[2003crf450r]

Hey everyone I need some help getting my bike running right if anyone can help me it would be greatly appreciated. My problem is I installed a boyesen quickshot 3 on my 03 Crf450r and when I took it for a ride the bike sounded weird in idle and running in general and it didn’t want to stay running I had to keep chopping the throttle and revving it up to stay running and it would keep dying but started right back up. I have spent around 8k on the bike since and havnt even tried riding it since and last night I took the subframe off to replace the rear shock spring and I noticed that when I give the bike gas there was no fuel squirt coming from the accelerator pump. It did make a slight noise I think like air was coming out it could be from something else and or I didn’t hear anything haha but I didn’t know if that might tell something. One thing I regret doing is not replacing the diaphragm o ring and d ring I used the ones already in my carb. I’m prettt sure I installed it right but the directions say to replace if it’s more than a year old and for all I know it could be the original one or it could be fairly new. I just don’t know what to do I’m not sure what would cause no fuel squirt. Like I said any help at all would be greatly appreciated.

Thank you

[JimDirt]

Hopefully Leardriver will chime in soon , he is the resident carb guru ....... but to somewhat help the QS3 has the adjustable leak jet , and if it is not set right , it will give issues including fuel pump squirt , so that may be part of your issue , you also mentioned not being sure on the installation of the pump diaphragm , and that might also cause no or minimal squirt , so there is that ....... sitting for a long time .... If I am understanding correctly , you let the bike sit for a log period (not sure if you mean weeks or months) , if the gas was left in it , chances are the pilot jet is clogged , which also could cause the running issues you described , I personally was never a fan of the QS3 , I do like the QS2 , which does not have the adjustable leak jet , I remember a buddy putting a QS3 on his 11 KTM 450SX , and we fought with that thing for a week , trying to get it set where it was happy when you changed elevations , and it was always a bear to start till we figured out how to set it correctly ...

So while we are waiting for Leardriver to show up and hopefully save the day ..... try going over what I listed and see if you find anything ..... you did not say if you have a manual or not .... if not , I have a Factory Service Manual for it (I have a 02 and the Honda Service Manual is for 02-03) so I can post images of any section you need , just ask ....

[2003crf450r]

Hey thank you for the reply. I only ride supermoto on the streets with this crf and I just got it in March as a dirt bike so I did all this stuff to it over the corona virus lockdown here in mass. To clarify it wasn’t sitting at all I did a big gun rev box, the qs3, and the power x wing and went to take it out for a ride and that’s when it wasn’t running right so I assumed it was the qs3 because of the no squirt. It was such a pain in the rear with the carb getting the float bowl off and stripping half the screws I didn’t want to do it again but I got it off now and I think what I did was put the diaphragm on upside down which is what I thought I did. Would this cause no squirt? And the bike wanting to die unless I keep revving it and only ran in the high rpms? It had a different sound to it to too? I got it all apart right now and I’m going to flip the diaphragm around and see if it was that simple I hope so.

[JimDirt]

OK , well you are good on some of the stuff I mentioned then ..... as far as the diaphragm , yes , and also if you put the spring on the wrong side , ......The correct setup for the diaphragm is like shown below , the diaphragm has the lip on one side to retain the spring , that goes to the spring side facing the cover


And you also should double check the adjustment on the adjustable leak jet screw ...... Also , if you want to get at the bottom , just loosen the clamps (f/r) on the carb and twist it so the bowl faces the shifter , it will go about 45 degrees , otherwise , to get to the AP , you need to remove it completely .... And the best thing to do on the bowl screws is to replace them with Allen heads ... no more stripping the screws https://www.crfsonly.com/catalog/produc ... ts_id/4498

[2003crf450r]

Yea I replaced them with Allen head screws already after the first time but my hands are too big to get in there so it’s a real pain in the rear. I did what it said to on the instructions my leak jet was a 55 so it called for 1 1/4 turn. The diaphragm on mine looked the same on both sides pretty much except the little thing that sticks out I figured that thing should be pointing up and it looks like it should be facing the pump cover not the carb but there is a ring that holds the spring on both sides but letters/numbers on one side and one ring is a complete circle and the other side has breaks in it but also holds the spring I must have flipped it and not payed attention because the directions looked like the side of the diaphragm that I had it on but I guess they made a diaphragm upgrade that doesn’t have such a big thing sticking out so it looks the same as the pictures on the instructions. I’m just about done getting carb back on I’m praying that’s what it is because I’ve just been working on this thing for 3 months pouring money into it and have only ridden it a couple miles I have almost everything on it brand new.

[2003crf450r]

Wow that was it.... I had the diaphragm on upside down. I’m that guy I can build a motor from top to bottom but can’t put a diaphragm in the right way. I really appreciate your advice and help thank you so much.

[JimDirt]

No problem , but you figured it out ....so you deserve the credit

[Leardriver]

It is a glorious moment when we find the problem, fix it, and the bike runs afterwards. Very rewarding.

I would open up the fuel screw to at least 1.75 turns out, regardless of accel pump hardware, because the fuel screw affects idle, even when you are not twisting the throttle and calling for an accel pump squirt to smooth out the lean surge as you come off of the pilot and on to the needle circuit. How's that for a run-on sentence.