Acceleration Loss

[mmaddix]

Alright everybody i have had a problem with my bike since i have owned it but have been dealing with other problems so i have always ignored it. But it is time to look into it now. Here it is, when I am cruising at freeway speeds and gun it to pass someone or just fooling around my RPM's go up but i do not feel any acceleration until i let off the throttle a little bit. Once I do let off the throttle a little bit I feel some acceleration but not as much as i think should be there. If i roll on the throttle slowly it works better. It has done it in 4th and 5th gear with the same results. I feel it more when I'm going up hill. I have replaced the middle and final drive oil and I think it got better but true fully i don't know if I just expected it to get better or it actually got better. either way it still does it.

Any help is greatly appreciated.

[motoman]

Sounds like your scoot has a fueling, or lack of issue.......or over abundance of the same. Lack of info on bike, what has or has not been done,......anybodies guess at this point.

[BA80]

Sounds like your scoot has a fueling, or lack of issue.......or over abundance of the same. Lack of info on bike, what has or has not been done,......anybodies guess at this point.

Could be fuel, could be vacuum advance-centrifugal advance problems.

The first thing I would do, the easiest, would be to check for proper vacuum advance operation and also centrifugal advance operation. Next, check proper installation and pinholes in the slide diaphragms.

[mmaddix]

but since the rpms are going up isn't it getting fuel? Isnt fuel required to get the higher rpms when i gun it.

Also when it does it i feel somewhat of a vibration coming what feels like the middle or final drive. Maybe the engine its self but i feel it on my feet, the lower part of the bike, rather than the whole bike.

My bike doesnt have any mods that I know of other than air pods and the first/second gear fix.

[BA80]

It actually kinda sounds like there is a pickup coil wire trying to go bad.

Pull off the left engine cover and start the engine and let it idle. Tug around on the pickup wires and see if it dies or runs differently.

See the pickup coil wire repair in the repairs section.

[ViperRon]

Ok I am a little confused so I am going to ask specific. Do you see the tachometer raise like 1000 RPMS or do you here the engine sound like it is picking up and its slow week accelleration. If you gun it and the RPM's go up quick and then it starts to move faster slowly then it appears to be possible slippage of the clutch. There are other things but that is the most prone to slip under load.

Now if you here the engine try to pick up and there is no great movement of the RPM's then it could be either a carb problem or issues with the pickups.

[TopCatGr58]

I agree with Ron, the problem shows up in 4th and 5th gears, it's more likely to show up there when the clutch is slipping...there's a higher load on it in those gears, and will let go if you give it too much throttle beyond what the clutch can hold!

Depending on the age of the bike, the springs, etc., it may respond to just the basic clutch adjustment at the engine, but if after doing that, and it still slips, then you probably need to put in some Barnett Springs. Also, if you're using full synth oil, that has also been known to contribute to slippage when the springs are weak!

T.C.

[skids]

Possibly too lean? Floats set for economy? Aftermarket exhaust and/or mods to the air filters without enough jetting compensation?

[CaptonZap]

Clutch slippage. CZ

[mmaddix]

well I dont have a tach so I just assumed the rpm's were rising because I can hear the engine speed up.

Clutch slipping might be it. I do use full synthetic oil. I will try to adjust the clutch as per the manual and see what happens.

I actually have the bike taken apart upside down on my porch doing the First/Second gear fix because I didn't do it perfectly the first time(second gear only worked for about 6 months) so when i get it back together this week I will let you guys know what happens.

Oh i also forgot to mention I am running straight pipes. and still working on some carb problems.

Thanks for the input.

[BA80]

Now that I've gone back and reread through this thread I have to concur with the others about a clutch slippage problem.

As long as you have it down anyway go ahead and order some Barnett Springs and put them in and when you put oil back in get some motocycle specific oil like Castrol 4T 20w50 that is designed to work with the wet clutch. The synthetic works for some with more gentile riding habits but people who tax the clutch notice slippage with it.

[DGXSER]

If you can hear the engine revs going up, and the bike is not moving any faster, then you have a clutch slippage issue. The synthetic oil may well be your problem. Some folks run it without issues, but it is not uncommon that it causes clutch slippage like your experiencing.

Most folks use standard dyno oil (non-synthetic). You do want one without friction modifiers. Otherwise, your favorite brand you like for your cage of a 20W50 weight will work perfectly.

You can get a set of clutch springs for about $15 or so. Since you already have it all broken down, I would recommend replacing them also.

[BA80]

If you can hear the engine revs going up, and the bike is not moving any faster, then you have a clutch slippage issue. The synthetic oil may well be your problem. Some folks run it without issues, but it is not uncommon that it causes clutch slippage like your experiencing.

Most folks use standard dyno oil (non-synthetic). You do want one without friction modifiers. Otherwise, your favorite brand you like for your cage of a 20W50 weight will work perfectly.

You can get a set of clutch springs for about $15 or so. Since you already have it all broken down, I would recommend replacing them also.

Which is pretty much in all automotive oils today.....

[crazy steve]

Which is pretty much in all automotive oils today.....

+1. If you're trying to save a few bucks and not buy the generally expensive 'motorcycle' oil, you definitely have to check the automotive oils. Locally, I found the AutoZone 'house brand' 20-50 doesn't have the modifiers and seems to work well... That's a national chain, so they should have it everywhere.

[79XS11F]

I agree with Ron, the problem shows up in 4th and 5th gears, it's more likely to show up there when the clutch is slipping...there's a higher load on it in those gears, and will let go if you give it too much throttle beyond what the clutch can hold!

Depending on the age of the bike, the springs, etc., it may respond to just the basic clutch adjustment at the engine, but if after doing that, and it still slips, then you probably need to put in some Barnett Springs. Also, if you're using full synth oil, that has also been known to contribute to slippage when the springs are weak!

T.C.

I agree. If RPMs rise quickly but the bike does not keep up with that change it is likely the clutch adjustment or cluch plate condition.
Rob