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-   -   87 gsxr stops running @ high speeds (http://www.motorcycle.com/forum/showthread.php?t=7290)

longride 02-22-2008 06:46 AM

Quote:

Originally Posted by pplassm (Post 179271)
My bike had K&N pods, and a slip on muffler (I do not remember the make). I believe the needles in the carbs were shimmed up a bit, and larger main jets fitted.

If the vent hole in your tank is rusty, you really should drain the tank and see how badly rusted the inside of the tank is. If rust particles are getting to your carburetors, that will really screw things up, too.

Good luck!

I'd say there are so many things that could have screwed things up, it would be difficult to list them all. Getting the bike to some guy with experience will probably solve the problem faster than anything.

Mike18212 02-23-2008 04:25 PM

Quote:

Originally Posted by pplassm (Post 179271)
My bike had K&N pods, and a slip on muffler (I do not remember the make). I believe the needles in the carbs were shimmed up a bit, and larger main jets fitted.

If the vent hole in your tank is rusty, you really should drain the tank and see how badly rusted the inside of the tank is. If rust particles are getting to your carburetors, that will really screw things up, too.

Good luck!

Yeah, when i bought the bike i had the tank cleaned out so it shouldn't be too bad. But to be sure we put a fuel filter on the gas line. My first thought when this issue began was that the fuel filter had become clogged but it seems to be perefectly clear and when i set it on prime i can see that fuel is flowing. I'll probably change it anyway though.

Mike18212 02-25-2008 09:50 PM

Quote:

Originally Posted by sarnali2 (Post 179125)
Another possibility since the carbs were serviced 800 miles ago is the float height, if that's not correct you could just be running out of fuel at that speed...


so i called my mechanic and he immediately said this was most likely the problem. SO my new question is, has anyone done this before? i downloaded a manual today about but i was wondering if anyone had some tips. Do i need special tools? And i was wondering what the right float level would be since i have pods. Or should i re-install an airbox and just refer to factory settings? I'd prefer not to have to buy an airbox.

seruzawa 02-26-2008 06:03 AM

Quote:

Originally Posted by Mike18212 (Post 179456)
so i called my mechanic and he immediately said this was most likely the problem. SO my new question is, has anyone done this before? i downloaded a manual today about but i was wondering if anyone had some tips. Do i need special tools? And i was wondering what the right float level would be since i have pods. Or should i re-install an airbox and just refer to factory settings? I'd prefer not to have to buy an airbox.

I've done carbs on various I-4 and the worst part is generally removing and installing the bank of carbs. Some have room enough but many bikes are a cast iron bytch. Once the carb assembly is out doing the maintenance is a breeze. Getting them back in can be a special "treat".

It just takes some patience and perseverance.

Mike18212 03-10-2008 08:57 PM

Quote:

Originally Posted by seruzawa (Post 179459)
I've done carbs on various I-4 and the worst part is generally removing and installing the bank of carbs. Some have room enough but many bikes are a cast iron bytch. Once the carb assembly is out doing the maintenance is a breeze. Getting them back in can be a special "treat".

It just takes some patience and perseverance.



ok, so i took the carb assembly off, removed the lower housing of the carbs to gain access to the floaters. i measured their height to the best of my ability and they seem to be just a tiny bit off. maybe 2mm or so. anyway i was mainly wondering if [1] the carb adjustment would be different since the bike has pods rather than an air box? or should the carb floats be bent to the standard measurement they're supposed to have? [2] what is the proper method of bending them? my manual just says "bend the float arm" but in the exploded view, no part is listed as "float arm". hey as always, any insight is appreciated.

The_AirHawk 03-10-2008 10:56 PM

Quote:

Originally Posted by Mike18212 (Post 180325)
ok, so i took the carb assembly off, removed the lower housing of the carbs to gain access to the floaters. i measured their height to the best of my ability and they seem to be just a tiny bit off. maybe 2mm or so. anyway i was mainly wondering if [1] the carb adjustment would be different since the bike has pods rather than an air box? or should the carb floats be bent to the standard measurement they're supposed to have? [2] what is the proper method of bending them? my manual just says "bend the float arm" but in the exploded view, no part is listed as "float arm". hey as always, any insight is appreciated.

