GZ 250 Forums - No Acceleration at 40MPH

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- - No Acceleration at 40MPH (http://www.gz250bike.com/forum/showthread.php?t=7405)

the idler screw is not your problem set it 2.5 to 3 turns to have a good idler and easy cold start.
check the main jet and make sure the slider move freely up an down
carbon build up may prevent the slider to open all the way

Quote:

Originally Posted by anesde (Post 83486)

Changed the oil two months ago and used synthetic royal purple 10w-40. Also changed spark plug back then - guy at Napa told me it was NGK DCPR8E

I thought it was the oil so I changed back today to Castrol GTX conventional 10w-40. Only had about 70 miles with the synthetic - what a waste!

Anyway the bike did not perform any better so I thought maybe the spark plug. Looked up the spark plug and found the internet says it's NGK DR8EA, not what I have in there. Took the old one out and it's black - covered in soot. Not wet which is what I thought I might find. Took her for a quick spin after changing the plug. I think I notice a slight uptick but it got dark so I'll have to wait until tmrw

I think you answered your own question, slipping clutch. Both oils you mentioned are for car use, not bike use. You must use a JASO certified oil. Look on the oil container for the designation. Shell Rotella, Dino or Synthetic will work fine and are the cheaper than most others. Had excellant results in 2 of our bikes with the dino variety.

I agree with Water Warrior 2. Wrong type of oil. I have dealt with this problem in the past while working on friends bikes. One was a Honda Rebel and two were Suzuki. Problem went away after changing to correct oil.

I found it hard to believe that oil was the only culprit. Bought new clutch plates and took the clutch apart this morning. Clutch plates had nothing on them and friction plates were scoured and bluish. I didn't have new friction plates so I put it back together with the old ones and new clutch plates. Took it for a quick spin and she's still slipping.

I had bought the clutch plates off amazon for 35 but the entire assembly (new springs too which I don't think I need - old ones look good) is more like 135. Anyone know of a vendor that just sells friction plates?

Bike only had 6300 miles when I bought it so previous owner must have treated it terribly.

If the steels were blue'ish then they've been overheated. At least that was my experience from 15 to 20 years ago when I used to work on bikes all the time. I would just take extremely fine sandpaper and give the steels a very light roughing up. After you clean the old oil off first.
Did you presoak the friction plates in fresh motorcycle motor oil?

I have put , a long time ago, car motor oil in a wet clutch bike and felt the clutch go from 'just fine' to 'slipping kinda bad' nearly instantly so oil is a serious issue..

A slipping clutch diagnosis is easy. Try to launch the bike. Does the motor rev out while the bike barely moves? Or do you end up with a stalled engine?

Obviously show care not to get to fast, flip bike or otherwise case it on this test.

Rather than use fine sandpaper you should use emery cloth that is made for metal. That and varsol to aid the cleaning. Then use oil to clean the residual off and soak in fresh oil prior to assembly.

Yes I did soak the plates overnight. Used motorcycle oil this time. Going to bite the bullet and buy the whole new assembly instead of messing around with trying to clean up the current plates.

I still find it hard to believe it would have no difference after I changed up the clutch plates so I'm double checking all adjustments first.

I use that 1000 wet sand stuff.

Quote:

Originally Posted by spldart (Post 83577)

I use that 1000 wet sand stuff.

Yup, that is fine enough. Never ever would have thought of wet sandpaper. :doh: