View Full Version : What product to use to bog up engine internals

19th April 2004, 09:41
Following on from my broken powervalve saga, I discovered that my fix wasn't completely successful. I pinned the middle moving powervalve bade to the stationary one, which has worked fine (stopped it whacking into the piston), but the hole left by the broken slider bolt, has allowed the exploding gas to escape too soon in the cycle, causing low power at low revs. (Well, thats what I figure anyway).

So what I need to do is bog up the hole in the powervalve, with some sort of hard filler stuff which can withstand heat. Any idea's?

19th April 2004, 11:02
it is a pretty ferocious environment, can't think of anything based on hydo-carbons that is going to live in there. Can it be aluminium welded then recut?
it the damaged area when the piston or rings contact? If so, I would say you're SOL 'cos the cylinder is hard chrome plated. If it is down a port, welding should sufffice.
how much is a new power valve spool?

19th April 2004, 11:15
Its a hole in the middle of one of the powervalve blades, where a bolt used to be (it got loose, wiggled itsself off, and rattled around for x years grinding away at the aluminium blade). The hole itself doesn't come in contact with the piston, it just lets exhaust gases escape too soon before the exhaust valve (powervalve) has started to open. Really hard to explain without a diagram.

Yeah, I'll look into getting it welded up. Was just afraid that the welding would distort the blade (which obviously needs to be flat and straight to slide properly).

19th April 2004, 11:17
The nice man at Suzuki told me they don't sell the buggered blade separately, and a whole new left PV mechanism would cost me $300 :Pokey: ... hence my kiwi DIY approach.

19th April 2004, 11:19
what material is the blade? Considered getting one made? Know any toolmakers? Where could I find a picture of one - my son is a toolmaker.

19th April 2004, 12:41
Have sortof considered it. Bit of a bitchy shape tho (see the attached diagram). the side radius is so it fits down a tube in the cyclinder wall. The other curved egdes are because the tube meets the cylinder at a funny angle, because theres actually another PV beside this one. So, not a nice shape to make.

It originally slid past two flat surfaces on either side, the length of travel limited by a bolt sticking through the place where the hole now is, on either side. Seeing the bolt came off, the blade slid around, banging into the piston. Now I've pinned it to the stationary blade on one side of it, so it won't move.

Its made of Al, but not sure what type. I was hoping there was some hard heat resistant bog out there, which I could use to fill the hole.

curious george
19th April 2004, 14:52
I'm not sure it matters that much....?
The cover over the powervalves should contain any leaky gases, making a no-loss system.
I don't know about bog though, what if it melts out!
What is the problem here?
Your bike is a small 2-stroke, it doesn't make much power at low revs anyway! -yes, much like mine.
Unless there is a MASSIVE power loss???
Got a camera?

19th April 2004, 15:59
Yep, there is a pretty big power loss until it hits about 6krpm and it takes off. Its like you open the throttle right up from take off, and nothing happens til it creeps up slowly to 6k, then it gets going. I know 2-strokes are crap down low, but I reckon it should have more power than this.

I've attached photos of the powervalves,
pic 3. "Closed" as it is at 0-8000rpm
pic 4. "Open" as is it after 9000rpm

(From 8000 to 9000rpm its meant to be open 1/2 way, and using the middle blade to redirect the exhaust out. Seeing my middle blade is broken and I pinned it to the stationary blade, it won't move.)

So I figured the cylinder was showing signs of pressure loss somewhere... so out came the piston and rings. They look fine. Then I remember what I found when it was running, and I took off the powervalve cover... air shooting out the small hole in the end of the PV in photo 1.

What is happening is that instead of all the exhaust air being directed out the exhaust port by the big sliding blade, some air escapes between the blades* and out the small hole as in photo 2, therefore releasing exhaust gas EARLIER in the expansion cycle than it should. Wheather or not this has a big effect on the performance, I dunno, but I figure it might... therefore this essay I'm writing.

*(theres actually a groove in the big slider, which is meant to limit the middle slider from going too far towards the piston. Normal this groove wouldn't be exposed to the exhaust gas, but because the middle blade is pinned back, the exhaust gas can get into the groove (A in photo 2) up the hole left by the missing bolt (B), into groove C in the stationary blade, out the hole a spring was meant to go in, and out into the big wide world.)

Its seriously the last thing I can think of, before I toss the bike over a cliff. I've totally dismantled and cleaned the carb, changed sparkplug, checked reed valve, decarboned head and piston, checked gaskets, and reset throttle/choke/mixture/oiler. Any other idea's?

19th April 2004, 16:17
Try giving Hawera Motorcycles a call, they have wrecked just about everything and may have 2nd hand part available, you'll find them in White & Yellow pages.

19th April 2004, 18:00
Thanks gpercivl, I'll give them a call. :2thumbsup