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'88 XT600U bog and backfiring
I recently bought an 88 XT600 that wouldn't start easily or stay running, but sounded good when it did. It sat for 2 years so I figured clogged carbs. Well I cleaned them(twice actually) and made sure no plugged holes. I got it running and it ran great, full throttle and all.
I filled with gas(it was old gas in it), 93 super unleaded here in the states, went 2 miles toward home and it suddenly bogged like it was working real hard and kept popping/ backfiring. till it died, wouldn't restart. after a bit with full choke it did start but same thing and died. Recleaned carbs, made sure no air leaks(even put light silicone sealer on some things). It then started up and ran perfect, idle smooth, let idle for a couple minutes then bog and popping again and it died. I belive it would be the cdi or coil( it didn't seem to have great spark, but the bike is new to me so I don't know how good it should be) the plug color looked a bit lean and even after kicking on full choke it was dry. That says fuel issues, but outside of some internal air leak or out of spec part it isn't a clogged jet or port. BUT the popping and bog when it gets warm says cdi. Any of you that have been running these bikes have some possible solutions? Thanks JJ |
No I didn't , the pin wouldn't come out easily and until I had a new needle valve and pin I didn't take it out, which I have ordered because I wanted to replace it anyways. I also didn't know it had a screen like that and that would make sense. The one question on that would be, when it did quit, I opened the bowl drain screw to check for fuel and it did come out, but whether there was enough,I don't know. It wouldn't start this morning after 8 kicks on full choke. I'm going to squirt some gas and a little oil in the cyclinder tonight. If it fires up, I know it is mostly fuel related.
Thanks for the picture, it shows what is in there. |
Try a simple one first - a new spark plug. I had an XTZ that did something similar thing once and it turned out, after multiple carburettor cleanings, to be that. The plug gave a fine spark when out of the cylinder but was breaking down when under load.
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A quick update today, I put in a different plug, still nothing but backfiring( had to stop and sleep with icepack around my ankle, afraid of it being broke from one nasty pop). Now decided to kick with my motocross boot on right foot.
I decided to rollback to when it quit running, about 1.5miles AFTER filling up with 93octane GAS. Drained gas out of tank and float bowl and got 87octane from a different company. About 6 good kicks it fired up and is running, let it idle for 3-4minutes, went around the block a couple times. It does still have a skip in the firing, runs perfect under acceleration(easily hit 85mph and still going), with a steady throttle it has a stumble. Any ideas what the steady misfire would be? Has no backfiring, plug now looks good color. Over tightened valves? Do these motors get tight or loose with wear? No knocking or ticking at all, entire motor sounds smooth and has great power. I'm going to really like this bike once it is straightened out. |
Dirty fuel filter
Carb failure Faulty ignition coil Faulty pickup coil Bad CDI unit |
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They are rubber bonded to steel and they deteriorate over time. Unless they have been replaced in the bikes life you almost certainly have this problem. |
The boots are in perfect condition, the previous owner apparently recently replaced them. This morning it took squirting gas down the spark plug hole to get it fired up without a bunch of kicking, then it ran as normal. Dies when I pull the choke out, so it is working. Spark plug now is all sooty black. I'm looking into getting a CDI and coil, even if they turn out to be backups. More carb work is in the works also.
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Yes, it has now been replaced along with the needle(or plunger) since the parts came in yesterday morning. It wasn't plugged, but it wasn't completely clean either. ran it to work today and bombed around, takes about 8 kicks on full choke or a squirt of gas down the plug hole to get started after it sits for a couple hours and has that steady stumble but stays running and runs perfect accelerating. It's definitely something in the pilot circuit(low speed) or an electrical thing.
