I just bought an 89 honda 250r this is the first two stoke I've owned so I don't know a whole lot about them.The guy I bought it off of said it had been bored .30 over last spring other than a K&N and jetted it's stock.First off it has a hesataion right off the bottom end once you get on pipe it's all right, ohh forgot to mention it has an Lrd pipe and silencer too. I think it's jetted wrong it has a 145 main in it.Another thing is I do alot of tight woods and alot of hillclimbing so I want alot of bottom end what sprokets,jets,pipe,reeds, stuff like that do I need to really wake it up.Also what do you guys mix your oil at I've been running a klotz synthetic blend at 32:1 and it runs pretty good is that to thick or do I need to go to 40:1. any help would be appreciated

 

1st- The hestitaion could be from wrong carb. settings.
2nd- A 145?!?! that sounds really small to me unless The tempature is always above 100 there. TAke the plug out and see what color the round part in the middle is. If its a whitish/tanish color it is lean (not good) if it is a really dark brown or black it is rich (thats ok but your just sacrafising power) If the plug is a paper bag brown color or a little bit darker that is perfect. If the plug shows that it is lean then your main jet needs to go up. If the plug shows that it is rich it needs to come down, but im pritty sure you wont be rich with that main jet.
3rd- If your front sproket has 13 teeth on it then leave it alone, but if it has 14 or 15 then you could drop it dwon to a 13 for more bottom end,.
4th- Boyseen reeds have good bottom end.
5th- Yes keep mixing at 32:1 for you (because you ride trial)

 

If you are looking for more lowend power get an ESR trx6 pipe.

 

the plug is black also if you leave it set it with the gas on it will run all the fuel out of overflow ,float set to low?second I heard that the lrd pipes are adjustable if so are all of them and how do you do it.what jet do you think it should have in it.Also would a 12 tooth sprocket be even better don't care about top speed.

 

I just dont understand how a 250Rs plug could be black with a 145 main...... And i have ALOT of jetting experience. And no when the gas comes out of the over flow tube its not because the float is to low. Its because the float valve is worn out most of the time. I really canty help you with LRD's adjustable pipe (yes they are adjustable) because i have no experience with them. When I had just a pipe and filter My main was 152-158. (it depends on humidity and tampature along with altatude) Yes you can buy a 12 thooth sproket for the front if your really not concered about top speed, BUT when your chain gets moving and parts get moving really fast and harder than before its going to stress sertain parts with i wouldnt recomend. You could get a 42 tooth back sproket and that would be equal to 1 tooth in the front. so 13/42 would be the same as 12/38

Ok back to jetting. Dose your bike spudder? Or dose it ping? or backfire? If none of these then you need to do a plug chop and find out what color your plug really is. to do a plug chop you put it in gear then you start going and then you hold the throttle to the bar for about 10-12 seconds. It must be at least this long to do a proper reading. dont worry about blewing it up. trust me iv done this about 60 times and never had a problem. Then you keep the throttle open and turn the biek off WITH THE CLUTCH PULLED IN. You may take you hand off the gas to shut it off but then put it right back on and coast to a stop. THen look at the color of the plug.

 

It's more likely the float needle and or seat. When the float rises it pushes against the needle, onto the seat. My old bike would do this and I would shake the whole bike and it would stop, but after awhile that didn't work anymore. I just bought a new, bigger carb.

 

clean the carb.

 

The float valve seat is not replaceable on the stock carb, so when it wears out you need a new carb.

It will definitly be worth the money, it will make tuning much easier. Also if you want to keep your lowend power don't go too big on the carb, stock is 34mm don't go bigger than 36mm.

 

Just for the heck of it I searched through my original owners manual from my 89 250R and it states that a 155 main jet, 3rd groove on the needle and air screw 1-1\2 turns out is what it supposed to be in complete stock form. From my experience each modification (most of them) requires an additional single step up on the main jet. You can use the stock settings to figure a baseline of where you should be, and then figure accordingly for your specific mods.

By the way, all these stock specs are for altitude of 0-5000 ft and temp of 22-104 degrees F.

 

fourtrax650ex- right now if i were you I would just try going up on the main and if it gets richer then go back down. The only other thing I can think of is that you have an air blockage somwhere. Weather the filter is cloged up or carb is cloged up or soemthin because then with less air you would have to go down on the main. If you got he money get a 36mm a/s carb. It also makes the bike run sooo much smoother.