HELP!

I have a 1982 XJ650 Yamaha Maxim. This bike has been sitting in a garage for the last 8 years. The carbs have been cleaned and synched. The issue that I am having is that when your accerlerating thru the gears, the engine revs like the speed of the bike. I parked it in the garage, and put it up on the center stand, engine off tranny in neutral.....spun the back wheel with my hand...everything fine.....eng off,pulled in the clutch put tranny in any gear and it feels like maybe the clutches are dragging...is this normal?....also whe I am running at 40,50,60..or the RPMS are running about 1000 rpms less then the actual speed of the bike...is this normal?.....to have such a high revving bike?.....it red lines at 9500
Any help would be greatly appreciated

 

You'll feel some drag with the clutch pulled in with the bike in gear especially with a cold crankcase since the clutches are wet and submerged in oil. The drag is the result of the viscous nature of the oil.

My question is, how do you know there is a 1,000 RPM difference between the engine speed? Is it a perceived difference? I know my tach doesn't start up right away when I start the bike, but I've never watched it close enough to see if there was a lag during revving, but there shouldn't be.

I guess you question is rather ambiguous and needs to be clarified because I'm not quite catching your drift (and I'm an engineer capable of figuring out most problems no matter how well they were communicated).

 

Well, Ok, here goes, if I am doing say 50 MPH, then the tach is sitting at 4000 RPMS.
What about drag after say 20 miles at 55mph.....would there still be a very signaficant drag?

 

@ 50 MPH
In top gear
4000 sounds normal.

Of course there are other variables that can effect engine speed.

BTW add your bike's info in your signature
add your location in your acct options
and might as well check out the XJBikes Map, and add yourself there too.
http://www.xjbikes.com/dfmaps.html

 

cant see how clutch drag would affect RPM-MPH ratio, clutch slip would affect that i would have thought, drag would give you a crunchy selection of first gear and may need to use brake to hold it back.
Mine is a Seca and 5 speed @ 4.5k rpm i am doing 60mph.
Maxim as far as i know is 6 speed so maybe should need less rpm to hold same speed but not sure.

 

Gear ratio for a Maxim sounds about right... thank the 16" rear wheel. You can go with a Seca 18" wheel, and gain a few more mph for the same engine RPM, at the cost of a narrower tire (120 instead of 130). IIRC you will gain about 5% speed for the same RPM.

There will be some drag on the clutch even after 100 miles of riding... Although it's usually more pronounced when it's cold.

You know you have too much drag when you put the bike in gear (clutch pulled in, cold) and it kills the motor.


soooo... sounds like a normal XJ so far

PS you can always try adjusting the knob on the clutch perch to see if it helps... but it will still always drag a little.

 

what about at 50 MPH.......the rpms at 4000...and when I pull in the clutch, the rpms stay at 4000 rpms then slowly decrease?

 

sounds like your carbs wouldnt pass the clunk test.
Does it happen when in neutral, then you rev?
Or is it responsive up and down, and only occurs while in gear.

 

+1 on the clunk test..

it could also be a vacuum leak. check all the vacuum plugs, carb boots and the vacuum line that goes to the petcock for any signs of damage.

 

CLUNK TEST?.....what is that?.....ok...say I am going from a dead stop....to say 50 MPH, as I am changing gears and speeding up, I change into 3rd gear, then pull the clutch, release the throttle, and the engine stays revved......then of course change into 4th gear and so on. This only happens when I am driving...it never happens when i am say in the garage, and just revving the engine.

 

You might need to lube your throttle cable.

 

with the clutch pulled in, does the bike try to drive away when you put it in first from N ? also, at what rpm is your idle set?

 

Sounds like your RPMs are right for high gear. I turn just a hair under 6K ad 70MPH.

If you pull the clutch and let go of the throttle the RPMs should drop fast. If you don't pull the clutch and let go of the throttle your eyes should just about fly out of their sockets (at 70mph).

 

If the RPM's are staying high when the should be low or falling-off ... then, ... I would say you need to de-oxidize the Diaphragm Piston Bores.

Get you Carbs to pass "The Clunk Test"

http://xjbikes.com/Forums/viewtopic/t=1 ... +test.html

If you have Diaphragm Pistons not responding to the variations in vacuum
then you have a situation where the Carbs are not performing as they should.

They will either Rob you of power ... by not opening as quickly as they should ... or, ... keep your revs up by allowing Main Jet Fuel Supply to be wasted when you close the Throttles.

Easily rectified.
Recommended maintenance for Carbs older than 15 years.
Absolutely necessary for Carbs that are mounted on a bike that just sat for more than a few months.

Race prep for performance Carbs
Polishing the Bores after aluma-oxidation removal highly recommended.

 

Thanks all ...for all the input info