Jet question

[hondaREX]

Does anyone know if 2 stroke pilot jets will work in the 450r carb? A 2 stroke pilot is approx. 4mm longer than the 450r one. Same numbering and they look to be the same from the flat head end to the tip as the stock one. Im not sure if the jet being further down into the bowl will work. Ive got the 2 stroke jets sitting around and dont want to wait to get others later this week. I want to test the carb tomorrow. The 450r carb came with a 50 pilot and im only running an open airbox with K&N w/outerwear and ground header welds. Thanks.

[hondaREX]

Did a little research on jetsrus. The pilot that was in the 450r carb is a size 50 with no brand stamp. Looking at jetsrus, there is none with no brand stamp. Also, when searching for 450r jets it states they are 28mm length. But the one supplied with my carb is a 23.5mm length!?!?!? The 2 stroke pilots i have are 28mm!!! So im very confused now. Can anyone measure a pilot they might have lying around that you pulled from a running 450r? I have what i need if the longer ones are correct as jetsrus states. Any help is appreciated

[Stickman400]

I think a member on here used the longer series pilot jets in their 450 carb. swap and it worked. Might want to wait until they or someone else comments.

[CJM]

I used the longer ones, perfectly fine.

[hondaREX]

Just the guy we all like to hear from!! What pilot you think I should be at CJM? Open airbox with K&N and ground header welds @ sea level. Maybe a main suggestion too. I'm thinking around a 160 main. And a 45 pilot.

[CJM]

Start at a 165 main and check the plug. Id keep the stock 48 main for the carb and try that.

[hondaREX]

Thanks man. I actually didnt have a 48 but dug one out of an old 250r stock Keihin i had hidden away. Didnt get to try it today. Hope to sometime this week or weekend. Sorry last question. Should i keep the needle at the stock 3rd position?

[CJM]

yea try 3rd pos on the needle, mines on 4tyh but I got alot more done than you do to the engine.

[hondaREX]

Well just came in from a lil test and tune, dont really have much room till saturday but i did some runs and this is where im at. Started up great, idles great, nice and smooth. Im at about 2 turns out on the mixture screw. Pilot is 48 like suggested. It runs smooth when under steady throttle. There is no surging, no pops or spitting, or backfiring so i think the pilot jet is good. But when hitting the throttle coming out of corners it stumbles a little bit. Not sure where i am in the throttle range, basically just stabbing it, maybe up to 1/2 but this is just in my yard so im unable to really get on it without creating yardwork!! As for the main, i was unable to do any real good 3rd gear WOT, best was 2nd and it didnt stumble, but again not really the best place but still i get WOT. And last, didnt get to check the plug as my new ones wont be in until the end of the week.

My questions are do you think i need to change the needle position to make the midrange respond better? And should i go up on the main until it starts to stumble at WOT then go back down until the stumble is gone? Hate to up it to find out i was good at 165 but want to get best performance. Should i be stumbling in my yard in any gear at WOT or should i worry more about 2nd or 3rd? Thanks again.

[CJM]

Drop the needle down to the 4th position.

[hondaREX]

Youre the man. Thats what i was thinking. Any thoughts on WOT in my yard. I want to up the main and run it in my yard before i get out and really test it saturday. Is 2nd WOT even a true test? I will be plug checking a new plug saturday and just want a "feel" in my yard. 1st and 2nd i can hold WOT in my yard with no stumble. Or just stay where i am with the main and wait for a plug reading when i can get into 3rd?

[CJM]

I think the main will be fine, if not a little rich.

I run a 168 main in mine and im slightly rich.

[hondaREX]

So how much does the pilot circuit affect throttle response? I'm still stumbling or hesitating coming out of corners. When I roll into a corner in 2nd or 3rd, and hit it to say pull a wheelie out of the corner, it falls on its face. Then comes back alive. But if I throttle into a corner, and hit it it isn't as bad. Does the pilot circuit have anything do with this? Thought the pilot was mostly start up and idle. Any help?

[CJM]

The pilot effects start up to about 1/4 throttle, the needle from 1/4 to about half or so and the main is the rest.

If your getting a stumble it could be slightly too rich or you might need to adjust the needle to the 4th notch.

[hondaREX]

Sorry forgot to mention I did change the clip position. 4th position is 4 down from top of needle right? So drop the pilot down a size would lean the pilot circuit? I need to get out tomorrow and get some actual runs in so then I can get a better feel.

[CJM]

Top of the needle is the flat part, bottom is the pointy end.

Id agree, you need to actually run it and see.

[TheAwesomehonda]

Originally posted by hondaREX
So how much does the pilot circuit affect throttle response? I'm still stumbling or hesitating coming out of corners. When I roll into a corner in 2nd or 3rd, and hit it to say pull a wheelie out of the corner, it falls on its face. Then comes back alive. But if I throttle into a corner, and hit it it isn't as bad. Does the pilot circuit have anything do with this? Thought the pilot was mostly start up and idle. Any help? Not to discurage you or anything but i had the same problem with my 450r carb when i was running one.. I could never get it to run quite right so i ended up selling it(to a member of this forum) and going back to the stock carb. I'm still wanting an aftermarket carb but i'm not sure what one i should get that isn't really expensive.

