Pinging XR600

[Mick DMember]

Since I lifted the needle on Geoff Ballard’s advice, the ping has gone, now another problem rears it’s head. She is running too rich now and blowing a bit of black smoke. It is certainly running well though. I put a new plug in when I raised the needle and here is a pic of the new plug with the old plug. The new plug is on the right. Looks real rich to me, where to now?? [img size=640]http://www.obtrailriders.com/media/kunena/attachments/legacy/images/DSC01791.JPG[/img]

[GregMember]

Review this thread Mick its simple, it wont be the main jet as you havent been riding Finke, go down one or maybe two I would go down two sizes on the pilot jet or slow jet as they call it here, let me check something else while you look at this, stay tuned

1. IDLE: Set idle speed to correct r.p.m. by adjusting the IDLE SPEED SCREW. Turn The AIR SCREW to achieve the highest idle speed and best response. After this adjustment has been made adjust the IDLE SPEED again back to the correct r.p.m.

2. OFF IDLE to 1/4 THROTTLE: The SLOW JET and the AIR SCREW are most effective in this range. When you want a richer mixture use a larger SLOW JET or turn the AIR SCREW in. The opposite holds true for a leaner Mixture.

3. 1/4 to 3/4 THROTTLE: The JET NEEDLE is the most effective component in this range. Raising the needle by lowering the clip position at the top of the needle will richen the mixture. Lowering the needle will lean the mixture.

4. WIDE OPEN THROTTLE (W.O.T.): Changing the MAIN JET effects this range. Select the size which offers the best W.O.T. performance, then install one size larger MAIN JET for ideal engine durability.

NOTE: Not all Carbs have AIR SCREWS. Some have FUEL SCREWS, it is important to differentiate as to which one you have. This depends on the location of the screw on the carb. (looking at the center of the carb) If the screw is in between the cylinder and the carb body , it’s a FUEL SCREW, turn it OUT to get more fuel (richer) if the screw is in between the carb body and the air box, it’s an AIR SCREW, turn IN to richen it. As far as I know this rule of thumb is correct. Check with your dealer or manual if at all unsure. Note: most air/fuel screws should be set somewhere between 0.5 to 3.0 turns from seated, if it is outside this range you should look towards your slow jet.

[shaneMember]

Exactly what I was looking for to aid my failing memory.
I’d not be reducing the main jet, (after doing some reading and offerring crap advice!) too rich is better than too lean!
My dear old dad used to teach me that when a car is in good tune the exhaust tip is nice and grey (or something like that), but unleaded fuel has buggered that! now they’re all black!
Apart from the little black smoke, does it run well?

This was my link http://hondanighthawks.net/carb14.htm

[Mick DMember]

It was running lean mid range under load before I lifted the needle, now if you let it idle for a minute and give her a rev show blows smoke.

[Mick DMember]

Yeah Shane it seems to be running well.I did notice she spluttered (minor splutter) a couple of times when trying to keep at 50kmh in town.(Mid revs)

[GregMember]

That Picture the Yuri posted of a dude holding up a XR600 before, well the dudes name is Scott Summers and heres his tips for a fast XR 600, including jetting

10 Go-Fast Tricks

One strong thumper pilot.

Here’s what Scott Summers and his mechanic, Fred Bramblett, do to his XR600Rs to make them more competitive. These ten tips can be applied to any production thumper, but the jetting specs are for recent-model XR600s only.

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1. To increase airflow, remove the airbox lid and use an aftermarket air filter. Do not remove the backfire screen from the cage. Removing the screen changes the intake velocity and causes the bike to have poor throttle response at low rpm.

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2. To increase exhaust flow, Scott replaces the stock muffler with a White Bros. Megalloy system, with an open end-cap for closed-course competition. Scott says, “Please don’t use the open end-cap for trail riding, as it is way too loud to use on public land.” He also recommends sealing the muffler to header junction with high-temp sealant – they use Hondaline Hondabond H.T.

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3. Check the header pipe where it mounts to the exhaust manifold. Sometimes the welds are overdone, and the extra material can restrict airflow. Grind away the protruding material to increase flow, but don’t overdo it to the point of making the area weaker.(br>

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4. With these mods, Scott uses the following jetting:

Jet Stock Mod

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Main 152 155
Pilot 62 68
Airscrew 2.5 turns out
Scott says, “Most four-strokes come jetted on the lean side and must be richened when you increase intake and exhaust flow.”

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5. To make the race bike run cooler and extend clutch life, they mount an XR250R oil cooler to the steering head and remove the headlight for more airflow.

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6. For better cooling they sometimes wrap the header pipes with exhaust wrap made by Thermo-Tech to keep heat from being transfered back into the cylinder and head by airflow.

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7. If a course or trail isn’t going to be too muddy, they trim 4″-5″ off the back of the front fender to allow more cooling air to reach the cylinder.

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8. Scott recommends against the use of plate-type skidplates. You got it, he feels they restrict air flow and trap engine heat.

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9. Run good pump gas with an octane rating of 91 unless you have a modified high compression engine. Scott runs a stock engine because “the increased compression braking throws off my timing.”

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10. Keep your valves and valve decompression systems adjusted properly! This is extremely important for any thumper.

[Mick DMember]

8. Scott recommends against the use of plate-type skidplates. You got it, he feels they restrict air flow and trap engine heat.

Exactly what I said the other day. Hence no bash plate on my XR.

[GregMember]

When Scott punches a hole thru his crankcase Honda gives him a new one dopey, not you, Scott would have worn a cold sore if his sponsors wanted him to, every trail rider I know uses one bar you :blush: Just a thought will never speak of it again :blink:

TB

[Mick DMember]

OK, to keep a peaceful medium, is there one available that allows more airflow than the conventional after market ones on most bikes.

[GregMember]

As you have asked I ran an XR 600 since JC played half back for Jerusalem and never once felt I had oil over heating issue, but you could drill some air flow holes in it with a hole saw like Crash’s or Ollie or Mac could arrange to do it for you. We have just ordered a special plastic one for project DRZ as they are supposed to be the latest and greatest better than aluminum.

TB

[shaneMember]

Heat rises…usually. The bash plate on my little 280 never caused any problems even when filled with mud. I wouldn’t bewithout one.

Maybe you should consider ‘speed holes’?

[Mick DMember]

What do you guys think about dropping the needle back to its original “pinging position” and going up one size in the pilot jet then?
Would that also fatten up the mid range? I am trying to get my head around TB’d jetting chart and from what I can work out the main jet is the one that is the go mid range.

[Mick DMember]

Another thing. Should I remove the plastic splash guard from the side of the air box,to open it up a bit?Or does it serve a reasonable enough purpose to keep it there?

[GregMember]

micknmeld wrote:

Quote:

What do you guys think about dropping the needle back to its original “pinging position” and going up one size in the pilot jet then?
Would that also fatten up the mid range? I am trying to get my head around TB’d jetting chart and from what I can work out the main jet is the one that is the go mid range.

Lifting the needle makes a bigger change than going one or two jet sizes, go back to the same needle setting, go one bigger pliot jet (or slow jet) than if thats not enough borrow some jet drills and take it one step at a time till its right.

TB

[Anonymous]

Mick you goose,those 38 mm Mikuni carbies come from Ballards already set for XR600s, I presume that is where it came from.
From memory they come with 12.5 pilot, go up to a 15 and see how it goes once the needle is back at the original setting.
See I don’t always cause crap, maybe I will turn over a new leaf. This do good thing kinda feels nice.:kiss:

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