Jetting and timing a DR177 with Vespatronic
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Hooked
Bodgerific 150 Super, 50s in progress
Joined: 18 Aug 2016
Posts: 201
Location: Melbourne, Way Downunder
Wed Mar 07, 2018 6:10 am quote
Mocked up the BGM to get a before shot last night.



Then I put it on with the flyside, torqued it steadily down to 11ftlbs, ultra coppered the cylinder base and packer, and installed the head.

Gave it all till tonight to settle down, then checked all the torques, and tried the pressure test again.

Then swore a lot. Same bloody result. No discernible leak at the seals, head or cylinder, but a gauge needle that marches steadily down.

Time to get medieval I got out my car engine leakdown test and wound it down as far as I could, and set it loose, which hit the engine with about 18psi via the spark plug hole.



A discernible hiss could be heard from inside the case. I think it's fair to say I was not well pleased.

So off came the flyside. Compared to the original shot, it's obvious the silicon has been squeezed most of the way around.



And it looks like the cylinder wall was tightened up



So - new plan. I want to know where (if any) the highs and lows are, and if it can be made airtight by any means...



That's going to be a bitch to clean, it's once again torqued down, and when it's dried tomorrow I'll find out if nefarious means will actually seal this sucker.
Veni, Vidi, Posti
74 Super, 75 Super, PX project, LML off-roader and new to 2018, '66 Blue Badge Smallframe
Joined: 30 Nov 2011
Posts: 6783
Location: Victoria, Australia
Wed Mar 07, 2018 6:01 pm quote
Well hopefully that stops it completely. To be honest I haven't found RTV that difficult to remove.

I remember there was talk a while back about porous cases, although I think that was about later PX cases.

If you could get the smoke machine sorted out, maybe you could get one of those little cameras you connect to the phone inside the case to have a better look.



Safis did you have grease on the BGM gaskets?
Molto Verboso
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 1126
Location: London UK
Wed Mar 07, 2018 7:35 pm quote
If you put the cases together without the gearbox in there, you might be able to get better access to find the leak.

The only things I can think of is the casings are not flat or close with a gap.
Molto Verboso
1979 P150X, 1983 P200E, 1987 T5, 1996 PX200E, 2011 Yamaha Fazer 600 S2
Joined: 02 Aug 2015
Posts: 1384
Location: Veria, Greece
Thu Mar 08, 2018 12:48 am quote
What about the circled area?? Seems like the gasket has slipped...

@Ginch: No grease. BGM says clean surface and no sealants, etc. Piaggio has similar gaskets, on almost all of their modern scooters. No leaks there...

IMG_1108.thumb.jpg.041511b1f2ad52ff85b62e8fee32e245.jpg

Hooked
Bodgerific 150 Super, 50s in progress
Joined: 18 Aug 2016
Posts: 201
Location: Melbourne, Way Downunder
Tue Mar 13, 2018 5:32 am quote
SaFiS, I think thats the angle the photo was taken on showing up the lip behind it. I pulled it apart pretty carefully, and looking straight down, it was squashed in place.

Anyhow...

With the UltraCopper throughout, I was pretty confident it should hold air.

Nope.

So I took a few days to think about the logic of why it's leaking.

It was a slow leak, the sort that really hard to find, so first I blanked off the shifter area, bolted on the clutch cover, blocked off the oil filler, oil drain and breather, and slid on the hub.

The leak was unchanged, so logically, it probably wasn't internal to the case.

That left:

The intake blanking plate, or
The exhaust bung, or
The case to cylinder join (including the spacer), or
The cylinder to cylinder head join,or
Something else, like porus cases, or stupidity on behalf of the meatware (me!).


So, step one, I RTV'd the intake plate on, and RTV'd the bung. Nada.

Step two, I mounted the dummy blanked off head. Still nada.

So, it looks like it might be the cylinder and or the cylinder to case join.

So I hit the mill, and built this blanked off cylinder.



It's got a 30mm deep pocket for the piston to sit in at BDC, wide enough for the rings to fit into.

