CR250 keeps revving
Posted 17 April 2012 - 09:42 PM
Couple things first:
Top end has strong compression
reeds not cracked
silencer packing good
Using a PWK carb from a 2000 CR250
1. Bike smokes out the silencer
2. Lots of black splooge
3. Takes 6 or 7 kicks to start when cold
4. This is the worst: If I'm running it in high RPMs, the bike revs high after I stop. Put me into a tree at Sandy Lane after the open section after one of the start controls. I was running wide open in the open section, then when I hit the woods the bike kept revving and I hit a tree with my shoulder pretty hard.
Any thoughts as to what my problem could be from? And yes, part of the problem is the connection between the seat and the bars. I'm a pretty lousy mechanic as can be seen by my very frequent DNFs.
Posted 17 April 2012 - 10:11 PM
I don't consider sponge a variable to judge jetting as there are too many other considerations like oil, fuel, rider style.
Posted 17 April 2012 - 10:41 PM
Either use a leakdown tester (with the proper tools) or the poormans method......
remove the pipe and the carb, plug the openings with expanding freeze plugs.
Take an old spark plug and drill out the center and braze on a tire valve.
Get a bike pump with guage and start pumping.
take the trans vent hose and put it in water/liquid
look for bubbles.
Posted 18 April 2012 - 06:45 AM
This did not fix my "running on" condition. I do recommend checking & replacing the seals as they are cheap insurance.
Double check the reed valves. I found the stock reeds will hit the inside of the intake tract while opening and chip the corners.
I replaced the entire reed block with a new stock one and the same thing happened again a couple races later.
The fix I found was to replace it with a moto v-force reed block, or a simaliar aftermarket one.
I agree it is a lean condition that is causing this and makes for a scary ride.
There was a post from Lisa about the current "Ethanol" in the fuel causing the seals to harden. I use VP C12 mixed 50/50 with quality super unleaded. Good luck
Posted 18 April 2012 - 08:45 AM
Posted 18 April 2012 - 06:12 PM
Is that the first year cable operated exhaust power valve.. if you are dealing with a big smoker and gooing everthing up that may need a look also..
and a really off the wall item is the throttle cable routing correct.. as I owned a 01 and if it was not routed correctly it would pull at times and hang up.. produced some better scores..but also produced some brown shorts too..
Posted 19 April 2012 - 09:29 AM
Posted 19 April 2012 - 03:52 PM
Adam's right. The Basics. Check the slide to see if any of the chrome has worn off of the slide. If so,the bike will pull a lean condition with the symptoms being a leaky crank seal. Check the bore specs. of the carb in the slide area too.