sparks advance timing key

[my250ex]

anybody have one on their 400? i saw it on ebay and i wanted to know if anybody had one/what their opinoin was on it. i want to put a hmf slip-on on, uni filter, and wb rev kit. will i still be able to use the timing key because it says it doesnt work well with a lot of mods.

[2004exrider]

It'll be safe with your mods. When they mean a "built" engine, they mean with a high compression piston and it will run hotter and requires a higher octane in turn. Im not sure if the WB rev box advances the timing any or not, but if it does i wouldnt use the key because you dont wanna overly advance it. Anyways, its supposed to give it a snappier throttle and good power.

Jimmy

[my250ex]

so do you think it would be better to get the timing key only becasue that would be a better deal than spending 60 bucks on the rev kit

[GPracer2500]

I'm 99.5% sure that the WB rev box does advance the ignition timing. Don't use a timing key with any rev box unless your possitive that the rev box is NOT allready giving you some advance.

[GPracer2500]

One thing the rev box will do that the timing key won't is give you an extra 1000 rpms before the rev limiter kicks in.

[2004exrider]

Honestly if it was me i wouldnt get the rev box. The 400ex redlines at 9200 RPM and is making all its power at 8,250 RPM's. So even if you raise the rev limit up to 10,200 RPM's your still making all of your power at 8250. The only time they are good is if you have a fully built motor that is still making power past the stock limiter and you need the extra RPM's to get the effect of it. Plus ive heard a lot of bad, like they make it harder to start in the winter due to a weaker spark, and they are just a XR250 rev box with a WB badge on it. It's up to you though...

Jimmy

[my250ex]

thanks for the advice

[GPracer2500]

Last weekend at the dunes I took my WB box off and put the stocker back on to help avoid the mild detonation I was experiencing. It helped with that but I did find I occasionally would bumping into the rev limiter. I never did with the WB box. Can't say I could tell a performance difference concerning the ignition advance (other than reduced detonation).

My point is that with my particular engine setup, riding style, and normal riding terrain I DO use that extra 1000 rpm.

It's a 415cc, 10.8:1, Hotcams stg 2 (old style), and I'm 1 tooth down in the front.

[hauck400ex]

i have a stock bore high comp piston, stage 1 hotcam, and the flywheel key and it is nice... i did it all at once, so i couldnt say for sure if there is any difference, but doing all that to my bike made a huge difference... its worth $20 to give it a try, and you could always sell it for that much, plus you get a flywheel puller