[Cub10]

How's it goin everyone? Just trying to see if anyone has any input on getting my Bruin 250 to run properly.

I just recently bought this Bruin off an older couple who didn't ride it anymore. They bought it new and has been garaged all its life. It practically looks like a new bike. They had bought it a new battery in August and told me they had the carb rebuilt, new spark plug and put in some gas right before putting it up for sale.

The Bruin starts up and idles perfect. When you drop it into gear and hit the throttle it moves but maybe to only 1/3 or 1/2 throttle then it starts to bogg down like it wants to die. It has never died, it justs boggs down.

I tried adjusting the air/fuel screw and also tried running without the air box cover (which made it bogg down even more!). When I moved the air/fuel screw out It seemed to have changed it just a bit to get more response from more throttle and not bogg down as fast, but it was still bogging down. I didn't want to back it out all the way.

I haven't messed with the Idle adjustment yet, as the idle sounds perfect where it's at. What should I do to get this thing running like properly?

I am planning to give it an oil change, replace gear oil, new spark plug and fresh gas this weekend. I just don't know what else to do?

Any info/input is greatly appreciated!

 

[Cub10]

I'm not sure if the gas in it was old or not? So I was planning to put fresh gas in it this weekend after I change all the fluids and spark plug.

I thought I read somewhere that old gas may cause bogging?

 

[cory52000]

sounds like the main circuit in the carb has some varnish in it. even after a rebuild it can lurk around in the small passages. run a tank of new clear super mixed with sea foam and I bet it takes care of things. after you get it clean only run clear fuel and use stabil if it is going to sit more thana month and you wont have any more issues. if 1 or 2 tanks of fuel with the sea foam don't work you may have to clean the carb one more time. it can be very difficult to get that varnish out. shine a light down in the tank and make sure its clean, no floaters. if there is dirt in there and it sucked into the carb the sea foam wont help and you will have to go through the carb again.

 

[Cub10]

sounds like the main circuit in the carb has some varnish in it. even after a rebuild it can lurk around in the small passages. run a tank of new clear super mixed with sea foam and I bet it takes care of things. after you get it clean only run clear fuel and use stabil if it is going to sit more thana month and you wont have any more issues. if 1 or 2 tanks of fuel with the sea foam don't work you may have to clean the carb one more time. it can be very difficult to get that varnish out. shine a light down in the tank and make sure its clean, no floaters. if there is dirt in there and it sucked into the carb the sea foam wont help and you will have to go through the carb again.

I have heard good things about seafoam. So do I run a full tank of super unleaded with the recommend amount of seafoam through it? Or how much do I run through it?

After putting seafoam in your gas, how long does it smoke for. until the gas mix is completely empty or does it only smoke at first?

 

[cory52000]

yes run a full tank or maybe 2. I have only used it once and it was on my sons d 50 truck. I mixed it with new gas. it did not smoke much, just a hint of smoke. I would run it about 10 miles, let it sit for a day and do it again. after about a week it cleared 99 percent of the problem and I think the rest is bad carb. the way I understand it is it only smokes bad when you inject it directly, I have never done it myself so I cant speak to how it works. the way I look at mixing it is like you are soaking the parts over and over in fresh cleaner and it has more time to break down the varnish. like you, I have heard good things about the stuff and had one good experience and it did not hurt anything so it is worth the 5 bucks or so to avoid tearing down a carb. even with what I had heard I was a nonbeliever but my parts guy talked me into trying it, what did I have to lose right. I am still not convinced it will replace dissembling, cleaning and installing a carb kit in most cases but this sounds like a pretty low use machine and the gas went bad. so its worth a try. maybe someone else on here has more experience with the stuff and can chime in.

 

[Cub10]

Ok looks like I still need some help with my bruin!

- I've ran out all old gas with sea foam
- I put new fuel with sea foam
- Changed out all oils/fluids & spark plug
- Opened up the carb, had a little bit of dirt but nothing major, pretty much clean
- Main jet (size 60) didn't look clogged or dirty but blew it out with compressed air.
- I tried to remove the pilot jet (size 94) right next to the main jet and it wasn't budging. It didn't want to come out and I didn't want to break the head.


I don't know what else to do or try? It loses all power and Boggs down at 1/3 throttle or so. It just seems like it's not getting enough to gas in the carb? Like it's running out of gas in the bowl?

Any ideas what's goin on?