Mounted up with a spacer and the dummy head acting as a second spacer, it ends up like this



And...

It holds 6psi psi. It lost .2 of a psi in 60 minutes.

So the case holds air when it's glued together with RTV.

Now to find where the leak is. Cylinder to case, or maybe still the bung.

Ginch, is your smoke machine available?
Ossessionato
1980 P200E, 1974 Primavera, 04 Ninja 250
Joined: 04 Apr 2013
Posts: 3670
Location: San Diego, CA
Tue Mar 13, 2018 6:55 am quote
Nice work and good on ya for not giving up.

Why not RTV the crap out of the cylinder base to see if it's the stub next?

Could also be something exotic like a crack in the cylinder.

Can you use another cylinder and see if it seals?

I can't wait until you find this sucker and kill it.
Veni, Vidi, Posti
74 Super, 75 Super, PX project, LML off-roader and new to 2018, '66 Blue Badge Smallframe
Joined: 30 Nov 2011
Posts: 6783
Location: Victoria, Australia
Tue Mar 13, 2018 1:33 pm quote
I'm glad you narrowed it down, but an incredible pain to get there!

Smoke machine - the only container I could find was a cookie jar, and the lid didn't seal well either. So I put a thick layer of grease inside the thread of the lid. Not a perfect seal but good enough. Try that on yours, otherwise you're welcome to borrow mine. However I think it'd be easier (as in less time consuming) just to find a better jar or paint can.

I'm not sure if it's been suggested, but since you've narrowed it down to the base seal, then maybe try flattening that area? Get some glass, stick some wet & dry to it (maybe 320 ish?), oil it and do figure 8s with the bolted-together case. Like you would to flatten a carb.
You'll know then that it's as good as it can get.
Ossessionato
05 Stella, '62 VBB, 76 Sprint V, 63 GL
Joined: 16 Jun 2011
Posts: 2005
Location: Chicago. Well, Evanston, but that's almost Chicago
Tue Mar 13, 2018 2:41 pm quote
Based on what he's able to fab up for blanking plates, mock cylinders, etc, I'll guess he can do better than some glass and emery paper to lap that face...

Veni, Vidi, Posti
74 Super, 75 Super, PX project, LML off-roader and new to 2018, '66 Blue Badge Smallframe
Joined: 30 Nov 2011
Posts: 6783
Location: Victoria, Australia
Tue Mar 13, 2018 5:55 pm quote
chandlerman wrote:
Based on what he's able to fab up for blanking plates, mock cylinders, etc, I'll guess he can do better than some glass and emery paper to lap that face...

Ha ha! You're probably right!

Hooked
Bodgerific 150 Super, 50s in progress
Joined: 18 Aug 2016
Posts: 201
Location: Melbourne, Way Downunder
Wed Mar 14, 2018 4:52 am quote
Ha! Wish I had access to that one!

I'm lucky that my day job as a network nerd has taken me into an incredible range of factories where I still have contacts, and even luckier still that a few of my friends own their own facilities. On the "Favourites" page of my phone there's a metrologist who has his own tool shop with a CNC Bridgeport in the shed at the base of his house block, a former programming engineer who runs the local franchise for one of the major CAD/CAM providers, and a fab shop owner with 20 years of tin bashing and all the toys to take on major projects.

15 years ago I didn't know much more than one end of a spanner from the other, but when I started restoring my first project car, I was determined to learn to do the work myself, not just ask others for favours. So my mates have guided me along the way, frustrating as that can be at times for both me and them. Today I can happily rebuild a 6 cylinder 1960's Triumph engine from scratch in a day, and I've got 2 of them that run Megasquirt EFI in my current project cars, with all sorts of custom parts made from scratch. Being able to dream up, and then create parts that never existed before scratches an itch at the base of my soul.

Frustrating as it may be, I'm enjoying transferring the earned skills across to a new tech, and a new set of problems - and really enjoying how compact a Vespa project can be, as compared to a car rebuild. I will make this thing right!

