177 / Big Box PWK28 Carb setting
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Lurker
LML Star Deluxe 125 (177)
Joined: 08 Aug 2020
Posts: 3
Location: Japan
Sat Aug 08, 2020 2:42 am quote
Hi All

I'm new to this forum and have a few questions about a DR177 bore up project that I'm just about to undertake (currently LML PX125)

I'll be using a BGM Big Box Sport and PWK28 with the 177 kit

1. Does anyone have the same or similar set up? If so, can you tell me the carb jetting and settings?

2. What is the recommended degree for timing?

3. It seems like the DR kit comes without a head gasket. Any pointers on this?

4. Any recommendations on porting?

Cheers
Addicted
2007 Stella 150
Joined: 02 Nov 2019
Posts: 765
Location: Rochester, Minnesota
Sun Aug 09, 2020 3:13 am quote
The DR does come without a gasket and that is how I and several others run ours.
Lurker
LML Star Deluxe 125 (177)
Joined: 08 Aug 2020
Posts: 3
Location: Japan
Sun Aug 09, 2020 3:30 am quote
Thanks for your response

So, are you saying that no gasket but, are you saying that a silicon sealant/gasket isnít required at all?

I mean, the engine head, bolted directly to the cylinder will work fine?
Addicted
2007 Stella 150
Joined: 02 Nov 2019
Posts: 765
Location: Rochester, Minnesota
Sun Aug 09, 2020 4:57 am quote
Star177 wrote:
Thanks for your response

So, are you saying that no gasket but, are you saying that a silicon sealant/gasket isnít required at all?

I mean, the engine head, bolted directly to the cylinder will work fine?
Thatís how I run mine.
Ossessionato
05 Stella, '62 VBB, 76 Sprint V, 63 GL
Joined: 16 Jun 2011
Posts: 2620
Location: Chicago. Well, Evanston, but that's almost Chicago
Sun Aug 09, 2020 9:44 am quote
I use copper spray head sealer on my top ends. DR heads and barrels are notoriously leaky. Lap them both a little bit before you install. You might be surprised how much variance there is.

The DR is a great intro-to-tuning top end, because it's cheap enough that when you blow it up, you won't feel too bad about it.

As to the PWK 28, you'll need to do a fair amount of porting to see the benefit of that change. Is your LML a reed or a rotary valve?

Honestly, you're better off just sticking with an SI 20/20, maybe a 24/24, with the DR. I built a Stella (LML 150) with a DR 177 and an SI 24/24 that got 14-15 HP a few years back. Eventually went to a big ol' reed block (VForce 4 reeds) and PWK 28, but didn't get that much more HP out of it.

I don't recall what sort of port timings the DR has, although I have some I could measure and estimate, but you'll want to make sure those are spot on, too. People have basically replicated Polini porting on a DR here, but it's a lot of work and at the end of the day, it's still a DR.
Lurker
LML Star Deluxe 125 (177)
Joined: 08 Aug 2020
Posts: 3
Location: Japan
Mon Aug 10, 2020 8:24 pm quote
Its a reed valve

I've ordered a copper head gasket

I was aware (due to the price and the reviews I've read) that the DR kit is a budget kit, but its kind of a stepping stone to higher quality kits and I didn't wanna splash big cash until I get a good grip of the porting mods necessary for high spec tuning. Also, I'm not bad around the mechanics of a motorbike

The reason I wanna stick a PWK 28 in it, is coz basically I've got one (with the whole jet kit) knocking around. I assume that the 28 will work with correct jetting and barrel porting

I've got other bikes (non Vespa) that I've tuned to high performance with great success, but not at all suitable for zipping around town with the missus on the back, so I decided to get this 125 and give it a bit of a tune up (There are reasons I didn't go straight for a 200)

I've owned plenty of Vespas previously to moving to Japan some 20 years ago, but they were either stock or modified by the previous owner, so never got a chance to go elbows deep into one (however, my housemate was a Vespa nerd and got into mine as much as he possibly could)

Any advice on main and pilot jet sizing for my set up (177, BGM BB Sport)?

All advice on timing, porting and jetting (and any other NECESSARY mods) is very helpful and I appreciate your time

Thanks
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