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Post by potatopl on Dec 2, 2015 11:10:55 GMT
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Post by tzsteve on Dec 2, 2015 11:39:30 GMT
not a bad frame to start with. are they going to be standardish or buggerd about a bit?
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Post by triffid on Dec 2, 2015 12:31:05 GMT
good base for your project
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Post by potatopl on Dec 2, 2015 13:06:13 GMT
Enginewise, standardish setup build from garage leftovers: DR75F1, 3,72 primary, cut crank, proma cannon exhaust. I hope that my wife will use it for her scooter riding lessons, therefore more power is not required and there is no point in investing in the bodywork.
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Post by henri on Dec 2, 2015 14:37:47 GMT
good solid base for a project , an good point about the bodywork , H
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Post by Juan on Dec 2, 2015 19:57:01 GMT
I like that stripped back, I take you're going to underseal the underneath of it and put a protective wax on the paint?
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Post by kev on Dec 2, 2015 20:54:33 GMT
Great work, I'm looking forward to the next instalment .
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Post by kev on Dec 2, 2015 20:55:53 GMT
Great work, I'm looking forward to the next instalment .
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Post by potatopl on Dec 4, 2015 6:29:49 GMT
I like that stripped back, I take you're going to underseal the underneath of it and put a protective wax on the paint? Was thinking more of painting it with transparent lacquer. Wax woudld reqire frequent re-application or the rust will come out again.
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Post by potatopl on Jan 17, 2016 20:06:51 GMT
Lack of free time made me change the bodywork plans. I just repaired the floor edges using DIY pliers (idea copied from this forum thread). The inside of engine cowligs was cleaned from rust, treated with Bruox Epoxy and protective paint. Rest of then bodywork will be painted with Owatrol Rustol Rust inhibitor. Also made this DIY fuel tap spanner, as the tank requireas a bit of cleaning. Also started with the engine build: Transfers in the cylinder foot opened a little (top one already in progress): After: Piston skirt opening matched with cylinder: Boost port windows matched with cylinder: Working on matching the casings transfers: Added some "chemical metal" on the outside of transfers for more meat. Unfortunately, the casings have short sealing pad. Opened it up and inserted Mazzu race crankshaft (small cone) but it gives only 160° inlet time (110° BTDC->50°ATDC). Still better than 130° with standard crank, but hoping to get it around 170°. I don't want to cut the crank, so 160° inlet it is Carb wise I went for Dellorto PHBG 20 (clamp mounted) on standart 19.19 SHB manifold. Cylinder was installed with 0.8mm foot gasket. The timings obtained are 118°/170°. Will raise and widen the exhaust port to get 118°/178°. Will also need to mill the head or cylinder top to lower the squish (going for 1.5-1.3mm).
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Post by potatopl on Jan 25, 2016 5:56:45 GMT
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Post by triffid on Jan 25, 2016 12:33:15 GMT
Wow, what pipe is that, never seen one like that before.
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Post by potatopl on Jan 25, 2016 13:07:25 GMT
It's an oldschool Proma "Cannon" I got off ebay. Not much info about it unfortunately. It is cone-shaped, so I hope it will give some resonance.
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Post by Juan on Jan 25, 2016 22:35:44 GMT
The fact it's on a girls bike is a good thing, if it's shit then nothing lost. Can't be any worse than the standard box pipe anyway.
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Post by tzsteve on Jan 27, 2016 16:11:44 GMT
the blending work looks good
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Post by bikegrim on Jan 27, 2016 21:35:18 GMT
is that sealing pad ok?
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Post by tzsteve on Jan 27, 2016 21:51:48 GMT
that pad wouldn`t worry me, but that pipe looks like it would rob the engine of any power (too narrow in the mid section for me)
i like the way this is coming along
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Post by potatopl on Jan 28, 2016 9:11:24 GMT
Not perfect but there is a polish saying: "If you don't have what you like, then you better like what you have". that pad wouldn`t worry me, but that pipe looks like it would rob the engine of any power (too narrow in the mid section for me) The pipe is a big ? for everyone. Not much info about it in the web. If it's crap, I'll just swap it to something else. I am theoretically building it for my wife, but will have a go with it from time to time as well That's why I want it to have better performace than P&P kit. Still not sure about port timings and intake time. Tried to get advice on GSF but didn't get definite answers. My measurements: Inlet with Mazzuchelli "Race" crank 160° (110° bTDC -> 50° aTDC). Exhaust port originally oval shape 66% width. Cylinder times: 0,8mm base gasket: tr 118° ex 171° -> Blow-down 26,5° 1,2mm base gasket: tr 121° ex 173° -> Blow-down 26° 1,6mm base gasket: tr 123° ex 175° -> Blow-down 26° I think I will install 1,0-1,2 base gasket and then raise the exhaust to get timings of about 120°/178° which seem universal. Or is 29° blowdown too much for semi-expansion pipe? To get the squish close to 1,2mm I’ll have to mill the cylinder top. GSF guys encouraged me to open the exhaust port to 70%. I’m a bit afraid if cast DR rings will withstand it. I was also advised to get more inlet time, planned 170° but the “race” crankshaft allowed for only 160°. I was told to go for 180° at least and cut the crank. Let’s say I want to get 125° bTDC -> 55° aTDC, I need to cut about 12mm off x and 4mm off y. But what about the crank balancing? I was told on GSF not to bother too much about it. Unbalance will be neglible for performance with this horsepower. But what If I wanted to do it right? What is the correct procedure? I’d do it in the following manner (values are strictly theoretical): 1. Weight the crank -> ex. 2000g 2. Check the pin position ->ex. pin at 2 o’clock 3. Cut at x and weight the crank -> ex. 1950g (-50g) 4. Cut at y and weight the crank -> ex. 1940g (-60g) 5. Check the pin position -> ex. Pin at 3 o’clock Should I focus on retrieving the initial crankpin position or should I dremel out the same amount of material weight I’ve cut out (x+y)? If yes, where should it be dremeled out? At area z or on the flywheel crank side?
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Post by henri on Jan 28, 2016 10:10:08 GMT
i also saw the nick in that pad ,not ideal but it will have to do , our version of the sayings "make do an mend" sometimes said as "like it or lump it" . ive a mazzy crank with damage to the sealing face of web ,looks like a machined groove the same size as your nick the whole length of face ,havent noticed any massive increase in spit back an primary compressions still good enough . the advice from gsf ,i dont think i'd risk wide cast dr rings out to 70% , 65% would be my max i reckon . an there probably right about the balance factor ,but that depends on how much weight you remove ,an how high you want the scoot to rev .higher the rpm the more critical balance will become .with the added complications that theres a chance of "harmonic vibrations" developing somewhere in the rev range unpredictably . so long as this isnt at a preferred throttle opening/rpm it can be ridden around .ive a similar thing on 1 of my bikes ,at 4500 it rattles your eyeballs but above/below its real smooth, its a inbuilt design thing .H
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Post by tzsteve on Jan 28, 2016 16:25:09 GMT
it is better to have the barrel shortened on a lathe using a mandril, `cos when you get the barrel bored the barrel is turned upside down, bolted to a vertical miller or rebore machine then bored through from the bottom, if the top of the barrel has been skimmed on an angle you will get the rebore on a tilt. this is not a good idea.
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