Im "throwing in the towel" on this Tri Z

[Racer-X]

I hate to say it but I may have to bite the bullet and take this machine to the shop and pay (money that I don't have) for them to figure it out. I don't understand why it starts for a minute or two but only if its cold and its the very 1st attempt at starting it for the day. It starts right up but runs sorta boggy (if I give it throttle it wont rev up high at all and instead it boggs down) and I have to blip the throttle a little bit just to keep it idleling but it eventually gets slower and slower and boggs out completely. Then after that it wont start again? Not even with a shot of starting fluid even though it was just running for a minute. But it will start tomorrow and do the same thing. It will run like crap for a minute, just Bogg out, and wont start again? I bought it a few years ago, put plenty of miles on it, and it ran ok. It just smoked more than its supposed to which I assumed was due to an old worn out piston and jug. Then it started doing what's its doing now. I figured it needed rebuilt or reeds or something. so now I finally got it all back together after having it bored .040 over. (fyi don't bore a tri z jug to .030 because for some reason nobody makes rings that size? You can get .010, .020, and .040 only) Its got a new air filter, carb is squeaky clean, new reeds, new piston and rings, plug, ect.... The compression gauge is reading 155psi. the spark plug is definetly sparking. I even tried another plug just in case and they both spark fine. So it seems I have fuel, air, and spark but its not running? I thought maybe the stator but its sparking fine. And I also thought maybe the fuel pump but why would it not start with a shot of starting fluid and why does it pump fuel for a minute or 2 and then stop? With starting fluid sprayed in the cylinder it should at least run for one second or 2 even if the carburetor was completely missing and it literally had no fuel in the tank right? It doesn't even try to start. It doesn't even hiccup? Once it runs for a minute and boggs out its done for the day. I could kick it 100 times and absolutely nothing happens? Maybe I'll try gravity feeding the carb and eliminate the possible faulty fuel pump completely. But the possible bad fuel pump doesn't explain why it doesn't show any signs of life with a shot of gogo juice.
I just don't get it?
Any thoughts?
248911
248912

[muthey]

I hate to say it but tear the cylinder off, and check the rings, I had mine do the exact same thing and found out that one of the rings had bent a corner at the opening. I could get a good read out on a compression gauge but it would do the exact same thing yours is doing.

[lndy650]

what did your reeds look like when you rebuilt it? i would try gravity feeding the carb see if that helps. sounds like it could also be a sheered flywheel key or another timing issue.

[Racer-X]

Well, when I was installing the jug I was able to look in through the intake port and see that the rings where exactly centered in their correct location on the pins. One actually moved just a little bit and the jug wouldn't slide on. I went in through the intake port with a screwdriver and spun the ring a little bit to the correct position and the jug slid right on. Then when I pumped the kick starter and cycled the engine before I put the top onto the jug it sounded and felt smooth as butter. Also I was having this exact same issue before I rebuilt it with the old piston and rings. It quit running and was doing the same thing. That's the whole reason I rebuilt the top end in the first place.

[Racer-X]

The old reeds didn't look bad. One of them had a small area on the side where the reed wasn't touching the cage but not by much at all. Both the old and new reeds are Boyesen. I not familiar with what exactly a flywheel key is or how it could be out of time. Ill look into it. But yeah, I'll try bypassing the fuel pump next.

[lndy650]

does it backfire or kick back on your foot when you try starting it? the flywheel is behind the cover on the shifter side. theres a sensor that picks up the position of the crankshaft and if the keyway on the crankshaft is sheered off it will fire at the wrong time and will pop and backfire but usually wont run. only other thing i can think of is a weak cdi they can play all sorts of games. if you have a multimeter i can get the specs you need to test the electrical. dont give up buddy youll get it running.

[jeswinehart]

It sounds like a crank seal problem imo. Doing a leak down test is rather simple + cost hardly nothing.

john

[Imdone]

Classic symptom of a failing canooter valve. Unfortunately an NOS one is extremely hard to find. Best of luck in your search.

[atc300r]

X2 on crank seals.Also sounds to me like your crank case has to much gas in it and its flooding it out.

[fieldy]

Squeaky clean carb, whats that mean? When you are kicking 100 times and no fire does it have spark then? If it always has a blue spark then cdi should be ok. Yellow/orange spark-bad, electrical. Can we get a plug picture? The timing and flywheel need verified as mentioned, probably need a puller and a gasket. If electrical is shotty can a YZ ignition be found today? I know, no head light......honestly don't know on Yamaha. Yes gravity feed the carburetor!
I would wait and check a few of these things before worrying to much. 100% leakdown test it or the shop will be getting in your pay. I agree you will get it, just gonna take some garage time. Working on em is the fun part anyway!

[ironchop]

.... (fyi don't bore a tri z jug to .030 because for some reason nobody makes rings that size? You can get .010, .020, and .040 only).....

