P200 Performance Build-Up
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Veni, Vidi, Posti
'80 P200E, '76 Primavera 125 ET3. '59 Vespa 150
Joined: 30 Apr 2007
Posts: 6851
Location: GT, Texas
Sun Feb 12, 2012 5:25 am quote
Great project, man.

I need to get one of those upper shock mounts. I should have done it when I did my recent engine rebuild. I bought the Clause engine mounts but didn't get the shock one.
Hooked
78 P200 05 PX150
Joined: 06 Jul 2010
Posts: 214
Location: Fort Collins, CO
Sun Feb 12, 2012 7:23 pm quote
Al sent me a set of his stabilizers to use when I did the rebuild. I opted to use the Clauss bushings and mounts instead. I decided the aluminum stabilizers would be nice but from what I can see would be effectively the same as running hard mounts. I knew the urethane mounts would cause more vibrations but the stabilizers would vibrate even more. Besides my stock rubber mounts were shot.

Al was really against me using the Clauss upper mount. There are some stories about them leading to broken shock shafts etc. I guess they are more resistant to lateral movement but I felt that with the stiffened swingarm bushings that wouldn't be an issue. Anyway, most of the time my scooter is headed to Home Depot or a cruise down the beach. Not really railing around corners.

Chuck
Hooked
78 P200 05 PX150
Joined: 06 Jul 2010
Posts: 214
Location: Fort Collins, CO
Sat Feb 18, 2012 4:35 pm quote
The head finally got back from Al today. I sure wish Vespa used a central spark plug so any machine shop could cut the head. Instead it requires a custom fixture to chuck the head in a lathe. My head ended up getting over 5k frequent flyer miles just to get about 0.6mm trimmed from it.

Anyway I got it back and decided to dowel it in place on the cylinder. The idea is to minimize the slop between the cylinder and the head so the combustion chamber stays relatively central with the bore. Turns out the hole sin the head and cylinder are about 9.5-9.8mm and the studs are 8mm. When I tightened the head down last time I found you could shift it around alot. I think this was contributing to my squish numbers being off when measured in 4-points. Here are the dowels I found for the purpose and a 10mm carbide bit.



Hmm... with even chamfers like these, you'd never guess they were Chinese.

The holes in the head all measured about 9.8mm like this one:



There was one oultier that was over 10mm in diameter. My 10mm sleeve dropped right in. The threads you see in the holes are from the bolts Al uses to hold the head to his jig. He lightly taps the holes and uses 4 bolts to hold the head during machining.



Here is a shot of the sleeve in the big hole.



I picked two of the smaller holes that were diagonal from each other to install the sleeves. I counter-bored two of the holes in the top of the cylinder about 12mm deep to accept the sleeves.



I then counter-bored the head about 6mm deep in the corresponding locations.



I either had some issues with the bit walking a little or the holes in the head and barrel were not perfectly aligned to start with. Either way, I ended up enlarging the holes in the head to about 10.5mm. While this does allow a little play, it is insignificant to the amount I had prior.



Here is a shot of the cylinder back on the motor. You can get an idea of how nice everything is going to line up.



I went ahead and remeasured the squish and got just about 1.2mm this time and fairly consistent across all four measuring points.



And now the top end is back on and the motor should go back in the bike tomorrow.

Chuck

Last edited by chuckactor on Sat Feb 18, 2012 6:51 pm; edited 1 time in total
Mr. Clean
P,SUPER,V90, 50 Special
Joined: 27 Jul 2010
Posts: 10207
Location: This is't my locker!
Sat Feb 18, 2012 5:11 pm quote
Just awesome... as per usual. Damn nice work!
just a question: was the play in the head going to be noticeable when it's bolted on? meaning are your sleeves just a precaution, something to do, or necessary as per your setup ? looks very tidy and solid though.
Cheers
Hooked
78 P200 05 PX150
Joined: 06 Jul 2010
Posts: 214
Location: Fort Collins, CO
Sat Feb 18, 2012 6:56 pm quote
Not sure how much difference it makes in the long run. I first noticed it when I was bolting the head on and found the socket would hit the fins on the head unless I pushed the head away from it. I just found it odd how much slop there was. The main thing was I was getting annoyed when I'd take a squish measurement that was 1.5mm in two places and 2.1mm on the opposite side of the piston.

