Hey all DRZ250 owners thinking of getting a 300 kit.
I've *nearly* finished sorting my jetting out (after alot of waiting for jets to turn up in the post and a few rides with a terribly tuned bike)
my specs:
02 drz 250
300cc wiseco 11.5:1 and LA sleeve
removed snorkel and opened up air box
ground down header welds
opened up tail pipe on stock exhaust.
14:44 gearing
TM33p carb upgrade.
So with the above set up the jetting i am running is a 30 PJ, but i am waiting for the next 2 sizes smaller to arrive in mail so i can get a bit better off-idle responce. (yes thats right with a bigbore kit your pilot has to go ALOT smaller) I have just gone up to a 132.5MJ and riding on street today seemed quite good, but i will do a WOT check on way home from work today to see if i should go richer.
but for anyone else doing it these are good ball park figures or maybe do as i am about to do and go PJ 27.5 and MJ 135
Oh yeah the power is f%^&n brilliant!!!!!!!! I'm concidering going taller with my gearing because it pulls so well from idle.
300 Big Bore installed on DRZ 250
Started by
poppy
, Mar 15 2008 04:55 AM
23 replies to this topic
Posted 06 August 2008 - 11:16 AM
That is correct. With a number of 2 stroke and 4 stoke big bore kits I've worked on they have all ended up being jetted leaner than stock bore jetting. I know that sounds strange but it is true. Particularly so with the main jet. On a DRZ125/190 conversion I did I thought the top end was prtty good until I experimented with jetting it down a couple of sizes and then it was MUCH freeer reving and more power. It wasn't bogging down before but just not revving freely as it dod with the leaner jetting.
ALWAYS when you go leaner with the jetting check plug after a decent run just to be sure you are not running too lean!! Also try going back one richer until you note a drop off in performance.
ALWAYS when you go leaner with the jetting check plug after a decent run just to be sure you are not running too lean!! Also try going back one richer until you note a drop off in performance.
Posted 24 August 2009 - 12:22 PM
I finally got through all of the cluster****ery surrounding my big bore, and got it on. It worked decently with the stock carb, but you could tell it was lean riding it around (Thumper Racing, after asking me what carb I had and hearing that I had the CA CV carb, naturally sent me jets for a different carb). As I had found a good deal on the TM33 pumper, I just swapped the carb instead of trying to sort the jetting on the CV.
The carb swapped over very nicely. I did have to wiggle it a bit to get it in the boots, but it went in without drama. The throttle cables were too tight, as has been mentioned in this thread. I just Dremeled off a bit of the bracket, as it is solid and beefy; with that done, the pull and return cables fit fine and work fine.
I left the PJ with what was in there (I didn't note it, but it idles dandily); I put in the 132.5 MJ proactively, as I had seen this post, but it surges rather a lot at mid-throttle.
There's a fellow here in NorCal who does carb tuning and did miracles for my CRF150R race bike; I might just throw this puppy at him, as that's a pumper as well.
The carb swapped over very nicely. I did have to wiggle it a bit to get it in the boots, but it went in without drama. The throttle cables were too tight, as has been mentioned in this thread. I just Dremeled off a bit of the bracket, as it is solid and beefy; with that done, the pull and return cables fit fine and work fine.
I left the PJ with what was in there (I didn't note it, but it idles dandily); I put in the 132.5 MJ proactively, as I had seen this post, but it surges rather a lot at mid-throttle.
There's a fellow here in NorCal who does carb tuning and did miracles for my CRF150R race bike; I might just throw this puppy at him, as that's a pumper as well.
Posted 28 June 2012 - 11:32 PM
Just wondering if the TM33 pumper can utilize the existing throttle cable as the BSR 32 CV carb uses on the DRZ 250/Djebel 250XC?