Time to put in my pair of Mikuni's from a Raptor 660:funmeteryes: This bike is awfully skittish, it wants to shift back and forth like on glare ice. Picture hanging the bike by the frame and swinging it side to side, that how it drives, even on asphalt, worse on gravel. Needs some better tires. |
There was no inline filter other than the petcock tank one. I have one that is going in. Right now it will hardly start unless I squirt fuel directly into the cylinder through the spark plug hole or kick with all I've got 8 to 10 times(it messed up my ankle again this morning when it backfired trying to start it normally:censored:). That says it isn't getting enough gas to start, BUT, once it starts, it'll run till the tank is empty, so I know it is getting enough fuel into the carb, plus I've made sure the bowl is full repeatedly.
It simply is the carb start circuit or a spark issue, I've checked spark multiple times now and it really snaps, but whether it is doing it on-time(aka bad cdi or coil) or under compression is the question. If it was an issue with fuel delivery to the carb, it would run out of gas after it is started, but it doesn't and plenty of fuel comes out of the bowl when I open the drain screw. My ankle is telling me to walk away from this bike right now.Or should I say limp!! My Honda XL600r starts up in one kick!! But the Yamaha is in way better shape. |
your problem with having to kick it 8 times is either technique or decompression cable is not well adjusted.
Personally, I believe the decompression cable/adjustment is The weak spot on the XT I do not have the decompressor assembly fitted on my 1990 XT600E (retrofitted the kickstart) and I find it very easy to kickstart her in one, sometimes two kicks if she's been sitting in the garage for weeks.. Have you gotten your ankle checked out before? heal fast! |
When it pops is imediately after the decompression lever snaps back shut. With it set right now, as soon as the kick starter starts its cycle the cable begins pulling on the lever. It opens it further all the way till about the halfway point(kick start lever is approx level with the ground), then the lever on the motor snaps closed, so from that point on there is no decompression. Its at the point the the motor fires, if it starts, or pops and kicks back on the lever.
As for my ankle , right now it is swollen and a big black and blue bulge , hurts like h**l to walk on. If it turns greenish-yellow, time to get an exray! |
With some time to look and tinker, I hate the decompression system on this bike, and have an extra handlebar perch and lever for my Honda's manual system, I am thinking of running that on the Yamaha so I have control over it. The whole setup is similar on both and all it would take is a long enough cable to loop around the motor so it comes from the same side as the kicker cable. As long as the bike can fire without full compression, it should fix a big part of the issue.
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I feel the pain of the kicking. :funmeterno: It might help, or even amuse, you to know that I have been down that road back in 2007 with my ttr600. I suggest you take a quick read of this thread about kicking over that engine:- http://www.horizonsunlimited.com/hub...arting-26306-2 |
By the sounds of it the TT600 has a handlebar mounted decompression lever? The TT model must have been a Europe version of the XT or something like that, none of my OEM parts sources lists a TT600. I found a picture of a TT head and it has the same decomp. lever and bracket as mine so the handlebar perch and cable from a TT should be a direct bolt on.
I did rotate the kick start lever by hand slowly till it hit tdc and just barely went passed it, my brother gave it a good kick and on the second try it fired up and ran smooth, no squirting gas down the sparkplug hole first. It idled smooth with no miss or stumble for about a minute then slowly started to do its normal uneven firing. We went for a 15mile ride and it ran fine with just the stumbling at 2600 to 3200rpm range, above that it didn't miss. Once warmed up, at idle it sounds like it fires only every other compression stroke instead of each one. Doesn't die or seem to even want to die but just has that slow and steady pattern of firing. Motor is dead quite as far as ticks or knocking. I did notice that my headlight dims each time the turn signal blinks( engine at or just above idle rpm), I think it's normal for that age of electronics. I'm going to switch all bulbs out with LED's if possible. I'm hoping to get a spare cdi and coil to swap out as a possible cure to the missing(unless this is the normal way these engines run, as I said, this line of bikes is new to me). I doubt it though. Thanks for all the help and suggestions , it saves lots of hours of guessing and parts changing(when they are not needed).bier |
An update, after a week or so, I had been running the bike, it started good in about 2 kicks on full choke, it always ran perfect for about 1 minute, didn't matter if choke was on or off(high idling). then it would start to do its stumbling, never acting like it wanted to die but just nothing will stop the miss. Going down the road, under acceleration, it ran perfect, steady throttle=miss. Filled up with premium(it had 87octane in it), ran it 2 miles home, missed the same. Next morning started up first kick, ran for 5seconds, quit and won't start, even dumped some gas down the sparkplug hole, it just backfired at messed up my ankle again and actually broke a buckle on my motocross boot plus broke the kickstarter stop bolts inside the motor.