Carbs need to be off the bike, and held so the float-arm is vertical to get an accurate measure. Slowly tilt the carb until the float closes the valve. The point when the needle "just" seats is the spec. It also depends on what the mfgr. sez as to exactly where you measure on the float. (but it's usually at the "apex" of the float)

The best tool I've ever used for float-height measuring is a tire-tread depth guage - they're usually graded in inches as well as mm.

If the carbs have been rejetted, the spec-height might be different, but 2mm is a crapload of difference, and likely wrong. Especially if that measurement is lower (i.e. higher numbered measurement) than stock.

seruzawa 03-11-2008 05:58 AM

Oh Lordy.
 
Quote:

Originally Posted by The_AirHawk (Post 180328)
Carbs need to be off the bike, and held so the float-arm is vertical to get an accurate measure. Slowly tilt the carb until the float closes the valve. The point when the needle "just" seats is the spec. It also depends on what the mfgr. sez as to exactly where you measure on the float. (but it's usually at the "apex" of the float)

The best tool I've ever used for float-height measuring is a tire-tread depth guage - they're usually graded in inches as well as mm.

If the carbs have been rejetted, the spec-height might be different, but 2mm is a crapload of difference, and likely wrong. Especially if that measurement is lower (i.e. higher numbered measurement) than stock.

Pod filters. When will people learn?

The_AirHawk 03-11-2008 06:44 AM

Quote:

Originally Posted by seruzawa (Post 180329)
Pod filters. When will people learn?

I thought they were on the bike when he got 'em? Just coping with what he's got.

And I just realized; I didn't answer his "float arm" question, exactly.

You see the floats, right? The "float arm" is that stamped-brass piece the floats are attached-to, that has the pin in one end, that the needle attaches-to with a small clip. If there are two floats attached to one arm (in a "Y" or "U" shape), you don't want to bend the arm - rather, you should gently tweak the tang that the needle attaches-to with a needlenose pliers. (DON'T distort it - it won't take much tweaking here to move the floats a relatively-large distance!)

Avoid putting pressure on the needle-valve when bending the arm.

The reason you tweak in one point on dual floats is, if you bend one float more than the other, it can bind-up and cause some of the same problems you're experiencing right now. If it's just one float and arm, be certain to bend the arm parallel with the float-travel - bent off to the side slightly, it might rub and bind against the bowl or the jets that protrude into the float chamber.

And again - keep carb cleaner off rubbery-bits, especially the diaphragms. It causes 'em to swell and stretch, making your work all that much harder when you re-assemble everything.

sarnali2 03-11-2008 09:09 AM

I would say the float height would be the same no matter what filter you had on there, it's two seperate circuits in the carb. I think at this point you need to find a good tuner and start at ground zero with the carb settings, you're basically chasing a rabbit down a hole here. Start with the basics like float height then idle mixture, then needle settings, then pilot, then main jets. each circuit overlaps to some extent so you or your tuner needs to be methodical, start at the basic settings and work up from there. tweaking and fiddle-f*cking around without a clear course isn't going to get you anywhere.

Mike18212 03-11-2008 01:33 PM

Quote:

Originally Posted by The_AirHawk (Post 180328)
Carbs need to be off the bike, and held so the float-arm is vertical to get an accurate measure. Slowly tilt the carb until the float closes the valve. The point when the needle "just" seats is the spec. It also depends on what the mfgr. sez as to exactly where you measure on the float. (but it's usually at the "apex" of the float)

The best tool I've ever used for float-height measuring is a tire-tread depth guage - they're usually graded in inches as well as mm.

If the carbs have been rejetted, the spec-height might be different, but 2mm is a crapload of difference, and likely wrong. Especially if that measurement is lower (i.e. higher numbered measurement) than stock.



Yeah i have the carbs off and sitting on their heads, upside down when i measure. i have been measuring at the apex from the lip of the carb edge-exactly as described and pictured in the manual. i suppose i need the tool ur referring to cause it's hard to tell if they're right or not. since the problem was the bike running out of gas at high speeds, what would that dictate in terms of the direction the floats need to be bent in? Now speaking in temrs of the carbs being upside down would that mean the floats need to be bent up (down when right side up) or down (up when right side up).


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