Next stop after this one is running will be to find a nice (t)rusty local Super or Sprint that I can do a full restore on, and/or maybe find a smallframe to restore and give to the Mrs.

As to lapping the casing face, one of the biggest lessons I've learned is how bloody hard it is to fixture and set a complex part like a casing into a mill. I reckon if a glass plate might be easier (and I run the network for a glazier, so I might be able to find one...) I was actually thinking about putting an old cylinder in and spinning it with some fine lapping/grinding paste, and smoothing it that way. I thought that might be an easy fix.

Thanks for the encouragement/advice

C
Veni, Vidi, Posti
74 Super, 75 Super, PX project, LML off-roader and new to 2018, '66 Blue Badge Smallframe
Joined: 30 Nov 2011
Posts: 6783
Location: Victoria, Australia
Wed Mar 14, 2018 1:39 pm quote
Voodoo did the lapping thing (after removing the locating peg) and it worked well. But if it's any distance out then you'll be there forever.
Even if you have a stone benchtop in your kitchen you could use that. Cost you the price of a sheet of wet & dry and years of scorn from the Mrs.
Ossessionato
05 Stella, '62 VBB, 76 Sprint V, 63 GL
Joined: 16 Jun 2011
Posts: 2005
Location: Chicago. Well, Evanston, but that's almost Chicago
Wed Mar 14, 2018 1:49 pm quote
Gt6MK3 wrote:
I was actually thinking about putting an old cylinder in and spinning it with some fine lapping/grinding paste, and smoothing it that way. I thought that might be an easy fix.
sdjohn and Safis have both used this approach to do a light lapping on their cases this way with good results.
Ossessionato
1980 P200E, 1974 Primavera, 04 Ninja 250
Joined: 04 Apr 2013
Posts: 3670
Location: San Diego, CA
Wed Mar 14, 2018 2:28 pm quote
Yeah I did it but I think mine could still use a bit more. Nevertheless a bit of lapping and a bit of motoseal and it did seal fine. I just think it still could be flatter than where I stopped. Definitely my fly side is still riding a bit higher than the clutch side.
Ossessionato
1980 P200E, 1974 Primavera, 04 Ninja 250
Joined: 04 Apr 2013
Posts: 3670
Location: San Diego, CA
Wed Mar 14, 2018 2:33 pm quote
I bet if I used a more aggressive grinding paste it would've made it easier. I had an old tube of valve grinding paste, and I don't know how aggressive it is.
Molto Verboso
1979 P150X, 1983 P200E, 1987 T5, 1996 PX200E, 2011 Yamaha Fazer 600 S2
Joined: 02 Aug 2015
Posts: 1384
Location: Veria, Greece
Wed Mar 14, 2018 2:55 pm quote
sdjohn wrote:
I bet if I used a more aggressive grinding paste it would've made it easier. I had an old tube of valve grinding paste, and I don't know how aggressive it is.
Did it again on the new build. Used the coarse side for the first two passes and the fine side to get a clean surface. If you place the engine vertically, the weight of the cylinder helps a lot...

4605775132.jpg

Ossessionato
1980 P200E, 1974 Primavera, 04 Ninja 250
Joined: 04 Apr 2013
Posts: 3670
Location: San Diego, CA
Wed Mar 14, 2018 4:17 pm quote
Thanks for adding that Safis, Iíll have to get some sometime,
Hooked
Bodgerific 150 Super, 50s in progress
Joined: 18 Aug 2016
Posts: 201
Location: Melbourne, Way Downunder
Thu Mar 15, 2018 1:12 am quote
Lap Dancing.



