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GP150 lockdown project

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Re: GP150 lockdown project

Postby Storkfoot » Mon Apr 26, 2021 8:17 am

I know the difference.

I ran this engine to Davos on 2014 in a S2. It had one of those MB panel filters that wedges between the carburettor and panel. Every afternoon, the performance would die. I would take the filter off, clean it in petrol, and go again.

Needless to say, the filter was consigned to the bin upon my return. It was replaced by the Breath Sweet I refer to in this thread. That filter has been spot on.
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Re: GP150 lockdown project

Postby Warkton Tornado No.1 » Mon Apr 26, 2021 11:20 am

I think that modern foam filtration materials are very good & adequate for uprated carburation.

The trick is ensuring that the air getting to the carburettor is not restricted by tight bends & has adequate volume.

The next experiment for my Rapido 71 x 61 (I state that as an indication of the likely volume of air required) is to put together my own interpretation of an air filter box in place of the OEM taking fresh air via the air scoop (50 mm) hole. The under panel air is stale/warm by comparison to the 'outside' air & cooler air offers several advantages. That said, better than unfiltered air.

With respect to anybody happy with their purchase, I don't believe that the re-engineered OEM boxes are adequate for anything above a medium tune.
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Re: GP150 lockdown project

Postby Storkfoot » Sun Jul 11, 2021 5:33 pm

It is still not finished but I did manage to start the carb setting process today.

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Re: GP150 lockdown project

Postby nsaints » Sun Jul 11, 2021 6:24 pm

nice job, that looks lovely
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Re: GP150 lockdown project

Postby superhooper » Sun Jul 11, 2021 11:33 pm

Looking good Paul!
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Re: GP150 lockdown project

Postby coaster » Mon Jul 12, 2021 12:36 pm

Very tidy job mate 8-)
Last edited by coaster on Wed Jul 21, 2021 12:54 am, edited 1 time in total.
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Re: GP150 lockdown project

Postby Storkfoot » Mon Jul 12, 2021 4:47 pm

I suppose I should mention (own up) that my first run was only around the block as I couldn’t get out of second gear (gear cables the wrong way round - never done that before) whilst the second attempt resulted in me pushing it home a mile having run out of petrol :oops:
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Re: GP150 lockdown project

Postby Toddy » Mon Jul 12, 2021 4:48 pm

Storkfoot wrote:I suppose I should mention (own up) that my first run was only around the block as I couldn’t get out of second gear (gear cables the wrong way round - never done that before) whilst the second attempt resulted in me pushing it home a mile having run out of petrol :oops:


Least your honest Paul :lol: looks great mate
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Re: GP150 lockdown project

Postby bsso78 » Mon Jul 12, 2021 6:52 pm

Straightening forks is a piece of cake and doesn’t need heat or laser guided straight edges. Just know where you are looking and apply the right amount of force and they will drop into true.
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Re: GP150 lockdown project

Postby gaz_powell » Mon Jul 12, 2021 7:05 pm

Looks very nice and built well Paul
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Re: GP150 lockdown project

Postby Storkfoot » Mon Jul 12, 2021 7:47 pm

Toddy wrote:
Storkfoot wrote:I suppose I should mention (own up) that my first run was only around the block as I couldn’t get out of second gear (gear cables the wrong way round - never done that before) whilst the second attempt resulted in me pushing it home a mile having run out of petrol :oops:


Least your honest Paul :lol: looks great mate


I try not to take myself too seriously :D
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Re: GP150 lockdown project

Postby Andy B.L.C. » Mon Jul 12, 2021 8:28 pm

Storkfoot wrote:I suppose I should mention (own up) that my first run was only around the block as I couldn’t get out of second gear (gear cables the wrong way round - never done that before) whilst the second attempt resulted in me pushing it home a mile having run out of petrol :oops:


Anyone who denies ever having done either of the above is either 1. a liar or 2. an owner of a far east built placcy ped & on the wrong website... :roll:
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Re: GP150 lockdown project

Postby dickie » Mon Jul 12, 2021 8:32 pm

Excellent job.

Absolutely right about not taking things too seriously. Once you do, the fun evaporates.
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Re: GP150 lockdown project

Postby Storkfoot » Sat Jul 17, 2021 11:55 am

Storkfoot wrote:I doubt it’ll win any design awards but I am confident it’ll work well in the space between the toolbox and tank.

Image


Having now done a few miles on this now, I think I have too much foam in the space.

It is, therefore, compressed, and strangling the air flow. I am going to try it (I) without a foam filter, just the elbow, (2) with the breath sweet running backwards and (3) with a smaller home made sock one so as the foam isn’t compressed as much.
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Re: GP150 lockdown project

Postby Warkton Tornado No.1 » Sat Jul 17, 2021 2:26 pm

Storkfoot wrote:
Storkfoot wrote:I doubt it’ll win any design awards but I am confident it’ll work well in the space between the toolbox and tank.