That's because metric pistons come in oversize increments of 1/4mm (.25mm), 1/2mm (.50mm) and 1mm

.25mm = .0098 inches so it rounds up to .010

.50mm = .0196 inches , rounds up to .020

1mm = .0393 , rounds up to .040

To convert mm to inches, divide mm by 25.4

To convert inches to mm, multiply inches (in decimal format) by 25.4

Sent from my Z958 using Tapatalk

[lndy650]

i was thinking the possibility of crank seals but for them to be bad enough to where it wont stay running there would be gas in the transmission oil and probably gas/oil in the flywheel cover. so i would also look for drainage around the crank seal when checking the flywheel and see if you can smell gas in the transmission oil.

[Racer-X]

Aha, the good ol' canooter valve. Why didn't I think of that sooner. I think I have a new one somewhere around here. Maybe its with my pipe stretcher hahaha. I think you guys may be onto something the crankseal . If it was electrical I think it would be broke all the time not just a minute after running. And it does start right up after it has sat for a long time and aired out. So maybe when it starts for the 1st time the bad crank seal is gradually building up too much air or oil and eventually screwing up the air/fuel mixture to the point it cant run anymore.
I'll drain the oil and inspect it and I'll try to rig up something for a leak down test or blow some air in there once I have the side cover off and can listen to see if there's air coming from the actual crank seal.
Why am I always fixing stuff? I just want to ride!

[jeswinehart]

http://www.3wheelerworld.com/showthread.php/96856-Make-a-leak-down-tester-for-about-20?highlight=leak+down+test

http://www.3wheelerworld.com/showthread.php/71487-Building-and-operating-a-leak-down-tester-My-technical-process-and-suggestions?highlight=leak+down+test

Best to do it right,,, the first time.

[schlepp29]

My 250r did the same thing and it ended up being the secondary coil. A stupid 50 dollar part was all it was. But all the other stuff these guys are saying is most definitely possible as well. When my r was acting up we did everything to it, leak down, top end ,carburater ,reeds and spark plug wire and boot. I hope you figure it out. Good luck

[El Camexican]

Well, when I was installing the jug I was able to look in through the intake port and see that the rings where exactly centered in their correct location on the pins. One actually moved just a little bit and the jug wouldn't slide on. I went in through the intake port with a screwdriver and spun the ring a little bit to the correct position and the jug slid right on. Then when I pumped the kick starter and cycled the engine before I put the top onto the jug it sounded and felt smooth as butter. Also I was having this exact same issue before I rebuilt it with the old piston and rings. It quit running and was doing the same thing. That's the whole reason I rebuilt the top end in the first place.

If I’m understanding your post above you’re saying that with a ring in the wrong position you managed to get the piston far enough into the cylinder to see and move the ring through the intake port? If so it is possible that you broke or damaged a ring. Not saying that’s your problem, but if I was you I’d pull that cylinder off and check.

[Racer-X]

when your 250r was doing the same thing and it ended up being the coil were you still getting spark from the plug? Because I get blue spark no matter what plug try. I'm only asking because I have only had to replace a coil one other time before but when I did, I wasn't getting spark at all.

[lndy650]

El Camexican i think what he meant is how sometimes when you put the cylinder on the rings can stick out and get caught on the intake port. i think hes just saying he had to push the ring in to get past the port. i know he kinda explained it like it wasn't lined up but sometimes it can be a little too far one way and you gotta spin it a tad to get the side stuck on the port to fit. its playing with fire when these rings catch on the port like that but i think he got it because if hes getting that much compression I'm thinking the rings are ok. thats just my thoughts on it.

re-reading the post i thought it was only running for seconds but i see it says a few minutes so i don't think its the flywheel key, it still could be electrical I've seen cdi's work till they warm up then go out. doing a test on all the electrical components couldn't hurt. just let me know if you need the specs.

[El Camexican]

El Camexican i think what he meant is how sometimes when you put the cylinder on the rings can stick out and get caught on the intake port. i think hes just saying he had to push the ring in to get past the port. i know he kinda explained it like it wasn't lined up but sometimes it can be a little too far one way and you gotta spin it a tad to get the side stuck on the port to fit. its playing with fire when these rings catch on the port like that but i think he got it because if hes getting that much compression I'm thinking the rings are ok. thats just my thoughts on it.

re-reading the post i thought it was only running for seconds but i see it says a few minutes so i don't think its the flywheel key, it still could be electrical I've seen cdi's work till they warm up then go out. doing a test on all the electrical components couldn't hurt. just let me know if you need the specs.

That's not what I'm reading in his post. As well, one good ring will give just as high a compression reading as two (some engines use only one) Lots of variables come into play when doing a compression test, including the quality of the gauge, but 155# isn't much for that engine. I just torn down a stock Tri-Z engine that had damaged rings and still gave a reading of 165#

Again, I don't think this would be causing his running problem, but I'd look at it again if it was mine.