Veni, Vidi, Posti
74 Super, 75 Super, PX project, LML off-roader and new to 2018, '66 Blue Badge Smallframe
Joined: 30 Nov 2011
Posts: 6783
Location: Victoria, Australia
Thu Mar 15, 2018 2:29 am quote
You may have your fancy machines, but that setup is so damn cheap it makes me weep.
Molto Verboso
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 1126
Location: London UK
Thu Mar 15, 2018 3:07 am quote
0.2 psi drop in an hour! I think you have the best sealed engine ever

I also think I prefer the American style lap dancing.
Hooked
Bodgerific 150 Super, 50s in progress
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Posts: 201
Location: Melbourne, Way Downunder
Thu Mar 29, 2018 4:46 am quote
I really didn't feel comfortable running with only ultra copper - the nerd in me feels like pulling the gasket out is wrong if the cases were designed to have one in there.

So I searched back through what I've used in the past, and remembered Threebond 1104. It's not nearly as viscous, but it's fuel resistant, and it sealed up a gearbox for me when nothing else would.

So, I went back to the paper gaskets, with the good method, and plenty of Threebond.

Success.

With the cylinder blank bolted on, it holds air (loses under 1/4 of a psi in 3 hours).

Which is good. But. I cant get the cylinder and head to seal.

I've lapped the cases, and I'm (reasonably) sure that the leak isn't between the case and cylinder (no bubbles), which points to the cylinder/head join.

It's bloody hard to check, because the join is recessed, and theres no room to get in there with test fluid.

My recollection is that the cutter I used when I cut the recess in the head was near the end of its life, so it's probably not as smooth as it could be. I lapped the head, but to smooth the cylinder recess, I'll need to re-cut it by 0.1 to 0.3 of a mm with a shiny new cutter.

Problem there is that my squish is already at the minimum.

I do have a spare 177 head, so I could the head then use it, but I have a longer term plan for it.

The other option is to cut a thicker spacer, but that will further change my port timings.

So, a question for Jack. Would spacing the transfers out another .4 or 1 mm (trying to think what stock I can get in a hurry) be good or bad? What effect would it have? ( I think I have some 1.2 mm stock, and some 3mm). Tat would let me recut the cylinder and head.

Otherwise, I can tidy up the cylinder, and cut down the spare head.

Which would be better?
Addicted
1974VLB 1979VSX 1974V9A
Joined: 12 Sep 2014
Posts: 632

Thu Mar 29, 2018 7:46 am quote
Are you using a high temp sealant on the base gasket/head and letting it cure before you test it? Btw, itís impressive how far youíve gone with this. Looks great.
Molto Verboso
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 1126
Location: London UK
Thu Mar 29, 2018 9:00 am quote
Keep the gasket you have and don't worry about that tiny head leak. Will probably seal better once hot.
You have very little left on the transfers, so no bigger packer than now. When it comes to transfers 0.1mm can be a noticable differance. And as with everything 2 stroke the nearer the limit the more sensitive and then falls off a cliff.
Hooked
Bodgerific 150 Super, 50s in progress
Joined: 18 Aug 2016
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Location: Melbourne, Way Downunder
Thu Mar 29, 2018 2:22 pm quote
PureDrivenSnow wrote:
Are you using a high temp sealant on the base gasket/head and letting it cure before you test it? Btw, itís impressive how far youíve gone with this. Looks great.
Yep, Ultra Copper on the cylinder joins, 24Hrs cure. It's a frustrating wait every time. If you like this one, wait till you see the next project.
Jack221 wrote:
Keep the gasket you have and don't worry about that tiny head leak. Will probably seal better once hot.
You have very little left on the transfers, so no bigger packer than now. When it comes to transfers 0.1mm can be a noticable differance. And as with everything 2 stroke the nearer the limit the more sensitive and then falls off a cliff.
Should have been clearer - the nil/negligable leak (Now at 1.5pSI in 14 hours) is with the dummy cylinder in place. If I put the real one and the cylinder on, I lose about a PSI a minute.

So if i'm not going to change the packer, I reckon I'll clean up the cylinder/head join, and mill down the other head to match. That way the timings wont change.

