That's because you're not a professional mechanic like me who builds race engines.
FYI, it's too much compression, and or timing, not a lack of compression that will cause detonation. Modern aluminum cylinder heads, with good combustion chambers easily allow 11-1, or higher on 87 octane.

 

It's possible for detonation to cause bottom end damage, but I think this was more prevalent in plain bearing engines than in roller versions like our KLX. However, if the detonation goes on long enough and/or is severe enough, it's possible in extreme cases. Burning holes in pistons or melting piston crown areas is a more common issue.

I don't know...the money spent on a big bore kit seems a much more logical pursuit than this much dough for a timing box. OK, already have a BB 351 kit?...now you have a 12:1 compression ratio instead of an 11:1. That has probably reduced how much you can/should advance the timing curve even more. However, I'd love to see someone try one of these to see how it shakes out.

I love MSD products. They usually work as advertised. I have a full ignition box and a variable timing control box on my heavily modded Chevy 4X4. I can run a slightly wider spark gap and adjust the timing a full 15 degrees while going down the road. On our KLX's, however, I wonder how far it's worth going to keep pushing this little bike's envelope? I got this bike for its reliable, trouble-free nature. But hey...I'd still like to see someone else give this thing a try. It may turn out to be great.

 

I might not be a mechanic, but I AM an ASE certified Master engine machinist with a speciality in Blocks, Heads, and Assembly... I worked for several speed shops as a machinist, and was key in building at one time what was the fastest Pontiac powered car in the country when I worked in Brooksville.... I drove 26 miles one way to work and home every day back then in an 11 second Duster that I built in my garage for less than I paid for my KLX

Your gonna see piston damage long before you hurt a roller bearing from detonation... That's just my humble opinion, what would I know?

Just imagine if I stay at a Holiday Inn Express....

 

Then you'd really be my hero

 

4 deg advance rotors often hurt the power on 4 cyl bikes, more timing doesn't always translate into better power. It's one of those mods you have to experiment with on a bike by bike basis.

One on things we tried with mod sled motors was protruded tip plug. It "acts" like a degree or two more timing. If it showed more power we'd go ahead and try some offset keys on the rotor. Many times when compression was raised the engine made more power with less timing. Big bores usually ran better with a little more timing. All generalizations but their was a trend. If i had a 351 it would be something I'd try, a stock bore bike I think I'd try a (cheaper) bump in compression before timing.

 

ebay/ebay japan. seen a write up or two, and they say theres a noticable diffrence but not durastic, but this also wasnt on a 351. i think it would work fine, but a msd it would be easy to put too much timing and lighten your wallet some.

 

Looking at the MSD box, it doesnt seem that you can add total timing above what's there already. Looks like you can adjust the curve, but not total advance...

 

You can dial in as much timing as your flywheel, and sensors will allow.

 

What year to look for? Here is one off a 95 http://www.sekaimon.com/i310158303911

 

That wont work its AC vs DC. Wont work.