Reed has done it again. He has re-done his M900 (still a 944) for the fourth time.
This time we put larger (44mm) inlet valve in it, and ST2 cams, which have a little more exhaust than stock 900SS cams that we used for all of the previous lives. For the time being, we've just checked on on the dyno, and found that the main-jets are too small. We put in larger mains, and it runs great. I'll put the dyno sheets up soon.
But, here is a picture of it.
Below is the third iteration of Reed's. I think it's an incredibly thorough example of 'retro-style' while keeping an entirely contemporary look. Reed felt that it would be incomplete if the modifications didn't go below the skin.
There is no 'about 90 Horsepower' here, it goes as good as it looks!
Here is a dyno chart to show just how strong Reed's bike is. You'll notice, at 6000 RPM the M900 has 16 more HP than an 888 SPO.
The blue trace represents the same bike (Reed's) last year with stock displacement. You can see why the 'real world' performance is so good!
If you'd like to ask Reed anything about his 'Monster', here's his E-mail linkReed's mail
The ports were welded up a lot, including the seat I.D.s. The intention was to have the seat I.D. optimized (smaller than stock) with the appropriate seat O.D. Just a little larger than the valve O.D.
The heads flowed very well (particularly, the exhaust ports) and that would be the key to higher RPM, which is the key to higher HP.
I chose to use stock cams because the race cams available, have a lot of over-lap which requires sinking the valves, to keep them from hitting each other. Improving the low lift flow effectively increased the over-lap without increasing the combustion chamber volume.
Sinking the valves increases the chamber volume and lowers the compression ratio, requiring higher domed pistons. This can hurt the combustion efficiency.
I had looked at using some aftermarket 'street' cams which have huge lift, but my testing experience told me that the ports don't flow well, much above stock lift.
That can be fixed by, among other things, unshrouding the combustion chamber side of the valve, but that lowers the compression ratio.
Also, the exhaust duration of these is less than the stock cams, (I think that increased exhaust duration is necessary for higher RPM operation) with much more lift, which I don't feel is necessary on the exhaust.
Our first test of the bike proved to be disappointing.
The surprise was that the Peak HP RPM didn't increase (essentially). In fact, most of the power we'd eventually extract from that combination, was there already.
I had expected that port flow improvements on the order of what we had achieved, would increase the RPM capability significantly.
Over the summer we made several improvements until the bike was making a smooth 83 HP across the top of the power band.
Still no significant RPM increases, but the performance was quite good.
I was still disappointed that we couldn't get the RPM out of the thing, was it cams? pipes? I couldn't ask any of my customers to spring for expensive hardware, and the labor to install and test it, without having some idea that it would gain anything.
Finally, Gary Johnson couldn't stand it any longer ( I couldn't give my blessing) and bought the Termignoni 'spaghetti' system. I just couldn't say whether that would help, and certainly, couldn't guarantee any results. The 'spaghetti' system is supposed to help the way upper RPM ranges, but that doesn't include 7500 RPM.
Testing showed that my skepticism was well founded.
At the end of the season, a local Ducati racer wanted to test his stock carbs vs separate Keihins. With 12:1 pistons, stock ports and no tuning it made about 79 HP at 7000 RPM with stock carbs.
The change to short manifolds increased the RPM and power to 87 HP at 8200 RPM. Still not very impressive, but it showed the way.
Reed and myself said 'those carbs have to stay here for a couple days'.
The next day we tried to put the Keihins on the Monster, but one of the frame cross-members was in the way. Reed grabbed the cut-off wheel and they were installed in short order. (He was going to have the frame re-powder coated anyway, and he would replace the cross-member with another one at a different location.)( He is brave, but neither of us is fool-hardy.)
The results were what we had looked for in the beginning. The RPM was limited by the stock inlet length.
Over the winter season, we increased the displacement to 944cc and Reed bought a pair of Malossi 41mm carbs.
Reed wanted oversized inlet valves this time (he had wanted them the previous year too), but I still felt that with properly proportioned ports they weren't necessary. One supplier's valve prices were hidieously expensive, and another was out of the 44mms, I tried until it was time to assemble and it went together with the stock inlet valves.
So, good ports, high compression and stock cams, give huge torque and power figures within a few horses of the best BEARS racers, and at 1500 to 2000 RPM lower than the racers. Plus, the engine is still a 'street-bike' in every way except throttle pull. Reed wants to give up and get Kiehins because of the improved throttle pull, and I can't dis-agree. They are better mechanically, and we'll make them better from a fuel delivery stand-point by converting them to emulsion type by using ZX7R emulsion tubes. Then they'll be superior instruments.