Cheers Guys.
Veni, Vidi, Posti
74 Super, 75 Super, PX project, LML off-roader and new to 2018, '66 Blue Badge Smallframe
Joined: 30 Nov 2011
Posts: 6783
Location: Victoria, Australia
Thu Mar 29, 2018 2:27 pm quote
Gt6MK3 wrote:
It's bloody hard to check, because the join is recessed, and theres no room to get in there with test fluid.
Smoke.
Molto Verboso
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 1126
Location: London UK
Fri Mar 30, 2018 12:07 am quote
Maybe you could machine an O ring groove into the head? I think if anyone could it would be you
Hooked
Bodgerific 150 Super, 50s in progress
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Fri Mar 30, 2018 6:44 am quote
Jack221 wrote:
Maybe you could machine an O ring groove into the head? I think if anyone could it would be you
I actually have some 66/2/70 Viton O rings on order, but the Bearings Wholesaler couldn't supply before easter.

Instead, today I wen't up to my mate Alan's house (he owns the toolroom in the very large mens shed at the base of his yard.)

I like to earn my shed time, so first we rebuilt the starter in his stranded trusty rusty Hilux ute (you can hurt em, but you can't kill em), and I reinstalled it for him (much crawling underneath and swearing...). Then we chucked up the cylinder in the lathe, and clocked it carefully with a dial gauge. It had enough variance to be a worry, so we cut it back a few hundredths till it was nice and smooth.

The new Pinasco head then went on, and squish started at 2.2mm. We trimmed that back little by little till we ended up at .75mm - .8mm Couldn't go any further without having to undercut the material surrounding the business part of the head for fear of interference with the cylinder itself due to the undercut in it.

So we called it a day, and I dropped into work, reset some servers, than came home and cleaned the cylinder, head, casings, piston and rings again, and lightly assembled them with some ultra copper. Waited an hour while I cleaned up the workshop, than torqued it all down.

Judgement hour awaits tomorrow night.
Hooked
Bodgerific 150 Super, 50s in progress
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Tue Apr 03, 2018 6:01 am quote
[quote="Ginch"

Smoke.[/quote]

If only.

Ossessionato
1980 P200E, 1974 Primavera, 04 Ninja 250
Joined: 04 Apr 2013
Posts: 3670
Location: San Diego, CA
Tue Apr 03, 2018 7:13 am quote
clutch side cylinder head had the most audible hissing as you moved around the areas.
Ossessionato
05 Stella, '62 VBB, 76 Sprint V, 63 GL
Joined: 16 Jun 2011
Posts: 2005
Location: Chicago. Well, Evanston, but that's almost Chicago
Tue Apr 03, 2018 7:32 am quote
Gt6MK3 wrote:
Ginch wrote:
Smoke.
If only.
I think Ginch was implying you're probably ready to just set the damn thing on fire and be done with it
Veni, Vidi, Posti
74 Super, 75 Super, PX project, LML off-roader and new to 2018, '66 Blue Badge Smallframe
Joined: 30 Nov 2011
Posts: 6783
Location: Victoria, Australia
Tue Apr 03, 2018 6:24 pm quote
That would be "Fire" by the Crazy World of Arthur Brown rather than Smoke on the Water...

Yes if you watch the video I think John is right.
Hooked
Bodgerific 150 Super, 50s in progress
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Wed Apr 04, 2018 3:23 am quote
chandlerman wrote:
Gt6MK3 wrote:
Ginch wrote:
Smoke.
If only.
I think Ginch was implying you're probably ready to just set the damn thing on fire and be done with it
A fire? Nah, waaaay to easy. Havenít you seen I like to play the long game? If you watch the vid, youíll see Iím setting the little bugger up for a cancer diagnosis 20 years from now
Hooked
Bodgerific 150 Super, 50s in progress
Joined: 18 Aug 2016
Posts: 201
Location: Melbourne, Way Downunder
Wed Apr 04, 2018 4:57 am quote
sdjohn wrote:
clutch side cylinder head had the most audible hissing as you moved around the areas.
Yep. I'd tried all sorts of bubbles and smoke, but the iphone turned out to be the better diagnostic tool!

The video was from before I lathed the cylinder smooth, and it turned out with that one that the "one hour cure" silicone I was using for the test was still wet on the inside when I pulled it apart (4 hours after it went on).

