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Old 06-04-2013, 05:12 AM   #16
lineaway
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http://advrider.com/forums/showpost....&postcount=157
Brewtus`s bike ran really good after a little effort. Retarded timing is the likely cause of dry sooty deposits on a poorly jetted carb.
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Old 06-04-2013, 07:45 AM   #17
UtahGuido
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Originally Posted by lineaway View Post
http://advrider.com/forums/showpost....&postcount=157
Brewtus`s bike ran really good after a little effort. Retarded timing is the likely cause of dry sooty deposits on a poorly jetted carb.
I've read about these adjustable cam sprockets elsewhere. I think I'll have to get me one. And I seem to recall some advice (probably from my friend Tom, my guru for things engine - most of the time) about advancing timing one degree per 1000' elevation. That would make sense given Brewtus' results.

So you think if I advanced the timing my sootiness would go away, or at least diminish, short of rejetting? Sorry IJ, don't mean to hijack the thread.
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Old 06-04-2013, 07:52 AM   #18
Irish John OP
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Hmmm, seems to be several schools of thought here. As I won't riding at elevation all the time, the idea of the adjustable cam sprocket is probably not worth the effort. As the engine will run lean at higher elevation from thinner air, could I increase the air flow by removing the snorkel on the air box? Don't think I want to switch carbs. When I checked the part number for the pilot jet with my dealer, it came back as no longer available. As most of my riding is at lower elevation, won't drilling the existing jet to a larger size effect performance when I come back to lower elevation?
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Old 06-04-2013, 10:31 AM   #19
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Originally Posted by brewtus View Post
Okay. Here goes.






Brilliant. Yet another response from a Troll who as far as I can tell has no real-world experience, yet enjoys telling others how to do it. With a theoretical jetting link (accurate, but theoretical nonetheless) for Mikuni carbs when the TLR came with Keihin carbs. What's the matter, did it get cold in the shadow of your keyboard and you came out spouting your usual surface knowledge nonsense to get warm?? A great link to TLR jetting can be found here, a big thanks to Taxonomy for the info -

http://www.advrider.com/forums/showp...44&postcount=1

Twintroller you can argue with me all you like, I really don't care. We both know what you are. All of us who actually work on bikes do. Irish John, have fun with your 'Flex, and sorry about the hijack. Brewtus out.

If you feel that the laws of physics can be altered to suggest rubbish posted here which suggests bigger jets are required for proper running at higher altitude is in fact correct, it would seem not only are you a troll but a pretty stupid one at that!

Here is another link that provides rather more accurate information than that issuing from under the bridge: http://www.4strokes.com/tech/howtojet.asp
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Old 06-04-2013, 10:38 AM   #20
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Originally Posted by Irish John View Post
Hmmm, seems to be several schools of thought here. As I won't riding at elevation all the time, the idea of the adjustable cam sprocket is probably not worth the effort. As the engine will run lean at higher elevation from thinner air, could I increase the air flow by removing the snorkel on the air box? Don't think I want to switch carbs. When I checked the part number for the pilot jet with my dealer, it came back as no longer available. As most of my riding is at lower elevation, won't drilling the existing jet to a larger size effect performance when I come back to lower elevation?
A motor will run rich at higher altitudes with sea level jetting, as the air density reduces as altitude increases, and the amount of fuel must then be reduced to compensate for lower air density.

Removing the intake silencer on a TLR doesnt do very much at all (at least according to a dyno), but removing the flame trap and running a foam pod type filter inside the stock air box, will improve things quite a bit (and does make a difference to dyno readings).

In the world of the net chat forum though, its very easy to rewrite the laws of physics, and to claim that you need to fit bigger jets to compensate for thinner air at high altitude, which will mean bikes running far too rich, and may result in engine damage on 4T motors.
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Old 06-04-2013, 10:43 AM   #21
Sting32
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Let me rephrase the question for my Buddy (Irish John) to my new buddy Lineaway, see if anything changes.

Irish John found himself a Reflux (tlr 200, the usa steel wheel version AKA OJ wothout the "J" --> it is like new.). It came to him via (correct me if I am wrong at any time John) Missouri or there a-bouts. Ks is about 1000ft or can be less, lol.

On 2 strokes, as I "think" I learned this weekend (yet I could have gotten it confused, aka backwards). I went UP on the pilot Jet, and down several on the MAIN jet, which helped with lost power at half throttle when at 8000ft.

Not sure as to how or why this would be different on the 4 strokes, other than the TLR has so many issues in stock form, with being able to draw air, and not very powerful in the 1st place.

Here it is, the re-question:
So Irish John's question was, since he's heading to (like sipapau-ish elevations, but not competing just trail riding) what do you guys that take your TLR's to high altitude do for jetting? Again taking a bike that is jetted and runs OK at 1000ft, headed to a minimum of 6000 ft (colorado)?

Can anyone help him out with JUST jetting ideas, what you have, or what should he try? (jets are cheap, but he needs to probably get a few for each, but I texted John and told him probably get better answers from you guys here in ADV... Don't let me down now, lol)

I know I could have trail ridden my bike (300 gasgas Kehin carbed Raga) but I sure as hell wouldn't want to have to get up a hill I might have went down, since anything over half throttle just blubbered like hell, I think.

I bet the 200 4stroke could be left if there was a hill between him and the truck, but you ADV guys have a LOT more experience jetting...
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Old 06-04-2013, 11:46 AM   #22
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Thanks Sting, that is exactly what I wanted to know.

