Wheelman-111 wrote:Greetings:
So Flash II's now running with a high-compression Malossi 47mm/65cc - installed sans gaskets thanks to ScooterWerx's skillful O-Ringing. Also plugged in my own version of Werx's design of SE/SA reed port adaptor, permitting me to install Toasty's tasty CT manifold, which in turn opened up the possibility of the VE24 Constant Velocity carb from the GY-6 150. All this pushing out through the LV exhhaust, and running RPMs in the 8000+ range. Aye, verily there's the rub.
Honda-san didn't anticipate this prodigious power output when his engineers penned the Aero's Spree-based forced-air cooling system. Colder plugs help a little, surely. I've been steadily upjetting the CV carb upwards and beyond the 110 size, but still flirting with 400 degrees F. and the Dreaded Meltdown at WOT for more than a half-minute or so. The 112.5 and 115 jets are in my pocket, but I anticipate that this over-rich mixture will soon approach plug-fouling proportions, and another dead end.
First of all, go with a DIO. Parts and performance potential are plentiful for the AF16E, the conversion is painless.
Choosing plug heat range is determined by the average (mean) range of temperatures your bore (and thus head) will be operating nominally. Some of this will be affected by the ambient temperature of your riding climate as well (a colder/frozen climate will definitely use a plug range much hotter than one from a temperate area). The spark plug choice for a motor that averages 150-250F will differ from one that operates normally between 350-500F. In my experience about 75% of the bikes I see are using plugs of an incorrect range. Colder does not mean better if you don't know what's going on inside the motor. In fact using the wrong heat range of plug will guarantee that your plug chop readings will be incorrect all the time (this is why I despise using plug chops in favor of reading the mixture ring).
Do any of the aftermarket fans truly provide tangible cooling benefits? Remember daytime temps here in Deepinnaharta, Texas have been over the Century mark several times already, and it's only June. I'm not prepared to liquid-cool this thing, as if such a kit were even available for Vintage 1987 AF05E blocks. I have read about some cooling fans with a predilection for self-destruction. Any Aftermarket brands recommended or to avoid? Do the higher-output fans produce enough additional drag inertia to self-cancel any benefits?? Otherwise, anyone know of an NGK BPR10 plug??
Aftermarket fans are junk. If you intend on spinning over 8k rpms, the stock fan will always be the best. Those whistle fans (KOSO) are simply going to blow up, ask the Hawaii guys and they'll tell you from first hand experience. When we used to build drag air cooled bikes, the stock Honda fan was more than sufficient. We even went as far as to shave down some of the fins to reduce drag further and the temps were always in control. I don't recommend altering the fan for a street driven bike as the tuning approach we use for race is completely different from the approach we use for bikes for the street. An AF05E, even radically modded will never see any benefit from altering the fan, it simply doesn't "hit the performance benefit wall" to justify that mod. A Yamaha Jog (or copy) will always outrev a DIO engine without any modding. A Jog benefits incredibly from reducing drag related to the fan because they can spin 15k all day without blowing up, unlike a DIO which tops out around 11-13k depending on the state of tune.
Temperature control on a bike (like everything else) is about total balance. A lot of folks are under the impression that it takes a lot of heat to seize the engine. Your engine can seize at 100F if you don't know what you're doing. I've built bikes that operates at 400F at part throttle all the way up to 650F at full wide open without seizing riding the bike all day, everyday, for several hours a day (although the belt takes a pounding). I've seen engines that seized with 15:1 oil ratios as well.
The "basic" tuning formula is this, how well you execute it depends on a combination of parts availability and your experience.
- Determine what kind of riding is going to be done.
- Determine the way the rider intends on riding the bike (part throttle, wide open, spirited, etc.)
- Choose a bore and pipe combination that compliments that style of riding.
- Tune the carb and trans to the pipe being used.
- Install CHT gauge and have the rider take the bike around for a spin, noting operating temperature range.
- Put at least 300 miles on the engine before taking a plug reading, noting mixture ring.
- If the mixture ring is good but the plugs shows rich, go 1 step hotter on the plug range.
- If the rider plans on riding for long periods between 1/8 to 1/4 throttle with some 1/2 thottle periods, go 1 up on the pilot jet.
- Based on the average riding temp of the engine, now choose the best oil combo for that purpose. Always start with 32:1 (4 oz per gallon) and rejet if necessary. There's no such thing as an oil that's ideal for 200F temp avg riding all the way to 600F peak temps. Don't change the plug heat range as you've already determined that earlier.
Good luck with your project WM.
Reliable and dependable tuning from 15+ years of experience.
