Started a thread before winter, here's the initial discussion:

A little background info...



I recently acquired an 01 Dyna T-Sport FXDXT. Apparently when it was bought new in 01 it had a 95" kit, shaved, ported, polished heads, cams, Crane Fireball ignition, etc... but no actual proof of the work.

I had the bike "pre-inspected" at a reputable HD shop and also dyno'd. The bike pulled around 90hp and 100ft. lbs, so I'm pretty sure the motor work is correct.



The shop did mention that it would detonate if it was lug'd down low but other than that, it ran like a champ. Also during a compression test it pushed 220psi on each cylinder.

It's only ran on premium 91oct fuel or 93oct containing 10% ethanol.

After putting on 1000miles, I decided on playing with the ignition. I know the high compression is playing a tole as it hesitates to start and that hot of a motor isn't "streetable".

The ignition, model # 8-3160:



I spoke with S&S today to try and play around with it a bit, they didn't know a whole lot because apparently they bought Crane Cams and all of these ignitions are now obsolete. They pretty much just went over the instructions that I found online.

Manual available here: http://www.cranecams.com/uploads/ins...s/90003160.pdf

Right now they only way it won't detonate is on the following set-up.

Mode : 0 (single spark pre-loaded tables)
Rear Cyl Offset : 0
Initial Timing : -5(minimum advance)
Advance Slope : 0(minimum advance)
Rev Limiter : 6200rpm

When I purchased it, it was the same minus...

Initial Timing : -4
Advance Slope : 1

It is a little better now, but I can still make it detonate if I whale on it below 2500rpm. I tried some Octane booster in today's tank and it did seem to improve a little more.

I ride pretty aggressively and usually never under 3000rpm, but it's still not right. I can stand it straight up and carry a wheelie easily, but if I catch myself off guard I dont want to run the risk of detonation causing engine damage.

It looks like I'm going to have to take it in over winter and straighten it out, maybe add some decompression valves and see what cams are in it.

I have a feeling they're the main culprit... I bet it's too short of a cam with not enough overlap that's driving the compression up.

It's hard to really say anything right now without knowing whats on the inside, but I just want to make the most out of the rest of this riding season.

Anyone have any pointers or suggestions on how to deal with this now? Or even what to look for down the road once I get this thing apart?

I'm thinking it might be more cost effective if the cams are the issue to just install a set of S&S easy start cams... that way I dont have to mess with machining the heads.

............and here I am as of today:

I got it tore down by a local shop, life's been to busy for me and I just don't have time to figure it out myself. Did another compression test to be certain and it registered around 220psi on each jug.

Pulled the camchest and it had Woods TW-6h cams installed. Verified that it has high lift springs, adjustable rods, a 0.30 gasket and the intake/exhaust has been ported. Based on those numbers the heads must be shaved and possibly has domed pistons. Run out on the crank was 0.003, oil pump and everything else looked good.

Pics of the cams and intake/exhaust porting:



I'm trying to do this on some sort of budget so they opted not to pull the heads.

I played around a little with the BigBoyz Compression Calculator, I inputted my known variables and guessed at head volume to achieve the 220+ CCP. It's telling me I have 11.7:1 static compression and 10.8:1 corrected compression with the Woods TW6H cams. If I simply leave all the values the same and then switch cams to the S&S 625's, static compression will obviously stay the same 11.7:1, but the corrected compression drops to 10:1 and the CCP should be around 198psi.

Plans are to swap in a set of EZ start S&S gear drive 625 cams, Feuling lifters, S&S stealth intake, Bassni 2-1 road rage pipe and hope for the best.

The longer duration should bring down the compression to a more reasonable number, and the ez starts should take care of my hard starting issues. I'm hoping the reduced compression will allow me to put some timing into this thing, right now the only way to keep it from detonating is to pull all the advance and use the slowest curve the Crane ignition offers.

Any idea what kinda numbers or how this set-up will change the curve? I've got a feeling it'll come on strong around 3000rpms then scream to the top end... I ride aggressively so it should work for me, but I don't have many options right now. What's been done to the heads is already done, I just want to "fix" it as best I can with what I've got. Any input or suggestions would be appreciated?

 

I would have checked the chambers for buildup of carbon. That could have possibly raised your compression readings just a tad. At least ran seafoam through just to clean things up a bit, and recheck. I would have expected more from the compression being so high, but it's all about how things work together.
. Looks like there is a thin set of gaskets on the heads right now. See if you can get a feeler gauge in between the head and jug to get an idea of what thickness. Sounds like you have a good plan. So good luck, and BTW nice looking bike.

 

Head gaskets are 0.030".. carbon or not, that compression is through the roof. Thanks for the insight though.

 

ide really be checking everything,with the 6H`s & even half *** heads and anything around 10.5-1,this should be doing at least 100/115+,and with decent heads 105+/115+.with closer to 11.0-1+,close to 110 HP should be seen.somethings not right at all

 

I would check the condition of your compression gauge.. I can't see this engine cranking over with that much squeeze, without releases.

 

All this work/investigation is being done at a reputable shop, I'm sure there compression gauges are in check. It tested the same numbers 6months ago so I know its correct. Starting it is always a hit or miss, it needs a full charge and it will even stall the starter sometimes... but it has never left me stranded though.

As for making power, its so high of compression I have to pull all the timing out of it to keep it from detonating. The advance slope is set to minimum and its max retarded -5*. I'm not about to start running AV gas in this thing...

 

I would be pulling the heads and checking pistons for domes and measuring chamber volume; without those numbers you are flying blind. Would agree with Kirby on the numbers but maybe so much timing has been pulled out, the numbers just aren't there.. Timing has to be way off to have that sort of impact on the numbers though.

Once you have all the accurate data, look at making whatever changes you can afford and shoot for CCP about 185-190psi and corrected CR less than 9.8; should run good, cooler and make better numbers.

Holding off on a plan until you have accurate data/measurements would be wise and "hopeing for the best" is not much of a plan. Do it right and you can predict the outcome; do it wrong and you could be jumping from the frying pan into the fire and spending more money at the same time.JMHO

 

Looks like Ray Charles got after that intake port...............
Nothing against 'ol Ray, I like alot of his music he did.........he just couldn't see.......

 

Yeah...those ports are definitely 'backyard' jobs! The theory/design looks right, but you should have the heads flowed and cc'd to make sure they have not been buggered.

Your exhaust port looks way too black....i would suggest that your running too rich. What carbby settings are you useing or are you injected?

 

Probly richend up to prevent detonation.
wonder how well the intake manifold matches to the intake port.