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02-24-2010, 9:57 AM treybrad Joined on 02-06-2010 PF, TX Posts 86 Round Slide Carb Tuning Has anyone fooled around with changing the pilot jet on the old carb? Mine ran like crap at 2.75 turns out (very hard to start, lean surge at very slight throttle openings), but it's pretty smooth at 4.5 turns out... In fact, it seems to run just fine until the screw comes all the way out -- never tries to die at all. Is that normal? I figure it should be overly rich at some point and start to stumble... but no dice. Everything I've read says 4+ turns is way too many turns out and I need to go up a size. If it's running well though, is there a downside to keeping it that far out? The next larger size I've seen is a 45 from a 40 -- 5 'steps' seems like a lot, but I have no idea. Bike starts wonderfully now. No choke, even this morning in the 30's (F) (probably 45 in the garage). In fact, if I add more than about 1/2 choke, it wants to die. That doesn't seem normal either... My new main jet should be here soon - maybe I'll be able to reset the pilot screw a few turns closer in afterwards... trey *edit* I changed the title/subject of the thread so it's a little closer to the current topic... '07 Suzuki Bandit 1250SA '97 Yamaha TW200    Report

02-24-2010, 12:20 PM JoMomSophat Joined on 07-12-2006 Seattle WA Posts 824 Re: Round Slide Carb Tuning try turning it in than using the choke.    Report

02-25-2010, 7:02 AM treybrad Joined on 02-06-2010 PF, TX Posts 86 Re: Round Slide Carb Tuning Jo -- For now, if I turn it in, the bike runs terribly everywhere off idle. Not really terrible, but lots of lean surge, and bad pinging at WOT. Hopefully the larger main jet will allow me to close up the pilot screw a bit -- I'm probably compensating for the other lean areas with the pilot jet a bit right now. trey '07 Suzuki Bandit 1250SA '97 Yamaha TW200    Report

02-25-2010, 7:34 AM JoMomSophat Joined on 07-12-2006 Seattle WA Posts 824 Re: Round Slide Carb Tuning ok yer doing it rong thu idol skrew dosnt chang the way yer bike will run at wot. you shud git a 118 main jet than yer bike wont be leen.    Report

02-25-2010, 9:04 AM treybrad Joined on 02-06-2010 PF, TX Posts 86 Re: Round Slide Carb Tuning I know, I know... I've got main jets on the way -- I'm hoping that will fix all my problems... trey '07 Suzuki Bandit 1250SA '97 Yamaha TW200    Report

02-25-2010, 9:15 AM talon Joined on 09-04-2008 Posts 323 Re: Round Slide Carb Tuning Sorry board won't let me post chart. The Voice of America, Glenn Beck Calling an illegal alien an 'undocumented immigrant' is like calling a crack dealer an 'unlicensed pharmacist' The United States Government, changing citizens into subjects one day at a time.    Report

02-28-2010, 7:01 PM QWERTY Joined on 11-22-2006 Posts 2,360 Re: Round Slide Carb Tuning Assuming the carb is thoroughly cleaned and in good repair, carb tuning sequence: Main jet; Needle; Pilot screw; Pilot jet; Pilot screw. Repeat. This goes for every carb I've ever done, from tiny model airplanes to Merlins. Hold off until your jets arrive, Start with the main, then worry about the rest. Until the main is right everything else will do all sorts of weird stuff and will drive you crazy. Be aware the number sequence for aftermarket jets may not correspond to the Yamaha designations. Your new aftermarket 115 may be significantly leaner than a Yamaha 112. By the way, a screwdriver bit for an electric drill is good for adjusting the pilot screw when the carb is on the bike. I found a 3/8 square drive bit holder, sanded the chrome off, and dipped it in tool handle plastic. Perfect homemade specialty tool for pilot screws.    Report