In a motor that might make 15hp, it probably makes no difference. The last motors I really worked on were 125cc making almost 40hp. For them, you'd be surprised how much this insignificant little things matter.

One other thought. I noticed the o-ring on the top of the cylinder was already showing some damage. I wonder if the head could have been moving around on top of the barrel and wearing the o-ring. The motor only had a 200-300 miles on it when I tore it apart.

Chuck
Primasarah
1979 P200E, 1977 Rally 200, 1974 Primavera
Joined: 15 Mar 2011
Posts: 3087
Location: Lake Worth, FL
Sat Feb 18, 2012 7:11 pm quote
You're only expecting 15bhp out of this? I'd figure more in the range of 18bhp from the Ported Pinasco, Jap Rod Flowed Crankshaft, Vortex, and 226 Hot Wing.
Hooked
78 P200 05 PX150
Joined: 06 Jul 2010
Posts: 214
Location: Fort Collins, CO
Sat Feb 18, 2012 7:19 pm quote
Who knows. It will be more than 10 and less than 20 is my guess. I'd rather shoot low and be pleasantly surprised. I need to sweet talk my buddy down at Riva and see if he'll let me put it on their dyno. Of course it would have been more fun to have dyno numbers all along to watch the progress.

Chuck
Primasarah
1979 P200E, 1977 Rally 200, 1974 Primavera
Joined: 15 Mar 2011
Posts: 3087
Location: Lake Worth, FL
Sat Feb 18, 2012 7:22 pm quote
I challenge you to a race once both our bikes are done!
Hooked
78 P200 05 PX150
Joined: 06 Jul 2010
Posts: 214
Location: Fort Collins, CO
Tue Feb 21, 2012 7:33 am quote
I finally got around to putting the bike back together. It went pretty fast. I guess I'm getting the hang of it. I decided the easiest way to work was to just lay the bike on it's left side and put the motor in that way. I spread a big moving blanket on the ground and got to work. Luckily one of my neighbors walked up just as I was getting started. I handed him a greasy swingarm pivot bolt and put him to work. The motor went right into place and was in the chassis in about 20 seconds.



Since the bike was laying on its side, I figured I'd keep moving. the selector box, clutch and brake cables went right on next.



If you guys don't have one, the park cable cutter works great for cleaning up the ends of frayed cables. A set of regular cutters either won't cut the cables or make a big mess of the ends. The bike tools work great on the Vespa. My shift cables are bike parts. I used teflon lined brake cable housing and teflon coated cables to do the shifter. They work great.



While I was there, I put the pipe back on. I got some new O-rings from 226 to replace the leaking ones. While I was at it, I replaced one of the cylinder exhaust springs with a longer one I bought. I didn't like how tight the outside spring was. I'm sure it is due to the hole location I drilled into the fin. I'd rather buy a new spring than risk redrilling the hole. Besides I like alot of meat on the fin around the hole so it doesn't break. The spring is a stainless one off a KTM dirtbike.



Here's the 226 pipe installed. It's definitely a nice piece of work. http://www.226vintage.com/



Just remember, it's for off-road use only.



I love when they label these things.

Here is a shot of the new 226 lower shock bolt. Finally a bolt long enough to allow me to run the lockwasher. If you had a Bitubo shock or one with an alloy body, you'd have a heck of a time trying to make the short stock bolt work.



I had some issues with the slide no closing 100% previously. It seems that on my bike, there was not enough slack in the cable to allow the slide to close fully. I think some of this is due to the bored out carb. In order to get enough travel, I had to remove the locknut from the cable adjuster.



When I did this, the adjuster screwed into the carb body and blocked the slide from opening all the way.



Here is a shot that shows the corners of the slide sticking into the airstream a bit. I fixed the problem by lopping off the bottom 1/4" or so off the adjuster.



I've seen this happen all the time. make sure the slide opens and closes all the way. Especially when you go to aftermarket carbs etc.

Anyway... motor in and assembled. Well, actually not assembled yet but thats the picture I had....



