Page 1 of 1
It finally happened
Posted: Mon May 11, 2015 1:52 pm
by Stilts
So, after 13121 miles and 2 years and 2 months on my beautiful 2012 Stella 4T, the crank (I believe) finally snapped while cruising around 50mph down US-29 on my way to the Dogwood Classic put on by Richmond's Seven Hills Scooter Club. I was in between Warrenton and Culpeper thinking, "Wow, the upjet to 102 on this (relatively) new Mikuni carb was perfect!" when there was a sudden power loss...and then a clickity-clack-clack noise from the engine reached my ears. I immediately pulled over, did some side-of-the-road-diagnostics, swore a bit, then started pushing. A good samaritan with a pickup pulled over and got me pretty close to the campground before he had to split off in the other direction and I finally got a hold of some folks at the rally site who came to get me and my bike.
Of course, I didn't allow that to stop me from partying and generally making an ass of myself (at least two points, quite literally by getting nekkid!).
So, that leads me to the big question. Assuming it is the crank, we're talking an engine rebuild. Since I'm pulling everything apart (and assuming the cylinder is f****d), I might as well add the 165 kit, too. What kind of special tools are we talking about in addition to the $500+ I'll be laying out for the crank assembly and 165 kit?
Posted: Mon May 11, 2015 4:23 pm
by ArgonV
What do you think caused the crank to snap? Just a lot of driving, or a lot of hard driving?
Posted: Mon May 11, 2015 4:47 pm
by Stilts
Both. I like long rides. From what I've read, the life of a stock crank is about 10k, so I've got my money's worth so far.
Posted: Mon May 11, 2015 4:55 pm
by Neurotic-Hapi-Snak
Might have been a bearing, Lambrettaman on LMLOCGB had a bearing go and that's the only crank related problem I've heard of on the 4T. A stretch of the 2Ts had crank problems, but LML fixed that before they stopped selling the 2T in the US.
Posted: Mon May 11, 2015 5:01 pm
by Stilts
Neurotic-Hapi-Snak wrote:Might have been a bearing, Lambrettaman on LMLOCGB had a bearing go and that's the only crank related problem I've heard of on the 4T. A stretch of the 2Ts had crank problems, but LML fixed that before they stopped selling the 2T in the US.
that's good to know. would that maybe just require a bearing replacement rather than the full crank?
Posted: Mon May 11, 2015 6:38 pm
by az_slynch
Have you replaced the timing chain yet? Replacement interval is 18K kilometers, or about 11K miles. That may have bought the farm.
Posted: Mon May 11, 2015 7:10 pm
by Stilts
az_slynch wrote:Have you replaced the timing chain yet? Replacement interval is 18K kilometers, or about 11K miles. That may have bought the farm.
That's an idea I hadn't though about. No, I haven't.
I'm dropping the engine later this week and we'll find out soon enough what the problem is!
Posted: Mon May 11, 2015 7:16 pm
by az_slynch
Was it still running after it started ticking?
John K's motor had a similar issue. I suspected the chain because I found chunks of his chain tensioner in the oil after an oil change. He had it professionally repaired so I was never able to properly diagnose it. Maybe we should buy some NOS tensioners and duplicate them in a more robust, less brittle plastic.
Posted: Mon May 11, 2015 7:50 pm
by Stilts
az_slynch wrote:Was it still running after it started ticking?
John K's motor had a similar issue. I suspected the chain because I found chunks of his chain tensioner in the oil after an oil change. He swapped it so I was never able to properly diagnose it. Maybe we should buy some NOS tensioners and duplicate them in a more robust, less brittle plastic.
Yeah, it ran for a little bit as I pulled off the road and then I shut it off. I turned the flywheel by hand with the plug out (why, I don't know, but I wanted to do *something*) and there was definitely air coming out, so the piston is probably still solid (to my thinking).
Posted: Mon May 11, 2015 7:55 pm
by Stilts
az_slynch wrote:Was it still running after it started ticking?
John K's motor had a similar issue. I suspected the chain because I found chunks of his chain tensioner in the oil after an oil change. He swapped it so I was never able to properly diagnose it. Maybe we should buy some NOS tensioners and duplicate them in a more robust, less brittle plastic.
Yeah, it ran for a little bit as I pulled off the road and then I shut it off. I turned the flywheel by hand with the plug out (why, I don't know, but I wanted to do *something*) and there was definitely air coming out, so the piston is probably still solid (to my thinking).
Posted: Tue May 12, 2015 2:29 am
by Neurotic-Hapi-Snak
az_slynch wrote:I need to get one of those chains and see if there's a beefier analog for SOHC horizontal Hondas that can be used in place of this weak-ass chain. Those Honda chains tend to last as long as the motor, for Pete's sake!