Image


Having now done a few miles on this now, I think I have too much foam in the space.

It is, therefore, compressed, and strangling the air flow. I am going to try it (I) without a foam filter, just the elbow, (2) with the breath sweet running backwards and (3) with a smaller home made sock one so as the foam isn’t compressed as much.


I think you are correct in that the filter is 'too enclosed' as it is positioned, further restricted by the bigger tank. A similar set up on a VHB (with two stroke internals) worked for me with a standard tank. The 'space envelope' thing with modified OEM air boxes that I have been banging on about :roll: has been proven again IMO via your findings

I believe there is a tendency with the PH & VHB to hot flood. They have virtually identical float/bowl arrangements. The VHSB etc have an overflow incorporated in the bowl though they don't glob out fuel through it after a hot run. I think they allow expansion of the fuel which eliminates hot start flood issues. Yesterday, I was meticulously rebuilding a VHSB34LTD & removed the brass overflow tube from the bowl for cleaning, prior to replacement. It never crossed my mind to consider replicating that set-up in the PH/VHB bowl, even though I must have about six in my Dell'Orto spares box, gathering dust! I will look later.....

When I say 'hot flood' with the PH/VHB's they don't actually gob out fuel either, but it's as though they cause an over-richness to make hot starts a test!

If you reposition the elbow, I'm sure you'll try to prevent any fuel mist saturating the filter or elbow by ensuring as much incline above horizontal as possible.

BTW. Red really suits the GP design, though we already knew that :)
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Re: GP150 lockdown project

Postby Warkton Tornado No.1 » Sun Jul 18, 2021 2:15 am

As i had the bits out, I checked fuel floats for the facility to add a breather/overflow vent.

The PH bowls show no indication of a cast in feature/drilling to add a tube. The alloy & the plastic examples I have are identical in being feature free.

The VHB bowls have both a cast in feature & a drilling to add a tube. All that would be required is the tube once the exit hole had been drilled to connect.
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Re: GP150 lockdown project

Postby Storkfoot » Thu Sep 16, 2021 10:55 pm

Having just put this GP through its paces for 1200 miles across Scotland (the picture below is in Ullapool), I have come to a few conclusions:

Good:

The DSC tuned GT186 engine, now on a first oversize RD350 piston, continues to perform well. It’s about 9 years old now and has been to Davos and Adria during this time. We had plenty of heavy tools and spares slowing us down but it was as at home climbing hills in the Cairngorms as it was on the M90 and M8. It did struggle, understandably, to keep up with a GT240 though.

The simple home made sock air filter worked well. It was clearly dirty by the end but I still did not get the sense that the engine was being strangled in any way. Having said that, I am going to change carb to a Mikuni TM24 but that’s just because I really like that carb and feel it would suit this engine well.

The Chiselspeed rear shock absorber ( I am pretty certain this is the same shock as made by Protech), set at a mid position, along with a standard springed seat, made for a comfortable ride. Since I have come back, I have changed front dampers to a set of Indian ones though.

Reverse pull front drum brake. I did spend some time setting this up so I am not surprised that it works really well. I wouldn’t use such a set up on anything more powerful and, it has to be said, I didn’t test it in emergency conditions, but I was pleased with how progressively it worked.

Bad:

The in-line spare wheel carrier. They look good, in my opinion, and if I ever decide to go back to a Snetterton seat, it may get reinstated. However, for the time being, it is going. Difficulties accessing the toolbox, filling with tank and getting your leg over when you are vertically challenged :P , make long distance travelling hard work, well harder work than it needs to be.

The exhaust, an old Mb/ bgm Clubman which has had major surgery twice, would need a third cutting open and welding again if it was to continue in service. I have decided to replace it with a Ron Moss ex box over the Winter.

The legshields. These are original but heavily patched and welded. Having lived with them for a week on the road, I am thinking that maybe my passion for reconstituting old stuff blinded me from the reality that the GP needs new legshields.

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Re: GP150 lockdown project

Postby Cgt75b » Fri Sep 17, 2021 7:45 pm

Completely agree about the in-line Paul it’s a proper pain tbh. Would like to take trip round the Highlands, one day maybe.
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Re: GP150 lockdown project

Postby Storkfoot » Fri Sep 17, 2021 8:57 pm

Cgt75b wrote:Completely agree about the in-line Paul it’s a proper pain tbh. Would like to take trip round the Highlands, one day maybe.


The LCGB rally on Mull a few years back was one of my favourite events. I spent this ride through the Cairngorms, passing two ski resorts, thinking that would be a great riding event for the club too. But, it is a long way and you’d need one or two overnight stopovers on the way if you weren’t going to blast it on the motorways.

My in-line Cuppini would work well on a Lambretta that wasn’t used for rallies and did have a snet or fixed seat.

Having sat on standard seats for the last few years, I am not too sure I could go back to a Snet now though :?
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