Bogging Out!!

[Matt3126]

Hi, i'm new to forum and motocross, I have lingered in the back ground and have found the site useful.

I have a 2003 CR125, recently its started bogging out when snapping back the throttle to accelerate quickly and has started to stall when idling. Also if I hold my hand over the exhaust it gets painted completly black with runny old oil/black puss in seconds. I did all the checks for air leaks plugs ect and bike seems perfectly fine when I get moving. I think its running richly and was going to take carb off but had a few questions.

If I remove the carb do I need a new gasket, cos the gaskets are $15+ OEM and cant afford to buy a load if I need to remove my carb many times while I test different jets ect?

Can you get generic gaskets for the mitaka 38mm carbs? if so what would they be called or come under as I searched many sites but got nothing apart from full top end gasket sets?

If I do use a new gasket but need to take my carb off several times within the day to get my jetting right will I need a new gasket everytime I remove it or will the same one do for the days work on my bike?

Someone sugggested first putting a 15:1 mixture in and see if problem gets worse, then try a 50:1 mixture to see if it is the fuel/air mixture, he said this is just a test and wont resolve the problem and don't keep this mixture for riding very long, would this work as I'm hesitant to take off the carb as I have never doine it before, but i do have the confidence to try if it is needed.

Sorry for my newbish questions.

[crazyrydermx]

First of all, welcome to
Ok, now, there is no gasket that needs replaced. You can remove the carb as many times as wanted without any of that.
I would not change the mixture of gas and oil, many members will agree, that's a bad and pointless idea.
You should need to rejet. Sounds like it's running too rich.
What mixture are you currently running?

[AKColby]

Don't change the mixture, that's what we call a band-aid fix. My 2003 CR125 used to have the worst bog ever, I wound up changing every jet AND a different needle. Make sure everything is good before you jet, set the float, fresh gas etc...

[Matt3126]

Thanks for the reply, I know this site as my bike had a allthingsmoto.com sticker on my old front fender I have a 04-06 fender now so i'll have to get another.

After reading all the jetting guides I thought with all the talk of air leaks around the carb there was a gasket especially after looking at this parts finder

[Only registered and activated users can see links. ]

and part number 23 is a gasket 16163-KZ4-L22 on the bottom half of the carb, do you not need to remove the bottom part? and is any type of seal needed?

My mixture is 150ml to 5l of fuel (just less than 1:30), my fuel is 97 octane and I use putoline MX7 pre mix not sure if you have simular stuff in the states.

Thanks for all the help and I have found the setting floats and jetting guide very usefull and has made me confident to try it on my own although as I have never done it before I could do with a parts/tools required list, I have been looking for a workshop manual on cd from ebay but so far have only found them for 2003 cr250.

[crdemon]

WELCOME TO ATM!!!!

Now down to buisness. Did the bike run good before? Usually if you have your jetting on unless you change something ie exhaust, motor mods, ect...., you shouldnt have to change your jetting. Is it fouling spark plugs? First thing i would do is completly go though your carb and clean it out. Also I would check for spark and make sure it is sparking good. But even before that i would check the air filter. This should give ya a few places to start. OH and for mixture there is no need to change that, jetted correctly the bike should run on anything from 28:1-50:1 Most people run 32:1 or 40:1, but switching it up will not tell you anything.
Good LUCK Let us know how it goes and with a little more info maybe we can help ya narrow it down.

[crdemon]

Originally Posted by Matt3126

Thanks for the reply, I know this site as my bike had a allthingsmoto.com sticker on my old front fender I have a 04-06 fender now so i'll have to get another.
After reading all the jetting guides I thought with all the talk of air leaks around the carb there was a gasket especially after looking at this parts finder
[Only registered and activated users can see links. ]
and part number 23 is a gasket 16163-KZ4-L22 on the bottom half of the carb, do you not need to remove the bottom part? and is any type of seal needed?
My mixture is 150ml to 5l of fuel (just less than 1:30), my fuel is 97 octane and I use putoline MX7 pre mix not sure if you have simular stuff in the states.
Thanks for all the help and I have found the setting floats and jetting guide very usefull and has made me confident to try it on my own although as I have never done it before I could do with a parts/tools required list, I have been looking for a workshop manual on cd from ebay but so far have only found them for 2003 cr250.

Your quicker than me! lol. the gasket on the carb is rubber. Unless it is showing signs of wear or leaks there is no need to replace it. Ive had 5 bikes many jetting problems and never had to replace one.
hope that helps

[crdude]

im not sure if this has been sagested yet or not, but look at your spark plug.

if its running rich it will be socked and black, it should have a coco color to it.

[ossagp1]

I am going to assume that your aircleaner is clean etc. Start with the float setting,,that adjustment "moves" with time. Those guys you see on TV winning nationals and SX's have them set before each moto. Yours may have been set 3 years ago.

Warmer weather requires leaner jetting for optimum performance,,but start with setting the float.

Good luck.

[Matt3126]

Thanks for all the comments, and yes my air filter gets cleaned every ride and most of the standard stuff I have checked from the jetting guide ion the knowledge base.

As I mentioned before i've been after a owners manual or a workshop manual for a CR125 2003 but have had no luck, only found 1 for a 250 but i'm thinking some of the differences could send me really wrong if I forgot after buying, but it was only $3 for a copy of the CD so i thoiught it might do for basic maintenace as the bikes are pretty simular.

I was wondering if anyone could tell me the float measurement and what the standard jetting sizes ect should be for my bike so I know when I dismantle the carb this weekend. Thanks. Any relevant info from the manual regarding the carb would be great.