So like a 100 years?
Posted: Thu May 21, 2015 1:58 pm
by Stilts
Finally got to work on it which only lead to all sorts of new questions. Here's what we found:
GOOD NEWS
1) Piston looks fine and the rings look brand new.
2) Cylinder is as smooth as a baby's bottom.
3) Crankshaft still in place and in one piece.
4) Timing chain all in one piece and doesn't look worn at all (will probably swap out anyways just because)
BAD NEWS
1) Some grimy metal grit in that "well" area behind the piston. Some of it was pretty large, but this could just be the detrius of 13k miles of hard riding. It doesn't look like anything shattered or exploded in there, it's just "dirty."
We then decided to remove the flywheel and take a peek but the extractor we had, for a P125, was a wee too small, like 1 or 2 mm too small, which made me scratch my head because I've been told by numerous people that it should be the same. At that point, it was nearing 10pm, so we just put everything gently back together and set it aside until I can get back to my friend's garage with the right extractor and work on it some more.
Another friend suggested that the sound may be the valves, as she asked if the "clickity-clack" I heard sounded like a sewing machine. It did and is probably the best description of the sound I heard as I pulled over. She thinks the valve levers are done. However, my friend and I turned the cam over and over on the head and the valves appear to be moving just fine and seating properly.
Thoughts?
Posted: Thu May 21, 2015 2:18 pm
by ArgonV
Is has got to be the clutch and/or transmission then... You've ruled out every thing else!
Posted: Thu May 21, 2015 3:48 pm
by BuddyRaton
Does this have a traditional cush drive? I've heard sounds like that when the springs fell through the gears. I would pull the clutch and have a peak.
Posted: Thu May 21, 2015 3:53 pm
by Stilts
BuddyRaton wrote:Does this have a traditional cush drive? I've heard sounds like that when the springs fell through the gears. I would pull the clutch and have a peak.
We pushed on the springs (with the clutch cover still on) and tehy all seemed to be seated. Pulling that off is part of our next session.
Posted: Thu May 21, 2015 4:07 pm
by Neurotic-Hapi-Snak
Check your timing chain tensioner, if that isn't applying pressure on the chain, the chain makes a clacking nose.
Posted: Thu May 21, 2015 4:24 pm
by az_slynch
BuddyRaton wrote:Does this have a traditional cush drive? I've heard sounds like that when the springs fell through the gears. I would pull the clutch and have a peek.
The 4T reportedly has a 68T drive gear, but reportedly has the dual-spring setup like the P200s do. It also has a 7-spring clutch.
When John K's bike was having an issue, the ticking would go away as long as the engine was accelerating under load. It came back when cruising and got loud on deceleration. If the bike was in neutral, the tucking happened no matter what was done to the motor. Valves were checked and adjusted repeatedly with little to no effect.
Posted: Thu May 21, 2015 5:33 pm
by Neurotic-Hapi-Snak
az_slynch wrote:BuddyRaton wrote:Does this have a traditional cush drive? I've heard sounds like that when the springs fell through the gears. I would pull the clutch and have a peek.
The 4T reportedly has a 68T drive gear, but reportedly has the dual-spring setup like the P200s do. It also has a 7-spring clutch.
When John K's bike was having an issue, the ticking would go away as long as the engine was accelerating under load. It came back when cruising and got loud on deceleration. If the bike was in neutral, the tucking happened no matter what was done to the motor. Valves were checked and adjusted repeatedly with little to no effect.
Far as I can tell, it has a 21T 7 spring clutch, 68T primary and a gear stack similar to a P125X and the early P150X (if they had a 21/68 primary gear ratio), though only the 4th gear overall ratio matches, the others are close but not the same. The P125X ratios I got off of the Vespa P-series Gearing Calculator, the 4T ratios are out of the Service Manual.
Gear P125X 4T
1st 15.38 17.07
2nd 10.91 10.71
3rd 7.77 7.89
4th 5.83 5.83
If they're using the dual spring setup in the primary gear to handle the increased momentary torque of the four stroke engine and reduce wear on the clutch, it isn't working very well. I already have to rebuild my clutch after only a little over 4000 miles, not because of worn corks, but because the plate tabs are beat to crap. Either cheap plates or the clutch can't handle the increased momentary torque, so I'm switching to an SIP banded Cosa clutch with a 22T gear (banded because my stock clutch also showed signs of expanding under load/high RPM). The 4T's fly wheel is even 6.5lbs/2.9Kg, a heavier flywheel reduces wear on the clutch by smoothing out the power pulses and reducing the sudden acceleration of the crank during a power stroke. No wonder they switched to a small motorcycle clutch in the 200.