[lndy650]

ya i hear ya you could be right. i just cant see how someone could shove a cylinder over a ring thats not seated properly but i guess it can happen. and ya i agree one ring can make good compression all im saying is i dont think compression is an issue here.
i wasnt tryin to say your wrong sorry if you took it that way im just thinking of all possibilities
im not new glamy ive been here longer than you. another thread youve now hijacked and given zero help

[Poppa Wheelie]

Im throwing in this towel:

248969

http://www.3wheelerworld.com/showthread.php/185362-Hello?p=1468451

[sledcrazyinCT]

Anyone else concerned with 28 to 1 mix? I would run closer to 50 to 1 on your rebuild. Too much oil in your gas mix will affect the air/fuel ratio.

[ironchop]

Anyone else concerned with 28 to 1 mix? I would run closer to 50 to 1 on your rebuild. Too much oil in your gas mix will affect the air/fuel ratio.I'm still wondering about 155# compression. That seems too low to me.

Sent from my Z958 using Tapatalk

[El Camexican]

ya i hear ya you could be right. i just cant see how someone could shove a cylinder over a ring thats not seated properly but i guess it can happen.

I don’t know exactly how it might have been done, but I’ve broken a couple rings trying to load some four cylinders up.

You never know who your dealing with on the Internet, but I’m sure somewhere out there is a guy that has used a deadblow hammer to get a cylinder over a tight piston at some point.

[El Camexican]

Racer X, you made the comment that “it pumps fuel for a minute or two and then stops”. Once the float bowl on a properly working carb is full the fuel is supposed to return to the tank via the return line at the grey plastic tee under your seat on the RH side, so you’re not going to see fuel flowing into the carb through a clear line if that’s what you’re referring to. If you have doubts just remove the line at the carb and kick it over, fuel should come out. Make sure that both fuel valves are open before you give up on the pump.

Then remove your reed cage, clean it up real good and push the rubber manifold into your face, block the boost bottle hole with your finger and suck. If you face doesn’t pucker up like your sucking on a bottle it means your reeds are leaking and need to be replaced.

With the cage off, rotate the engine a couple times and then run the piston up to TDC, take a flashlight and look inside the case to see if you can see fuel and oil running off the crank and rod. You MIGHT have it till of fuel which would explain why it will start after sitting and evaporating for a day.

This is a bit of a reach, but it can happen. The cause is either a leaking float needle, or bad fuel. You would have to soak it out with rags, or remove the engine and dump it and then fix your fuel system before trying to start it again.

No matter what you find you still need to check for leaks as was recommended by others. That’s a must on every 2 stroke rebuild.

Regarding your compression reading, do you know how to do a proper one? Carb wide open and kick it over till the gauge stops going up, takes at least half a dozen kicks of not a dozen. You can find it on YouTube.

[schlepp29]

Racer x believe it or not I was getting a blue spark but it must have been very intermittent. That's the only thing we could figure.

[fieldy]

Got the plug picture?

[schlepp29]

I don't. That's been awhile

[fieldy]

I hate to say it but I may have to bite the bullet and take this machine to the shop and pay (money that I don't have) for them to figure it out. I don't understand why it starts for a minute or two but only if its cold and its the very 1st attempt at starting it for the day. It starts right up but runs sorta boggy (if I give it throttle it wont rev up high at all and instead it boggs down) and I have to blip the throttle a little bit just to keep it idleling but it eventually gets slower and slower and boggs out completely. Then after that it wont start again? Not even with a shot of starting fluid even though it was just running for a minute. But it will start tomorrow and do the same thing. It will run like crap for a minute, just Bogg out, and wont start again? I bought it a few years ago, put plenty of miles on it, and it ran ok. It just smoked more than its supposed to which I assumed was due to an old worn out piston and jug. Then it started doing what's its doing now. I figured it needed rebuilt or reeds or something. so now I finally got it all back together after having it bored .040 over. (fyi don't bore a tri z jug to .030 because for some reason nobody makes rings that size? You can get .010, .020, and .040 only) Its got a new air filter, carb is squeaky clean, new reeds, new piston and rings, plug, ect.... The compression gauge is reading 155psi. the spark plug is definetly sparking. I even tried another plug just in case and they both spark fine. So it seems I have fuel, air, and spark but its not running? I thought maybe the stator but its sparking fine. And I also thought maybe the fuel pump but why would it not start with a shot of starting fluid and why does it pump fuel for a minute or 2 and then stop? With starting fluid sprayed in the cylinder it should at least run for one second or 2 even if the carburetor was completely missing and it literally had no fuel in the tank right? It doesn't even try to start. It doesn't even hiccup? Once it runs for a minute and boggs out its done for the day. I could kick it 100 times and absolutely nothing happens? Maybe I'll try gravity feeding the carb and eliminate the possible faulty fuel pump completely. But the possible bad fuel pump doesn't explain why it doesn't show any signs of life with a shot of gogo juice.
I just don't get it?
Any thoughts?
248911
248912

Is it possible to see a picture of the spark plug. The one that was in it when it quit running?