deckheight

I believe they were also re-chambering with the .030" cuts. Just facing without re-chambering yeilds something like .024" squish clearance with OEM thickness gaskets.

I personally wouldn't. Facing .030" without re-chambering will, in all probability, leave you w/a squish velocity that is through the roof and a compression ratio that, in all probability, is too high for pump gas. I have no idea what your starting with so I do not know what you should do, exactly.

Didn't know about "joining" Greenhulk... Try this link, looks like the same video. I took the time to load it on dialup. If you have never trued a twin (or triple like the video) it is worth watching. http://www.slednutz.com/showthread.php?t=36

The crank is placed on a fixture or V-blocks resting on the bearings, indicated and then smacked around with a mallet until it is within spec... Real high tech! :biggrin: :biggrin: I am on dial up so I didn't watch the video in the link, but the description sounded pretty good and mentioned "phase" for a twin cylinder. http://www.greenhulk.net/forums/showthread.php?t=38113

Yeah, that looks much better :cool: Like has already been said... Good idea to check the "before" dome volume and an especially good idea to check the "after". Then all the geometry for squish velocities has to be addressed... IMHO, you probably want to send it to someone competent who knows about these things or just get aftermarket...

After re-reading my previous post this morning... That wasn't a very nice reply. Sorry! Nobody can tell from a picture what is really going on with a port job... They can however get a sence of wether or not that person knows what they are doing. And your new porting looks to me like whoever did it has done it before and is familiar with porting tools. I would think you should be happy with it. I would also think that whoever did the work could tell you what you want to know. However, if for whatever reason, they cannot... And you can provide accurate port mapping data, I would be more than happy to tell you exactly what you have and what it is supposed to do. Again, I apolagize. Good luck

Cylinder deck heights and piston dome volumes are all the same, but very early shees came stock with larger combustion chamber trapped volumes. All of the 87 shees that I am aware of came with 24.2cc OEM head domes. Add another .8cc for head gasket volume = 25cc total (84 octane). Most everything else came with apx. 22.4cc head domes plus gasket volume for 23.2cc total (87 octane). The above octane estimates assume relatively fresh fuel...

Because your question had already been answered and the thread was wandering anyway. Sorry, Jeeezz! 10-4 on the carbon fiber booster BTW...

Depends on what year it is... You can run 84 octane in a stock 87. Most other years, as you already know, run just fine on 87 octane in stock form. 91 octane is good for all years and puts you way off the detonation zone. Rule of thumb is don't run higher octane fuel than is needed though.

They are decent pipes for what your doing IMHO. Same with the single carb. Easy enough to put the dual carbs back on if you don't like the single...

Is it one of the unobtanium alloy booster bottles? :cool:

Hey, this is a compression gauge oriented site. Watch your language bud! :biggrin: :biggrin:

Different compression gauges read different numbers. Sometimes even gauges of the same brand and model read different numbers. Unless you have a calibrated gauge or you have previously logged a reading on that exact motor with a fresh top end with that exact same gauge... 90 psi is as good as 140 psi IMHO. With what relevant info you have provided so far... Both cylinders read the same and the bike runs real strong, you can either pull the head and possibly cylinders for inspection, just run it as is or you could just go ahead and fix something that probably isn't even broken to start with. Replacing a top end simply due to a low compression gauge reading obtained through a questionable gauge and method when both cylinders blow exactly the same and the engine runs good makes about as much sense to me as estimating fuel octane requirements with the same method and numbers...

Hard to tell... One persons "dune port" might be anothers "trail port"... If you really want to know about your porting you will need to find out what the durations and time areas are for both the exhaust and transfers.

If the bike is running good and you have no other reason to suspect a problem and both cylinders are within 5 or so psi of each other I personally would probably call it good enough.

