neil.nu.archive :: TZR The TZR forum

TZR » Tech » 3XV » Ugly plug.

[ Track this topic :: Email this topic :: Print this topic ]

pdxjim Group: Members Posts: 94 Joined: Oct. 2005 Posted: June 04 2007,06:48 Things were going great on my big ride until about 150 miles from home when I started dropping the right/lower cyl.  It would cut in and out, and I couldn't quite tell if it was ignition or fuelling.  I pressed on until it got too bad to bear, and pulled the fairing and the right side BR9EG.  This is what I found: The insulator and electrodes are covered with grey deposits that look suspiciously like melted aluminum(!).  This was after extended running at 7-9k rpm for maybe 4 hours.  I would slow down and speed up as the roads demanded, but for the most part 7-9k rpm Freeway and A/B roads. I swapped out the fouled BR9EG with a B9EG scrounged from a fellow rider.  The bike ran great once again, and we pressed on for maybe 30 more miles until I remembered I had a proper BR9ECMVIX stashed away in the tail.  The B9EG looked to be going the way of the previous plug and was growing similar deposits to the one in the pics.  I swapped it out for the BR9ECMVIX for the remainder of the trip(100 miles), and it now looks the proper chocolate color, shows none of the symptoms of the previous plugs, and the bike runs great.   WTF happened?  Bike is a '91 R model with everything standard, properly oiled filter elements and standard pipes with carbon cans.  Temp guage never climbed above 90c the whole trip. I haven't peered in the plug hole yet, and haven't pulled the head, as I haven't a replacement gasket on hand. Back to top

pdxjim Group: Members Posts: 94 Joined: Oct. 2005 Posted: June 04 2007,07:09 The only variable I can think of is altitude.  Altitude varied from maybe 1000ft. all the way up to almost 6000ft.  The plug started acting up at (guessing) around 3500ft. cleared up as we dropped down closer to sea-level, and then got worse as we climbed back up.  Final plug swap was back at about 3500ft. and run down the mountain back to Portland which is at about 750ft. As I understand it, higher altitude makes the bike run richer, so don't really see the corellation. Back to top

Warwickb Group: Members Posts: 1911 Joined: Sep. 2003 Posted: June 04 2007,12:09 Certainly looks to have been running pretty hot, Jim! It would probably be best to check the piston, cylinder and head for damage too, as it looks as though it's been detonating quite a bit. What size main are you running in that cylinder? Looks like it might be an idea to go up a bit - and check the needle position too if it was more mid throttle running that caused it. What pipes and air filters are you running? It would also be worth checking fuel filters in the tank and in the carb stubs to see if they are causing a bit of fuel stravation? And maybe check the float/fuel heights for teh same reason? For info: I run B10EVX pulgs in my 'hot' motor, but have never had any problems with B9s on a stock motor. Luck Wb -------------- A garage overflowing with old stinkers... Back to top

pdxjim Group: Members Posts: 94 Joined: Oct. 2005 Posted: June 04 2007,15:57 As stated, all carb settings, filters and pipes are standard except for carbon silencers. I will clean the petcock filter and carb inlet filters asap, but will need a head gasket before I can get the head off. Back to top

Warwickb Group: Members Posts: 1911 Joined: Sep. 2003 Posted: June 04 2007,17:34 You can remove the cylinder and head complete at the cylinder base instead, Jim if that's easier. This has teh advantage of leaving the head gasket undisturbed if the head is OK and you don't need to seperate the cylinder and head. I have also re-used head gaskets many times without problem - you need to clean all the  rubber cotaing off them with wire wool on a flat surface and then re-coat them with a good HT gasket sealant when putting back together. But I have done this successfully on countless occasions. I'va also re-used base gaskets without problem too, but these are quite a bit cheaper than the head gaskets so new ones are a better idea.  You can use TZ250 base gaskets instead of 3XV ones (go for the .6mm size) if these are more easily available. RS Cycles in California (they have a website with online ordering and part number search) should be able to provide the base gaskets form stock. They may have to order teh head gasket though so if you do replace it, you could probably oredr from any Yam dealer with the part number and it would probably be just as quick. It certainly looks to have been running pretty lean there somewhere. This could just be a result of using diff silencers with the stock pipes, so maybe jet up a bit on teh mains and do a plug chop to see if it gives a good plug colour. If it were me though. I'd get both cylinders off and get them ported to SP spec, and look for some better pipes. SP porting, with good pipes and the stock R type -00 CDi should give you an extra 10 Bhp or so. Then you'll be wanting a sugo box to really get it flying... So think of this minor setback as a development opportunity. Good luck Wb -------------- A garage overflowing with old stinkers... Back to top

gbowie Two stroke spirit Group: Members Posts: 264 Joined: May 2006 Posted: June 04 2007,19:32 Looks to me like you picked up some water in a fill-up..I have seen similar signs in outboards. Water tends to migrate to the bottom carb. The outer rim of the plug should indicate the combustion chamber colour, in this case oily - from misfiring. Could be way off the beam though. -------------- You'll live a lot longer if you give up the things that make life worth living ! Back to top

