in time learned how to manage the throttle and clutch to avoid the lurching..

I assume that the chain is not loose...

 

[Stablefull]

Yeah, l was gonna say that too...l just went through the same thing with my bike...the shifting was rough, it wasn't smooth at all, tried this and that and everything else...in the end, the chain had stretched over time and was wreaking havoc. Tightened her up and it was much better.

 

[Porky]

Great minds think alike!

These are the symptoms of a worn out chain. Try this: Get up to about 50 mph, pull the clutch in and shut the engine off with the kill switch, coast and listen for an irregular 'binding' sound. You should also feel a vibration if the chain is bad. Tightening a badly worn chain is a no-no as it puts a huge load on the 'countershaft' output bearing and can cause the seal to leak and the bearing to fail, not to mention to ruin both front and rear sprockets.

I would buy a matching chain and sprocket set, with the "X" or "O" ring oil less chain, if the chain is bad.

Of course it could be your carbs are old and need to be rebuilt, which is an easy job, once they are off of the bike.

If it's not the chain, try running some Chevron 'Techron' fuel/ carb cleaner in the gas or even Lucas or Seafoam and let them do their magic to the fuel system.

Plugs should be checked, cleaned or replaced.

Let us know the outcome.

Sam:biggrin:

 

[Cover Tune]

Chain is definitely loose. Very frustrating since the mechanic just had the back tire off a few weeks ago.. you'd think he'd have set it up right.

 

[Dodsfall]

The chain should be somewhat loose to take into account movement in the suspension. Too tight will cause a lot of problems!

Look at the spec in the manual and set the chain slack as stated there.

 

[Cover Tune]

Spec is 1.3" and it's over 2"

 

[hogcowboy]

Your mechanic may have adjusted it with a link that was bond up and has since freed up.

 

[Stablefull]

How new is the chain, and how many miles since it was put on?2/3 of an inch seems like a lot, but l would think that a new chain would stretch faster than an old one.

 

[Cover Tune]

Original chain, as far as I know, and if that's the case, then it's got 17,000km on it (about 10,000miles).

 

[Stablefull]

Yeah, it's probably time. I would change out the chain and both sprockets. Shouldn't be too spendy. Hey, look at it this way...you won't have to do it again for quite a while

 

[hogcowboy]

Original chain, as far as I know, and if that's the case, then it's got 17,000km on it (about 10,000miles).

Yep, it's time for a new one. And like hawk says, replace the sprockets. I didn't know that when I changed my first and the chain didn't last nearly as long as the first chain. Like about 1/3 as long actually. Sure isn't worth the savings trying to skimp by for sure.

 

[Cover Tune]

FML. I'm so tired of issues with this bike and I really don't have the cash for this. :frown:

Still haven't figured out what's up with the fuel system either.

 

[Stablefull]

FML. I'm so tired of issues with this bike and I really don't have the cash for this. :frown:

Still haven't figured out what's up with the fuel system either.

I hate to say this, l know you love your bike, but maybe it's time to cut your losses and buy something a little newer?

 

[stevekozak]

FML. I'm so tired of issues with this bike and I really don't have the cash for this. :frown:

Still haven't figured out what's up with the fuel system either.

It can get frustrating. The chain issues, you are going to get on any bike with a chain. They take maintenance and adjustment. Dont give up. Try to find someone to help you. Not to sound sexist, but I bet there are any number of motorcyclists in your area that would be happy to help a cute girl adjust her bike chain.

 

[Cover Tune]

A new bike is out of the question hawk.

I can adjust the chain myself, not sure I can replace the chain and sprockets.. or even afford it right now.

 

[hogcowboy]

If you was closer I would help you out. So maybe there is someone locally that would lend a hand. We all need help from time to time. Reach out.:thumbsup:

 

[Cover Tune]

Pulled the chain and cleaned it. Pulled off the side casing around the front sprocket and cleaned out the PILE of gunk that was in there. Sprockets really don't look very worn to me. Put everything back together and tightened the chain a little.

Took it for a quick test ride… didn't seem to lurch when letting off the throttle, but was a little jerky on acceleration (perhaps my fuel issue?). However, noticed an audible "clink" when releasing the clutch on a downshift. Wonder if I somehow buggared up something on the clutch or shifter when cleaning it out.

 

[hogcowboy]

And you did oil it back up correct? It maybe a link that bound a little and is freeing up. Long shot but possible. I'd keep an ear on it but it may clear up. The chain has got to be in a different place than before and may wear in a little. But I admit I'm not that good with chains. I went belt and drive shaft rather quickly because of that. There's an art almost to running chain I think.