This is the last straw for me and this setup. If I can't make it electric start( I can't find "E" model parts here in the US, only kickstart years, except brand new$$$$, I wonder why?? Since I will not ever attempt to kick it again, I won't be able to even try to fix it unless there is some mechanical way to turn it over soooo I'm ripping it apart to 1) put in a Honda motor I have that Will not kill me 2)recoup my money by ebaying as much of the parts and say good riddens. The sad part is the bike is in mint shape, never tipped over, never run offroad, adult owned, it looks like it is maybe a couple months old!! It just does no good if it can break bones at any moment or be impossible to keep running. Ya for another $500-600 I can buy every electrical component and "hope" it works, nobody can say what is failing, so all that can be done is to buy, buy, buy and hope! I bought this bike to save money on gas, :thumbdown: |
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No, the decomp system is automatic on the TTR600, much as you have been dealing with I guess; a cam system that lifts the valve as the engine is turned over. Anyway, sorry to read about your ongoing issues with your own kicker. I got into the habit of kicking over the TTR600 engine while standing next to the bike - on the RHS and kicking with the right leg. This was partly because of the height of saddle but also because when it did backfire I did very little damage to my foot/ankle because I used the forward (toe) part of my boot rather than the instep. When it did backfire, my foot was more flexible and would just fly off the kicker instead of taking a "rebound" via the length of my leg. It's also an easier kicking stance when you are fiddling with the carb at the same time (I had float valve problems). |
My XT600 has never injured me. Actually I can kickstart it with slippers! It probably only backfired once, when I had a broken decompression cable, and had to start the bike without it for a few days in a row... I don't really know why but it's really easy kicking.
I had a Suzuki DR600 before Yamaha, and the Suzuki was a pain in the ass to kick! It had both manual (with hand-lever) and automatic (with kickstart lever) decompression systems. I was fiddling with both cable tensions, and nothing worked. I got some backfires, but they only threw my leg in the air so my boot sole scraped the top of the tank. But one time it backfired so bad it really injured my ankle, and I almost passed out from pain. I ended up selling the bike and getting an XT600 with kick and electric start (back then I did not know how easy XT600 starts... At least the ones I looked at and took for a spin before buying). Maybe it's because of it's age (different model I mean). Your Yamaha is '88, my Suzuki was '86 or '87 I can't remember now. And my Yamaha is '93 with '97 engine. Maybe they improved something over time? I'd say don't do quick decisions, heal up, let it sit a while, and if it doesn't kick over EASILY with ignition off, then don't try it with ignition on... Or it will hurt you again. I was limping for a few months when I injured myself. Don't know what advice to give right now... Just heal and think. It will come to you. P.S. maybe your ignition timing is too early? |
Zergman, I had a '91 Suzuki DS650 and it kicked easier than this one, plus never backfired on me, though I bought it new and owned it for 3 years so it wasn't to that "aged" point where things act up. I regret selling it to this day!!
