Engine won't run at high revs

[Jakobi]

Just out of curiosity.. have you tried bolting someone elses carb on? Generally I'd say check all the mechanicals before you even consider this.. but you pretty much have!

 

[bergerhag]

((Do you have a spark plug without resistor? CDI's dont like that.))

[edit] Never mind. I just read first post again..

 

[Elvis74]

what about your reeds, are these ok?

 

[motopsycho87]

((Do you have a spark plug without resistor? CDI's dont like that.))

[edit] Never mind. I just read first post again..

The spark plug has a resistor, but the plug cap does not...

Just out of curiosity.. have you tried bolting someone elses carb on? Generally I'd say check all the mechanicals before you even consider this.. but you pretty much have!

Anybody got a spare carb kicking about?

what about your reeds, are these ok?

 

[Jakobi]

Reeds look a bit frayed at the bottom right of the picture, but by no means the worst around. Hold the block up against the light and try and look through. Well sealed reeds will be just that; you won't see light passing through any gaps.

 

[motopsycho87]

Reeds look a bit frayed at the bottom right of the picture, but by no means the worst around. Hold the block up against the light and try and look through. Well sealed reeds will be just that; you won't see light passing through any gaps.

I have a higher resolution picture, and assure you there is no problems with the reeds.

Brief synopsis so far...

Reeds - VForce 3, good condition, reed to carb boot in good condition (surface cracks, none through)
Piston - Brand new, Wossner (obviously head and base gaskets changed at this point)
Powervalve - Tested open and shut manually, centrifugal mechanism works fine, and can easily see all ports opening through the exhaust port
CDI - Bypassed all bike's own electrics, also tested RM125 CDI
HT Coil - Brand new, tested new and old ones with multi-meter, seem fine, new plug cap, no resistor (tested with resistor also)
Spark plug - Tried 3, BR8ES
Stator coil - Old one tested fine, replaced with complete new electrex assembly, measures the same as the old one
Carb - PWK38 airstriker, pilot - 42, main - 180, needle - don't know, haven't touched it. - +16'c sea level (bike ran absolutely fine prior to this problem, suddenly just went half way through a ride)
Exhaust - tested without spanny, with spanny without silencer
LH Crank seal - appeared bone dry, replaced (no play in bearing)
RH Crank seal - no visible damage, replaced (no play in bearing)

Not tested new crank seals yet, awaiting gaskets.

Honestly cannot think of anything else to check, might just get some cheap 2 stroke from the petrol station and see if it runs up with that at all????

 

[motopsycho87]

first set of pictures... the red stuff is just rubber grease

 

[motopsycho87]

seconds set of piccy wiccies

 

[motopsycho87]

and the last set.

Basically these are showing that all the vent lines are perfectly clear, the choke is closed etc...

But what happened to the piston?!

 

[bergerhag]

and the last set.

Basically these are showing that all the vent lines are perfectly clear, the choke is closed etc...

But what happened to the piston?!

Contaminated fuel?

 

[motopsycho87]

Fresh tank of fuel went in after the piston

 

[pscook]

Contaminated fuel?

To expand on this question- Do you purchase fuel from a known good source (mega-retail/high volume source) or do you buy fuel from a small quantity vendor? I found that my (small quantity/low turnover) vendor was selling contaminated fuel after spending an entire day chasing similar symptoms as yours. Once I poured in a gallon of cheap pump gas my problems evaporated (pun intended). I believe that you are in the UK? I know that here in the states I can buy small quantities of stabilized and purified fuel, it might be worth it to eliminate contaminated fuel as the source.

 

[motopsycho87]

Tank it died on was Tesco 99 octane (recommended by GG dealers), currently running Shell VPower 98 octane.

 

[motopsycho87]

Starting to think both the EC300 CDI and the RM125 CDI are toast, the bike runs a lot better with the RM125 CDI, the EC cdi dies before the power valve opens, the RM gets another 3/4000 RPM before it starts coughing and spluttering, the RM CDI also idles perfectly, the EC300 one doesn't now.

 

[motopsycho87]

http://www.youtube.com/watch?v=GVynXjPsIuA - EC300 CDI

http://www.youtube.com/watch?v=P0L-PxEVomE - RM125 CDI

 

[motopsycho87]

ooo, looks like the rm125 CDI, + the old ignition coil = win... just got to get it all back together and test it...

 

[motopsycho87]

Yup, the new coil i put in when it started running lumpy must have killed the cdi and self destructed at the same time, goes like absolute hell with the rm cdi, thank ************************************************************************