I fired it up and rechecked the timing. Luckily, it was 18deg on the nose again and there was no need to readjust it. I let the bike warm up to about and then shut it down and let it cool all the way. After it was cold, I re-torqued the head. I torqued it to about 15 ft-lbs when I built it and re-torqued it to 16 ft-lbs after it cooled. Then it was a matter of adding fuel and oil and taking it for a ride.



Since the oil pump and lines weren't full, I mixed in some oil into the gas. I figure the extra oil wouldn't hurt as everything was breaking in. I used 32/1 in the fuel.

Then off for a test ride....

Chuck

Last edited by chuckactor on Fri Feb 24, 2012 4:28 am; edited 1 time in total
Primasarah
1979 P200E, 1977 Rally 200, 1974 Primavera
Joined: 15 Mar 2011
Posts: 3087
Location: Lake Worth, FL
Tue Feb 21, 2012 8:26 am quote
Looks great Chuck. Can't wait to see that bad boy in person.
Hooked
78 P200 05 PX150
Joined: 06 Jul 2010
Posts: 214
Location: Fort Collins, CO
Tue Feb 21, 2012 7:40 pm quote
Bike is running great. Well pretty great. Since the last runs, I made the following mods:

HRS crank
Mildly ported cases
Squish reduced to 1.2mm

Plus new seals and crank bearings. First off, the new seals helped the bike alot. The idle is better and the bike just seems to carburate that much cleaner and consistent. And I finally have a scooter that starts with one kick. That is one solid kick. A wimpy kick can be deadly with this thing. It can bite back. No flip flops when starting this motor.

I am very happy with the new crank. It has very little spitback of fuel even with the increased duration. It actually seems no worse than the stock crank. This is a new design from Al that incorporates modification to the leading and trailing edge of the counterweight. I think I actually have the first one in a running motor.

The motor is still running rich. I think I'll keep it this way for awhile. It's alot more fun to ride now. The modifications made a big boost in power. The bike will still pull from off idle just fine. There is absolutely no need for a short 4th gear with this setup. There is tons of torque.

And herein lies the problem. The clutch I have in the bike goes south as soon as the power comes in strong. If I get on it in third while cruising down the road at around 40+, the clutch just lets loose. Guess I'll be babying it for awhile so I don't totally fry the plates. I have a set of Pinasco sport springs on order. Hopefully that will cure the problem. Till then, no top speed attempts.


Chuck
Primasarah
1979 P200E, 1977 Rally 200, 1974 Primavera
Joined: 15 Mar 2011
Posts: 3087
Location: Lake Worth, FL
Tue Feb 21, 2012 7:49 pm quote
The springs should keep it from slipping.
Mr. Clean
P,SUPER,V90, 50 Special
Joined: 27 Jul 2010
Posts: 10207
Location: This is't my locker!
Wed Feb 22, 2012 8:33 am quote
Dude, again... your pics and step by steps are great. Nice work.
If I can get to FL, I'm in for a screamer with you and Travis.
I've got to get to somewhere without a "winter".
Hooked
PX200E
Joined: 17 Oct 2008
Posts: 172
Location: Norway
Thu Feb 23, 2012 6:25 am quote
Great thread, refreshing to read something other than what helmet to buy or threads like "show me your stickers"

Just one question.. how much do you trust that JB weld patch in the intake, not worried its going to come off and wreak havoc with the bearings ?
Hooked
Sprint 166, P150S
Joined: 02 Nov 2011
Posts: 315
Location: Saigon
Thu Feb 23, 2012 7:10 am quote
Glad to hear that the bike is delivering closer to what you were hoping for now. I think this has a lot to do with your attention to detail and know how. I've only ever ridden one kitted bike (mine) and I was amazed at how torquey it was compared to standard. You seem to hear people making comments along the lines of a kitted bike will be peaky and a nightmare to ride around town etc, especially Malossi. That hasn't been my experience. I know that when my engine was put together, the engine was worked on to get the right amount of squish. You spent a ton of time getting that right. Is getting the squish measurement correct critical to good torque?

