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Discussion Starter #1 (Edited)
I've had this big bore kit on my bike for about 2,500 miles. Although it is a slight possibility that this issue could have occurred previously, I highly doubt I would have failed to notice it in well over 2 thousand miles of riding in many different conditions. I have only noticed a two or three times in the past week or two...the exhaust pipe (header/outlet pipe) sometimes will start to glow red-hot. I remember two specific times during which I noticed this problem. The first was after the bike had been sitting idling for about 3 minutes (I've done this plenty of times before and don't remember ever seeing that happen); the second was on my way home from school today. It was dark outside and I could look down and see my pipe glowing orange (more orange actually, not really cherry red as the title says...) from right where it comes off of the cylinder head back to about 2 or 3 inches from where it connects to the muffler. I was cruising at about 65 as I normally do, and it was staying orange like that. I got off the freeway a couple minutes after noticing that and slowed down a fair bit for surface streets; the glowing went away pretty quickly after that, but then I sped back up again to 55-60 mph and it started glowing orange again. Anyway, I have a few simple hypotheses...most of them involve PITA diagnostic work which I really don't have time for right now!

*Low coolant (the overflow tank is at the normal level and the radiator has been verified-full)...

*Some debris or something caught in one of the coolant passages, causing hot-spots

*Water pump not working (it's a mechanical pump on a practically new bike...can't be this!?)

*Something stuck in the exhaust causing excessive back-pressure (I checked the header and don't see anything. But I do hear a quite-slight metallic pinging sound if I shake the [stock] muffler back and forth fairly vigorously [as though a piece of metal inside is moving back and forth about 1 mm] - worth noting is that I noticed this with the muffler when I first got it and put it on the bike. It could possibly have worsened. It may be no problem at all...).

*exhaust valve sticking open slightly due to malfunctioning Kawasaki Automatic Compression Release on that exhaust valve (broken spring on this part, maybe???)...?. But I didn't notice any power loss or poor running conditions; wouldn't this cause those? Maybe not?

*Extremely excessive exhaust valve clearance(s)...same as above...? +I checked them 2,500 miles ago during big bore installation and all were well within spec - perfectly in the middle, in fact.

*excessively rich or lean air/fuel mixture (this seems fairly unlikely to me since I haven't messed around with any of that since I did the initial setup after the big bore, and the bike hasn't been sitting for a long time. I didn't see any big tears in the carb intake boot or anything like that, and I can't imagine my air filter is missing or something lol... even if there were a problem in this area, it seems that if it were drastic enough to cause my header to glow orange, it would also cause running/idling/performance issues...?) EDIT: I have the OEM a/f screw (I think...), but could vibration have caused it to loosen a freakin junk load of turns and totally throw off the mix? Guess this is next to check...

*header is just too small for big bore (but again, I'm 98% certain I've not had this problem until about a week or two ago)

*bent/kinked/twisted/tweaked header, or possible cracked near the mounting point and/or not seating evenly where it mounts to the head??? Or an exhaust leak where it connects to the muffler (I did have to tweak the pipes slightly at that point to get everything to line up right, since the muffler was bent in a little on its mounting tabs that hold it to the frame [from a drop several months ago]...). I didn't notice anything obvious on any of this though...




That's about all I can think of right now. I'm getting really sick of this crap; I just want to ride! And I don't have time to mess around with this shit every damn day - seems like I have been lately! Any input on my ideas or any other possibilities...all very welcome. Thanks much in advance!
 

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Discussion Starter #2
I just checked my air filter and it does seem very dry; even when i squeeze it, absolutely no oil at all is left on my fingers... I used this "synthetic water washable" air filter fluid crap from "Rock Oil" that I bought from Parts + Accessories + Performance = ProCycle. Maybe this stuff doesn't work very well? Maybe it needs to be applied every 500 miles? Water is getting in there somehow when it rains? IDK...but it seems somewhat feasible that this dry filter could be causing a leaner air/fuel mixture, in turn causing my hot orange header, especially if my jetting is already borderline (almost too lean). Maybe I'll turn the fuel screw out 1/2 turn (richer) and also buy a new filter (use some god damn conventional filter oil this time...). I guess I'll try this and report back. In the meantime feel free still comment.
 

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My KLR headpipe glowed from a too lean mixture. A bigger main jet did the trick. Also you will need to check the pipe is flush with the head and yes perhaps a dry filter can cause a problem.
 

