Questions about jets and excess oil...

LOUD MOUSE · Post by **LOUD MOUSE** » Sat Apr 02, 2011 4:12 pm

These engines were not designed to have the carbs go Wide Open "full to the top" instantly.
That said ya can roll the throttle smoothly to wide open and as ya do ya can/will feel the engine gain RPM and feel the power.
I'd say that if ya install the 135 and 42 and use the CB77 needle with the clip at 2 from the bottom then adjust from there ya MAY have a good runnimg engine. ..........lm

MBellRacing wrote:Hmmmm... Well that is confusing then. Here's essentially what I'm feeling:

Imagine first that the bike is idling in the garage. If I slowly crack the trottle it jumps up in RPM happily and very quickly. If I snap on full throttle quickly, it sputters and even chokes to death. I got this with every single jet I've tried (110, 120, 125, 130, 140, 145). Yesterday I rode on the 145 main and it was best it's been. Whenever I hit a hill and eased it into WOT the bike would be very unresponsive to the change, as if I had left the trottl only 1/2-3/4 open. At the crest of the hill, where I'd close it a bit, the bike would lunge forward again with more power and sort of "skip" like you hear a 2-stroke do.

Since the best change was up to the 145 I figured progression was the best change, obviously wrong!

The engine has Wiseco pistons (stock size), no filter, stock intake hoses, stock pipes with no baffles, stock carbs (with the exception of the ClassicHondaRestorations.com needles which I'll replace with the original ones again).

I'll read through Vince's thread today and see what's in there! Thanks!

MBellRacing · Post by **MBellRacing** » Sat Apr 02, 2011 10:45 pm

Okay, so here's the happe-haps...

It runs MUCH better with the needle moved up and 140 (best I can do for now) jets. HUGE improvement. It still has that shuddering if I WOT too quickly, but I can really feed it in and FEEL it. It pulls straight up to 80mph, when the clutch isn't slipping. That's a new issue and the next one to be addressed. I'm very happy with it so far and will be trying the 135 jets once I get my hands on them. Thanks so much for the help!

Excuse the hooliganism, but I unwisely let my brother ride it around the parking lot. As you can hear, it accelerates very well and sounds smooth.

http://www.youtube.com/watch?v=p38j1-eCOEg

jensen · Post by **jensen** » Sun Apr 03, 2011 2:00 am

Hi,

Were was the needle when you started ?

Jensen

MBellRacing · Post by **MBellRacing** » Sun Apr 03, 2011 2:26 am

The opposite, second from the top. I dropped it two notches.... I think?

jensen · Post by **jensen** » Sun Apr 03, 2011 5:52 am

Hi,

How many notches are there on your needle ?
And what did actually fix the problem ?

The first time I rode a direct slide carb, I had the same experience.
Like LM says, it's not a CV carb which filters out sudden movement of the throttle.

With the CB400F I experienced the phenomenon again, thinking it would be a lot smoother then a twin, but not, it won't rev when opening the throttle quickly. In the beginning I didn't like the behavior, but I got used to it.

When I ride my XRV750 (modern CV carbs), after driving the classics, I act if it is a direct slide carb, resulting in very smooth and well controlled, but slow, acceleration.

A modern two stroke is behaving the same as a CB72 bike, but does have the same effect on a quick throttle hand.

I do have a KR1-s' 89, I don't think the model was sold in the US, but it has 62 Hp out of a 250 cc twin engine, and weights only 150 kg, and that is with fluids.

It has flat slide carbs, and when you drive this one, you learn to open the throttle slowly, for different reasons, that is. The only issue with the bike is that is has many problems with keeping in one piece.

Jensen

MBellRacing · Post by **MBellRacing** » Sun Apr 03, 2011 11:45 am

That thing looks awesome! I WISH we got bikes like that! One of my other favorite bikes was the RD400. Again, the US got the heavily-restricted version that made quite a bit less horsepower and torque.

The more I think about it, the more I think my needle has 5 notches. I was 2nd from the top, now 2nd from the bottom.

jensen · Post by **jensen** » Sun Apr 03, 2011 12:45 pm

Hi,

I had a RD350, a RZ in the US, and drove to school every day,
nice bike but very sensitive to weather. I did 75.000 km with it before I sold it.

The pictures shows what happens when not jetting for wintertime.

Jensen