So, as above, I lathed the cylinder grove, and milled the new head slow and smooth.

Wasn't plain sailing though - I didn't think I needed to undercut the cylinder head body, because I had just under a mm of clearance to the head under the contact ring after milling it down for squish. What I'd forgotten was the lettering from the manufacturer, which is raised about 1.2mm.

When I torqued it all together, I had a sinking feeling again as the needle went south. The iphone revealed an audible hiss from the head, but then I realised the lettering was fouling on the cylinder.

So in the mill it went (again!).



Put it together again last night after work, with a smear of ultra copper.

Was my birthday today, so I spent the day happily doing zero work, and pottered in the garage all day. Was sorely tempted to run a pressure test, but equally determined to let the ultra copper cure for 24 hours.

Dropped into the garage after dinner (my poor wife is used to me), and it's mostly good news. It drops from 6psi to 5psi in just on an hour, so it's not perfect, but I think my OCD is going to let me call it good enough. As Jack said, it'll seal better when hot, and I'm confident it's all top end, not an oil sucker.

So I'm going to run it up and see how compression is, and see if it leaks oil at the head. If it does, I'll pull it again and carve an o ring slot into the cylinder.

But for now, onward and upward is the plan.

Thanks

Craig

Last edited by Gt6MK3 on Wed Apr 04, 2018 6:02 am; edited 1 time in total
Ossessionato
1980 P200E, 1974 Primavera, 04 Ninja 250
Joined: 04 Apr 2013
Posts: 3670
Location: San Diego, CA
Wed Apr 04, 2018 5:19 am quote
Itís awesome that you found it! But itís only a few more minutes work to cut the oring and kill it for good. I vote for finishing it off!!!

Itís like Thunderdome, ďtwo men enter, one man leavesĒ.
Hooked
Bodgerific 150 Super, 50s in progress
Joined: 18 Aug 2016
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Location: Melbourne, Way Downunder
Wed Apr 04, 2018 6:10 am quote
sdjohn wrote:
Itís awesome that you found it! But itís only a few more minutes work to cut the oring and kill it for good. I vote for finishing it off!!!

Itís like Thunderdome, ďtwo men enter, one man leavesĒ.
It's 127 days since I rode.
Ossessionato
1980 P200E, 1974 Primavera, 04 Ninja 250
Joined: 04 Apr 2013
Posts: 3670
Location: San Diego, CA
Wed Apr 04, 2018 6:33 am quote
But with your skills you'll knock that o-ring groove out in an hour, right? Totally worth it. I hear you on the delay, but set yourself up for success.
Hooked
Bodgerific 150 Super, 50s in progress
Joined: 18 Aug 2016
Posts: 201
Location: Melbourne, Way Downunder
Tue Sep 11, 2018 8:26 am quote
Right.

So I met Buffy http://modernvespa.com/forum/topic159075, and work on poor Hanoi Jane ground to an immediate halt. The lure of riding the Aussie Mille http://scootermille.weebly.com/, on a bike I'd built from scratch in under 6 months seemed do-able, especially after I teamed up with Ginch and started shadowing his One Smallframe build.

About 10 days ago, we realised we were kidding ourselves, and that the bikes wouldn't be ready. Ginch reached into his vast stable of Scooters and started preparing a bike (or two), and I remembered I'd been tripping over Hanoi Jane every time I needed tools for the last 6 months.

Basically, a week ago I realised I had 2 weeks to Install the neglected rebuilt DR177, re wire and re-cable her, then jet and run in the engine.

Forgot to mention, I'm going to Europe for 3 weeks, one week after the Mille. So my work clients are (of course) queuing up with work projects they hadn't mentioned that have to be done before I go.

It's gonna be tight.

I figured I'll need all the help I can get (and I'm a nerd).

So, an EGT probe went in



Followed by a AFR wideband and 2 stroke adapter.



Getting that right took a couple of go's and a lot of luck. I can get it tight, just!

