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Should leave it alone, but


AP996

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22 hours ago, Joaoduarte said:

Also can you tell me the lenght of your new velocity stacks? And the older ones that you used lenght?

The previous inlets were about 89mm from the throttle body to the end of the bell mouth, so the new ones are less than half that at 40mm.

I saw this picture of a Spanish mt07 race bike for sale that appeared to have very short velocity stacks as well.

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On 2/9/2023 at 12:44 AM, Joaoduarte said:

Damm without filter eheh risky or not

On the street i definitely wouldn’t but if I was racing and I thought removing the air filter might gain me 6 inches on the straight then the filter would be in the spares box.

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M. Hausknecht
On 2/8/2023 at 7:44 PM, Joaoduarte said:

Damm without filter eheh risky or not? What do you think? 

I've road raced motorcycles for over 10 years, most without running an air cleaner or filter. With at least annual motor teardowns, a little extra wear on the rings, pistons, and valve seats doesn't matter to me. Except when required by the rules, I'd say air filters are used on race bikes fairly rarely.

Edited by M. Hausknecht
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32 minutes ago, Joaoduarte said:

@AP996 iam about to buy the ramair filter that you are using but ive a doubt how do you atttach the filter to your setup? It doesnt have the risk of falling? 

I just pull it over the bellmouths/velocity stacks and that's it, i haven't ever had it come off on it's own yet.

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  • 4 weeks later...
On 2/15/2023 at 3:17 PM, AP996 said:

I just pull it over the bellmouths/velocity stacks and that's it, i haven't ever had it come off on it's own yet.

@AP996AP996 thanks a lot for your help, UK should have stayed in EU, got a month for the Ramairfilters to arrive in Portugal eheh. Finnaly finished the project now I start to think on more something eheh. Do you think that the bored throttle bodies would be OK in a stock engine.

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8 hours ago, Joaoduarte said:

Do you think that the bored throttle bodies would be OK in a stock engine

Probably not worth doing on a stock engine judging by the result that @T1oas got when he tried it.

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On 3/11/2023 at 6:40 PM, AP996 said:

Probably not worth doing on a stock engine judging by the result that @T1oas got when he tried it.

 I’d definitely agree @AP996 not worth doing.

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  • 1 month later...

Update on the short velocity stacks, not had chance to get back on the dyno yet so just going by seat of the pants feel I’d say it feels pretty good, I’ve not noticed too much difference at lower revs, still pulls strong and no flat spots etc. I think there’s an improvement at high revs, where before power plateaued from 9000 to 10000 I think it now continues to make a little more, of course this could just be an illusion and the dyno will eventually prove otherwise, but for the moment the short intakes are staying.

I lent the bike to a good friend who had recently test ridden the new Honda 750 Hornet, he thought that my mt07 was faster with better mid range as well which was encouraging.

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M. Hausknecht

The dyno will reveal all. Or will you have an opportunity to compare lap times, or gears and revs at particular spots on a track (before and after)? I've never been able to trust my butt dyno. 

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11 hours ago, M. Hausknecht said:

I've never been able to trust my butt dyno.

I wouldn’t call mine a precision instrument either so I could likely be way out with how it feels.

Hopefully I’ll get a chance to get it on the dyno again in the next few weeks.

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  • 4 months later...

This has me all excited. Iv done a fair amount of port work myself in the past and would be curious to attempt it on this motor. 

Wonder if port and ECU flash would be good, or if it would force my hand at learning how to adjust timing.

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10 hours ago, Paulb5950 said:

This has me all excited. Iv done a fair amount of port work myself in the past and would be curious to attempt it on this motor. 

Wonder if port and ECU flash would be good, or if it would force my hand at learning how to adjust timing.

Think of the airbox/intake filter(s), throttle bodies, intake ports, and camshafts as a single system. Together, they determine the shape and rpm range of the motor's useful powerband. The exhaust ports and exhaust system play a roll as well, but their effect is much less than the stuff on the intake side of things. As built by Yamaha, the CP2 motor has a very broad, flat powerband that essentially disappears above about 8800rpm. The intake tract is very long, and the camshafts don't have much overlap. For optimum fill, the intake ports are already too big in places even with higher lift and longer duration camshafts. For this reason, the best flowing CP2 heads used in racing feature both epoxy fill in spots and some mild shape changing in other areas. The "devil is in the details". I could suggest more to you if you state your goals, but I wouldn't bother messing with the ports on a CP2 with stock cams and throttle bodies. You could pretty easily lose lower end power and gain little elsewhere. 

 

 

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14 hours ago, Paulb5950 said:

This has me all excited. Iv done a fair amount of port work myself in the past and would be curious to attempt it on this motor. 

Wonder if port and ECU flash would be good, or if it would force my hand at learning how to adjust timing.

