800 cdi in 93' 750

I must say this was easier than I expected. I didnt have to take any mulligans or anything. The hardest part was getting the old CDI out of the sled. I must say though having extra parts made this upgrade many times easier. I was able to wire up an 800 CDI in my '93 750 without touching any of my original wiring in my sled, on the transplant CDI, or my original CDI. What I did was take the plugs off a '92 CDI which match the '93 plugs and a set of plugs from a '94 wiring harness which match the 800 CDI. Then all I did was bare the wires on my donor plugs and match them all up, plug the 800 CDI into the 94 ends and braapity braap she had fire. I think it was a great job. If I ever want to return to stock nothing is ruined other than some extra parts I had, which to me isnt ruined but simply re-used. Putting an 800 CDI into a '94 750 would be the easiest, simply plug and play. I am sure lots of people have done this, I just wanted to post it here so people would be less scared to try it. If someone had any electrical experience it would be even easier.

-Rustman

is there an advantage to running an 800 cdi?

The 800 CDI makes more horsepower and has no rev limiter, which makes it much more useful when running high rpm pipes. Do not run quad pipes without a welded crank.

-Rustman

rustman said:

The 800 CDI makes more horsepower and has no rev limiter, which makes it much more useful when running high rpm pipes. Do not run quad pipes without a welded crank.

-Rustman

Click to expand...

It does have a rev limiter starting @ about 10,000 rpm with minimal timing due to this limiter, but it is better than the 750 '92-'94 CDI box limit around 9100 rpms. 750 bottom-ends weld crank gears for 9100+ rpm, but no need to weld gears on the 800 bottom-end (ultra tough!)

sorry i always forget that some people really rev these engines, high rpm for me is anything over stock.

-rustman

the 8BU cdi has a much improved timing curve then the stock 750cc box with the rev limiter kicking in 10,000 rpm. The 750 box has a programmed timing retard in the system which reduces horsepower after 8300 rpm and at 8700 rpm a rev limiter takes over.

I have a question on this rev limiter thing. When they say rev limiter, will it simply not allow it to rev higher than this or what is going on. I had quad pipes on my '93, removed them for fear of crank twisting, and I know for a fact that my tach showed over 9,000 on a few long pulls down the river with the stock CDI. I am certain that I saw 9300 RPM, I even stopped the sled to tell my friend I was running with because I found it hard to believe. Can someone explain how and why I was able to rev up to 9300 if there is a rev limiter.

First off, I wouldn't trust the stock tach as there could be a discrepency. What happens with any of these CDI boxes is they begin to reduce timing greatly over about a 400-500 rpm range, ultimately reducing timing to 0 degrees at the rpm limiter. When you "hit" the rev limiter on a Vmax-4, the sled will "pop and bang" plus sound violent when it does this. Basically with no timing your sled now goes real fat on the jetting due to lack of ignition, its all a good safety feature!

Great information guys! :rockon:

Dillon

I don't what you're running for pipes but this is what I have and what I have found. I am running a set of bender quads and I have put the 800 cdi box on my 750 (93). It pulls like a race horse on the long hauls - quarter mile and better, but coughs like a bugger when I am cruising at about 20-25 miles pr hour. If you're running quads - bump your mains to about 150 and open your fuel screws to two turns out. If that doesn't help turn your fuel screws out to 2 1/4. If still coughing go to about number 52 on your pilot screws. That should put you in the ball park. If you need anymore info just phone me. (807) 548-5269 Ask for Willy.

Thanks guys. i have a 92 and am looking for a few performance upgrades that don't break the bank. thinking 800 cdi and 800 pipes should get me a few more ponies. not that i don't have enough already lol