Quick question, grease my rod? (on the bike, not me)

[ForestHasAnXS650Too]

So I have an issue with my revs sticking higher than normal. One thing is, if I blip the throttle up to 2k and let it close, it will hang and suddenly want to go further BY ITSELF and reach up to 4k RPM. This is both in neutral and idling, and in any gear with the clutch pulled in.

I did some extensive searching on this site about sticking RPMs and RPMs going up without the throttle open, and I think it's my rod.

I'm pretty sure it's not a vacuum leak around the carb manifolds going into the engine, but I took the advancing mechanism rod out (the rod that goes horizontally through the top of the top end) and it is bone dry on a good 90% of it. Should the whole rod be greased, and would that cause my RPM's to stick and/or go high by itself?

It's a 1979 XS650 Special, and it does have an electric start.

 

[5twins]

Yes, you can grease the whole rod. It's just plain steel so any moisture that got in there could cause it to rust. So, just smear it with a light coating of grease. The important part that needs greasing is the ends, and the bushings pressed into both ends of the cam that the rod turns in. If you look into the ends of the cam, you'll see the I.D. of the first bushing has grooves cut into it .....

These are for lube and to provide a reservoir of lube to keep the advance rod greased. So, clean them out and pack them full of fresh grease. The factory shop manual recommends a grease with moly in it ......

Even though this isn't mentioned in any of the manuals, it should be considered a maintenance item. You don't need to do it very often, like maybe every 5 years or so, but it does need doing.

 

[Its been a long time]

Yes, a good idea to use a grease loaded with moly or graphite there. Will continue to give some lubrication even if the grease dries out from heat. I did mine a couple of weeks ago after reading about it here.

 

[Its been a long time]

So I have an issue with my revs sticking higher than normal. One thing is, if I blip the throttle up to 2k and let it close, it will hang and suddenly want to go further BY ITSELF and reach up to 4k RPM. This is both in neutral and idling, and in any gear with the clutch pulled in.

I did some extensive searching on this site about sticking RPMs and RPMs going up without the throttle open, and I think it's my rod.

I'm pretty sure it's not a vacuum leak around the carb manifolds going into the engine, but I took the advancing mechanism rod out (the rod that goes horizontally through the top of the top end) and it is bone dry on a good 90% of it. Should the whole rod be greased, and would that cause my RPM's to stick and/or go high by itself?

It's a 1979 XS650 Special, and it does have an electric start.

Might be worth checking that the auto advance unit does advance and retard properly. I found one spring was stretched by maybe 2mm and the bob weights were not being pulled in properly by the springs. Just a two minute check to do that while you're reassembling the ATU.

 

[ForestHasAnXS650Too]

Might be worth checking that the auto advance unit does advance and retard properly. I found one spring was stretched by maybe 2mm and the bob weights were not being pulled in properly by the springs. Just a two minute check to do that while you're reassembling the ATU.

Strangely, I pretty sure this is a pamco electric ATU. And there are no weights or bobs on one side, I know exactly what it looks like, don't I still need those?

 

[Its been a long time]

Strangely, I pretty sure this is a pamco electric ATU. And there are no weights or bobs on one side, I know exactly what it looks like, don't I still need those?

View attachment 324848View attachment 324847

OK, you don't have the mechanical advance unit. Ignore my comment.

 

[Wingedwheel]

I chased a similar issue and it ended up being my throttle cable was one turn too tight on the adjuster. Backed it off, problem solved. Not saying that’s what your problem is but it’s an easy check.

 

[ForestHasAnXS650Too]

OK, you don't have the mechanical advance unit. Ignore my comment.

LOL OK thank you. I also wound up greasing the rod, and the issue, in fact, seems worse. I'm going to buy new carb manifolds anyway, and,

I chased a similar issue and it ended up being my throttle cable was one turn too tight on the adjuster. Backed it off, problem solved. Not saying that’s what your problem is but it’s an easy check.

I'll also look at the cable, the play is free, and it lands securely on the idle screw, but the revs still hang out really high and wind up jumping past 3k if I bring it up and let it go.