On the 72 R5 i am sort of intentionally 'doing it wrong' as far as carburation. I put a set of stock RD350 ('a' i think) carbs on, with the 08 jet tube and 5IE(?) stock needle. No dave f mod, no air jet mods. wanted to see if i could get it to jet ok with a k&N and y boot, fpps and stock porting on repop cyls.
Yes, i had pwks on it but wantd to see
so, after playing with it on and off here and there, i was trying to tune out the sort of weak spot in the throttle, was only at certain rpms. i man, anything over 6k and its a rocket. (it does have a zeel, mzb cdi and v force reeds)
this has stock r5 heads on the kveldwulf cyls, and a crossover intake, with an rz crossover tube. (i just had it laying around).
Jetting landed at 270 mains, needle ont eh 5th (richest) postition, 27,5 pilot and 1.75 out on the air screw.
(ign curve isnt anything exciting. just starts at 18, jumps to 23 degrees at 2200-5k, then at 7k its at 19. then tapers down from there with it at 17 at 10k and the rev limiter at 10.5 ) it pulls from down low up just fine.
the issue was a quick rap on the throttle at 4500 or so it 'gulped'. I was at 4th clip but decided to move to 5th and boom. cleared it up. its been like that for a few mos and was fine and rideable but def got better pretty much everywhere over 1/2 throttle on 5th.
Yes, i have better carbs, heads, etc available but wanted to do it this way. sort of nostalgic to the 90s pre dave f/dale a mod became the norm.
Point being, there are 5 clips. done be afraid to use them if your motor tells you it needs to be there. (we all know it can be a mental block).
heres a plug after about a 3/4 mile pull 4th gear 1/2 to 3/4 throttle. motor was fully warm.
very helpful info. thanks for sharing :thumbs:
Righteous :celebrate:
That's exactly how I set my needle clips, with the snap of the throttle. It's more noticeable when it is not warmed up. Start engine, choke off, warm up about 30 seconds, start riding. If it gasps (falls on its face) when you quickly turn the throttle to about 1/2, too lean. I'm not letting it rev it up, just checking how it reacts. And then if it is too rich it will take longer to accelerate and not feel crisp, when you roll on the throttle at speed. That's a little trickier to feel. :thumbs:
My experience is it also need to be done under load at full temp. but i do do that in the shop as a preliminary and it gets it really close. the other 'in shop' method i use is for the pilot, and thats open throttle just over idle, hold it, see if it climbs or falls. falls: rich. Holds: close. Rises, lean.
Are you also doing actual plug chops or just looking at the top of the insulator? You're getting into the weeds technically on the carb setup, but then only offer a very general indicator as proof of results.
I carry a jewelers loupe and a flashlight to see the bottom of the base of the insulator. that's what matters but kinda hard to pick up on a cell phone camera. 😉
I had one of my buddy's bike at position 5 but decided to bring it up a notch to get out of that heavy rich spot. Especially with a 35 pilot jet.