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Discussion Starter · #1 ·
Hi guys, I recently purchased a 79 cx500. I've taken it out on the freeway recently and at about 6-7k rev's I'm only sitting on about 50mph. It has a custom exhaust with a muffler with the baffle removed. I was guessing the lack of back pressure could be the reason for the lack of power? Other than that I think the carbys need a rebuild as there is a slight leak.. Any advice or help would be much appreciated, as this is my first bike and my knowledge is quite minimal..
 

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Welcome Adam. Please take a few moments to put your bike year and model in your signature line and your country in your profile info.

79 alone doesn't tell us what model we're looking at. If it has a 16 inch rear wheel the revs sound about right. Will the bike not rev beyond this?
 

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Discussion Starter · #3 ·
Great will do. It's actually a 78 model. (Typo) obviously new to this. I'm not sure how high I'm supposed to be reving it but it'll get to about 7500rpm at about 90 kph. I'm reluctant to push it much further as I'm not sure where the comfortable rev range is for the bike.
 

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If it is a 78 model, as standard it should have an 18 inch rear wheel. It probably should only be revving 5000 or so at 50. Can you give us the frame number? You can ### out the last few digits. Also tell us what the size on your back tyre is.
 

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Sydney Aye?

We'll probably milk you for a bit more info.

Do you have any reason to suspect your instruments aren't accurate?

The bike tops out at 50 {80k} with the tach indicating 6 to 7000 RPM but the motor won't rev any higher?
 

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As Trev says - 50 mph / 80 kph is normal reading with a 18" rear. For my -81 standard too. But the instruments aren´t wonders of precision. I´ve spun a bunch of instruments with a handheld drill at max speed. Seems the speedos often are more off than the tachos.

According to a gear speed diagram in the owners manual for 18-inchers 1000 rpm in fiifth = 18 kph or 11.2 mph. Real speed.

Also - in fifth gear the instrument needles follow each other pretty well over the scales. Gives you a rough idea about accuracy.

/Sture
 

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Discussion Starter · #14 ·
Ahh this sounds like it could probably be the problem with mine. I'm yet to conduct the test as it's been raining for 3 days straight. Have you looked into a replacement stator?? Is it an expensive repair?
 

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do the tests and see where you are at - then there are options -

Regards
Rayman
 
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Sorry guys but how is high reving / low top speed a stator problem? If the stator is at fault you may not get the high revs, although you may get speed restriction with limited revs. As stated above, surely the problem must be clutchslip, gearbox issues (ie you are not in 5th) or crazy instrumentation. Maybe your stator is at fault as well though but this would be a supplementary issue - doesn't cost anything to check it.
 

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Ahh this sounds like it could probably be the problem with mine. I'm yet to conduct the test as it's been raining for 3 days straight. Have you looked into a replacement stator?? Is it an expensive repair?
I have looked into replacing the stator but I have decided to put a Rae San module on mine (link below). If you put the Rae San on you most likely will not have to replace your stator.. the site describes how it works much better than I could. Its definitely worth considering if you're having stator problems.

CDI Power Supply | Rae-San Electronics
 
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