pre warm-up bogging?

[schmanman]

my yz 175 bogs before it is all warmed up, after the engine is hot, the bike runs perfect.

I do not mind this, I am just curious as to why this might be?

it sparked my curiosity, and where better to ask than here!

 

[_JOE_]

Fuel sticks to the cylinder walls of a cold engine. This creates a lean condition and thus, the bogging.

 

[2-Strokes 4-ever]

This happens when you have shut the choke off? You may also be slightly lean on the pilot jet... but then again, we jet our bikes to run crisp down low (pilot) and what you're experiencing is normal on our 2-strokes until the bike is reaching running temps. It doesn't overheat or develop a high idle when good and warmed up does it? (signs of too lean) If this condition gets worse in our cool fall temps, you may need to go fatter with the pilot. Do a jetting "search"... big help there.

 

[schmanman]

It doesn't overheat or develop a high idle when good and warmed up does it? (signs of too lean)

nope, no high idle or overheating.

 

[RM85rider123]

my yz 175 bogs before it is all warmed up, after the engine is hot, the bike runs perfect.

I do not mind this, I am just curious as to why this might be?

it sparked my curiosity, and where better to ask than here!

my friends CR does that. My RM doesn't. weird.

 

[SpDyKen]

my friends CR does that. My RM doesn't. weird.

Your friends CR is jetted to run optimally; your RM is jetted rich, so it provides plenty of fuel for your cold engine. I'm sure you do not have to use your choke as much as your friend, either.

 

[RM85rider123]

Your friends CR is jetted to run optimally; your RM is jetted rich, so it provides plenty of fuel for your cold engine. I'm sure you do not have to use your choke as much as your friend, either.

Thats very true. The only time I need to use the choke is when I'm warming it up. And I cut it off about 5 seconds later. And the catch is mine always starts on the first kick :laugh: . His takes about 3-4, and then cuts off.

 

[schmanman]

yea, I think I might also mess with my main jet, since it's either rich or too lean.

 

[SpDyKen]

yea, I think I might also mess with my main jet, since it's either rich or too lean.

You might want to read up on the various jetting threads first, instead.

Main jet is the last thing to address when jetting.

 

[whenfoxforks-ruled]

yea, I think I might also mess with my main jet, since it's either rich or too lean.

Go to the advanced search on jetting and reading your plug. Read them twice if it takes it. That statement you posted told it all.

 

[Tom68]

I recently pondered the same thing you think the bikes half warmed up and you expect to wheelstand out the driveway as you hit the band, but instead the motor stumbles. It's possibly that the pipes too cold and the pressure waves aren't forming properly, the burn rate in the chamber is too slow also the fuel won't be atomising properly at the lower temp and will then burn slower. My bike runs a thermostat so with 2 thou piston to bore I'm half safe, if you don't have a thermostat be careful you don't want a cold seize.

 

[Tom68]

YZ100/IT175 I guess its air cooled, don't worry about cold seize just don't hot seize it. Had a YZ100 in about 1981 had to cut a V out of the frame to get a sensible fork angle.Drilled some holes in the back plate of the muffler and it sounded like a big bore, didn't go like one though.

 

[schmanman]

the whole range of throttle, previous to my unifilter, was fine, except wot.

so whay would I change everything else?

 

[SpDyKen]

the whole range of throttle, previous to my unifilter, was fine, except wot.

so whay would I change everything else?

So why would we answer your questions if you are not interested in listening to our advice?

Or:

If you already know what to do, why would you ask the question?

:whoa: :bang:

 

[schmanman]

ok, thanks a lot.

I was never worried about the bogging pre-warm up, I was more curious as to why it happens. :)

 

[Tom68]

the whole range of throttle, previous to my unifilter, was fine, except wot.

so whay would I change everything else?

No need to, just warm it up. Your unifilter might be less restrictive than what came off making the bike a tad leaner.Atmospheric conditions will also play a part.

 

[schmanman]

yep, thanks.

I did some plug readings today, and she eems to be running good. no white plugs!

the bike did not seem as hot after a little faster,longer ride I took today, so she might be fine now!

god, this is such an addiction!