Then a buttload of wiring got run



And marking out began



So that gauges could be installed



Tonight (finally), noise got made, and I got a first shakedown run in. Actually, I got to the end of the driveway, touched the rear brake, discovered I'd over adjusted it, got sideways on new tyres, and almost high sided myself. Rolled back to the garage, slight adjustment, and on my way.

And I discovered that my battery isn't holding charge, and the Vespatronic can't make enough for the gauges unless I'm over 3000 rpm. Fun

So... onto jetting.

It's all weird. It starts 2nd kick with no choke, but wont start with it. It (according to the AFR) is lean right across the range. Idle it's at 15s, and it runs on the road at 14.5 to 19. I only went out for 15 minutes or so, but it's lean lean lean. CHT on the SIP (under plug) never got over 125(c), but the EGT sits at about 850(F) most of the time and got up to 1150(F) when I help 2/3rd throttle uphill for about a minute.

Current setup is a new 24/24 SI, drilled out to 1.8mm, with 55/160 AC160 BE3 MJ135. Pollini Venturi and a spaced airbox cover.

Any thoughts or suggestions on what I should look at in the morning? BE5 maybe? Jack???

Craig

(Oh, BTW, some other upgrades are ready to be added this week once jetting is getting sensible. Stuff like this first)




Then the serious Scooterporn

Molto Verboso
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 1126
Location: London UK
Tue Sep 11, 2018 7:55 pm quote
I was wondering what happened to the 177. Got as far as engine built and that was it. Thought you got her running and all done but I guess not.

You've brought her some serious presents. Disc brake is hopefully essential. Is that a 26/26 carb too?

The EGT and AFR unfortunately won't help as much as you think.

To get the jetting done as quickly and safely as possible for your set up you will need a different AC and Atomiser. As suggested a BE5 is the most likely to be appropriate and with an AC120 it will settle down much better.

You will need quite a few jets but to start with.

AC120 BE5 120MJ 45/140 pilot

If you take the AC120 and BE5 as fixed. All work will focus on the main jet and pilot.

Main jet just needs to be big enough to feel a machine gun splutter at WOT then drop down two sizes.

Pilot jet is much more difficult to get perfect but fast tickover mixture screw needs to be 2.5 turns out. Only the small number on the pilot jet affects the mixture screw turns.

Go easy with that cast cylinder, they need plenty of running in before they can be thrashed hard.
Hooked
Bodgerific 150 Super, 50s in progress
Joined: 18 Aug 2016
Posts: 201
Location: Melbourne, Way Downunder
Tue Sep 11, 2018 8:35 pm quote
Thanks Jack

Struggling to find a 120AC here in Aus, Any compromise you can suggest?
Molto Verboso
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 1126
Location: London UK
Tue Sep 11, 2018 8:43 pm quote
Soft solder up any other AC and drill a 1.20mm hole through it. Be sure to scratch off the old size number.
Hooked
Bodgerific 150 Super, 50s in progress
Joined: 18 Aug 2016
Posts: 201
Location: Melbourne, Way Downunder
Wed Sep 12, 2018 6:23 am quote
Excellent -

Made a "Roll your own" 120AC with soldering iron and a 1.2mm drill. Ordered a range of pilot jets.

Chucked in the 120AC with a BE5 and a 130MJ. Added in a 38-120 (only other PJ I had).

Still lean, but much closer to the numbers at low idle. still a little high (but better) at mid range, slightly rich at WOT.

Took it for a few km's down the freeway at at about 90kph (55mph). About 1/2- 2/3 throttle in 4th. CHT was about 130C (266F), EGT was 1050F. Interestingly, going to WOT (Briefly, it's a new iron cylinder) dropped the EGT.

Reckon I need to go richer in the early and mid range. 45/140 30/140 50/120 and 52/120 jets arrive tomorrow, so I'll take them out and see what they give.

Also have BE 4, (lower the same as BE5 but no upper holes) and a (marked as)E3 (Lower the same as BE5, but 2x 0.8 upper holes.)

Looks like I've got some riding to do.
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