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Help with carb settings please! 87 XR600R. Dual carb.

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hey guys! i recently picked up an 87 XR600R so my brother or dad can ride with me. it wasn't running when i got it but had good compression and spark. we cleaned the carbs and have already gotten the bike to run but its not quite right.

 

can you guys please tell me what the factory settings are for the carbs? also, the bike has a supertrapp muffler and an opened up air box with a hi-flow filter.

 

could anybody recommend a "ballpark" carb setting for these basic mods?

 

i haven't been able to find a manual for the bike yet. i have found one for the XL600R though. does anybody know if the carbs are the same on the XR and the XL? and are the setting the same?

 

thanks! were all pretty excited to ride it.

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Turn the air screw out 1-1/2 turns and start the motor and turn the idle screw up until it will run on its own without giving it throttle by hand. In a perfect world this will be about 1200-1300 rpm but may be higher depending on how far off the mixture is. let the bike warm up and then adjust the air screw with the bike idling until you find the highest idle rpm. Now that you have found the highest idle speed, turn the air screw in (right) to slow the idle speed about 100 rpm. You now have the mixture adjusted correctly and can use the idle speed screw to set the idle speed to your preference.

If after this process your air screw is more than 2-1/2 turns out, you need a smaller pilot jet by one size. If your air screw ends up less than 3/4 turns open, you need to go larger by one size. I have found that the stock 45 pilot in an 87 xr6 is too lean and a 50 is usually about right but use the process above to determine proper idle mixture and jetting.

Once the pilot/idle mixture is right, you can turn to the main jets. This is a less systematic adjustment process and can be tough to get absolutely perfect. The easiest way is to start by just bumping both mains up to 125's and then riding it and checking the plug color and adjusting main jet sizes based on how it runs and plug color.

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It's a FUEL SCREW. Out is richer , in is leaner. More than 2 1/2 out , 1 up pilot. Less than 3/4 , 1 down.

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well we can ask your threat creator what model carbs he has on his bike  👍

 

Funny the XL bike carbs moved to the newer model carbs with the feul screw in 84 

Edited by Oupoot

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thank you for the help guys. i actually have two sets of carbs for the bike. one came with the 87 XR and was TOTALLY out of whack. the other came from an 86 XL600R.

 

i don't know the numbers on them but i would be happy find out. il post it up this afternoon (they aren't infant of me at the moment)

 

were currently using the ones from the XL.

 

-Craig.

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So you are currently using the 86 XL carbs, that can change things.

There is some variations of what model carbs would be on an XL but most are similar. what will matter are the jet sizes and as noted above, wether it has an air screw or fuel screw. If the screw is located on the side like the pic I posted above, it is an air screw. If the screw is underneath the carb forward of the fuel bowl, it is a fuel screw.

The model number will help but also the location of the mixture screw is important.

Edited by Backwoods-Bomber

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alright sorry for the delay fellas. heres the numbers.

 

the XR carb is a PH52A CYJ with the screw on the side.

 

the XL carbs are a PH68GBAFE with the screw on the screw on the bottom.

 

again thanks for the help. i really appreciate it.

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alright sorry for the delay fellas. heres the numbers.

the XR carb is a PH52A CYJ with the screw on the side.

the XL carbs are a PH68GBAFE with the screw on the screw on the bottom.

again thanks for the help. i really appreciate it.

Ok, that means that joes statement above is correct about tuning since you are using the xl carbs instead of the stock ones. Still use the same procedure as I posted above, just with the correction he posted. It helps to know that the stock carbs have been swapped for something different.

Ph68g carbs should come stock with a 62 pilot jet, 118 primary main jet and a 115 secondary main jet. For reference, your stock xr carb had a 45 pilot, and a pair of 122 mains. So, you are probably rich on the idle circuit and lean up top.

Your next step is to pull those bowls off and report the jet sizes. You dont need to remove the carb to pull jets, it can be done on the bike.

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Thank you!

 

i will try to get you guys the jet sizes along with some pictures later today if i have time.

 

Are the jets interchangeable between the two carbs? il check and see what are in Both of them.

 

-Craig.

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Thank you!

i will try to get you guys the jet sizes along with some pictures later today if i have time.

Are the jets interchangeable between the two carbs? il check and see what are in Both of them.

-Craig.

The jets may be interchangable but also may not, there are two styles of mains, little short ones and taller ones. The ph52a uses the taller ones for sure but i dont know what style are in your xl carb.

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If the idle mixture screw is on the airbox side of the throttle slide its an air screw. If its on the engine side of the throttle slide its a fuel screw. Doesn't matter if its on the side or on the bottom its which side of the throttle slide its on that counts.

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the XL carbs have the short jets in them. a 115/118-62.

 

the XR carbs have the tall jets. 125/125-45.

 

fun fact. when we got the bike to run (not very well...) it was on my pair of XL carbs that i had donated to the cause. my brother didn't do anything to them. he just stuck them on.

 

well he pulled them apart today and heres what he found. the Choke was clogged up and not functioning. and both the 115 and the 118 were both sitting in the bottom of the bowl. lol!

 

well see how it acts with the XL carb now that its hopefully a little more "legit"

 

il let you guys know how its doing after we try to get it started again.

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.

 

well he pulled them apart today and heres what he found. the Choke was clogged up and not functioning. and both the 115 and the 118 were both sitting in the bottom of the bowl. lol!

 

 

That's amazing! I'd say that bike has a lotta spunk! Time to give it a name.

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I've got an 87 XR600R motor in a 94 chassis. I have gotten it to fire off but not stay running. I havn't pulled the carbs as I'm very deep into my XR250 and XR400 race prepping but I'm excited to get the dual carb setup at least running. 

 

Are parts still readily available for the XR600R carbs?

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I've got an 87 XR600R motor in a 94 chassis. I have gotten it to fire off but not stay running. I havn't pulled the carbs as I'm very deep into my XR250 and XR400 race prepping but I'm excited to get the dual carb setup at least running.

Are parts still readily available for the XR600R carbs?

Jets, floats and float valves are pretty easy to find but gasket kits are getting hard to find and are expensive. Hard parts are all discontinued for the most part.

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A buddy of mine does not go on the net, so I'm relaying for him. His 86 XR600r will only keep running if he screws in the idle stop quite far. How far is normal? How many turns after contact is made. ( I know different from bike to bike, but was looking for an average) Also when does the secondary open? He just got it and it is adjusted to open the same, is this proper? Because if idle stop is adjusted to keep it idling, it is opening the secondary also, which creates a lean condition, & hard to restart after he shuts it off. (also less effect of air screw adjustment) He pulled jets and emulsion tube and recleaned, even though he said they looked clean.

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A buddy of mine does not go on the net, so I'm relaying for him. His 86 XR600r will only keep running if he screws in the idle stop quite far. How far is normal? How many turns after contact is made. ( I know different from bike to bike, but was looking for an average) Also when does the secondary open? He just got it and it is adjusted to open the same, is this proper? Because if idle stop is adjusted to keep it idling, it is opening the secondary also, which creates a lean condition, & hard to restart after he shuts it off. (also less effect of air screw adjustment) He pulled jets and emulsion tube and recleaned, even though he said they looked clean.

Theres no spec for number of turns after contact but at idle the primary slide should have a ~2mm opening showing from the intake side. in stock form the secondary carb opens between 1/4 and 1/3 throttle which varies between xr/xl models.

Make sure he has in fact done a thorough job cleaning everything and then adjust the secondary to at very least be closed at idle. I personally prefer to have the secondary open a bit later rather than earlier, more in the 1/3 throttle range.

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