Love the thread. A real insight.
Hooked
78 P200 05 PX150
Joined: 06 Jul 2010
Posts: 214
Location: Fort Collins, CO
Thu Feb 23, 2012 2:30 pm quote
First question...

I'm not too worried about the JB Weld. The surface was pretty rough and a relatively large area to stick to. I have used it in the past with no issues. Since it is in the port, the odds are it would head into the combustion chamber if it started to come loose. At least I hope so. If the surface is prepped and clean, there is no reason it shouldn't last. Some people use Devcon titanium putty. I figure that the back boost ports are the farthest from the exhaust so temp shouldn't be an issue.

Second...

I found the cylinder head to be one of the most critical items in 2-stroke performance. I don't pretend to be an expert on MSV (squish velocity) numbers, bore/squish ratios etc. I just remember back to my RS125 racing days. I had an old 90 RS125 with a frankenstein 93/94 motor in it. I loaned it to a local TZ250 rider for the CCS finals in Daytona in 96. He took the bike and him and his brother tuned it for Daytona. They basically measured up the motor and cut a new cylinder head for it. All I know was when I got it back, it was a rocket. The bike finished 4th at Daytona against 3 factory backed 95 RS125s. The 95 was the next gen bike. The only difference was gearing, jetting and a new head.

I personally think that getting the compression, squish clearance and squish angle and width are very important to the overall performance of the motor. One of the problems with too big of a squish is that fuel and air will be in the squish area but the gap isn't big enough for it to burn completely. Unburnt fuel is wasted fuel. The squish forces all the fuel and air into the center of the combustion chamber so it burns properly. It helps to create turbulence to help all the fuel burn.

I know Al spent alot of time developing the squish angles and gap that work best in his motors. He recommended 1.2mm and that's what I shot for. Overall it seems to be working well. Right now I have a big issue with a rattle as the RPM comes up. At first I thought it was detonation but I think the kickstand spring is vibrating against the pipe. Almost sounds like the motor is coming unglued.... I need to find a piece of high temp hose i can put over the spring that is fairly thin.

I love the torque of the motor. The Pinasco kit is a joy for riding around town. Although mine does have some fairly extensive porting. I was all worried about needing a short 4th gear. That was short lived. The bike pulls like a train. I can lug it down in 4th and just roll open the throttle. If it wasn't for fear of breaking the cush drive, I'd be practicing wheelies. On and off first gear will easily pull the front end off the ground. It's fun, just noisy with the 226 pipe. I might try some fresh fiberglass in it the silencer to see if I can quiet it some more.

Chuck
Hooked
78 P200 05 PX150
Joined: 06 Jul 2010
Posts: 214
Location: Fort Collins, CO
Fri Feb 24, 2012 4:18 am quote
Mail man dropped off a package yesterday. Looks like I know what I'll be doing this afternoon.



I bought the Pinasco Sport spring / cup set from http://www.hotrodscooterparts.com/.

Delivery was quick via Priority Mail.

Chuck
Molto Verboso
Joined: 05 Apr 2010
Posts: 1917

Fri Feb 24, 2012 6:10 am quote
Nice work !
Hooked
Sprint 166, P150S
Joined: 02 Nov 2011
Posts: 315
Location: Saigon
Fri Feb 24, 2012 6:54 am quote
Thanks for the answer. Explains it so an idiot like me can understand! I think the reason some kits get this rep for being peaky and awful to ride at anything below the pipe power-band is because they just throw the head on straight out of the box.
Hooked
78 P200 05 PX150
Joined: 06 Jul 2010
Posts: 214
Location: Fort Collins, CO
Fri Feb 24, 2012 1:04 pm quote
I had all my new clutch pictures to show you guys. I decided to take it for a test ride to make sure it wasn't slipping. good news, the clutch seems to be working great. The new springs barely feel stiffer than stock.

Bad news... Motor go boom.

A chunk of the Nikasil plating came off the cylinder above the exhaust port and trashed the cylinder. Right now the chunk lodged between the top of the cylinder and the head and actually bent the top of the cylinder slightly near the o-ring groove. I haven't pulled the cylinder yet to check the piston.

At a minimum, I need to get the cylinder re-plated. Ugh...