Posted: Thu May 21, 2015 6:27 pm
by az_slynch
Dang, that's looking pretty torn up! I bought a 22T FA Italia clutch for a Rally 180 to drop in. Maybe I'll just flog my stocker some more before replacing it, though.
Posted: Thu May 21, 2015 6:57 pm
by Neurotic-Hapi-Snak
I wasn't too concerned with the bottom two tabs, yeah it's a little excessive mushrooming, but what worries me is the mushrooming on the T tabs from the basket expanding, if those tabs let go at speed it's bye bye retaining ring, hello exploded clutch. Hence my going to a Cosa, itself a stronger design, with a reinforcing band, probably over kill but it isn't that much more expensive than an unbanded Cosa.
I find the 4T's gearing very odd, it's so short it's like it was made for a higher revving engine, yet the 4T's engine is set up for low RPM torque. I always felt it was gearing, not power, holding it back from higher speeds, even stock but especially now you can feel in 4th when you pass the power band, you have a little bit more to get going a little faster but it takes a while to get there. I really want to swap in a 65T primary and go with either a 22/65 or 23/65 combo, but I don't want to crack the cases yet. I'll either stick with a 22T clutch for now or swap in a DRT 23T gear, which can mesh with a 68T primary.
Posted: Thu May 21, 2015 8:05 pm
by Stilts
Neurotic-Hapi-Snak wrote:I wasn't too concerned with the bottom two tabs, yeah it's a little excessive mushrooming, but what worries me is the mushrooming on the T tabs from the basket expanding, if those tabs let go at speed it's bye bye retaining ring, hello exploded clutch. Hence my going to a Cosa, itself a stronger design, with a reinforcing band, probably over kill but it isn't that much more expensive than an unbanded Cosa.
I find the 4T's gearing very odd, it's so short it's like it was made for a higher revving engine, yet the 4T's engine is set up for low RPM torque. I always felt it was gearing, not power, holding it back from higher speeds, even stock but especially now you can feel in 4th when you pass the power band, you have a little bit more to get going a little faster but it takes a while to get there.[/b[ I really want to swap in a 65T primary and go with either a 22/65 or 23/65 combo, but I don't want to crack the cases yet. I'll either stick with a 22T clutch for now or swap in a DRT 23T gear, which can mesh with a 68T primary.
I've come to believe this more since the upgrade to the 22mm carb and the GPR exhaust. The gearing sucks.
Posted: Thu May 21, 2015 8:52 pm
by Stitch
Wonder what gearing the lml200 has
Posted: Fri Jun 12, 2015 3:44 pm
by Stilts
Finally figured it out! Somehow I missed this during the first go around inspecting the head.
Nice hole, eh?
This would explain the loss of compression/power and the sewing machine sound.
Anyone got a line on a used complete head (with valves)?
Re: It finally happened
Posted: Sun Jun 14, 2015 7:11 pm
by quen047
Stilts wrote:So, after 13121 miles and 2 years and 2 months on my beautiful 2012 Stella 4T, the crank (I believe) finally snapped while cruising around 50mph down US-29 on my way to the Dogwood Classic put on by Richmond's Seven Hills Scooter Club. I was in between Warrenton and Culpeper thinking, "Wow, the upjet to 102 on this (relatively) new Mikuni carb was perfect!" when there was a sudden power loss...and then a clickity-clack-clack noise from the engine reached my ears. I immediately pulled over, did some side-of-the-road-diagnostics, swore a bit, then started pushing. A good samaritan with a pickup pulled over and got me pretty close to the campground before he had to split off in the other direction and I finally got a hold of some folks at the rally site who came to get me and my bike.
Of course, I didn't allow that to stop me from partying and generally making an ass of myself (at least two points, quite literally by getting nekkid!).
So, that leads me to the big question. Assuming it is the crank, we're talking an engine rebuild. Since I'm pulling everything apart (and assuming the cylinder is f****d), I might as well add the 165 kit, too. What kind of special tools are we talking about in addition to the $500+ I'll be laying out for the crank assembly and 165 kit?
I just took my Stella in after flipping 10,000 miles. My mechanic declared me to be now "in the bonus round" as I'm the highest-milage 4t they have seen. I ride similarly to Stilts- lots of urban commuting (she's been my DD for the last two years) albeit with fewer long trips. I've had her serviced carefully, changing the oil first every 2000 miles, and then every 1500 miles starting at about 7000 miles. I don't rev her to the limit for more than a few seconds. Here's hoping I get her through the summer and to my next job!