This one is for a stock stroke 100 octane motor. You can see the tig welded plugs in the thin areas. http://img442.imageshack.us/img442/6383/dsc01501jk8.jpg

Higher octane fuels burn slower thus the flame front in the combustion chamber travels slower. Advancing ignition timing is one way of compensating for the slower flame front so that maximum combustion chamber pressures occur at the right degree of crankshaft rotation. Other ways of compensating would be to increase combustion chamber turbulance with a higher squish velocity or increase combustion chamber temps with a higher compression ratio. Normally the compression ratio is matched to the fuel for a specific application and then ignition timing and squish velocity are used to fine tune things in the combustion chamber. Clear as mud? :geek:

My Banshee motor is set-up very close to the edge as far as requiring 100 octane gasoline... Four weeks max with a fresh leaded fuel and the gas goes into something else that is not so sensitive. I don't use unleaded gas or a "gasahol" blend in the Banshee, but if I did, it would be two weeks max. Old fuel and 2-strokes don't mix IMHO. been there, done that Gasoline can be stored for long periods of time before it actually goes bad by gumming or varnishing, however the octane level or rating or whatever it's called starts deteriorating almost immediately after blending.

I am not trying to talk you out of a stroker or big bore, most people that have those mods like them. Just pointing out the diminishing horesepower to $$$ spent ratio once you go past a certain point. Assuming an efficient tuned exhaust, cylinder porting, decent air filters, etc... 87 octane (stock compression) is about 48hp at the crank. 92 octane set-up is worth about 57hp at the crank. 100 octane is about 73hp at crank. Scrub maybe 10hp off any of the above for a rear wheel hp comparison. And add maybe 5hp or so for either the stroker or the big bore... An apx. 2.25cc reduction in trapped volume and an additional 9hp going from a stock head to a 92 octane head has always noticable to me LOL. If it's worth the $$$ to you I do not know? Plan on an extended swing arm for any of the 100 octane packages BTW...

Aftermarket head w/changable domes. Below is what most people consider safe for stock bore and stroke Banshee... 21cc domes = 92 octane = apx. 7.0:1 CCR 19cc domes = 100 octane = apx. 8.0:1 CCR 18cc domes = 110 octane = apx. 8.5:1 CCR If you decide to go with a big bore or stroker the above changes. Where do you live that high octane fuel is not available? Must be pretty rural? At any rate, there is no free ride. If you want to substantially increase engine efficiency beyond cylinder porting and tuned exhaust you will have to bump the compression. I personally do not recommend "octane boosters in a bottle" as a replacement for high octane gasoline. Good luck

With your mods I would be looking at 33mm PWK's :biggrin: So far they have been pretty user friendly on 350's with 100 octane and above type compressions. Plenty of signal, all circuits dial right in and meter fuel consistently through out the rpm range. They also seem to hold their tune real well under moderate RAD changes. Have not tried them yet with lower compressions, not sure how that would work out... Might not??? That would be my next move with your set-up anyway... For what it's worth.

Different exhaust systems are designed to make peak horse power at different specific rpm's/rpm ranges. Cylinder porting and tuned exhausts should complement each other IMHO. Like has already been said... One guys dune port is another guys who knows what

Blown head gasket/0-ring maybe???

What I was getting at is that for the cost of a stroker or big bore you could buy 150-200 gallons of 100 octane fuel (5gl at a time of course) and run higher compression which = instant horsepower. All the other stuff you would have to get anyway... Head, porting etc. As long as you can transfer the higher horsepower to the ground effectively you shouldn't have any problems with a stock 450. I don't think you would be happy with just the added 22cc displacement of the big bore on pump gas or the added 26cc of a stroker... And yes the +4 timing is a good mod. You will feel it in low end and midrange response.

Well there you go... some like em and some don't! Personally, I prefer the power delivery. I usually am either in the throttle or not. In fact, I would run a total loss ignition if it were not such a PITA for what I normally do. On the bright side, it is pretty inexpensive and easy to give it a try :biggrin: