Yamaha TW200 Trailway Discussion Forum

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02-10-2010, 2:24 PM MacBookProTW Joined on 08-04-2008 Salem, Oregon Posts 94 Stalls except under load - Changed Title to clarify problem Those of you that have followed me have seen some of the crazy things I have gone through with this bike. That has made me overly paranoid for sure. I ride this thing super easy 99% of the time and it has ran perfectly since the new piston went in. Well I went trail riding the other day and had some issues that seem to come and go now. The bike works totally fine at higher RPMs, but when starting out it sputters a lot. When starting out it sounds as if the carb takes too longs to open up or something. This carb is weird to me and different than others I have worked on. I cleaned it out and used compressed air everywhere on the thing so I'm sure it isn't dirt, but that doesn't mean that maybe one of the springs or weird rubber diaphragms isn't messed up. I checked the valves and got them all in spec. Checked compression and mine has always tested slightly lower than the books at 100-110psi. I think the book states 128 or something, but it has always been around 110 except when the valves needed lapped or the top seal was out. The plug looked normal and may have shown slightly lean, but mostly just chocolate colored. (I'm colorblind). The top of the piston looked good when shining a light on it and wasn't blackened like it was on my previous post. My thoughts are maybe the Cam chain has finally began to wear enough to throw the timing off. I haven't checked the timing yet and plan to tonight. If it is off then I will adjust and test it out on the trip to work again in the morning. Any other thoughts from the hive? 2005 TW200 14,500 miles some people's kids    Report

02-10-2010, 11:13 PM MacBookProTW Joined on 08-04-2008 Salem, Oregon Posts 94 Re: Sounds rough at lower RPMs I checked the timing tonight and it was spot on perfect. I also took the pipe off just to be sure it was all clear. The spark plug gap seemed slightly tight at .16 in and I put it in spec at .24 in. I will test out tomorrow on my morning ride and report back. some people's kids    Report

02-11-2010, 1:03 AM TrailWhale Joined on 04-20-2009 Lancaster, PA Posts 57 Re: Sounds rough at lower RPMs I sure hope you don't actually mean what you wrote.  The spark plug gap should be 0.024", not 0.24".  What you wrote is literally a quarter of an inch - which would certainly make the engine a bit rough at idle!  Good luck. - - - Happy trails, Jim Most problems can be solved with a suitable application of throttle! 2001 TW200 Yuasa YTZ7-S AGM Batt + Tender Jr.; fuel filter; socket head cap screws to fasten seat; homemade rear rack; D2Moto 1993 XT350 (sold) 1987 TW200 14/55+Oring (sold)    Report

02-11-2010, 7:58 AM TW-87 Joined on 02-01-2010 Manitoba, Canada Posts 305 Re: Sounds rough at lower RPMs If it's too lean "when starting out"(for any reason), putting on a little choke will improve performance. This is not a solution to your problem, just a test to help you diagnose the cause. TW-87 1987 TW200, 15/44 sprockets, DID O-ring chain, Award winning, "Quick Release" Action Packer :-))    Report

02-11-2010, 8:30 AM MacBookProTW Joined on 08-04-2008 Salem, Oregon Posts 94 Re: Sounds rough at lower RPMs It was late last night so yes it is .024 and not 1/4 inch. I'm not even sure it would start with .24 it ran slightly better this morning but as it warmed up it got worse. I can still run at high RPM great and the bike will go up to around 70mph no problem. I will try the choke diagnosis tonight on my way home. Could it be thy my carb needs a rebuild or something? It is totally unmodified from stock and has never been since I owned it. I have cleaned it a few times but this totally seems like a fuel/air issue. some people's kids    Report

02-11-2010, 8:43 AM TW-87 Joined on 02-01-2010 Manitoba, Canada Posts 305 Re: Sounds rough at lower RPMs If the choke helps, try a fill up with 100% real gasoline vs. gasohol. For an explanation, search this forum for "gasohol". TW-87 1987 TW200, 15/44 sprockets, DID O-ring chain, Award winning, "Quick Release" Action Packer :-))    Report

