Moderator Cynic Posted May 23, 2015 Moderator Posted May 23, 2015 When she dropped onto one cyl, wasn't the idle jet.... Not carb related at all, ring picked up on the exhaust and so no compression. Have about 12mm of piston ring with me now sat by the computer. bet we have a month of sun now guys enjoy....
blackhat250 Posted May 23, 2015 Posted May 23, 2015 Bugger jase " how come the snag ? chamfering of port not done,,,
Moderator Cynic Posted May 23, 2015 Author Moderator Posted May 23, 2015 Just wear mate, tore it down earlier and looks like its been running for quite a while with a busted ring. What I thought was fussy carburation and a thirst for plugs was just the compression getting lower and lower. She went a bit weird at squires do last year but she settled down then looking at the piston what was a dink became a lot bigger and finished it off. She would still run over 4000rpm believe it or not, just under that she would sulk. Getting the piston off was a real bstard, didn't want to fit past the wear ridge due to the damage. As to the cause, its never been bored so id go with 14000miles. Bout right for a 2t. Looks like 250 maybe 300 quid should see it right.
blackhat250 Posted May 23, 2015 Posted May 23, 2015 Phew more expence, , Spoke to a bike shop in Dundee,[ scooters dealer[] Hes says the wear on barrels nowadays in minimal with fully synth 2T oil, 20,000 miles easy,,
Moderator Cynic Posted May 23, 2015 Author Moderator Posted May 23, 2015 20kmiles maybe on the new coated barrels. old skool like ours john id still be expecting at least a set of rings by this kind of mileage, there is a definite wear ridge at the extremes of piston travel. The power valve is coked up as it is, stiff to operate by hand and the base gasket was wet too so something was going to go pop . Found the actual cause too, the ring peg was fitted too far into the piston. It is sat back from the edge by maybe a mm not much, looks like the ring made it past with a bit of ware and rotated till it reached the port and bang. Thankfully all the crap went straight out the pipe by the looks of things. 1
Moderator drewpy Posted May 23, 2015 Moderator Posted May 23, 2015 silver linings that it didn't do more damage I suppose Jason. I snapped a barrel stud today on the FZ so It either needs drilling or spark eroding.
Moderator Cynic Posted May 25, 2015 Author Moderator Posted May 25, 2015 The other piston was close too. Just trying to sort some pictures, keep making them too BIG.
Moderator Cynic Posted May 25, 2015 Author Moderator Posted May 25, 2015 That's better still too big though , you can see how the ring peg has worn on the rh piston. Ring gap max is 0.45mm, on this ring its .63, that's buggerd. And the one that makes you cringe, you can see where it was working till the final pickup.
Moderator Cynic Posted May 25, 2015 Author Moderator Posted May 25, 2015 Any smaller and you can't see the pin yer cheeky f.... 1
Moderator drewpy Posted May 25, 2015 Moderator Posted May 25, 2015 Any smaller and you can't see the pin yer cheeky f.... meant to say Can't. daughter "cleaned " my keyboard and the keys won't press down properly
Moderator DirtyDT Posted May 27, 2015 Moderator Posted May 27, 2015 Bloody 2 strokes. Who would want one! As Drewps said - it could have been a lot worse.
Moderator Cynic Posted May 27, 2015 Author Moderator Posted May 27, 2015 Believe it or not looking at the damage I think she had her first moment BEFORE I rode up to squires. The barrel showed signs of carbon build up on the barrel at a spot where the first contact was made, I think she did another 600miles before finally stopping when more of the piston failed. Bloody amazing really, 4 stroke wouldn't do it. On parts of that rideout we were well into 30mpg territory and she kept going. I felt something was off but the failing battery giving false ideas on the pv being at fault masked things would not have thought it was piston failure on that level. Talking of pv anybody with a yam 2 stroke with a pv system that's done a few miles it will be a mess. Mine has only 14k and the crap on the pv and built up on the bushings is shocking. Def affecting performance, I could barely turn the pv by hand.
Moderator Cynic Posted May 27, 2015 Author Moderator Posted May 27, 2015 Ker ching, £££££ Well that's £130quid in Fowlers coffers for the seals and gaskets to fix the TDR, not including £110 for 2 mitaka +0.1mm pistons although they are full piston kits. I have spent the extra on all the PV seals and o rings. They were ok but i'm not chancing them failing in 6 months time and I took the cost of a gen Yamaha cyl head gasket on the chin too. Don't want that going either.
slice Posted May 27, 2015 Posted May 27, 2015 Hell's teeth mate those bloody 2 stokes are expensive !!! All that for a ring ding-a-ding noise & a teeth rattling ride.
Moderator Cynic Posted May 27, 2015 Author Moderator Posted May 27, 2015 Worth EVERY penny, when that needle hits 6k its like being strapped on the back of the enterprise. Yeah a FZ6 will spank it these days, but offer me the keys to both and its the stroker all day long. They feel alive and hungry, they want to go. Not passive and obedient. 2
Moderator DirtyDT Posted May 28, 2015 Moderator Posted May 28, 2015 Hell's teeth mate those bloody 2 stokes are expensive !!! All that for a ring ding-a-ding noise & a teeth rattling ride. And the smell, don't forget the smell.......... My other half says I stink when I ride the strokers. It could be the oil; or it could be the smell of fear!! 3
Moderator Cynic Posted May 28, 2015 Author Moderator Posted May 28, 2015 Well, fowlers were there usual best, parts ordered yesterday at 12, arrived today at just after 10. 10/10. Lots of lovely Yamaha packets. Mitaka, well there in the system, despatched Tuesday by cart horse I think. Everything is cleaned up ready to go, will paint the barrels after their bored and do the head at the same time. Other than that till I get the pistons I'm stuck.
Moderator Cynic Posted June 14, 2015 Author Moderator Posted June 14, 2015 Yay she lives, and running better than she has in a LONG time. Compression must have been dropping badly as I can't turn her over by hand at the minute, I used to be able to START it by hand. Only a gentle tootle round the block so far but it feels like it could break the sound barrier if I opened the throttle. Feels crisp and sharp. Just got to run her in now, get 20 or 30 miles on the bores then ride normal avoiding full tit for as long as I can stand. 3
Recommended Posts