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Too lean.
 

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You didnt mention what your spark plug looks like. If I had spent the bucks for a big bore kit though , I would have changed the exhaust also. Balance everything! Then check your compression to be sure you didnt mess up the valve. Good luck!
 

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I think it has been said... likely a lean condition. It is fairly common for header pipes to glow orange particularly when running hard.
 

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My KLR headpipe glowed from a too lean mixture. A bigger main jet did the trick. Also you will need to check the pipe is flush with the head and yes perhaps a dry filter can cause a problem.
Your correct, but not about the filter being dry. All the filter oil does, is help trap dirt to filter. With the filter oiled, the dirt will stick to filter before passing through. But, and over oiled filter will not flow as much, but it's not that much of a difference. Oiled filters have to be checked and cleaned more often than a dry one.
 

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Discussion Starter #11
Thanks people. Too lean is pretty much my first assumption as well. It may be at a point where it causes JUST enough heat for the pipe to start getting orange (borderline, like I said). Werloc: It seems to me that if an over-oiled filter flows less than a correctly-oiled filter, then it stands to reason that a correctly oiled filter flows less than an un-oiled filter. Like you said I can't see this making much of a difference, but maybe a little difference is all it takes in my case. I will check the spark plug.
 

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Discussion Starter #12
I took a couple pictures of the plug, but I'm afraid they'll be completely useless since the camera isn't accurately showing the actual colors on the plug... The closest description to mine is probably this one "Normal - grayish-tan deposit on side electrode"... It doesn't look bad to me.
 

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Discussion Starter #13
Okay, I am doing the following: turn fuel screw out 1/2 turn (from 3 to 3 1/2) to richen the mixture a little, install snorkel into the air box lid to restrict air flow a little more (had debated whether or not to do this during the initial build process of this project, but ended up leaving it out), clean up current Uni air filter and oil it well with regular motor oil to further restrict air flow a little from its current state with the super-dry filter element (I'd buy a new OEM filter but they're like $50!!! and I've only had this stupid filter in the bike for 2,500 miles).

If the glowing pipe is being caused by a lean mixture, the above steps are almost sure to resolve the problem! We shall see.
 

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Yes, and over oiled filter will cut down some airflow. Your not looking to tune the filter to the carb. Clean the filter, oil lightly, then tune carb accordingly. The proper way to oil a clean filter is: oil filter well, place in plastic bag, then work oil thoughout filter very well. Remove filter from bag, squeeze out oil very well. Then wrap filter with paper towels, and squeeze filter again very well so paper towel removes exess oil. Now it's properly oiled, but not over oiled. It takes very light coat, but this is how to get the oil everywhere in the filter.....;)
 

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Turning the screw out isn't going to help your lean issue. That's only for mixture at idle, up to 1/8 throttle. You need to adjust your mid (needle jet) and high (main jet). Unlees, your pipe is glowing at idle only. Any mods on this engine or is it stock. Maybe I should go back and read the whole thread.....:)
 

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Ok, so I went back and read everything you posted, not any other replies. So, the 2 times you noticed this was once after idling for 3 minutes or so, and, the other while riding 55 - 60 mph. So, this is what I would do/check. First, clean the air filter, and oil it lightly. Then, take 3 plug readings at different rpms to see what jet is off. First one, let bike idle for 2 or 3 minutes, then kill motor. Read plug. This will give you reading for idle jet/fuel screw.
Then, take the bike out for a ride, and stay at close to WOT (wide open throttle or close to it), in any gear, then kill motor while its still reved up. Coast to stop, read plug. This will give you the reading for main jet.
Repete this at half throttle for needle jet reading.

Take pics of each reading and post. Clean plug before taking new reading. Spray plug with contact cleaner or brake parts cleaner and wipe with clean rag.

It's possible you may have an intake leak. Do you notice any erattic iding, or running different than normal? After blipping throttle, does it come back to idle slower than normal? You can also spray starting fluid around the intake boot between carb and cylinder while idling. If it reves up a little, it's loose or cracked. Air leak at intake. Replace with new boot. So, do these things and tell me what ya find. Post pics of all 3 plug readings. This is where I would start if you brought your bike to the dealership. Let's hope you find something so we can fix it.....;)
 

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Discussion Starter #18 (Edited)
You didnt mention what your spark plug looks like. If I had spent the bucks for a big bore kit though , I would have changed the exhaust also. Balance everything! Then check your compression to be sure you didnt mess up the valve. Good luck!
I know a few people who have successfully run stock carb and exhaust with these kits (the maker says it's fine, too). To me, the gains for your money are much more significant with the big bore kit than with exhaust. Full exhaust will get 10 or 15 % more horsepower at high RPM, at best; big bore kit gives you 60% more torque at 4k RPM. From a performance perspective, I am 100 % satisfied with the kit; it accomplished precisely what I wanted it to in that regard.
 