Warwickb Group: Members Posts: 1911 Joined: Sep. 2003 Posted: June 04 2007,19:58 Could be, I suppose, Geoff, but that completely melted electrode (esp' in the first pic) would indicate a good bit of heat in that thar cylinder head wouldn't it? My money would be on a lean burning situation. Though it is a little odd that teh outer rim of the plug is so dark. Maybe from misfiring when the plug was breaking down? Either way, I'd want to check the condition of the cylinder, piston and head - and (especially as it's the lower cylinder) that's a relatively quick and easy job. Let us know what you find, Jim. Whatever you find, you can bet that both Geoff and me will have seen sights much more horrific whjen uncorking 3XV motors   Cheers Wb -------------- A garage overflowing with old stinkers... Back to top

Warwickb Group: Members Posts: 1911 Joined: Sep. 2003 Posted: June 04 2007,23:45 Just noticed teh bit about the guage '...not going above 90 the whole trip.' I've never seen any of my 3XV guages go above 70 absolutely max - and if they got anywhere near 90 I would be very concerned . I reckon that you are running very hot (what was the other plug like?) and that that will be the reason for the burned out plug (though I'd also be really interseted  in what other's bikes normally run at. All of mine seem to run at about 65 degrees opr thereabouts whatever the conditions. If mine are typical then the question is why was yours running so hot?: Too lean? Fuel starvation? Poor cooling system? (check rad and thermostat, flush the whole system and ensure you are not loosing coolant) Doubt it is related to ignition or head volume etc., as you say that's all stock, but something is making it hot - and I'd be pretty surprised if the head and piston crown aren't a bit peppered with detonation (at least) when you open the motor. Out of interest what is the internal diameter of the silencer at the exit tube? If it's less than 23mm (the internal dia of the stock exhaust stinger), that in itself might be lifting up piston crown temp too much under the constant loads of the long journey you did. Thats the theory in any case... Let us know what you find when you crack it open. Cheers Wb -------------- A garage overflowing with old stinkers... Back to top

pdxjim Group: Members Posts: 94 Joined: Oct. 2005 Posted: June 05 2007,02:06 First off, The guage never went above 65-68c.  I'm not too familiar with the celcius scale, and was quoting that from memory.  Just went and had a look at the guage and 65-68 is where it was all weekend. The watery fuel theory is a likely culprit.  I was fuelling up at (very) rural filling stations whose tanks probably hadn't been flushed in decades. Not sure if this is the right thing to do, but I filled the coolant overflow bottle to between the lines before my trip.  It was nearly empty afterwards? I.D. of exhaust stinger is 25mm. The pics make the plug look worse than it really is.  The electrode isn't really melted, It's more coated with something. (hopefully not piston). Sadly, the 3XV is my only running bike currently as my TDR is getting a supermoto wheelset built up and is up on stands. I'll pull the plug and pipe and have a look in there.  I may not have time to get the head off for a few days. Rain is due tonite, though so maybe I'll get to it afterall. Thanks for all the help! Back to top

pdxjim Group: Members Posts: 94 Joined: Oct. 2005 Posted: June 05 2007,04:10 Wooooooo!! Still a mystery, coz everything looks as it should. Back to top

Warwickb Group: Members Posts: 1911 Joined: Sep. 2003 Posted: June 05 2007,11:07 That's really good news, Jim. Looks as though it was water after all, then. I've never seen anything like that caused by water myself though. If, as you say, the water level in the header tank went down noticeably over the run, perhaps it's worth investigating whether it's coolant causing the problem rather than fuel adulteration? Either way it looks as though you have escaped any really expensive damage. Might be an idea to run the head over a peice of class covered in fine emery to check that it isn't warped a little - allowing a coolant leak at the head. I'd also check the tension of the barrel bolts too to try to eliminate any possible leaks at the base. Cheers Wb -------------- A garage overflowing with old stinkers... Back to top

[ Track this topic :: Email this topic :: Print this topic ]

TZR » Tech » 3XV » Ugly plug.

© nobody in particular Powered by Ikonboard 3.1.2a © 2003 Ikonboard