FXR150 starting problems

[gijoe1313]

Righto, working on the bike with Donor, found fuel in airbox (lots ... 100 -150mls worth!) .. Sprag sez "should there be fuel in there and can I light it?"

So ... why the hell is fuel spitting back from the carb into the airbox ... and discovered also that fuel was also in the vacuum tube. This could be due to it sucking it back from the carb.

Any ideas people?

[gijoe1313]

Addendum : we have sorted out the airbox, on full choke will idle up to 5000rpm, using no choke and throttle cuts out around 2000rpm ... odd and odd!

[xwhatsit]

Some bikes have a situation where when the carb overflows, the fuel can run into the airbox. Wouldn't have thought it'd work like that on a sloped single like an FXR, but who knows. Check the float valve isn't dirty and causing overflow. Or the float isn't sticking or something.

Some people talk about checking inlet valve clearances if the carb spits back, but I can't see how that'd work, personally. I am an idiot though. And that much fuel due to spitting back? Seems odd.

First thing I'd do is replace the sparkplug. You never know :laugh:

EDIT: It was running right on the way to your house, Justin? Young Scorpio-killer wasn't red-lining it the whole way home and bent a valve or summat?

[EJK]

I read FXRs can fit GN250 carbs?

FXR carb: 28mm
GN250 carb: 33mm

Edit: What about the spark Justin? would that ignite the 100-150ml fuel? lol

[deanohit]

FXR carb: 28mm
GN250 carb: 33mm

If it fits on, there should be a slight increase in power with the extra fuel the GN carb should be pumping.:scooter:

[T.W.R]

Check your inlet valve clearance :niceone:

[EJK]

Justin is now saying its fixed??? :crazy:

[xwhatsit]

Check your inlet valve clearance :niceone:

Yeah, I keep hearing that, why?

Unless I've got the Otto cycle completely screwed up, how is the charge going to be forced backwards, unless the clearances are so ridiculously tight that the machine wouldn't run at all when even slightly warm?

Considering the machine was running before as well.

These things do my head in lol. Confusing.

[deanohit]

Justin is now saying its fixed??? :crazy:

Ummm, not quite. :argh:

[xwhatsit]

Oh yes, I was reading a thread where the bucket racers fitted GN250 carbs to ye olde FXR -- but even better, XL250 carbs (same as CB250RS).

I've got two spare CB250RS carbs, if you want to go really fast, fit one of them. 33mm round-slide (none of this GN250 CV shit), accelerator pumper. The thing would have some snap :devil2:

[EJK]

Give em to me! :devil2: lol jks

Yep, the bike is now all fixed (According to words from Justin and Donor). He is now putting all the pieces and bits together. I'll go and pick it up later :D

I'll have a BBQ one day inviting all of you guys :yes:

[deanohit]

I'll have a BBQ one day inviting all of you guys :yes:
Time and place man! :yes:

[T.W.R]

Yeah, I keep hearing that, why?

Unless I've got the Otto cycle completely screwed up, how is the charge going to be forced backwards, unless the clearances are so ridiculously tight that the machine wouldn't run at all when even slightly warm?

Considering the machine was running before as well.

These things do my head in lol. Confusing.

Vacuum pressurization

[Ragingrob]

Pics!!!

10char

[babyblade250rr]

Good new all fixed! let me know when you wanna pick it up E.J but be quick before i fall asleep!!

[gijoe1313]

It was none of the above!

Turns out it was a loose metal clamp on the seal between the carb and the engine. Donor accidentally ripped the carb off the engine ... swearing it was an accident and then he pushed it back onto the engine.

It started working and revved like a 150 should do! :whistle: Then we set about bunging all the bits on and it suddenly developed the ol'problem of cutting out again... :gob: Say what!?

Then a collective light bulb went on above our heads :rolleyes:

Donor retightened the loose metal clamp on the seal back to spec.

Job sorted.

Thrashed the nuts and tits off it around the 'hood.

Invoice for weekend rates and parts used and consumables in mail. :devil2:

[Ragingrob]

Wahoo! Sounds like EJ's gonna rip up on Sat :2thumbsup

[EJK]

Knee down time! :D

[skidMark]

Knee down time! :D


Congrats on the new toy, but remember what happened the last time ya got knee down?

Oh and when it comes time to change tyres put some pirelli MT75's on her.

ride safe bro

SM

[EJK]

I was thinkin Bridgestone BT-39s?

[Rosie]

I was thinkin Bridgestone BT-39s?

Do they come in the right sizes? When I got new tyres for the KR, the only matching sets I could find were MT75s and the dodgy stock IRCs.

[EJK]

I heard bucket FXR bikes uses BT-39's... Or do they have different rims? :crazy:

[motorbyclist]

S
Some people talk about checking inlet valve clearances if the carb spits back, but I can't see how that'd work, personally. I am an idiot though. And that much fuel due to spitting back? Seems odd.


when i first rebuilt my olsd xr200 i buggered up the timing somewhat ansd fuel was squirting back into the airbox when the choke was on. the inlet wasn't closed when the piston was compressing and so it squirted backwards through the airhole under the choke

funny thing was, it DID run, WITHOUT damage, just is was the roughest sounding thing you'll ever hear.... moved the cam sprocket over a tooth and she was good again


Knee down time! :D

lol good luck! i've been thrashing my one for two months now and still nowhere near a knee down:laugh: