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View Full Version : 250r Detonation??? HELP!!


Gregjy
08-03-2009, 07:20 PM
So spent the week at Dunefest and had hella fun. However the R is driving me F-ing crazy!!! Played with jetting and have a 200 main jet in it now and am getting a LOUD rattling noise on climbs. Banshee hill which is more like Blaster hill now it will rattle like something is coming apart at the tree line which is about half hill. Seems like usually when I am in it get out of it then back into it is when it is the worst. I was told she is detonating but not sure?? What are your guy's thought...
Gregjy
08-03-2009, 07:23 PM
OH little more info.... I am running 110 race with 927 oil at 32:1. Believe it is a 38 carb. No airbox with a K&N. Again HELP!! Plug was looking pretty good kinda a tan color. And I also have the needle clip on the bottom..
hondamancbr03
08-03-2009, 07:43 PM
Cylinder type? Stock? Pro-x? PSI? Ignition advance?

Bottom clip on the needle for a 38 is a lot of fuel at mid throttle and a 200 main seems big if it's a PWK.

My 350PV is middle clip with a 175 and seems just right....I was a t Dunefest as well so i was running in the same temp and elevation as you.
Gregjy
08-03-2009, 08:17 PM
It is a Paul Turner Eliminator cylinder and pipe. I have done NOTHING with the timing and don't know how?? It seemed to run better on the flats than the hills.. Frustrating is an understatement....
hondamancbr03
08-03-2009, 08:24 PM
Can you look at the side of your carb and see if it says PWK? TM? PJ? It should be one of the three if it's truly a 38.
Gregjy
08-03-2009, 08:47 PM
The carb says.... "PWK 72RAA FJ
hondamancbr03
08-04-2009, 09:13 AM
How much experience do you have working on carbs? Can you pull the needle out and look at the lettlers? They are just below the last clip. That will help with knowing where to start on the clip position.
Keep in mind that i have more CC's than you and the same size carb and my settings are:
55 pilot
2 turns out on the air screw
DDJ needle in the middle position (LED recommends starting in the 4th position)
175 main jet.

You seem to be extremely fat in the main and the needle (if you have a D series needle) which would cause the issue you are having.
RyanWsly
08-04-2009, 06:55 PM
Did it just start doing this? possibly bad or wrong fuel accidently? Fuel with low octane will self ignite, not a chemistry class here, but octane level is what designates where a fuel begins self combustion, basicly, possibly your "rattling noise" , higher compression needs higher octane so there is no combustion before the spark, if there is you have two explosions, and pinging, spark knock, detonation, pissed off little man with a hammer inside, whatever you want to call it, just something you might c
Gregjy
08-04-2009, 08:45 PM
Bought 10 gallons of 110 octane. That is what I have been running. I have heard this before and never new what it was. Now with a fresh topend I did not want to burn her down. Anyway I will pull the needle tomorrow and check it also. Thanks.
Honda 250r 001
08-04-2009, 09:33 PM
Exaust+leak%3F+Whats+the+compression%3F
regg187
08-04-2009, 10:14 PM
Man a 200 sure seems BIG, but says plug was nice and tan, very ODD!
86 Quad R
08-05-2009, 06:50 AM
i'd like to know what the compression is on it. also with it having a 200 main and the plug showing a tannish color i'm thinking i'd do a leak down test on it. juss my .02 worth.
Gregjy
08-05-2009, 10:23 AM
How do you do a leak down test on one??
86 Quad R
08-05-2009, 10:34 AM
go Here (http://www.exriders.com/vbb/showthread.php?s=&postid=2562163#post2562163)
hondamancbr03
08-05-2009, 01:07 PM
Originally posted by Gregjy
How do you do a leak down test on one??

If you don't have access to the plugs and gauges, another way to test for leaks is to have your bike running and spray choke cleaner or carb starter fluid around the intake boot and cylinder base gasket...Spray the center case gasket as well to make sure you're not pulling air through a bad gasket, and listen to any idle adjustments the bike might make while spraying the fluid.....It's not as proffesional as a leak down test system but it works for the driveway mech.

Have you asked the person who built the motor what jets they suggest?
RyanWsly
08-05-2009, 06:38 PM
86 Quad R i'd like to know what the compression is on it.

also believe this is where you need to start, fresh top end with noise being worse hints that you gained compression during rebuild to me. Change heads or domes or gaskets sizes when you did it? Don't know if you changed anything, but you may also look into that also.