In 1990 quite a bit changed on the Xt's bikes(now looking how to add electric). The carbs are different to a point, then totally change in '95-'96ish, after 1990, non here the states as far as can tell had kick, that is also the cutoff year for used parts on ebay, very few parts after '89, I think that says that once the electric comes out, most people keep them going rather than scrapping them. I'm quite sure it is firing early, and that's the backfire. I spun the motor over by electric drill yesterday on the stator nut and it was sparking like crazy, so spark+gas+air = running, unless timing is bad. No adjustment for timing though and $125-$200 for a used cdi that "may" work, or another $125+ for the used pulse pickup and stator, which is the other likely culprit. I'm trying to picture how Walkabout started his, by standing on the right, I'd have to kick with my left, and then a backfire would likely put my knee into my chin:nono:. Right now to kick mine, I have to push down on that kick lever like I'm tring to drive it 2 feet into the ground, it's that speed that it takes to fire it up, slower results in these backfires usually. I was hoping to do some traveling up north this summer, possibly into Canada, but I need a bike that I can rely on, my '83 Honda isn't a long distance runner anymore, though reliable, just getting worn out. |
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ttr600 in Motorcycles & Scooters | eBay Hence, with short legs, my starting technique was to stand next to the bike and kick it over using the right leg - kind of reaching across with that leg & with the body weight on the left leg and close to the bike for overall balance. Here's another earlier thread about kicking over the TTR, but it applies to the XT as well, IMO (but your use of the throttle on start up might vary):- http://www.horizonsunlimited.com/hub...00-r-how-32814 ps The search in here works quite well nowadays (it didn't always). You can see more threads about kicking over your bike in here:- Search | Horizons Unlimited |
Before this last "episode" I attempted the procedure listed above for turning it over 2 or 3 times then going till the decompression lever clicked, then let the kick lever up to top and then gave it the almighty startup kick. It backfired every single time I did that, so I quit it. Up till this it didn't backfire at all since the last bad one and it was starting reliable 1 or 2 kicks, just had that constant stumble/miss. Also the last time it did this I had just filled up with super unleade 91octane, then by draining and switching to 87 from another station, it started up again. I was running on that gas all the while till I filled up again with 91super, but at the same station that I got the 87 from.It wouldn't start after that. It couldn't possibly be that it HATES 91 octane (no ethanol), and will only run on 87(with ethanol)???? I do know the bike is running rich, black sooty plug, but I put in an iradium plug the morning before.
Is there any chance the regulator could cause the miss, due to it not missing for the first minute, then the miss starts. Also when I rode to work at 40F, it ran better(less missing/stumbling) than when the temp was warmer later in the day. Something was staying cooler and allowing it to run better. The rich running condition wouldn't cause that much missing could it? Smaller pilot? lower the needle in the primary carb? Out of sinc carbs? It ran great under acceleration! |
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Buying one is the obvious way, but swopping out, temporarily, with a buddies bike is an alternative. The prices you mentioned earlier are in the same ball park as those asked in the UK, if that is of any consolation. |
I know how frustrating it gets... Again, with a DR600, if I failed to kick it first try - forget it, it won't start (or it will backfire badly). Even warm/hot it was a misery to kickstart it. Always jumping on the kick lever as if I'm willing to break it, or as you say, bury my foot 2 feet into the ground. But it ran really good once started!
Get a manual, check the pickup coil for resistance, if it meets specifications, then CDI if it meets specs. Something is wrong with it, and it's no miracle... Find a good (bike) electrician, maybe he could shed some light on it. I've heard of electronic bike/car components that used to function too early when warmed up. It might be the case there too. Good luck! Tadas. |
Well I got the replacement parts that broke from the kickstarter backfiring. I see that when it does this I am still pushing on the kicklever and it prevents the starter cogs from disengaging and it slams into the stop plate, thus shearing the bolts(which are not made anymore).
I got a low mile cdi online to swap out plus drained the 91octane premium gas and put some 87 back in. I took the chance and decided to start it and concentrated on "the procedure". It fired up in 2 kicks and ran same as usual, purred great for a minute then started to miss, but not nearly as much. I did turn up the idle speed and that helps. The local Yamaha dealer told me in all the years working on these and other Yamaha's, the number 1 failure electrical part is the pulse pick-up, by a big margin to the next part =cdi. So I am looking for a new stator/pulse generator for the bike.(I don't care to buy this one used). I've seen several companies that offered some but they all are different from each other so I have to do some calling to find which one is the correct one. |
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