Ton with style - 250 => shiny parts pics page 6

Whatever its real horsepower, in standard trim (euro spec carb setup), my bike was capable of 83 mph on E10 fuel with 45K on the clock.

That's my baseline for further developpement.

I fancy having the new piston coated on both head and skirt as well as the head.
The power potential is almost nill on such a small engine, said to deliver up to 5% ...
But I hope it can help with the cooling of my air cooled engine (remember pinging marks on the exhaust side of squish area).

Thanks for following the year long thread ...
 
You don't need fancy coatings on pistons, they can improve things but only after you have everything else working properly.
I've built faster XL125's so there is a lot of room for improvement with a 4 valve TSCC head.
You should be able to get at least 25bhp at the wheel, the basic design is just 1/4 of a GSX1000
 
Hi PJ,

Thanks for following my oily dreams.
I am much interested in your fast XL 125 setup description, is there a thread somewhere ?

I bet there is power hidden in the GN since it has an evil twin called a Goose 250 and they apparently sport out 26 japanese HP.

I was contemplating the coating as part of the reliable side of the treefold stone of power (cheap, fast, reliable) and it's easier to do when the engine is appart than say a camshaft.
Thing is it would fit in the overhaul budget since I saved a fair few ordering chinese parts ...
 
You're chasing some difficult goals... even the 26-34 b.h.p. LS650 (652cc) aircooled single is rated for a factory top speed of 85mph. TSCC 4 valve semi-hemi cylinder head, BS40 CV carb, belt driven fixed final drive ratio... With a carb swap, chain conversion, and running lean to the point the exhaust pipe is glowing red they will do 120mph, once. As soon as you let off the throttle, the piston grenades... unless the poorly designed cam chain tensioner lets go first, falling into the clutch assembly, sending the valves into the piston at high rpms, effectively turning the top end into a bomb... while the bottom end seizes and sends you into a high speed slide down the road on your back...
 
You're right about how difficult it is polishing the piston crown - most modern pistons use a hypereuctectic Al-Si alloy which has around 18 - 22% Silicon in the mix depending on other alloying elements, specific end usage, stuff like that. The silicon increases the wear resistance significantly but makes it more difficult to machine and a lot more brittle - you don't get something for nothing. Did a metallographic analysis on a well used piston one time...
Pat
 
Well, regarding what I found in the sump, she's not after the ton anytime soon :


The rod doesn't spin too freely on the crank either and has some axial play (but not radial).
 
Scruffy said:
You're chasing some difficult goals... even the 26-34 b.h.p. LS650 (652cc) aircooled single is rated for a factory top speed of 85mph. TSCC 4 valve semi-hemi cylinder head, BS40 CV carb, belt driven fixed final drive ratio... With a carb swap, chain conversion, and running lean to the point the exhaust pipe is glowing red they will do 120mph, once. As soon as you let off the throttle, the piston grenades... unless the poorly designed cam chain tensioner lets go first, falling into the clutch assembly, sending the valves into the piston at high rpms, effectively turning the top end into a bomb... while the bottom end seizes and sends you into a high speed slide down the road on your back...
Click to expand...

Cam chain tensioner isn't the fault, it's the main bearing behind generator rotor/outside flywheel that wears and allows crank to tilt, the tensioner rins out of travel. Suzuki have known about it for at least 23yrs but never made any modifications as it won't happen unless bike is run at high rpm (just about always happens way out of warranty )
BTW, Sausage will usually do about 92~94mph ;)
 
The tensioner doesn't have a travel limiter, so the piston and spring fall out after the last click. The weak sister 125cc spec cam chain doesn't help either...

Mine has done an electrically timed 115. Once. And at 21K miles or so needed a new tensioner, and serious electrical work. Everything else is still fine.

I still think "Slow Pokey Salvage" is more accurate...
 
Scruffy said:
The tensioner doesn't have a travel limiter, so the piston and spring fall out after the last click. The weak sister 125cc spec cam chain doesn't help either...

Mine has done an electrically timed 115. Once. And at 21K miles or so needed a new tensioner, and serious electrical work. Everything else is still fine.

I still think "Slow Pokey Salvage" is more accurate...
Click to expand...

Any Suzuki dealer who has been working on the Sausage for a while will know to check the main bearing by removing generator cover and trying to lift crank.
115 is definitely enough rpm to make bearing a bit worn (even though it won't sound like it)
It's a big roller bearing, the crank flex wears the edges
The tensioner 'lift's' the right side as the left is dropping so you run out of travel and it falls apart
You can usually see wear on the inside edges of outside chain link plates
 
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