Plug was chocolate brown and the max CHT was 374F when it went. Bummer... This is actually the first 2-stroke I had blow up on me. It doesn't look like a seizure. I'll know for sure when the cylinder is off.



Chuck

Last edited by chuckactor on Fri Aug 19, 2016 10:13 am; edited 2 times in total
Primasarah
1979 P200E, 1977 Rally 200, 1974 Primavera
Joined: 15 Mar 2011
Posts: 3087
Location: Lake Worth, FL
Fri Feb 24, 2012 1:18 pm quote




Last edited by TravisNJ on Fri Feb 24, 2012 1:24 pm; edited 1 time in total
Ossessionato
GTS250
Joined: 26 Jan 2009
Posts: 2959

Fri Feb 24, 2012 1:23 pm quote
Fuck me dead, that sucks.

I won't offer any opinions on what happened, respect for the dead...
Hooked
cosa, rally, T5, italjet F125, Lambretta, plus junk
Joined: 07 Dec 2011
Posts: 306
Location: oxford
Fri Feb 24, 2012 2:09 pm quote
thats scooters for you..

why do we do it....
Mr. Clean
P,SUPER,V90, 50 Special
Joined: 27 Jul 2010
Posts: 10207
Location: This is't my locker!
Fri Feb 24, 2012 7:42 pm quote
Oh no... say it aint so Joe... I mean Chuck! Doooood! This isn't how this book should end. I'm really sorry to hear it... I was truly hoping for a rough, tough, happy monster... it was surely being written that way. Anyway do you have any idea what happened? What were the circumstances?
Sorry again man... I hate shit like that.
Ossessionato
GTS250
Joined: 26 Jan 2009
Posts: 2959

Fri Feb 24, 2012 8:10 pm quote
Vader19 wrote:
Anyway do you have any idea what happened? What were the circumstances?
Sorry again man... I hate shit like that.
The required moment of silence has been observed.

I am curious how the Nikasil lining pulled away from the wall like that. It seems almost crushed in around that chip.

Did the head centering issues you had bite you by distorting the lining?

Come to think of it, looking at the Feb 19 pictures, you can see the deformation in the 6th shot showing the top of the jug. Right around the 8 o'clock position.

Further on in the series is a shot of the piston at the top of the stroke. In that same area there appears to be nick in the edge.

Camara shots can be deceiving however, light and shadows can distort the appearance in a 2d format
The only other thing would be that some of the JB Weld came loose. I would really like to see how that held up over the short run.

P.S. I don't mean to pick over your misfortune like a vulture, but failure analysis and "root cause" are what I do for a living. Second nature.

Perhaps it will prevent a future occurrence for another go at it. I certainly feel like I am learning something.
Hooked
78 P200 05 PX150
Joined: 06 Jul 2010
Posts: 214
Location: Fort Collins, CO
Sat Feb 25, 2012 5:55 am quote
Yes.. there is a certain grieving process we must follow. As respect for my heritage, I will be sitting Shiva this week. Please feel free to come by with some bagels and a deli platter.

Piston is trashed as well. Looks like the majority of the "chuck" ended up lodged on top of the second ring. It smeared the piston pretty bad. Big debate is cutting a new Pinasco piston or perhaps adopting another piston. Turns out Grand Sport makes a 69mm Polini piston. It's only single ring though. They do make a 2-ring 68.5mm piston put I'm a bit nervous having to build up the Nikasil like that.

Good news is that I get a chance to try out Millenium plating and see how their work on Vespa cylinders is. For all you guys with scarred Malossi cylinders, there may be hope. Unfortunately, hope costs $$. This little hiccup is going to cost me probably $350+ to fix. For me it makes sense since they cylinder has a ton of porting work in it and the head is already matched to it. If it was a stock kit, it wouldn't pay.

I'm looking at maybe $125 for the piston and rings and another $175 for plating work. Then the piston needs to get 5k frequent flyer miles going back and forth to Fresno for mods...

Pictures to follow...