 

[cory52000]

is your float set correctly? pull the petcock out of the tank and make sure the little screen is clean. make sure the supply hose is clear and not kinked. look for an inline filter, if it has one is it clogged. ensure the vent tube on the tank is working correctly. if it not one of those things i bet the carb is still full of varnish and dirt. any visible dirt in in the bowl means there is dirt through the carb. pull the carb and pull off all of the plastic and rubber parts and soak the carb. there is a ton of youtube videos on cleaning carbs. i like to soak the carb in a can tied to my bench grinder to create an ultra sonic cleaner. after soaking you should be able to get that jet out. wash the carb with soap and water and carefully blow compressed air through every port and passage. replace the brass parts with new, the ethanol can eat away enough of the brass to change the jet size enough to make it run like crap. carb kits are available for most carbs.

 

[Cub10]

cory52000- I'm not sure if the float is set correctly? I was thinking the same thing when I pulled the bowl off last night.

When you say to replace all brass parts with new, will those all come complete in a carb kit? Or do I have to buy all parts individually? Just wondering to see how hard it will be to find all the replacement brass parts? When I buy a carb kit, it will have to be off the Mikuni model # right?

Sorry for all the questions...

 

[cory52000]

you will need to find a manual for the specs and procedure on the float as they are all different. if you dont have one yet the clymer are great manuals, cheap and easy to read. if you fix just on thing with it it pays for itself. i still use mine for the step by step on a warrior carb and i have done a bunch it keeps me from forgetting something stupid. the first thing i buy for a new machine is a manual i even put them in the parts box and take them riding with me. just go to ebay and type in 2006 250 bruin carb and there are a bunch to choose from, looks like 30 to forty bucks. and they will have everything you need. look for the manual there to they are way cheaper. when you do the carb use a white towel on the bench and be surgical clean, make sure you use screwdrives and wrenchs that fit correctly. the brass is soft and a nick in the wrong place can ruin the job. the towel will keep your parts from bouncing away and the white make the tiny little parts easy to see if you hae old eyes like mine. above all take your time. dont worry about the questions that is what a forum is for

 

[Cub10]

I have the original manual that came with the bike under the seat. When I removed the bowl to look at the jets. I was thinking maybe they were switched when the original owners had the carb rebuilt. Is that a possibility? That the 2 jets are in the wrong spot? Are they even the same thread size where they could be swapped in each other places/interchangable? From what I know, the main jet in this pic is the #60 and the pilot jet is the #94. Shouldn't the main jet be the #94?

Now should these be swapped?

 

[cory52000]

sure looks backwards to me but i have never been in that particular carb and yes the main should be bigger than the pilot. is it possible to swap them? i dont know i have never tried or made the comparison but that would explain why you cant get the "Pilot" out. the little owners manual will not help you here. it appears the old owner got ripped off by a shady mechanic. there is no telling what else he did wrong. that jet in the pilot spot is ruined it will never work right. my advice is to order the carb kit and the clymer and spend a saturday learning the inner working of your carb. you are probably only going to have one shot at that pilot jet i would pull the float, snap a small good set of visegrips on there and find a screw driver that fits as best as possible. clamp the carb in a soft jawed vise and have a friend turn the vise grips while you turn the screwdriver use as much down pressure on the screw driver as humanly possible. good luck. i am headed out hunting for a few days but i will try to check in when possible but i might not be able to get right back.

 

[Cub10]

Dang. Would it be possible to keep that #94 jet in that spot and just buy a bigger main jet to replace the #60 jet? That way I can order a bigger main jet from a local dealer. If so, what size would be good to run with #94 pilot jet? That way I don't have to chance breaking the pilot jet head off. I was trying to get this quad up and running properly before my hunt in 4 weeks.

 

[cory52000]

no that jet is shot either way it will never work right. if you do like i said it should come out if not the carb might be ruined it might be possible to drill that out as well but if you are not experienced in such thing it might pay to take it to a machine shop.

 

[Garrettb]

I have the exact same problem except I just put in a brand new carb, I think that the jet size is incorrect, I can’t really figure out what is the correct size. When the bike gets hot, sometimes gas pours out of the bottom of the carb because the float gets stuck and let’s the gas out. I am currently trying to find a mikuni or oem carb for it, they will be much more expensive but should solve the problem. I got a new air filter, I replaced the carb connection to the motor and I have a new spark plug coming in the mail. I don’t think the spark plug will solve the problem but it’s a shot in the dark at this point. I’ve asked a small motor mechanic and he said to get a mikuni carb but they are expensive and I can’t even find the right one for the bike.