03-01-2010, 7:47 AM treybrad Joined on 02-06-2010 PF, TX Posts 86 Re: Round Slide Carb Tuning Good tips QWERTY. I've been trying to make this as systematic of a process as possible -- I swore I'd never own another carbureted bike after have a couple of FI machines... oh well. I got my package for my jets the other day except... it was empty. The place I ordered them from shipped me an empty envelope. I called them this morning and they're sending out some replacements, so hopefully it'll be a short delay. Is the old carb a TK as well? I looked all over it and couldn't find any sort of branding. I'll be sure to measure and make sure I don't go any leaner. I've been using the same trick with my pilot screw. I've got a slightly longer than normal screwdriver bit that I can get in there with the bike running. Works like a charm. trey '07 Suzuki Bandit 1250SA '97 Yamaha TW200    Report

03-01-2010, 1:14 PM TW-87 Joined on 02-01-2010 Manitoba, Canada Posts 305 Re: Round Slide Carb Tuning All of the photos on this thread are of the TK carb. TW-87 1987 TW200, 15/44 sprockets, DID O-ring chain, Award winning, "Quick Release" Action Packer :-))    Report

03-03-2010, 8:58 AM treybrad Joined on 02-06-2010 PF, TX Posts 86 Re: Round Slide Carb Tuning Thanks TW. I guess all the TW carbs are TK? I've gathered that the newer one is, the old one must be as well, just the older, non-CV design. Got my #120 Mikuni main yesterday, the #115 is on it's way still. Think I'll pop in the #120 tonight and see what happens. From what I have read, the Mikuni jets tend to be larger than the equivalent TK/OEM jets, so a #120 should be a very big jump in size from the OEM #114... maybe too big. We'll see. IIRC, the Wiki page had a chart comparing TK to Mikuni, but it's down right now... trey '07 Suzuki Bandit 1250SA '97 Yamaha TW200    Report

03-04-2010, 10:42 AM treybrad Joined on 02-06-2010 PF, TX Posts 86 Re: Round Slide Carb Tuning Well... another swing and a miss. Ha. A Mikuni 120 is smaller than the stock TK 114. That was a waste of $15. I went ahead and ordered some 116, 118, and 120 OEM Yamaha jets from Ron Ayers ($40 -- ouch), but at least I know they'll fit. The waiting continues.... trey '07 Suzuki Bandit 1250SA '97 Yamaha TW200    Report

03-12-2010, 7:04 AM treybrad Joined on 02-06-2010 PF, TX Posts 86 Re: Round Slide Carb Tuning Got my new jets yesterday - 116, 118 and a 120. I started out with the 118. Better, definitely, but still slight pinging at WOT. Swapped in the 120. Better still, but honestly, I feel like I could go up another size. The bike feels much better, no more herky-jerky lean surge, and I can tell it's running cooler. I need to do some throttle chops and fiddle with my pilot screw some more now with the bigger main, but it is much better already. On flat ground, minimal wind, it'd do just shy of 70mph, 73-74mph with me hugging the tank and ducking out of the wind. I'm only 150lbs, but I have a top case mounted on the back which I'm sure doesn't help aerodynamics. My question is this.... why does mine want such a large main jet? I've read on this board where people with the old carb have swapped in a 116 and found it too rich, going back to stock. I'm at a 120, and I'm pretty sure it'd be a touch smoother with a 122. I'm at 700' ASL give or take, so I'm not at any kind of elevation. It's hot and humid here a lot (Austin, TX area). Bike is box stock best I can tell. The exhuast is typical thumper -- kind of loud, but I don't think it's been altered other than 13 years of use. Air filter is a foam material that I've cleaned and oiled -- I assume it's stock as well. Any thoughts or just call it good? trey '07 Suzuki Bandit 1250SA '97 Yamaha TW200    Report