02-11-2010, 9:16 AM TW-87 Joined on 02-01-2010 Manitoba, Canada Posts 305 Re: Sounds rough at lower RPMs A very informative and entertaining thread on this subject is at: http://tw200forum.com/forums/81471/ShowPost.aspx TW-87 1987 TW200, 15/44 sprockets, DID O-ring chain, Award winning, "Quick Release" Action Packer :-))    Report

02-11-2010, 9:26 AM MacBookProTW Joined on 08-04-2008 Salem, Oregon Posts 94 Re: Sounds rough at lower RPMs I have read all that, but I have changed no fuel source and the day it started my buddies Tw was running in the same exact gas with no issues. It starts fine, but when starting out from low idle it crackles and pops an when shifting sometimes too. It is basically when the RPMs drop below a certain threshhold that it feels like the carb isn't adjusting fast enough to the change. some people's kids    Report

02-11-2010, 10:50 AM uktw125 Joined on 06-05-2008 Devon, England. Posts 143 Re: Sounds rough at lower RPMs If it starts from cold fine and gets worse as it warms up then that sounds like it is too rich on the pilot jet. This jet controls fuel mx at idle and low RPM. Search on here for adjusting the carb and pay particular attention to the little screw on the underside of the carb, if you have not touched this before it maybe covered with a little cap. I doubt if it is a mechanical issue.    Report

02-11-2010, 2:09 PM MacBookProTW Joined on 08-04-2008 Salem, Oregon Posts 94 Re: Sounds rough at lower RPMs why would it all of a sudden be to rich? wouldn't it just be easier to change the jet than mess with that screw for mixture? some people's kids    Report

02-11-2010, 3:59 PM TW-87 Joined on 02-01-2010 Manitoba, Canada Posts 305 Re: Sounds rough at lower RPMs Another possibility is a problem with the CDI or magneto / stator coils. The output voltage from the stator coils and the pulser coil increases with increasing RPM. Any problem with the output of these coils (or the CDI) which is sensitive to lower voltages will therefore be worse at lower RPMs. TW-87 1987 TW200, 15/44 sprockets, DID O-ring chain, Award winning, "Quick Release" Action Packer :-))    Report

02-11-2010, 4:21 PM MacBookProTW Joined on 08-04-2008 Salem, Oregon Posts 94 Re: Sounds rough at lower RPMs I would think the CDI would be more likely if it ran rough when just idling, but if I keep a steady throttle it seems fine at most RPMs. some people's kids    Report

02-11-2010, 6:51 PM TW-87 Joined on 02-01-2010 Manitoba, Canada Posts 305 Re: Sounds rough at lower RPMs Have you adjusted your cam chain since your last rebuild ? TW-87 1987 TW200, 15/44 sprockets, DID O-ring chain, Award winning, "Quick Release" Action Packer :-))    Report

02-11-2010, 10:38 PM MacBookProTW Joined on 08-04-2008 Salem, Oregon Posts 94 Re: Sounds rough at lower RPMs It is auto adjusting on this model from what I understand. I also tried the choke thing and it seemed to make it maybe slightly better, but it still sputters. I noticed that it seems to sputter only when there isn't a load on the engine. As soon as the engine has to work some it accelerates just fine and with little to no sputtering. If I let off the throttle it sputters down quickly and then sputters some when I apply throttle until it is put under load. I noticed last night that I had one lose head bolt. Number 3 if you know the criss-cross pattern in the manual. All the rest were at the correct torque and when I went to torque that one it felt stripped so I stopped at 10 ft lbs. Not sure how it would be stripped and there are no leaks at all anywhere. Probably because there are the 2 hex bolts on that side of the engine. It looks as though I will have to take it apart to fix the threads though which sucks. some people's kids    Report

