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weskc35k

XR650r with an XR400 CDI

15 posts in this topic

Yes it seems to be better everywhere.

Revs further without dropping off.

Stronger from idle.

Pulls stronger under load.

Not much but enough to notice.

No pinging.

Now who's gonna put an XR250 CDI in a BRP ,it will fit.

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If ya got one i'll buy it.

Actually the xr250 CDI timing may just be a bit advanced for an R but hey we gotta find out right.

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Is cool is good.

It has cured the idle hick i picked up with the stage 2 as well.

interesting you say that... i know, i know, i have an "L"adies, but when i put my cam in, i have a slight "hick" as you had...

really need to try and get an inverter going so i can try the 600r cdi..

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OK i did some searching and the XR4hunjie advance at idle is 8 degrees and the 650 is at 6 degrees this explains the extra bit off the bottom ,all in on the 650 is at 31 deg and i haven't sourced the 400 yet.

Also if anyone has the specs for the XR250 CDI let me know please.

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i would guess the 400 is 31 at max also. i saw a post awhile back with cdi timing charts from about 8 different honda singles. they all had 31 max advance.

it was in this forum. i think crmcc posted it.

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According to the service manual, the XR250R's full advance is 28* +/-2* at 4300rpm with the initial advance at (the already mentioned) 8* at 1900 +/-200 rpm.

I know the TRX400EX full advance is also 28* at 4000rpm, tapering down to 27* starting at 7000rpm, with the initial advance of 8* ending at 2000rpm (according to MSD). The curve ramps up linearly between 2000 and 4000. Being that the TRX and XR are nearly identical engines it wouldn't surprise me if the XR400R's maximum advance is also 28*.

Many of the aftermarket TRX400EX CDI's are widely rumored to actually be OEM XR250R CDI's (complete with the "Shending" or whatever it is, manufacturing stamp).

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The total advance on the XR400 CDI is 31 degrees,not sure what revs though.

Remember there are 2 different XR400 CDI's pre 03(i think) and post 03.

The Aussie one that i have is the early type.

The XR250 only having 28 degrees all up makes sense if it revs to 12K as well.

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The model yr. difference is between the '96/'97 CDIs & '98-'02 CDI boxes. It has been said that the earlier 96/97 boxes have a slightly advanced timing curve over the newer boxes because of the richer jetting that the bikes were spec'ed with. The newer '98 model year U.S. bikes came with leaner jetting to pass more strict emissions requirements. So, part of the story seems to suggest that they retarded the timing to better match the leaner jetting specs. I believe the flywheels between these U.S. model years are slightly different also. It's about the pickup tab position.

There is another consideration. I thought I have also read somewhere along the line of a quote from Honda talking about "revised timing" on the newer '98-on XR400s for "easier starting".

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Here in OZ it's all the same from the first xr4 to the last no changes in the ignition timing.

I can feel the bike is stronger from idle.

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