03-12-2010, 6:19 PM TW-87 Joined on 02-01-2010 Manitoba, Canada Posts 305 Re: Round Slide Carb Tuning Treybrad. Congrats on your progress. I too am making progress with my bike. Right now I'm waiting for more snow to melt so I can test it. Re: "Why does mine want such a large main jet" It is possible that a previous owner removed the baffle from your muffler and "modified it". I've never tried to remove mine, but apparently it is possible, but difficult (according to other posts on this forum). It is also possible that your air box has been "opened" up. On my '87 the only air inlet to the air box is a a little "snorkel" tube on the top - right under the seat. Just thinking out loud here..... Another possibility is that your spark plug is too hot. That might explain the pinging. Did you check it against the manual ? TW-87 1987 TW200, 15/44 sprockets, DID O-ring chain, Award winning, "Quick Release" Action Packer :-))    Report

03-13-2010, 1:40 PM QWERTY Joined on 11-22-2006 Posts 2,360 Re: Round Slide Carb Tuning In Austin expect your stock jetting to be 2 or 3 jet sizes too small. It's an EPA regulation thing. The rest of the world gets jets 2 sizes larger than 49-state bikes. I suggest anyone with a 49-state bike to go up 2 sizes before doing any other carb tuning. If I was tuning the OP's bike at this point I would raise the needle a bit and test ride. By the way, I no longer look at the plug when tuning a carb. I increase main sizes one at a time while doing a long uphill acceleration run against the clock. Times will decrease, decrease, decrease, then stay the same or slighlty increase as jet size increases. That "stays the same" jet is what I run. I do all other tuning by similar "seat of pants" analysis. Works for me.    Report

03-13-2010, 6:38 PM JoMomSophat Joined on 07-12-2006 Seattle WA Posts 824 Re: Round Slide Carb Tuning my old xt200 has a 24mm carb with a 122 stock main it is a 1982 so i suspect that it was made before the garbage emmissions laws. it is the same carb used on tw125 till they changed to a diaphram carb.just a single pull round slide carb tk y24p.    Report

03-15-2010, 11:54 AM treybrad Joined on 02-06-2010 PF, TX Posts 86 Re: Round Slide Carb Tuning TW-87 - The exhaust is possibly modified, but it looks intact. I cannot remove the end cap without damaging it to get a better look because the screw is stuck in there for good.... The airbox looks unmodified too -- no holes in the cover, the snorkel is still there as well. Spark plug was replaced with the proper non-R plug as listed on the frame. QWERTY -- One or two sizes seems reasonable, but 3-4? I did raise the needle this weekend (what a pain to access). I only spaced it up 1 washer, ~10mm, and it seems to have helped. Smooth and no pinging until I get to 80%+ throttle. It would start pinging a little at over 1/2 throttle before. Your tuning philosophy has been similar to mine thus far. I have yet to do a real plug chop, but I can feel the bike when it's lean, and hear the pinging. My top speed with the richer jets has improved from struggling to reach 60mph to easily getting to 65mph and topping out a little over 70mph. Jo -- That's interesting. I'm going to go ahead and order some jets from boats.net tonight, a 122 and a 124. I wish I had found that site before, $2.00 shipping sure beats $15 from the other vendors... We'll see what the larger main will do for me. I don't think adding another washer under the needle will help since the only problem I have now is slight pinging at 80%+ throttle. I'll just keep upping the main jet until it's too rich... Thanks for the help, trey '07 Suzuki Bandit 1250SA '97 Yamaha TW200    Report

03-15-2010, 7:42 PM TW-87 Joined on 02-01-2010 Manitoba, Canada Posts 305 Re: Round Slide Carb Tuning Hey Treybrad I just got my '87 on the road for the first time this year and tried it at WOT. Guess what ! It pings too, from about 3/4 throttle and up. It's been so long that I've had it on pavement at WOT that I completely forgot about this behavior. But now I hear it, I recall that it has done this for a long time, if not ever since I bought it. I guess I'm going to have to go through the whole tuning process too, since I now see that there is opportunity to make this bike run better. Please keep this thread up to date. I think we can help each other. I've searched the old threads as well and haven't found much about tuning the old (round slide) TK carb. TW-87 1987 TW200, 15/44 sprockets, DID O-ring chain, Award winning, "Quick Release" Action Packer :-))    Report