02-12-2010, 1:30 AM uktw125 Joined on 06-05-2008 Devon, England. Posts 143 Re: Sounds rough at lower RPMs <BLOCKQUOTE><table width="85%"><tr><td class="txt4"><img src="/Themes/default/images/icon-quote.gif">&nbsp;<strong>MacBookProTW wrote:</strong></td></tr><tr><td class="quoteTable"><table width="100%"><tr><td width="100%" valign="top" class="txt4">why would it all of a sudden be to rich? wouldn't it just be easier to change the jet than mess with that screw for mixture?</td></tr></table></td></tr></table></BLOCKQUOTE> These things go out of tune occasionally. The little screw is to fine tune the jet that is installed as every engine requires it own set-up. You later said that using the choke improved things a bit, now that is strange because that is a symptom of a lean mixture but you also have symptoms for a rich mixture (easy starting, worse as it warms up). I would strip and clean and adjust the carb again and pay particular attention to the pilot jet circuit.    Report

02-12-2010, 8:39 AM MacBookProTW Joined on 08-04-2008 Salem, Oregon Posts 94 Re: Sounds rough at lower RPMs I will try that. I think that it only showed slight improvements because it raised th RPMs. It still was popping some. I will try pulling it and cleaning it again and then see if I can find that screw. I blasted everything with cleaner and blew it out with 90psi of air so I'm almost 100% nothing stuck around. I did clean the pilot more than anything because I figured that was the culprate. Should I look at getting a bigger pilot jet today or will that screw let me adjust enough to solve this issue? Is the strippedish 10ft lb head bolt maybe the issue? Last time I had a stripped head bolt my piston was burned up, but this thing runs better at high RPM so that seems unlikely. Though it ran totally fine until opened up last time. I just have bad luck I guess. some people's kids    Report

02-12-2010, 10:55 AM uktw125 Joined on 06-05-2008 Devon, England. Posts 143 Re: Sounds rough at lower RPMs I would not buy a bigger pilot jet. When you take the carb off turn it upside down and you should see a hole with a blanking plug (if it has not been removed) in it, drill a tiny hole through the plug, go very carefully and don't drill the screw underneath it, then get a small wood screw and screw it into the new hole 'till it grips then pull the plug out. You will now have exposed the adjustment screw, take it out along with all the other jets and components and clean it thoroughly. When you reassemble this screw should be screwed home gently then screwed back out about 2 1/2 - 2 3/4 turns. There are some good threads on here with step by step pictures that are much better than this explanation, so well worth searching for. Pilot adustment, blanking plug, adjust mixture etc, etc.    Report

02-12-2010, 11:18 AM MacBookProTW Joined on 08-04-2008 Salem, Oregon Posts 94 Re: Sounds rough at lower RPMs sweet I will give that a shot here shortly. It is my day off so I have a bit more time to play with the carb today. I'm pretty sure the carb is clean, but I will take it off and make sure. What about the partially giving out head bolt? nobody has commented on that yet? It is the one that would be left side of the bike while sitting on it and the one closest to the carb. I really don't want to take this thing all the way down that far again for awhile. some people's kids    Report

02-12-2010, 11:28 AM uktw125 Joined on 06-05-2008 Devon, England. Posts 143 Re: Sounds rough at lower RPMs If the head gasget is not leaking or the base gasget leaking oil I would just keep an eye on it and worry about it when and if it starts to leak.    Report

02-12-2010, 12:05 PM ckahler Joined on 09-11-2009 Posts 42 Re: Sounds rough at lower RPMs I had the same head bolt problem last year when replacing the head. I was using a torque wrench, but one of the head bolts stripped just before I got it to recommended torque. I just left it as it was and haven't had a problem with it yet. Should the need come up for me to remove the head in the future, I will deal with the thread repair then. Craig Kahler    Report

