RGV250, no top end power

[DaveyJones]

Hey guys
I have a 1989 rgv250 and has all of a sudden lost all of its top end power hit from about 9000rpm onwards.
We have tested cdi out of another vj21 still same problem.
Has had new pistons recently.
New ignition leads.
Cleaned carbs out.
No problems with powervalves and controller.

any help would be great.
Cheers

[Akzle]

what colour powerband?:sweatdrop

[RDjase]

Hey guys
I have a 1989 rgv250 and has all of a sudden lost all of its top end power hit from about 9000rpm onwards.
We have tested cdi out of another vj21 still same problem.
Has had new pistons recently.
New ignition leads.
Cleaned carbs out.
No problems with powervalves and controller.

any help would be great.
Cheers

have you got a VJ21 and your RS?

[Drew]

First thing I'd check, is battery voltage running and not.

Symptoms fit low voltage.

[FJRider]

Check compression too ...

[DaveyJones]

Its my friends RGV

[DaveyJones]

Its got new battery.
Compression must be fine, because power delivery as normal until 9000rpm where it just disappears.

[quallman1234]

Hey guys
No problems with powervalves and controller.


You 100% sure about that?

Assuming it runs fine up to 9000rpm (i.e it doesn't die on full throttle etc) you can rule out Main jet blockages/carb issue.
Does it die almost always about the same rpm? If so you can rule out Fuel supply issues.

I would double check your Powervalves. And try another CDI.

Explain the problem better as well. As if it just stop's wanting to Rev that would hint at PV's. But if it completely dies, i'd be looking electrical.

[Drew]

Its got new battery.Doesn't really matter. If it's not charging properly, the symptoms will present exactly as you describe. Check the voltage running at 3000rpm, and then with the engine not running. It costs nothing, and is very high on the list of possible causes.

Compression must be fine, because power delivery as normal until 9000rpm where it just disappears.I tend to agree here. Low compression presents worse at lower RPM in my experience.

The power valves opening and closing when you turn the bike on, means bugger all as to how well they work when running. The current draw at high RPM is much greater than just the servo turning. 8000-9000 is where they should be wide open. Disconnect the powervalve controller, and adjust the cables so they valves are wide open all the time. Take it for a hoon. That will eliminate that cause, or confirm it. Without any doubt or more speculation.

[DaveyJones]

Power valves working while reving bike. Could it be ignition coils as the manual said it might be?

[Drew]

Power valves working while reving bike. Could it be ignition coils as the manual said it might be?

Does the exhaust note sound flat when it gets to 9000 when free revving it? Because without the motor loaded electrical faults often won't present.

[DaveyJones]

You 100% sure about that?

Assuming it runs fine up to 9000rpm (i.e it doesn't die on full throttle etc) you can rule out Main jet blockages/carb issue.
Does it die almost always about the same rpm? If so you can rule out Fuel supply issues.

I would double check your Powervalves. And try another CDI.

Explain the problem better as well. As if it just stop's wanting to Rev that would hint at PV's. But if it completely dies, i'd be looking electrical.

The bike does continue to rev after 9000rpm but feels very flat on the power.

[FruitLooPs]

If it were coils it wouldn't rev out freely, unless they're breaking down due to heat but then the bike would rev out when initially ridden but start playing up later on. Doesn't sound like that to me.

Another vote for powervalves doing something tricksy. On my old RG150 i've seen the cables actuate for the valves up the top controller but no power, didn't know what was wrong until I checked down at the cylinder end and saw the bolt that held the cable holder to the powervalve shaft had rattled loose, so the holder was actuating but not the shaft & therefore valves :facepalm:

You guys are properly sure the valves are all working, nothings physically broken with the valves? A bike will rev out much easier without load than when being ridden. Fuel supply should be easy to check, filters etc.

[Katman]

What state are the reed valves in?

[Drew]

What state are the reed valves in?

You're the mechanic, but wouldn't that kinda happen over time?

[Kickaha]

You're the mechanic, but wouldn't that kinda happen over time?

I've seen them break with no warning

[onearmedbandit]

I've seen them break with no warning

I wouldn't call you breaking them through ineptitude 'with no warning'.

[roogazza]

You have new leads , so I'm guessing you have changed plugs ?
Basic stuff first before you start getting technical.

It's old, so do these more modern 2Ts coke up as they used to ?
Baffles etc ?
So no misfire, just flat under load ?

[Fast Eddie]

yea chuck new plugs in it.. 2ts like a good plug.

so does transdiesel.. www.transdiesel.co.nz for all your Agip 2t oil needs

[quallman1234]

The bike does continue to rev after 9000rpm but feels very flat on the power.

Thats the charastics of how my RG felt with fucked Power valves. Does it struggle to rev? I.e can you get it to the red line UNDER load?

As posted could be not charging correctly underload like drew says.

[DaveyJones]

Powervalves definitely fine. Can feel them moving when pipes are off.

[F5 Dave]

pull them out anyway,

if you do any research you'll find they love to flog out & cause damage. Its a brave or foolish owner that doesn't strip them every year & check for wear. get onto RGV250uk forum.