1987 XL250R Carbs

Hi, New to this forum.

I purchased a 1987 xl250r a year and a half ago and here and there i do a bit of work to it. Yesterday while washing it i noticed that the throttle link going to my second carb was not connected to the second carb so anyhow i connected it temporarily and then i noticed that this bike has more potential than i thought (the carb was disconnected from the day i bought it) having a parts bike i decided to change the linkage and took the time to clean the carbs. so now that you know my story :confused: here's my questions.

1 - the primary carb has a 105 pilot jet and the second carb has a 108 pilot jet. Are those jet sizes original size?

2 - the bike has a cobra exhaust should i use the jets mentioned in my first question?

3 - now from the very little info i found on the net i seen that the second carb opens after the primary carb. is there a precise way to adjust that? (i saw on a xr forum that the second carb should open as late as possible and still reach the fully open position at WOT...does that apply to my xl?)

4 - what would the symptoms be if the second carb does not open at the right time? before i noticed that the 2nd carb was not working the bike would bog at WOT and max speed was about 105km/h.

Thanks and great forum by the way i have used it alot in the past (as a guest) and it helped me alot.:thumbsup:

I can't help you with the jetting, but I was wondering how much of a job it is to remove the carbs? My wife has an 86 xl250r that seems difficult to start at times. I'm really dreading pulling the carbs off.

stock would be 102/105. Someone has upped the jets.

Did you open the airbox up? remove the snorkle under the seat and add a few holes to the top. You can do the same on the lid to access the filter.

I run a 105/110 with just the airbox mods. I am installing an XR headpipe and muffler here on it. Probably go 110/115 on it.

There is not a lot of adjustment on the secondary carb if any beyond the jet. As long as it opens to WOT with the primary you are fine.

@ jonboat

here's what I did.(some ppl don't remove the airbox you can unscrew the intake manifold from the head and follow the steps below skipping the airbox removal)

- I took off the seat

- removed the gas tank

- removed the 2 side plastics

- removed the battery (you just have to remove it from the airbox casing. you can leave the battery wired)

- removed the 3 bolts for the airbox holding on the bike frame

- unscrewed the boot clamps of the airbox side of the carbs

- removed the airbox from the left side of the bike

- removed the choke cable off the carbs

- removed the 2 throttle cables from the carb

- unscrew the clamps on the intake manifold

- removed the carbs on the right side

all of the above removal will let you inspect all of the removed parts.

took me about 20 to 30 min

good luck.

Edited by Freaky Beanie

@ JJRace

I'm not looking for more performance. i have a modfied airbox full of holes that i swapped with an original one from my parts bike because it was also full of mud :thumbsup:

i have a wide range of ajustment as i have no problem getting the second carb to fully open at wot. i can get the carb to open later but i have to bend parts and i find that a bit odd.

I didnt say anything about more performance. Just stating you may need to change your jet sizes.

I didnt say anything about more performance. Just stating you may need to change your jet sizes.

yeah thanks i got that part :thumbsup: i ordered from 108 to 112 jet sizes. i will do plug tests before swapping jet sizes.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now