From my experience with this motor I’d say that your best option would be a hordpower intake or similar and some reground cams with an ECU re flash to suit, the engine really comes alive and with the extra 1000 to 1500 usable rpm it’s whole load more fun.

If your on a tight budget, just do the intake cam, half the cost of the pair and less work as you won’t need to grind down the decompressor pins.

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  • 1 month later...

Fitted some Gilles rear sets a few days ago, really happy with them but they made the Mivv exhaust pipe work look even lower, never been that happy with the look of it so I cut it and had a 9 degree pie cut welded in.

Pretty happy with the improvement, looks much more tucked in.

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Had my bike back on a dyno today, with the short velocity stacks peak power had increased to 83.66 hp, just over 2hp better than the last time back in December when it made 81.49 hp. As expected the increase is all at the top above 8500 rpm with a corresponding small decrease below.

The longer inlet runners are definitely better for a road bike but shorter ones may benefit a race bike on tracks with long straights.

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M, Hausknecht

What are your thoughts about the AFR data? Accurate? Did you remap the fuel tables for the shorter intakes? Assuming what we're seeing is from a full throttle run on pump gas, you're way too rich from 2000-3800rpm, and then too lean 4300-5200rpm, then too rich thereafter. You won't hurt the motor running that rich above 5200  but you're giving up at least a few HP.

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Yes I guessed the afr trace would get some reaction, the thin green line is actually the map I’ve been running, still doesn’t look particularly good though. The last time i had it on a dyno at another place in December, the guy running it was adamant that I was running at least 10% too lean, although l was pretty sure he was wrong and ignored this whilst mapping the individual cylinders at WOT during the summer, I decided before taking it on the dyno for just a power run at this other place that I would play safe and add an extra 5% fuel from 4000 rpm, as you can see it was well rich and luckily the guy running the dyno was good enough to let me quickly swap back to my normal map and run again, unfortunately the rich map is the predominant one in red on the print out.

The rich running between 2000 and 3800 is there on my logs but that’s pretty much the same as the stock mapping and I’m not sure if that’s affected by any accelerator pump type function in the ecu when snapping to a wide open throttle, to be honest I’ve not taken too much time adjusting any thing much below 4000 rpm.

The 4300 - 5200 rpm and 8000 - 9000 lean running is something I will check but I have noticed before that I sometimes see a marked difference between the afr I see when running on the road and the afr running on the dyno in relatively still air.

 

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M, Hausknecht

I don't have a Yamaha ECU but instead an aRacer Super 2 with data logging. Among other things It has an adjustable "accelerator pump" function that briefly enrichens the mixture when there is a sudden opening of the throttle, and I assume the Yamaha ECU does as well. I've tuned that particular function manually after reviewing on-track AFR data, to get good throttle response and, ideally, to reach the target AFR as promptly as possible (minimizing the bouncing of the AFR between too lean and too rich).

I've noted "tuners" with differing perspectives on target AFRs. Running on the lean side of things (13.1-13.2 with pump gas with a stoichometric ratio of 14.7:1) will often generate the most power under heavy load but it also creates a lot of heat in the piston crowns and the motor more generally. A little richer, around 12.8:1, is cooler and safer, while generating almost as much power. Some tuners take that a bit too far in my opinion, however, and will target 12.5-12.6:1 for full throttle under heavy load. It is safe and can be prudent when you're also pushing the ignition advance a bit while experimenting (or with a modified air-cooled motor that otherwise suffers from heat-sag), but its too rich for best safe power.

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I checked and the Yamaha ecu does have a accelerator enrichment function, however this is turned off in the higher gears and would have had no part in the rich afr reading at low revs, as I have never before logged the afr at 100% throttle at 2- 3000 rpm I had no idea it was so rich, I always do my logs at WOT in 3rd - 5th gears and don’t like to lug the motor so usually crack the throttle from about 4000 rpm.

I’ve checked my own logs of the green line run and it pretty much match’s the printed one, my sensor was in the usual place and the dyno one was in one of the spare boss in one of the header pipes so only reading one cylinder.

My logs from the summer don’t show the lean and rich conditions at higher revs either. I tend to target 13/1 as I feel it’s little safer than 13.2.

This is one of my logs from the summer.

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  • 2 months later...

Picked up a Hel braided brake line kit for £50 on EBay awhile back (lists at £279 on manufacturer website), looked like the seller bought it took a look at the job and decided not to bother!
Thought if I was going to fit it I might as well upgrade to a R6 16mm master cylinder as well, that wasn’t as good an EBay purchase as the one I bought turned out to have leaking seals and a new pattern lever that was so poorly made that it would have been lethal, however pushing on with an All Balls rebuild kit, a proper Yamaha lever, a custom brake line from the master cylinder to ABS unit and some Motul 660 fluid it all came together.

Used a new Ducati rear reservoir I had laying around with a small Rizoma bracket to try and make it as neat as I could.

Looking forward to up rated brakes when the weather improves.

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