Proper warm up procedures for MX bikes? Or should you rev up a cold engine?

[1tontj]

My friend just bought a 2002 YZ250 and he starts it, and then revs the crap out of it after only a few seconds of idle, then continues to rev it up and down for a minute or so to warm it up.

Him revving the engine like that when it is still cold makes me cringe when I hear it. I told him I think that is bad for the bike, but he says "all the guys do it at the track - it clears out the bike and keeps the plug from fouling". I figured who cares if the plug fouls once in a while - better the plug than ruinning the non warmed up clyinder, rings, piston, etc.

So what's the right answer? Do all the guys do it because they get a new bike every year anyway, and just don't care, or is revving the crap out of a cold bike the right thing to do?

On my 04 KDX220R I warm it up by givingg it just enough gas to idle smooth until it warms up. Seems like this is way easier on the bike, no?

Thanks a lot,
Phil

 

[Ol'89r]

or is revving the crap out of a cold bike the right thing to do?


Thanks a lot,
Phil

Phil.

Reving a cold engine can cause a 'cold seizure'. What happens is, the piston heats up and expands faster than the cylinder. If the engine is not given enough time to warm the coolent, the piston can seize.

It's a good idea to warm your bike up properly. I usually put my hand on the cylinder or radiator to insure that there is heat in the coolent before pinnin' the throttle.

Just my $ .02

 

[1tontj]

So by "it is a good idea to let your bike warm up properly." You mean at idle the whole time until the cylinder is warm? So reving it over and over to warm it up is bad?

Phil

 

[RM_guy]

A quick blip now and then is OK but no winding it out.

 

[Ol'89r]

So by "it is a good idea to let your bike warm up properly." You mean at idle the whole time until the cylinder is warm? So reving it over and over to warm it up is bad?

Phil

Phil.

It's ok to rev it, just not pin it. I see many people at the track fire up a cold engine a hold the throttle wide open against the rev limiter to clean it out. This is not good. :ohmy:

You don't have to let it sit and idle, you can run the throttle up a little. Just don't hold it wide open until the engine is warmed up.

Ok, now ya owe me $ .04 :laugh:

 

[1tontj]

So reving it for like a second, then waiting a couple seconds, then reving it for another second and repeating is bad right?

Is there good detailed info on the right way to do this somewhere? I have searched and found nothing.

Words like a "quick blip" may mean a lot different to one person vs. another.

Anywhere say 1/4 throttle for 1/2 second once per 30 seconds or something like that? Looking for DETAILS ;)

Seems to me like warming up the bike properly is one of the most important things?


Thanks,
Phil

 

[Ol'89r]

Seems to me like warming up the bike properly is one of the most important things?


Thanks,
Phil

Absolutly, proper warm up is very important.

You can rev it up and let it drop back down to an idle. Just don't keep it pinned. Sometimes, you have to rev them a little to keep them cleaned out but, holding them wide open against the rev limiter is not good.

Alrighty now, we are up to $ .06

Where do I send the bill. ;)

 

[1tontj]

Ok, thanks a lot guys.

Phil

 

[tedkxkdx]

Guys who say they will foul a plug if they don't pin it have a jetting problem. Also when guys say they are cleaning it out they are actually getting rid of the excess 2stroke oil that has pooled in the bottom of the crank. For this reason the high ratio mixes of 80:1 were born. Guys with outboard motors would idle around and then go some where else for fish. They did not roll the throttle on slow they just pinned it (sound familiar) and then the excess oil got thrown onto the spark plug where it fouled.
When we say rev it, we mean go from no throttle to almost full and allow the bike to almost get to full rev and then let the throttle snap closed by letting go of the throttle. Some guys go less than 1/4 twists some more. I think it is personal preference and knowing your bike. Why do you think so many guys have to change their pistons. Usually from cold-seizure.

 

[Enduro_Nut]

Revving the motor has always driven me nuts! I let my 2 smoke idle for a few minutes and then go ride. My thumper is different, idle for no more than 1 minute then ride. Today's thumpers heat up very fast.
(it's only my worthless cents!)

 

[Reesknight]

I usually just blip the throttle to keep it running when cold, then after it has warmed up, rev it good to clear it out.

 

[RM_guy]

Quick blip = rotate to 1/4 to 1/2 throttle and immediately let it snap back to full closed.

 

[Thordian]

what me and my friend do is start our bikes, move the idle up, till we get a feel of the engines being just above idle and let them warm up, then we blip the throttle a few times to clear it up and move the idles down to how we like them. just my 2 cents

 

[fatty_k]

I just let mine idle when im getting dressed. This usually takes me about 5 minutes, and by then, the engine is totally warm and ready to ride. I have never fouled a plug and never give it any throttle. Just; choke on, kick, choke off, and it will idle for hours.

 

[Porstala F9]

My bike wont idle for crap, but I have never really gotten around to messing with the idle screw yet..

I basically just sit on my bike and rev it in and out for a little while, gradually going a little more in with the throttle as time goes by, and in the cold weather, I usually warm it up for about 6-7 minutes. Now that it is warmer, its usually like 5 minutes MAX, and I start off riding a little slowly, and gradually open it up.

 

[fuzzy]

Fatty K has what all should shoot for, and all this rev/no rev is a moot point after that! :)

 

[RM_guy]

Fatty K has what all should shoot for, and all this rev/no rev is a moot point after that! :)

If you ride an MX bike with it tuned to not idle then you have to blip it to keep it running. :ride:

 

[Reesknight]

If you ride an MX bike with it tuned to not idle then you have to blip it to keep it running. :ride:

Ditto :aj:

 

[Hucker]

Start the bike...


Gear up...


Ride it.



Pretty simple, don't let it just sit there and idle, its really not doing anything for the bike at all. By the time your geared up (usually takes me 3 mins or so ) the bike is ready to go.

 

[showtime586]

Some bikes will do better than others at low rpm ranges.
I had a 99 KTM 250 SX that had to be cleared out within 30 seconds of starting.If not, it required a new plug every race. Every possible jetting combo was tried and it still had to be done this way. The next year, they change the slide cut-a-way dimensions.

 

[Dino Y]

what i have been doin with all my bikes is keep the bike idle for at least a minute ( 2-3 recomended) and then get in the track and ride the bike slowly for the first lap, after that its good to go. For more tech the piston and cilider have get the proper temperture in order to work efficiently, the cilider's walls if not left to worm up properly it causes excesive wear to it and some times even seizure. If the spark is fouling up this is not the way to keep it clean in no way.

Regards
Dino Y