Chuck
Hooked
78 P200 05 PX150
Joined: 06 Jul 2010
Posts: 214
Location: Fort Collins, CO
Sat Feb 25, 2012 7:30 am quote
Wow.. Just spent awhile on the phone with Harry Barlow in the UK. I called him to ask his opinions on what piston to run. When I was racing my RS125's, Harry was in the states. He did a couple motors for me.

.. to say there is a difference in opinion between Harry and Al is an understatement. I think they have different views on everything. The only thing they agree on is timing.. 18deg. That and thin ring pistons. It's kinda funny when you talk to tuners. You tell them what the other guy did and you get a "no.. no .. no.. that's all wrong" and vise versa.

From the sounds of it, Harry is going to send me a complete 207 stage-4 top end kit (cylinder, 68mm piston, head & packing plate) for my bike to try. He was also going to send me his setup specs for the stock carb and the Vortex.

I guess I'll sit tight on the Pinasco and wait for the Pro-port top end to try. I'll reserve all the comments from Harry until I try his kit. I guess I'll at least get the Pinasco piston from SIP and a couple other bits Harry wanted me to get.

Ugh.. I was hopingot avoid this. I am stuck in the middle of tuner hell. Open your wallet and say ahh...

Chuck
Primasarah
1979 P200E, 1977 Rally 200, 1974 Primavera
Joined: 15 Mar 2011
Posts: 3087
Location: Lake Worth, FL
Sat Feb 25, 2012 7:55 am quote
chuckactor wrote:
I will be sitting Shiva this week. Please feel free to come by with some bagels and a deli platter.
I'll bring the chopped liver and pickled beef tongue.
Hooked
cosa, rally, T5, italjet F125, Lambretta, plus junk
Joined: 07 Dec 2011
Posts: 306
Location: oxford
Sat Feb 25, 2012 8:04 am quote
never heard a bad thing about Harry or his work...

shame about your Pinasco though...
Ossessionato
GTS250
Joined: 26 Jan 2009
Posts: 2959

Sat Feb 25, 2012 9:07 am quote
I think it is a hazard of the hobby/profession.

There are lots of ways to skin the cat, especially with old engines.

I will say this for Al tho: he will listen to ideas from his customer and try them out if it makes sense.

I would be very cautious about mixing approaches from two tuners. you might end up with either too hot of a config, or they might cancel each other out.

I will bring the whiskey, as I am Irish. =)
Mr. Clean
P,SUPER,V90, 50 Special
Joined: 27 Jul 2010
Posts: 10207
Location: This is't my locker!
Sat Feb 25, 2012 1:51 pm quote
That's killer re: the Hrry B kit... Personally I wouldn't sleeve it though.
You've got options though, and one sounds real good.
I'll bring beer as a "Hafner" (my last name) is a German beer barrel maker
Looking forward to chapter 2 or the 2nd edition... however you see it! Onward!
Hooked
78 P200 05 PX150
Joined: 06 Jul 2010
Posts: 214
Location: Fort Collins, CO
Mon Feb 27, 2012 2:43 pm quote
Might as well step backwards for the readers.

I had slipping clutch problems and Al recommended the Pinasco Sport spring set. I thought I'd publish few pictures of the new clutch parts.

Here's a shot of the stock spring next to the new Pinasco ones.



The difference in height is about 4mm. Actually here are the particulars if anyone is interested.

Stock / Pinasco
height - 28mm / 32mm
wire dia - 1.58mm / 1.50mm
ID - 14.40mm / 15.04mm
# turns - count them

The stock springs are nicer quality with the ground ends etc. Using my carfully calibrated fingers, the spring rate seems about the same. looks like you pickup more preload with the longer free length.

I did take a file to the Sureflex plates as I felt some burrs on them. I never looked to close at them when I installed them the first time. you can see by the cut marks, all the raised areas.





The Pinasco spring cups have a hole in them. I assume this is to help get oil to the clutch better for lubrication and cooling. they do make it real easy to make sure the springs are seated in the pressure plate recesses. You can just look in and see them.



And when you put it all together, it looks like this.



As I said earlier, it seemed to fix the slipping although I only had 5 miles on it.. probably less. The lever didn't feel any stiffer than stock.

Chuck

I'm going to throw the stock top end and Sito pipe back on the bike for now. I also still have the original carb.