03-16-2010, 5:26 AM treybrad Joined on 02-06-2010 PF, TX Posts 86 Re: Round Slide Carb Tuning Well it's good to know that I'm not the only one. I'll be interested to hear your results as you sort it out. I ordered my 122 and 124 mains last night from boats.net -- hopefully they'll be in soon. Rode the bike around yesterday quite a bit and it runs great everywhere except that last little bit at WOT. I think another step or two on the main and I'll be all set. I'll definitely keep updating this thread, if nothing else so that users find something when searching... There's a surprising lack of specific info on the old carb. I guess at this point, most people have their 15+ year old bikes sorted, ha. trey '07 Suzuki Bandit 1250SA '97 Yamaha TW200    Report

03-21-2010, 1:54 PM TeeWee Joined on 09-05-2009 Finland Posts 105 Re: Round Slide Carb Tuning  treybrad wrote: My top speed with the richer jets has improved from struggling to reach 60mph to easily getting to 65mph and topping out a little over 70mph. Jo -- That's interesting. I'm going to go ahead and order some jets from boats.net tonight, a 122 and a 124. I wish I had found that site before, $2.00 shipping sure beats $15 from the other vendors... We'll see what the larger main will do for me. I don't think adding another washer under the needle will help since the only problem I have now is slight pinging at 80%+ throttle. I'll just keep upping the main jet until it's too rich... Thanks for the help, trey That´s sounds intresting. I have troubles to reach 100 km/h (62 mph) too and I have considered bigger main jet before I read this. treybrad, have you got your bigger jet installed yet? Do you have original sprockets (14/50)? Btw. what you mean by "pinging" and "WOT"? My english dictionary don´t recognize those terms... 1995 TW200G M6006 & Ceros 26x9 ATV-donut, front disc brake, bigger rear drum, round headlight with Bi-Xenon    Report

03-21-2010, 5:56 PM treybrad Joined on 02-06-2010 PF, TX Posts 86 Re: Round Slide Carb Tuning Hey TeeWee -- From the look of it (your avatar), you've got a monster rear tire... that'll probably have a huge effect on top speed. I have installed my 120 main jet, and spaced the needle up with one washer and I'm close. I'm still waiting on the 122 and 124 main jet to try those and I'm confident one of them will solve my problems. I'm just waiting on shipping.... I have a 15t front sprocket, the rear is the stock 50t. I'm not sure how much it has increased my top speed, if any, but it does cruise at a lower RPM (I commute on the bike on paved roads). Pinging is the sound that occurs under heavy throttle with the fuel pre-ignites. Here's a link, which is in English, but maybe easier to translate: http://en.wikipedia.org/wiki/Engine_knocking#Pre-ignition WOT = Wide Open Throttle, or full throttle. Hope that helps, trey '07 Suzuki Bandit 1250SA '97 Yamaha TW200    Report

03-22-2010, 1:11 AM JoMomSophat Joined on 07-12-2006 Seattle WA Posts 824 Re: Round Slide Carb Tuning Attachment: connector.gif don't forget the needle it controls fuel for a wide range of throthe inputs while the needle is more important in a diaphram carb you can't discount the performance boost in your slide carb from this simple adjustment. i used a round electrical connector (pic) i just cut off the round part with some side cutters and shimmed the needle .025" aprox. it works great. you can try to find some washer that will fit but i just used what i had on hand. since my needle doesn't have adjustment slots i estimated that from one slot to another is about .025" so it worked out just right now it pulls hard from low down runs fast at 1/4 to 3/4 where i usually ride. total cost for parts < ¢.02    Report

