October 27, 2016 at 7:45 am #73552
So I’ve contemplated building a B stock someday maybe next year or so depending on my living situation. My issue is I’m 5’7″ 125lb fully grown adult (lol) and making 465lb with the IAME motors is going to be pretty much impossible for me or unsafe amount of ballast.
My question is, if I run the class but with Yamaha engines instead, weighing I think 390, would that be sort of competitive still? do anyone run Yamahas in b stock?
I struggle to make weight in sprint class, carrying 80lbs of ballast lol.
And input greatly appreciated 🙂
NHKA member, yamaha pipe srOctober 27, 2016 at 10:25 am #73562
Mark J SchoonoverParticipant
Yamaha & Piston Port engines: 395 lbs., 100cc Controlled: 465lbs.October 28, 2016 at 8:57 am #73579
2 Yamaha’s make only a little more HP than 1 Reedjet. Might work with a pair of Comer P51’s but kind of iffy. The new X30 laydown class might be a better choice. Almost as fast as a B-Stock. Weight is 410#. The CKI that Lindsey Read drove at Daytona last year weighs about 230#. Add your 125# plus gear & your getting close. Alum fuel tanks will add some. Pretty easy to get to 410#. BTW Lindsey weighs about the same as you & ran with 5# of lead to make 385# to run F125October 29, 2016 at 5:22 pm #73615
okay thanks, yeah i knew the controlled engines were a lot more powerful, but i didnt realise it was that much! yeah and thanks for the suggestion. I’m born naturally as a yamaha guy, grew up with them for 10 years, so the rotax laydown doesnt appeal to me as much, but still a nice comment. yeah i don’t have nearly the budget for f125 , or any knowledge on how they work, performance tuning wise. If that’s where the top laydown classes steer towards within the next decade, i might jump in later on. but the oldschool aircooled was always the appeal to me :). yeah i guess i will spend the next couple years scrounging for a pair of Pirellas or soemthing, thanks again for the advice Mike
NHKA member, yamaha pipe srOctober 30, 2016 at 8:09 am #73621
It’s not a Rotax, but it is water cooled. The X30 is an IAME/Parilla. Initial cost is a bit more but maint is less. I agree air cooled is a lot less hassle. Ran a pair of Atlas reed valves on my GPX200 back 30 years ago.November 1, 2016 at 8:13 pm #73701
Oh okay. Yes I remember now, reading about it awhile back. yeah it comes down to having (one) axle clutch already, quite a few kt100s, all the belt drivers and stuff so i think i’ll just stick with the 2-cycle stuff for now. it’s all still just planning 2-3 years down the line. yeah it really comes down to what i have for spares, if i switched to the watercooled stuff, it would be quite the investment just getting spares of everything.
thank you for the advice in any case.
NHKA member, yamaha pipe srNovember 4, 2016 at 10:34 am #73814
If you really want to go the Piston Port route under the current rules, I’d look at a pair of K71’s (AKA KPV, HPV).
Better quality than a Yamaha KT100. Not much more expensive to rebuild. Still uses a Walbro WB3a so tuning is similar. Each motor is about 5 pounds heavier than a Yamaha. And 3-5 more HP each.
Under current engine rules the K71 is very close to a Comer P51.
Since the TaG 125’s came in, there are a lot of K71’s available used. I bought 4 for under a grand.
JohnNovember 4, 2016 at 11:22 pm #73832
oh wow, thanks john. Yeah i’ve never run a reedjet before so I’d imagine they are a bit more expensive to rebuild.
Yeah i have seen the Komet’s around and yes we use the WB3a carbs as well so that will be nice.
The main problem I’d face is the fact that I’d need about 150lbs of ballast to make weight with a reed pair, which would be very terrible to balance, and wouldbe even worse news if i got in a crash. I’m not going for competitiveness, but I think with the lower weight and the Komet set up that might work. Like I said it’s kind of a crappy excuse but since i’m so short yeah it’s very challenging to make 360 for my sprint class, let alone 465 for the reedjet B stock lol.
Thanks for the suggestions John!
NHKA member, yamaha pipe sr
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