02-13-2010, 2:26 PM MacBookProTW Joined on 08-04-2008 Salem, Oregon Posts 94 Re: Sounds rough at lower RPMs okay so I have played with some different settings on that pilot screw. It was at 1/2 turn out stock which seems way further than most have said on here. I tried out at 3 first and still got the popping and hesitation until the RPMs got higher. I then tried 1/2 turn in from that with same results. Then stepped down at 1/2 intervals to 1 turn out. My best result was at 1 turn out and half to full choke on. It seemed closest to normal only with the choke out though. Riding it down the street it seemed a bit better than it did yesterday afternoon but it was still popping at 3 turns out. Does this mean I need to get a bigger pilot jet and then try this again? some people's kids    Report

02-13-2010, 5:31 PM TW-87 Joined on 02-01-2010 Manitoba, Canada Posts 305 Re: Sounds rough at lower RPMs I think that this means you are barking up the wrong tree. The difference between 1/2 turn and 3 turns on the pilot screw is huge. I'm sorry to say this, but your symptoms sound a lot like mine. My bike pops and misses at any and all RPMs but a little less at higher RPMs. I have isolated my problem to the high voltage coil on my stator. It started out as an intermittent, resulting in an intermittent spark. After much much testing and eliminating everything else but the kitchen sink I have isolated the problem to this coil (R Br) on my 1987 TW. (Fourcycle predicted this, based on my symptoms).This coil now measures infinity ohms (open circuit). I am planning to tell the whole story in detail under "another CDI question" because I think that thread may also share my root cause. In the mean time you can put an AC voltmeter across your high voltage stator coil, and mount it where you can see it while you're testing the bike, If the output goes away when your bike misses, you have found the cause. My bike does this. The meter should read continuously as long as your engine is running (with voltage roughly proportional to RPMs). TW-87 1987 TW200, 15/44 sprockets, DID O-ring chain, Award winning, "Quick Release" Action Packer :-))    Report

02-13-2010, 6:19 PM MacBookProTW Joined on 08-04-2008 Salem, Oregon Posts 94 Re: Sounds rough at lower RPMs I'm not ruling out an electrical issue just yet, but it has never popped or skipped at higher RPM. I know what a skip sounds like as I have had bikes that did that and this sounds like an adjustment issue and rich or lean issue. That being said I just put the carb in an ultrasonic bath of vinager and water and after removing the pilot adjustment screw all the way found a bunch of crud in there. Not sure I it was just from drilling and removing it for the first time, but it looked like it was in there to me. That could toally have been the issue and we shall see later tonight or tomorrow. some people's kids    Report

02-14-2010, 8:26 AM WINGNUT200 Joined on 01-16-2009 St. Paul Posts 65 Re: Sounds rough at lower RPMs I read your thread about a loose cylinder bolt I think if you ran the bike very long like this or real hard at high RPMs maybe you stuck or broke a piston ring??? I had just turned 10,500 miles on my TW and lost compression I bought a top end kit and after looking at the cam chain I think mine either jumped or broke. For those about to rock!    Report

02-14-2010, 8:35 AM MacBookProTW Joined on 08-04-2008 Salem, Oregon Posts 94 Re: Sounds rough at lower RPMs I'm only a few thousand miles into the piston and my compression hasn't changed since the new piston was put in. The bolt is at 10 Ft lbs and is next to the other bolt with no leaks so I'm certain it hasn't moved. I got the cab back together las night and took a little ride. I adjusted out to 3 turns on the pilot adjustment screw and it seemed to make a huge difference now. I got very slight popping when hitting the throttle from and idle, but none besides that. I'm going to ride a bit more today and tomorrow and possibly go out to 3 1/2 turns and see if it rids the bike of the popping. Keeping my fingers crossed. some people's kids    Report

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Yamaha TW200 Tr... » TW200 Forums » TW200 Technical... » Stalls except under load - Changed Title to clarify problem

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