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Old 04-23-2013, 06:11 PM   #38 (permalink)
Master EcoModder
Join Date: Feb 2009
Location: France - Paris
Posts: 762

la_voiture_de_courses - '03 Renault Megane Estate
90 day: 44.34 mpg (US)

xiao lan - '01 Audi A2
90 day: 38.88 mpg (US)

Brit iron - '92 Mini Mini
90 day: 45.5 mpg (US)

Prius - '09 Toyota PRIUS Lounge
90 day: 47.37 mpg (US)

Beemer - '06 BMW F800 ST
90 day: 53.06 mpg (US)
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Bike has been stored in the basement,
Head has been removed,
Cam chain tensioner guide has been checked, it's likely not his fault.
I'll renew the cam chain as it is opened and a good time to do so (bike has 40K miles on the speedo), also the cam tensionner is far out.

So the head has been cleaned, the exhaust ports (one for each valve) have a funky shape and they are very much shrouded on the begining.
I did some porting on one of the ports and I will crudely check its flow and comparing it to standard clean port shape flow.

Also I did some calculations and the end pipe diameter is much smaller than the equivalent surface of the exhaust valves minus the stems.
Spells back pressure to me.
Might as well hurt 3/4 throttle P&G

Inlets are 26 mm times 2, equivalent single diameter is 36mm, carb is 34mm
Exhaust are 22 mm, pipes are 22 mm inside, tail pipe is a SINGLE 18 MMM !!!

Valves were very whittish in color indicating a rather poor mixture (I used to run on E10 and the bike was probably set up weak for regular gas to start with).
Also there are some distinct knock scars in the quench area between the exhaust valves meaning the engine was runned too hot.

I have some ideas for improving engine cooling in this area (drilling holes in the fins as close to the quench area as possible).

I'll add some pics tomorrow.

(money is on the clutch now for the funky noises)
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