PS: see you and your Da this weekend.
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Old 06-04-2013, 03:13 PM   #23
UtahGuido
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Okay, straight answer to the jetting question Irish John. If your bike is running fine at 10000 ft and you are going to 8000ft - don't change anything at first. Maybe it will work just fine. If at 8000 ft the engine blubbers and stalls at anything over 1/4 to 1/2 throttle, but runs okay at WOT and idles okay, go down on the main jet 1-2 sizes. (I know, the main is supposed to work only at 1/2 to wot but it's been my experience that at WOT you are getting plenty of air and it will clean out a grossly rich mixture - happend on my KLX anyway but that's a long story.)

If your plug is black as coal and all you've been doing is idling around in first or second gear then maybe go a size smaller on the pilot jet.

So take two smaller main jets and one smaller pilot. And be prepared to yank the carb, something I have yet to do on my bike. Also be prepared for less power whatever you do since their are fewer O2 molecules up here to contribute to combustion, and thus power.

As I said earlier my plug IS black as coal and yet the engine is running pretty well, though I don't have anything except my KLX and KLR to comare it to. It crawls along, revs pretty well, and generally cruises right along. That's why I say, somewhat tongue in cheek, don't mess with it till you get up here and see what it does. But bring those three extra jets with you if you must.

My admittedly un-expert 2 cent. FWI, YMMV, etc.

Edit - can you twist a mixture screw on these carbs? If so (and I suspect you can - just haven't gotten that far with mine) then fiddle with that, and the idle adjustment screw; if hesitates or blubbers just off idle screw the screw out to richen the mixture and adjust the idle up just a bit. Again, that works on (my) Kawasaki liquid cooled engines.
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Old 06-04-2013, 03:41 PM   #24
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What you all are forgetting is the bike comes from the factory too lean in the first place. And it is not easy finding jets unless you know whwere to look.
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Old 06-04-2013, 06:07 PM   #25
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Originally Posted by lineaway View Post
What you all are forgetting is the bike comes from the factory too lean in the first place. And it is not easy finding jets unless you know whwere to look.
Right. So up at altitude a stock bike ought to be jetted pretty well then, right? Theoretically? And yeah, where do you get a jet, especially a smaller one? It's not like you can drill them out to make them smaller. If you can't find new ones it sorta makes a conversation about tuning with them moot. (Warning: off topic tangent approaching.) So what about these OKO taiwanese carbs, or Mikuni? I'm sure these have been discussed ad nauseum but...
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Old 06-04-2013, 06:24 PM   #26
lineaway
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No it is not jetted even close. You NEED a bigger pilot jet. Have you not read any of the threads? I give up, good luck.
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Old 06-04-2013, 07:21 PM   #27
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Lineaway is correct in my experience - the Pilot jet at high altitude stays the same or goes slightly richer on a correctly jetted carb at sea level. Since the Honda is lean to start, then I can definitely see his point.

FWIW: At very high altitudes - carbs circuits that utilize near ambient air pressure (pilot circuits) to push fuel through a small orifice can require a less restrictive fluid path to move an adequate amount of fuel when the "pushing" force (air pressure) drops. I think everyone assumes the carb works perfectly to maintain the correct Stoic ratio and the only thing that varies is air density. The air density also affects how the carb works! Carbs are usually designed to work at or near sea level, so severe altitude can create non- linear responses for a circuit design and hence the jetting adjustment isn't necessarily intuitive.

These issues come up as well in the 26mm dellorto vs 28 mm Keihin carb altitude sensitivity discussions too.
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Old 06-04-2013, 07:34 PM   #28
UtahGuido
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So what does your plug look like anyway Iron John? White, tan, or black?
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Old 06-04-2013, 07:59 PM   #29
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Originally Posted by Twin-shocker View Post
If you feel that the laws of physics can be altered to suggest rubbish posted here which suggests bigger jets are required for proper running at higher altitude is in fact correct, it would seem not only are you a troll but a pretty stupid one at that!

Here is another link that provides rather more accurate information than that issuing from under the bridge: http://www.4strokes.com/tech/howtojet.asp

Seriously?? You must be joking. You are calling ME stupid??? I think not. Once again, ONCE AGAIN, post pics and proof of your builds and accomplishments, and we'll just see who is the fuckin' troll here and who is not. We both know the answer.
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brewtus screwed with this post 06-04-2013 at 08:05 PM Reason: My buddy Sting told me to ignore you, but gawd, you are an idiot.
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Old 06-04-2013, 11:42 PM   #30
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Seriously?? You must be joking. You are calling ME stupid??? I think not. Once again, ONCE AGAIN, post pics and proof of your builds and accomplishments, and we'll just see who is the fuckin' troll here and who is not. We both know the answer.
As you seem to be suggesting the exact opposite to that which is correct, and actually seem to believe the nonsense you have posted (even though its very easy to find out that you are wrong completely), then I think the word STUPID is spot on!

Nonsense getting posted up on chat forums (which if it comes from belligerent trolls such as yourself, very rarely gets challenged!), is something that very often leads to those that take such rubbish as being correct experiencing problems, that could have easily been avoided if they had accurate information.

If what you are suggesting is in fact correct, then I am sure you will be able to post up something to clarify the fact that air density increases with altitude, and requires larger carb jets to provide more fuel to compensate for increased air density?

I guess I will be waiting a long time for an apology when you cant find anything to support your claims, but I think admitting they are wrong is something a troll such as yourself is never ever going to do!

http://www.hotrod.com/techarticles/e...g/viewall.html

Is a well written piece providing some accurate info on carb set up, which strangely enough doesnt mention the need to increase jet sizes to compensate for reduced air density at higher altitudes....................
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