03-22-2010, 11:29 AM TW-87 Joined on 02-01-2010 Manitoba, Canada Posts 305 Re: Round Slide Carb Tuning TeeWee I agree with what JMS said above, however, as Qwerty and others have recommended, if you intend to adjust your main jet and your needle position it is best to get the main jet right first. Otherwise, you will end up adjusting your needle twice. Trey and I are trying to get our main jets sorted out and are both experiencing very similar results so far. He is currently at 120 and I am at 118, but we both are still experiencing "pinging/pre-ignition/detonation/engine knock" between 3/4 and full throttle (WOT) over a wide range of RPM. More details are available in the "Best main jet for the old style carb ?" thread. TW-87 1987 TW200, 15/44 sprockets, DID O-ring chain, Award winning, "Quick Release" Action Packer :-))    Report

03-22-2010, 6:24 PM ckahler Joined on 09-11-2009 Posts 42 Re: Round Slide Carb Tuning OK, I want to play too. I am thinking of starting with the stock jet, with the bike in high gear crusing at 40mph, crack to WOT, and time how long it takes to get to 60mph. I will keep increasing 1 jet size and try again on the same stretch of road and see which jet gives me the fastest 40 -60 time. I know nothing about selecting jets, so if this plan doesn't make sense, let me know before I start. Craig Kahler 1990 TW200 Craig Kahler    Report

03-22-2010, 7:38 PM WIJake Joined on 11-05-2009 Waterford, WI Posts 11 Re: Round Slide Carb Tuning What octane fuel are you running?  I have 2 '87 TW's and while both run very lean, I have never changed the mains, or found it necessary to change any settings on the carburetor.  If you are running 87 octane, I would try a tank of mid grade (89 around here) and see if you have a difference. Another cause on a used bike is that the previous owner may have had the head or cylinder milled, raising the compression.  And yet another source of the problem may be an air leak due to a poor carb mount to the cylinder.  This you can discover by having the engine idling and then spray WD-40 around the carb mount.  If you get a change in RPM, you know you have a leak. (While one might be tempted to use gasoline for this please don't, the risk of fire/explosion is great.) Just my $0.02 worth. Ride safe. Jake  Thinking about adding a 2010 Ducati 796! 07 HD Nightster 05 Ducati 749s (my son's race bike) 71 Kawasaki KX125 - Family Collector Bike 87 TW200 - 2ea! 99 Honda Shadow Aero 01 Honda 50 Elite Scoot 86 Honda 50 Scoot 86 Kawasaki KLF300    Report

03-23-2010, 11:07 AM TW-87 Joined on 02-01-2010 Manitoba, Canada Posts 305 Re: Round Slide Carb Tuning Hi Jake Thanks for your input. Both Trey and I thought that there must be a lot of people (like you) out there with "old style carb" experience. The input is trickling in, as you can see from this thread and the "best main jet..." thread. Others are welcome and encouraged to contribute too ! I am currently running 91 octane ( Esso premium). This is as high as I can get here without going to aviation fuel. As far as I can tell my change from 87 octane (regular) to 91 had no effect on my bike's behavior or it's "ping problem". (Oh for the good old days when regular was 88 octane and premium was 98 octane !) I am the original owner of my bike (Since August 1987), so no, the head has never been off. Until Trey stuck his oar in,  I was happily riding my bike and thinking that the pinging was normal. If I can remember back that far, I'm pretty sure that the dealer told me this when I bought it. I did know better at the time, but I had other things on my mind, so I bought the story along with the bike. I have not tried the WD-40 test yet. An air leak would explain my (recent) poor idle, and I've definitely fiddled with the carb enough this winter to cause a leak. However, when I think about the geometry of a carb at WOT,  I wonder if a small air leak could explain my lean burn at WOT ? In any event, I'll do the test. Thanks again. That input was worth a lot more than $0.02 ! TW-87 1987 TW200, 15/44 sprockets, DID O-ring chain, Award winning, "Quick Release" Action Packer :-))    Report

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