the mod 880R
Well it's been quite the rocky road.
Basic motor runs really good. Need to send MPEM back to race dept. after season is over to pull some timing in the mid range. Running an 05" MPEM & harness in this 06' with the R motor. I guess that's quite a mouth full in itself! Over the years of building mod motors and trying to make then work with the modern electronics / smog noise control set ups I gave up a few years ago and went back to what works. Every time / everywhere.
A good mod motor doesn't have the character to be de-tuned / epa compliant. They don't like it, and it's a constant battle what with the enemic heads and exhaust valve setups.
After having run the Jaws twins with many hours of tweeking tuning etc. I'm going back to a big single to finish the season. When I go back on the dyno I'll do some cutting, welding and tuning to see if I can make them work like I hoped. As it stands now they sign off about 7,800 and will creep up to 7,900. These were built to be 8,250 rpm pipes.
This is with pipe pressures completely dialed in / fueling timing etc. If I could get these pipes to work on top comparatively this would be a monster.
It is really impressive in the bottom / mid but that's it.
When I had this motor on the dyno it was nuts on the bottom & mid but I have to make some changes to the dyno / add more inertia for it to be able to keep up as the motor lights so hard and so fast it gets away. I was seeing 100#'s of torque before 6,000 rpm.
Riding it is really fun. Totally linear power band. I'm engaging at about 2,700 and there is no hesitation pause, nothing!!! Just hang on!!!!!!! It usually just spins but if it hooks up>>>>>>>>>>>>>>>>>>> That cool sound you get in a hard pull when the track starts really winging it, I get at 6,500. It's nuts. It does pull good up to like I said 7,800, but sadly scary part is over.
Putting a modified SLP pipe on next week which I've been running variations of for years on 860's and we'll see.
Lectron carbs do not compensate for altitude like they told me. I don't know if it's because these pipes are so far off or what. Higher you go things start going fat but in all honesty I haven't taken my pipe pressure lately to see how bad the pressure is falling off @ altitude. If the pipes actually worked I'd be all over that but since they're not even close won't waste time. Also for anyone looking at any kind of project like this in Alaska, don't ever go under .008" piston to cylinder clearance on an 880. I don't care what kind of a "dog & pony show" they swear by!!! If you're making serious power up here, that's what I would run. If you're not running any power you can get away with less. How much I wouldn't know.
Oh, and don't buy into the belt drive scenario for the Rev with this kind of torque. It just "twists the idler bracket" and destroys your $ 100 belt. Maybe if you wanted to try and run a shorter belt, which I see now can be had, you could take some of the loop out of around the top gear and might work. Not going there. Went back to chain & sprockets. What a bunch of bull****!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!