A new Pinasco piston is on order from SIP thanks to Travis. I also got a packer plate and a thicker head gasket to experiment with timing and squish down the road.
Member
'80 p200, '76 150 super, '66 125
Joined: 20 May 2009
Posts: 48
Location: california
Thu Mar 01, 2012 10:29 pm quote
I run a kitted 210. Use heavy malossi springs and outrun smallies off the line. Slipping? What's that?
Hooked
PX125,200, T5, SS180,TS125 and some more...
Joined: 10 Mar 2012
Posts: 198
Location: Paris, Taxes!
Sat Mar 10, 2012 12:46 am quote
Hello,
I'm brand new on this forum, really found of o-tuning and I was carefully watching your step by step tuning of your P200 in a very close way that I several did on mine.
Seeing your platted nikasil blew away I wondered if you had got your (a bit too wide for sure) exhaust chamfered??? It's the only way to secure the platted nikasil from a pulling out...Keep your exhaust width under 70% of the bore. your method to cope with the exhaust width is not the good one: just measure the straight distance between the 2 marks on your piston; no sin,nor cosin....



Uploaded with ImageShack.us

just a tip for your throttle that stay a bit closed at WOT: grind the 2 upper side hedges of the throttle to allow it to enter the cover within 1 or 2 mm.



Uploaded with ImageShack.us
Hooked
cosa, rally, T5, italjet F125, Lambretta, plus junk
Joined: 07 Dec 2011
Posts: 306
Location: oxford
Sat Mar 10, 2012 11:03 am quote
looked like a too wide an exhaust port to me...classic ring dropper

too scared to say anything...I'm no tuner

but if there is any doubt theres no point re-lining that barrel...

throwing good money after bad....
Hooked
PX125,200, T5, SS180,TS125 and some more...
Joined: 10 Mar 2012
Posts: 198
Location: Paris, Taxes!
Sat Mar 10, 2012 11:10 am quote
+1 unfortunatly...
on a 68 mm bore you need to keep your exhaust width under 47mm between your 2 piston marks...
Hooked
cosa, rally, T5, italjet F125, Lambretta, plus junk
Joined: 07 Dec 2011
Posts: 306
Location: oxford
Sat Mar 10, 2012 11:27 am quote
maybe the dykes ring on the Pinasco piston doesnt help??

I've got a Pinasco 225 conversion on my Rally....
in standard form it has proved bulletproof...
although I did have to replace the old type piston after finding a crack right across the top
Hooked
PX125,200, T5, SS180,TS125 and some more...
Joined: 10 Mar 2012
Posts: 198
Location: Paris, Taxes!
Sat Mar 10, 2012 2:24 pm quote
not sure it's a matter of ring in this really case...
Hooked
78 P200 05 PX150
Joined: 06 Jul 2010
Posts: 214
Location: Fort Collins, CO
Wed Mar 14, 2012 2:05 pm quote
OK.. I'll get back on it. I have been ignoring this thing but it doesn't seem to want to go away. The new piston came in over a week ago and I haven't even bothered to pick it up from Travis.

I'll get the top end off tomorrow so we can see what really went wrong.

From what I can see in my 2 minute look was that a piece of Nikasil flaked off the bore above the exhaust port. Not from the edge of the port. Literally out of the middle of the cylinder wall. But, we will know more after we get it apart and can see the bore and piston clearly.

Chuck

In the meantime, I built a killer BMX race bike for my 8yo. Come to think of it, I get about 5 miles on the BMX bikes before my kids crash them and they require repairs.....
Primasarah
1979 P200E, 1977 Rally 200, 1974 Primavera
Joined: 15 Mar 2011
Posts: 3087
Location: Lake Worth, FL
Wed Mar 14, 2012 3:15 pm quote
chuckactor wrote:
The new piston came in over a week ago and I haven't even bothered to pick it up from Travis.
You better hurry up and grab it before I pick up that pinasco kit that needs a piston on scoot.net.

Cross Egypt Challenge - A 2400km ride throughout Egypt   Vespa Wasp Pin Badges   AF1 Racing Vespa Austin
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