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Discussion Starter #19 (Edited)
Hey Werloc, thanks for all the tips! I did the things I said I'd do. It was glowing at high idle if choke on, but not at normal idle (so the fuel screw turned out did richen that up). Then I figured the filter oil and installing the snorkel would richen the mix at higher throttle openings by restricting air flow a bit. What I did accomplish was an apparent reduction in upper mid range and top end power, but a definite improvement in true bottom end power - below 4k RPM (easy power wheelies at 2,500 RPM now, where before it wanted more like 3,500 to 4,000). This is all nice and fun, but my pipe still glows...sigh.


It will start glowing if I start the bike and let it high-idle on choke (~3k RPM) for about 2 minutes+, and/or when I start doing higher speeds/RPM - anything over 5,000 RPM/50 mph or so and it starts glowing, back it off down to 50 or below, and it stops glowing fairly quickly. Immediately when I got home from this test ride, I let it sit and idle (choke off) for 2 minutes and it still didn't glow. I also went out a few minutes later and let it idle with choke off for over 4 minutes - no glowing. Weirdly, even screwing around whacking the throttle wide open for wheelies repeatedly in first and second gear didn't make it glow...

Anyway, sorry for all this babbling. I do want to resolve this. What gets me is that this just started happening even though I haven't made any changes recently. I bought the bike as a 250cc, then installed a big bore kit to make it a 331cc. Stock pilot ("slow jet") jet is a Keihin #35; I changed it to a Keihin #38. Stock main jet is a Keihin #118; I changed it to a Dynojet #124 (Keihin 132). I also made other carb changes according to the directions for the Dynojet "stage 2" jet kit: http://www.dynojet.com/pdf/2152.pdf . This recommends 3 turns out on the fuel screw (IIRC, stock is about 1.5 or 2) - current setting was 3 turns out since big bore kit; just changed to 3.5 turns out AFTER experiencing this problem.


"Your not looking to tune the filter to the carb. Clean the filter, oil lightly, then tune carb accordingly." - True...I do have a tendency to over-oil a bit. I'll probably go remove a little more from the filter.


"First one, let bike idle for 2 or 3 minutes, then kill motor. Read plug." -

I'm not too great with plug reading. But I will give it a shot. My cell phone camera doesn't capture the true colors and details too well, so I don't know how much posting pics will help, but I will try anyway.


Oh and to answer your questions: There is no erratic idling at all - it purrs like a kitten, smooth as can be. It also returns to idle very quickly and smoothly when blipping the throttle. I've seen that hanging idle problem on other bikes a few times and my KLX is definitely not doing that at all. The only abnormal running condition that I've noticed - if it can even be called that, is an occasional SLIGHT hiccup at lower RPM (maybe 4 or 5k) occasionally. It's barely noticeable and seems to have mainly occurred before the bike is fully warmed up. It has also done that since I first did the big bore (the pipe didn't ever glow then). But I must stress that it's very minor and hardly noticeable even when you're looking for it. I dismissed it as a normal quirk of this machine since it doesn't affect riding enjoyment and hasn't seemed to be a reliability concern...

One more thing, please bear with me if this ends up taking longer than I'd like. I don't really have any spare time these days. I've got a lot going on, so it's really hard to get stuff like this done.

 

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Discussion Starter #20 (Edited)
Before first plug reading.jpg

Above photo is before the first plug reading (before cleaning the plug with brake cleaner).




Plug reading after hitting kill switch after idling for three minutes.jpg

Above photo is the plug reading after hitting the kill switch after idling for three minutes.




Plug reading after hitting kill switch while holding throttle half open in first gear.jpg

Above photo is the plug reading after hitting the kill switch while holding the throttle HALF open in first gear.




Plug reading after hitting kill switch while holding throttle wide open in first gear.jpg

Above photo is the plug reading after hitting the kill switch while holding the throttle WIDE open in first gear.
 
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