[CJM]

Originally posted by TheAwesomehonda
Not to discurage you or anything but i had the same problem with my 450r carb when i was running one.. I could never get it to run quite right so i ended up selling it(to a member of this forum) and going back to the stock carb. I'm still wanting an aftermarket carb but i'm not sure what one i should get that isn't really expensive.

FWIW I think you sold it to a friend of mine in NJ and when I put it on we had no trouble from it.

You capped off the hotstart with a bolt right?

[TheAwesomehonda]

Originally posted by CJM
FWIW I think you sold it to a friend of mine in NJ and when I put it on we had no trouble from it.

You capped off the hotstart with a bolt right? Yeah that is correct. How did that thing work anyways?? I just couldn't get it to stop bogging.

[CJM]

Put a 180 main in there and a 52 pilot and 4th notch. Turns out we were way rich cause he thought it was a 440 but in reality found out it was stock. Bored it to a 416 and put the right jet in and bingo no problem.

I cant recall but I also think I told him to buy the hotstart parts and plug the rest with rtv.

Alot of problems with these carbs is improperly setting them up. Im not saying you have to, but every one I have touched has ran fine once we got the jetting right. All of them used the ZR adapter, moved vent line, and hotstart parts with rtv.

[hondaREX]

I didn't take apart the hotstart to verify the internals but all other mods look good. I'm going to run it tomorrow and see what it does. Probably bring a few jets to try different setups. Will lowering the pilot lean the circuit?

[TheAwesomehonda]

Originally posted by CJM
Put a 180 main in there and a 52 pilot and 4th notch. Turns out we were way rich cause he thought it was a 440 but in reality found out it was stock. Bored it to a 416 and put the right jet in and bingo no problem.

I cant recall but I also think I told him to buy the hotstart parts and plug the rest with rtv.

Alot of problems with these carbs is improperly setting them up. Im not saying you have to, but every one I have touched has ran fine once we got the jetting right. All of them used the ZR adapter, moved vent line, and hotstart parts with rtv. Well i'm glad it worked for him but it pissed me off that i couldn't get it to run good or even fit well..... I'm thinking of trying a 39mm fcr but there like 600 bucks :eek2:

[CJM]

Originally posted by TheAwesomehonda
Well i'm glad it worked for him but it pissed me off that i couldn't get it to run good or even fit well..... I'm thinking of trying a 39mm fcr but there like 600 bucks :eek2:

Id sooner just send the stock carb to someone who can bore it. They do a good job and its like 150.

[hondaREX]

I didnt get to go riding today. So i did a few runs in my yard to give the jetting another try. I started with the 48 pilot at 2 turns out and began turning it out 1/4 at a time to see if richen it got it to respond better. It started to feel as if it was getting better and losing the spit or hesitation it had. So i decided to go up on the pilot because i was 2.75-3 turns out. So i threw a 50 at it, started at 1 turn out. It was popping when lettng off the throttle so i went up until that went away but the hesitation didnt get better like i was feeling with the 48 at 3 turns out.

So as jetsrus FAQs say: Lean symptoms - if the bike surges, carb spits when throttle is opened, exhaust backfires or pops when throttle is closed, or the engine has trouble idling down, engine needs a larger pilot or slow jet to correct. If the engine idles rough, fouls plugs, or is hard to start, pilot is to big, or rich.

I had none of the above rich conditions at 48 so i went up to 50. With the 50, it seems im the same as the 48. Idles great, plug looks great. Light brown in color. Starts great. Only symptoms that im feeling are the carb spits when the throttle is opened and pops when throttle is closed (which went away at about 2 turns out, 50 pilot), so it sounds like im lean correct? Im at 50 pilot with 2 turns out and no better yet.

Any suggestions? Again, i didnt tear the hotstart apart and clean it, i have no idea why i didnt. But i cleaned the rest of the carb thoroughly. Am i on the right path that it was lean at 48 and potentially still at 50 with 2 turns or am i going in the complete wrong direction?

[hondaREX]

I was able to clean the carb again yesterday, this time i cleaned EVERYTHING and checked all the mods.....well thats what i should have done from the beginning and i know what ill hear next.

I found the accelerator pump to be clogged in one of the ports. Hotstart was perfect. And all else checked out good. Put it all back together, warmed it up, and all the snap and response is there!!! And very noticeable, even on my setup!!!

I was getting kinda PO'ed that everyone abandoned my questions but i know now that it gets old telling members over and over what to do step by step. I know better than to half a@# clean an unknown carb. My assumption that it "came out of a running bike" was exactly that!!! Not the sellers fault, i should have just done what was supposed to be done and clean it. So thanks to all of you that did try to direct me.